WorldWideScience

Sample records for large pelagic fishes

  1. Large Pelagics Intercept Survey

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Large Pelagics Intercept Survey (LPIS) is a dockside survey of private and charterboat captains who have just completed fishing trips directed at large pelagic...

  2. Large Pelagics Telephone Survey

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Large Pelagics Telephone Survey (LPTS) collects fishing effort information directly from captains holding Highly Migratory Species (HMS) permits (required by...

  3. Deepwater Horizon crude oil impacts the developing hearts of large predatory pelagic fish.

    Science.gov (United States)

    Incardona, John P; Gardner, Luke D; Linbo, Tiffany L; Brown, Tanya L; Esbaugh, Andrew J; Mager, Edward M; Stieglitz, John D; French, Barbara L; Labenia, Jana S; Laetz, Cathy A; Tagal, Mark; Sloan, Catherine A; Elizur, Abigail; Benetti, Daniel D; Grosell, Martin; Block, Barbara A; Scholz, Nathaniel L

    2014-04-15

    The Deepwater Horizon disaster released more than 636 million L of crude oil into the northern Gulf of Mexico. The spill oiled upper surface water spawning habitats for many commercially and ecologically important pelagic fish species. Consequently, the developing spawn (embryos and larvae) of tunas, swordfish, and other large predators were potentially exposed to crude oil-derived polycyclic aromatic hydrocarbons (PAHs). Fish embryos are generally very sensitive to PAH-induced cardiotoxicity, and adverse changes in heart physiology and morphology can cause both acute and delayed mortality. Cardiac function is particularly important for fast-swimming pelagic predators with high aerobic demand. Offspring for these species develop rapidly at relatively high temperatures, and their vulnerability to crude oil toxicity is unknown. We assessed the impacts of field-collected Deepwater Horizon (MC252) oil samples on embryos of three pelagic fish: bluefin tuna, yellowfin tuna, and an amberjack. We show that environmentally realistic exposures (1-15 µg/L total PAH) cause specific dose-dependent defects in cardiac function in all three species, with circulatory disruption culminating in pericardial edema and other secondary malformations. Each species displayed an irregular atrial arrhythmia following oil exposure, indicating a highly conserved response to oil toxicity. A considerable portion of Gulf water samples collected during the spill had PAH concentrations exceeding toxicity thresholds observed here, indicating the potential for losses of pelagic fish larvae. Vulnerability assessments in other ocean habitats, including the Arctic, should focus on the developing heart of resident fish species as an exceptionally sensitive and consistent indicator of crude oil impacts.

  4. Large Pelagics Biological Survey

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Large Pelagics Biological Survey (LPBS) collects additional length and weight information and body parts such as otoliths, caudal vertebrae, dorsal spines, and...

  5. Fisheries conservation on the high seas: linking conservation physiology and fisheries ecology for the management of large pelagic fishes.

    Science.gov (United States)

    Horodysky, Andrij Z; Cooke, Steven J; Graves, John E; Brill, Richard W

    2016-01-01

    Populations of tunas, billfishes and pelagic sharks are fished at or over capacity in many regions of the world. They are captured by directed commercial and recreational fisheries (the latter of which often promote catch and release) or as incidental catch or bycatch in commercial fisheries. Population assessments of pelagic fishes typically incorporate catch-per-unit-effort time-series data from commercial and recreational fisheries; however, there have been notable changes in target species, areas fished and depth-specific gear deployments over the years that may have affected catchability. Some regional fisheries management organizations take into account the effects of time- and area-specific changes in the behaviours of fish and fishers, as well as fishing gear, to standardize catch-per-unit-effort indices and refine population estimates. However, estimates of changes in stock size over time may be very sensitive to underlying assumptions of the effects of oceanographic conditions and prey distribution on the horizontal and vertical movement patterns and distribution of pelagic fishes. Effective management and successful conservation of pelagic fishes requires a mechanistic understanding of their physiological and behavioural responses to environmental variability, potential for interaction with commercial and recreational fishing gear, and the capture process. The interdisciplinary field of conservation physiology can provide insights into pelagic fish demography and ecology (including environmental relationships and interspecific interactions) by uniting the complementary expertise and skills of fish physiologists and fisheries scientists. The iterative testing by one discipline of hypotheses generated by the other can span the fundamental-applied science continuum, leading to the development of robust insights supporting informed management. The resulting species-specific understanding of physiological abilities and tolerances can help to improve stock

  6. Trailing edges projected to move faster than leading edges for large pelagic fish habitats under climate change

    Science.gov (United States)

    Robinson, L. M.; Hobday, A. J.; Possingham, H. P.; Richardson, A. J.

    2015-03-01

    There is mounting evidence to suggest that many species are shifting their ranges in concordance with the climate velocity of their preferred environmental conditions/habitat. While accelerated rates in species' range shifts have been noted in areas of intense warming, due to climate change, few studies have considered the influence that both spatial temperature gradients and rates of warming (i.e., the two components of climate velocity) could have on rates of movement in species habitats. We compared projected shifts in the core habitat of nine large pelagic fish species (five tuna, two billfish and two shark species) off the east coast of Australia at different spatial points (centre, leading and trailing edges of the core habitat), during different seasons (summer and winter), in the near-(2030) and long-term (2070), using independent species distribution models and habitat suitability models. Model projections incorporated depth integrated temperature data from 11 climate models with a focus on the IPCC SRES A2 general emission scenario. Projections showed a number of consistent patterns: southern (poleward) shifts in all species' core habitats; trailing edges shifted faster than leading edges; shifts were faster by 2070 than 2030; and there was little difference in shifts among species and between seasons. Averaging across all species and climate models, rates of habitat shifts for 2030 were 45-60 km decade-1 at the trailing edge, 40-45 km decade-1 at the centre, and 20-30 km decade-1 at the leading edge. Habitat shifts for 2070 were 60-70 km decade-1 at the trailing edge, 50-55 km decade-1 at the centre, and 30-40 km decade-1 at the leading edge. It is often assumed that the leading edge of a species range will shift faster than the trailing edge, but there are few projections or observations in large pelagic fish to validate this assumption. We found that projected shifts at the trailing edge were greater than at the centre and leading of core habitats in

  7. Diet of three large pelagic fishes associated with drifting fish aggregating devices (DFADs in the western equatorial Indian Ocean

    Directory of Open Access Journals (Sweden)

    Malone, M. A.

    2011-12-01

    Full Text Available Several species of fish, aggregate around DFADs in marine tropical waters. We captured three predatory species: yellow fin tuna (Thunnus albacares, wahoo (Acanthocybium solandri and dolphinfish (Coryphaena hippurus from aggregations under DFADs in the Western Indian Ocean to characterize their diet and determine whether they fed on other DFAD associated organisms. Yellowfin tuna did not feed on DFAD–associated prey, while wahoo and dolphinfish did exploit resources aggregated by the DFADs, though they predominantly fed on other non–associated organisms. Opportunistic feeding on surface swarming stomatopod crustaceans was observed in yellowfin tuna and dolphinfish associated with FADs, but was not observed in wahoo.

  8. Energy density of marine pelagic fish eggs

    DEFF Research Database (Denmark)

    Riis-Vestergaard, J.

    2002-01-01

    Analysis of the literature on pelagic fish eggs enabled generalizations to be made of their energy densities, because the property of being buoyant in sea water appears to constrain the proximate composition of the eggs and thus to minimize interspecific variation. An energy density of 1.34 J mul...

  9. Energy density of marine pelagic fish eggs

    DEFF Research Database (Denmark)

    Riis-Vestergaard, J.

    2002-01-01

    Analysis of the literature on pelagic fish eggs enabled generalizations to be made of their energy densities, because the property of being buoyant in sea water appears to constrain the proximate composition of the eggs and thus to minimize interspecific variation. An energy density of 1.34 J mul......(-1) of total egg volume is derived for most species spawning eggs without visible oil globules. The energy density of eggs with oil globules is predicted by (σ) over cap = 1.34 + 40.61 x (J mul(-1)) where x is the fractional volume of the oil globule. (C) 2002 The Fisheries Society of the British...

  10. Evaluating analytical approaches for estimating pelagic fish biomass using simulated fish communities

    Science.gov (United States)

    Yule, Daniel L.; Adams, Jean V.; Warner, David M.; Hrabik, Thomas R.; Kocovsky, Patrick M.; Weidel, Brian C.; Rudstam, Lars G.; Sullivan, Patrick J.

    2013-01-01

    Pelagic fish assessments often combine large amounts of acoustic-based fish density data and limited midwater trawl information to estimate species-specific biomass density. We compared the accuracy of five apportionment methods for estimating pelagic fish biomass density using simulated communities with known fish numbers that mimic Lakes Superior, Michigan, and Ontario, representing a range of fish community complexities. Across all apportionment methods, the error in the estimated biomass generally declined with increasing effort, but methods that accounted for community composition changes with water column depth performed best. Correlations between trawl catch and the true species composition were highest when more fish were caught, highlighting the benefits of targeted trawling in locations of high fish density. Pelagic fish surveys should incorporate geographic and water column depth stratification in the survey design, use apportionment methods that account for species-specific depth differences, target midwater trawling effort in areas of high fish density, and include at least 15 midwater trawls. With relatively basic biological information, simulations of fish communities and sampling programs can optimize effort allocation and reduce error in biomass estimates.

  11. Abundance and tidal behaviour of pelagic fish in the gateway to the Wadden Sea

    Science.gov (United States)

    Couperus, Bram; Gastauer, Sven; Fässler, Sascha M. M.; Tulp, Ingrid; van der Veer, Henk W.; Poos, Jan Jaap

    2016-03-01

    The shallow coast of The Netherlands is an important habitat for small pelagic fish. They form one of the major links between plankton and the higher trophic levels. Predatory fish, sea mammals and birds rely on small pelagic fish as a major food source. Currently, monitoring of fish in the Dutch coastal zone mainly focuses on demersal species, using bottom trawls and fykes. Four hydro-acoustic surveys were carried out in May and October 2010/2011 in the Marsdiep area, a relatively deep tidal inlet in the western Wadden Sea, to quantify abundances of pelagic fish. The aims of this study were to (1) describe temporal and vertical variations in fish distribution and school dimensions in relation to tide, and (2) estimate biomass of pelagic fish and their proportion to total fish biomass. The biomass of pelagic fish in the Marsdiep area ranged between 23 and 411 kg/ha. These were mainly sprat, but also young herring, anchovy and pilchard. The fish was scattered in small schools with volumes smaller than 5m3 and concentrated in the top 10 m below the surface. There was a clear effect of tidal cycle on school volume and fish abundance, with larger densities and larger schools at high tide compared to low tide. In May, sandeel contributed substantially to the pelagic assemblage, whereas in October sandeel was absent in the trawl catches, most likely because they stayed buried in the seabed from late summer to spring. The presence of pilchard and anchovy confirmed their re-establishment in the Southern North Sea and Wadden Sea. The abundance of pelagic fish exceeded the biomass of demersal fish in the western Wadden Sea by an order of magnitude. This finding is relevant for ecosystem studies. The fact that this study suggests that small pelagics outnumber demersal species to such a large extent calls for a rethinking of the allocation of monitoring effort in the Dutch coastal zone.

  12. Large Pelagic Carcass Weights (Vessels)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Swordfish have been a commercially caught species since the early 1800s. During this early stage of the fishery, harpoon was the principal gear and the fishing was...

  13. Comparative analysis of depth distribution for seventeen large pelagic fish species captured in a longline fishery in the central-eastern Pacific Ocean

    Directory of Open Access Journals (Sweden)

    Jiangfeng Zhu

    2012-02-01

    Full Text Available The objective of this study was to estimate depth distribution of pelagic species captured in a longline fishery and to evaluate the difference in depth distribution among species. We estimated depth distribution for 17 frequently captured species based on a Chinese longline fishing trip targeting bigeye tuna (Thunnus obesus in the central-eastern Pacific Ocean in February-November 2006. The depth distributions of 13 bycatch species were significantly different from that of bigeye tuna. Although most of the bycatch species were found to be distributed in water depths shallower than bigeye tuna (i.e. increasing hook depths can decrease catch rates of these species, the rates of catch rates declined with increasing hook depths may be different. The depth distributions were found to be not significantly different between genders for 7 species. There was no significant correlation between fish sizes and capture depths. The information derived from this study can play an important role in reducing bycatch in pelagic tuna longline fisheries in the central-eastern Pacific Ocean.

  14. Recreational fishery catch and effort estimates for large pelagic species from Maine through Virginia from 2002-06-01 to 2014-10-31 (NCEI Accession 0137959)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — On the Atlantic Coast from Maine to Virginia, NOAA Fisheries uses the Large Pelagics Survey (LPS) to measure the total recreational catch of large pelagics fish...

  15. Fishing activity of small pelagic in Albania: 1948-1990

    Directory of Open Access Journals (Sweden)

    ROLAND KRISTO

    2014-03-01

    Full Text Available The small pelagic species are important commercial fishes of the Adriatic Sea. In Albania, the fishing activity of Sardines had a key importance still in 1990, as it represented about 70% of total catch. The main fishing method used was purse seine using light attraction that represented about 80% of total catches of sardines and the rest was mid-water pelagic trawl nets towed by two vessels. Albanian catches of sardines reached a maximum value, in 1982-1985 with value from 5,000 to 6,500 tons and maximum at 1984 with 6,596 tons. In 1990, the Sardine fleet consisted of 60 fishing vessels, from which 28 in Vlora, 12 in Durres, 12 in Shengjin and 8 in Saranda. The number of fishing vessels for bottom trawl fishing was as average 21 and 23 for 1985 and 1989 respectively, with a maximum of 28 fishing vessels. The average of fishing days was about 142 days/year. The production for 1985 was 1899.6 tons and for 1989 was 2324.2 tons. The number of fishing vessels for mid water pelagic pair trawls was as average 17 and 8 for 1985 and 1989 respectively, with a maximum of 27 and 16 fishing vessels. The production for 1985 was 2230.2 tons and for 1989 was 744.6 tons. The number of fishing vessels with purse seines with light attraction was as average 34 and 37 for 1985 and 1989 respectively, with a maximum of 38 and 45 fishing vessels. The average of fishing days was about 137 days/year. The production for 1985 and 1989 was 3319.2 and 2919.8 tons respectively. The number of coastal fishing vessels was as average 13 and 15 for 1985 and 1989 respectively, with a maximum of 14 and 19 fishing vessels. The average of fishing days was about 109 days/year. The production for 1985 and 1989 was 166.7 and 188.9 tons respectively

  16. Spawning ascent durations of pelagic spawning reef fishes

    Institute of Scientific and Technical Information of China (English)

    Caroline A. HABRUN; Gorka SANCHO

    2012-01-01

    Predation risks have been hypothesized to influence spawning behaviors of coral reef fishes that broadcast gametes pelagically.The duration of spawning ascents of 13 species were measured from video footage at a single spawning site for multiple coral reef fishes to investigate if this behavior was influenced by varying risks of predation.Fishes that spawned in pairs had ascents of longer duration than group-spawning species.Duration of spawning ascents did not vary between fishes spawning at daytime and dusk,nor between group-spawning species with specific anti-predatory morphological adaptations.These results indicate that risk of predation may not significantly influence the duration of spawning ascents of pair spawning reef fishes at our study site,while group-spawning behaviors are influenced by predation.Avoidance of egg predation by benthic organisms and female mate choice are more likely to influence the pelagic spawning behaviors of all fishes observed [Current Zoology 58 ( 1 ):95-102,2012].

  17. Status of pelagic prey fishes in Lake Michigan, 2013

    Science.gov (United States)

    Warner, David M.; Farha, Steven A.; O'Brien, Timothy P.; Ogilvie, Lynn; Claramunt, Randall M.; Hanson, Dale

    2014-01-01

    Acoustic surveys were conducted in late summer/early fall during the years 1992-1996 and 2001-2013 to estimate pelagic prey fish biomass in Lake Michigan. Midwater trawling during the surveys as well as target strength provided a measure of species and size composition of the fish community for use in scaling acoustic data and providing species-specific abundance estimates. The 2013 survey consisted of 27 acoustic transects (546 km total) and 31 midwater trawl tows. Mean prey fish biomass was 6.1 kg/ha (relative standard error, RSE = 11%) or 29.6 kilotonnes (kt = 1,000 metric tons), which was similar to the estimate in 2012 (31.1 kt) and 23.5% of the long-term (18 years) mean. The numeric density of the 2013 alewife year class was 6% of the time series average and this year-class contributed 4% of total alewife biomass (5.2 kg/ha, RSE = 12%). Alewife ≥age-1 comprised 96% of alewife biomass. In 2013, alewife comprised 86% of total prey fish biomass, while rainbow smelt and bloater were 4 and 10% of total biomass, respectively. Rainbow smelt biomass in 2013 (0.24 kg/ha, RSE = 17%) was essentially identical to the rainbow smelt biomass in 2012 and was 6% of the long term mean. Bloater biomass in 2013 was 0.6 kg/ha, only half the 2012 biomass, and 6% of the long term mean. Mean density of small bloater in 2013 (29 fish/ha, RSE = 29%) was lower than peak values observed in 2007-2009 and was 23% of the time series mean. In 2013, pelagic prey fish biomass in Lake Michigan was similar to Lake Huron, but pelagic community composition differs in the two lakes, with Lake Huron dominated by bloater.

  18. Fisheries oceanography of northern pelagic fish species

    DEFF Research Database (Denmark)

    Tsoukali, Stavroula

    of the species they consume now and increased availability of new species. In addition, there will likely be economic impacts on the local fishing communities. How species respond to climate change is a field of research that receives great attention because the responses will affect the management of fisheries...... range that maximizes survival among different species, but the sensitivity of egg development rate in a degree of temperature increase is similar among the 32 species and populations I analysed. I also found that adults spawn at temperature conditions that are generally close to the egg preferences...... seasons, at lower latitudes, are able to produce 10 times more eggs during their life time than species than have a limited spawning season. This may reflect the more un-predictable environmental conditions at lower latitudes. People are also familiar with the words "climate change" and "warming...

  19. Trophodynamics and diet overlap of small pelagic fish species in the Bay of Biscay

    KAUST Repository

    Bachiller, E

    2015-08-27

    Small pelagic fish are the link between planktonic production and higher trophic levels. Competition for resources may play a role in the population dynamics of species, some of them probably standing out from the others due to greater feeding success. It is therefore important to understand the trophic niche of species overlapping both spatially and temporally. In this study, we have investigated the diet, prey preference, trophic niche breadth and diet overlap of the 8 major small pelagic species (anchovy, sardine, sprat, Atlantic and Mediterranean horse mackerel, bogue, Atlantic mackerel and Atlantic chub mackerel) inhabiting the Bay of Biscay. Results indicate that all fish feed mainly on calanoid copepods, incorporating larger prey like euphausiids and decapods to complete their diet. Differences in ingested prey diversity seem to be more limited by the available zooplankton at sea than by a specific diet preference by fish species, resulting in an overall high diet overlap, especially within clupeids but also between clupeids and other (larger) predator species. Consumption estimations for different prey groups could therefore determine whether such a large diet overlap between small pelagic fish, together with spatial co-occurrence, results in competition or enhances the effects of intraguild predation, which is important in terms of an ecosystem approach to fisheries management.

  20. Ocean-wide tracking of pelagic sharks reveals extent of overlap with longline fishing hotspots.

    Science.gov (United States)

    Queiroz, Nuno; Humphries, Nicolas E; Mucientes, Gonzalo; Hammerschlag, Neil; Lima, Fernando P; Scales, Kylie L; Miller, Peter I; Sousa, Lara L; Seabra, Rui; Sims, David W

    2016-02-09

    Overfishing is arguably the greatest ecological threat facing the oceans, yet catches of many highly migratory fishes including oceanic sharks remain largely unregulated with poor monitoring and data reporting. Oceanic shark conservation is hampered by basic knowledge gaps about where sharks aggregate across population ranges and precisely where they overlap with fishers. Using satellite tracking data from six shark species across the North Atlantic, we show that pelagic sharks occupy predictable habitat hotspots of high space use. Movement modeling showed sharks preferred habitats characterized by strong sea surface-temperature gradients (fronts) over other available habitats. However, simultaneous Global Positioning System (GPS) tracking of the entire Spanish and Portuguese longline-vessel fishing fleets show an 80% overlap of fished areas with hotspots, potentially increasing shark susceptibility to fishing exploitation. Regions of high overlap between oceanic tagged sharks and longliners included the North Atlantic Current/Labrador Current convergence zone and the Mid-Atlantic Ridge southwest of the Azores. In these main regions, and subareas within them, shark/vessel co-occurrence was spatially and temporally persistent between years, highlighting how broadly the fishing exploitation efficiently "tracks" oceanic sharks within their space-use hotspots year-round. Given this intense focus of longliners on shark hotspots, our study argues the need for international catch limits for pelagic sharks and identifies a future role of combining fine-scale fish and vessel telemetry to inform the ocean-scale management of fisheries.

  1. Large Pelagic Logbook Trip Survey (Vessels)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains catch and effort for fishing trips that are taken by vessels with a Federal permit issued for the swordfish and sharks under the Highly...

  2. Large Pelagic Logbook Set Survey (Vessels)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains catch and effort for fishing trips that are taken by vessels with a Federal permit issued for the swordfish and sharks under the Highly...

  3. The role of large marine vertebrates in the assessment of the quality of pelagic marine ecosystems.

    Science.gov (United States)

    Fossi, Maria Cristina; Casini, Silvia; Caliani, Ilaria; Panti, Cristina; Marsili, Letizia; Viarengo, Aldo; Giangreco, Roberto; Notarbartolo di Sciara, Giuseppe; Serena, Fabrizio; Ouerghi, Atef; Depledge, Michael H

    2012-06-01

    The Marine Strategy Framework Directive (MSFD) establishing a framework for community action in the field of marine environmental policy has been developed and is being implemented, with the objective to deliver "Good Environmental Status" by 2020. A pragmatic way forward has been achieved through the development of 11 "qualitative descriptors". In an attempt to identify gaps in MSFD, regarding the data on large marine vertebrates, the SETAC--Italian Branch organised a workshop in Siena (IT). Particular attention was paid to the qualitative descriptors 8 (contaminants and pollution effects) and 10 (marine litter). The specific remit was to discuss the potential use of large marine vertebrates (from large pelagic fish, sea turtles, sea birds and cetaceans) in determining the environmental status of pelagic marine ecosystems. During the workshop it emerged that large pelagic fish may be especially useful for monitoring short- to medium-term changes in pelagic ecosystems, while cetaceans provided a more integrated view over the long-term. A theme that strongly emerged was the broad recognition that biomarkers offer real potential for the determination of good ecological status detecting the "undesirable biological effects" (indicator for descriptor 8). Copyright © 2012 Elsevier Ltd. All rights reserved.

  4. Relationship between pelagic larval duration and abundance of tropical fishes on temperate coasts of Japan.

    Science.gov (United States)

    Soeparno; Nakamura, Y; Shibuno, T; Yamaoka, K

    2012-02-01

    The influence of pelagic larval duration (PLD) and egg type dispersal capabilities of 35 demersal and pelagic-spawning tropical fish species is examined in relation to their abundance on the temperate coasts of Japan. The PLDs of pelagic spawners were significantly longer than those of demersal spawners, and a high occurrence of pelagic spawners on the temperate coasts suggests that these fishes are more easily transported to temperate coasts than demersal spawners. For demersal spawners, the common species on the temperate coasts had significantly longer PLDs than the rare species; this suggests that PLD is a major factor influencing the distribution patterns of tropical demersal spawners on temperate coasts. Moreover, a negative correlation between PLD and the abundance of some species of pelagic and demersal spawners suggests the presence of reproductively active fishes in northern subtropical and even in temperate waters.

  5. Bioaccumulation of mercury in pelagic fishes from the northern Gulf of Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Cai, Yang J.; Rooker, Jay R.; Gill, Gary A.; Turner, Jason P.

    2007-03-30

    Total mercury (Hg) concentration was determined in the tissues of 10 pelagic fishes in the northern Golf of Mexico, and dietary tracers (stable isotopes and fatty acids) were used to evaluate the relationship between Hg and feeding history.

  6. Identification of fish populations with particular reference to the pelagic fish stocks of the Indian Ocean region

    Digital Repository Service at National Institute of Oceanography (India)

    Dwivedi, S.N.

    The most essential step in any fishery management is the identification of discrete fish populations. This is particularly important for the development of Indian Ocean pelagic fisheries. The simple signal character analysis of meristic or metric...

  7. Late winter larval fish assemblage in the southern East China Sea, with emphasis on spatial relations between mesopelagic and commercial pelagic fish larvae

    Science.gov (United States)

    Sassa, Chiyuki; Konishi, Yoshinobu

    2015-10-01

    We examined larval fish assemblages in the southern East China Sea during late winter where large spawning grounds of several commercial pelagic fishes are formed. Our samples include a total of 187 species or taxa of larval fish belonging to 118 genera, 96 families, and 18 orders. Mesopelagic fish larvae, mainly Stomiiformes, Aulopiformes, and Myctophiformes, accounted for 66.5% of the total catch, while commercial species such as Trachurus japonicus, Scomber spp., and Trichiurus japonicus for 16.6%. Based on the species composition, three assemblages were recognized: Kuroshio (KUR), Shelf-Break (BRE), and Shelf (SHE) assemblages. KUR assemblage was mainly characterized by various mesopelagic fishes such as Sigmops gracilis, Diaphus spp., and Myctophum asperum, BRE assemblage by both commercial pelagic and mesopelagic species, SHE assemblage by demersal species such as Lepidotrigla spp. and Gobiidae spp. Both abundance and diversity were highest in KUR assemblage, although food availability for the larvae would be poorest. The combination of variables of sea surface temperature-chlorophyll a concentrations best explained the larval distribution. Except for Benthosema pterotum, the center of distribution of mesopelagic fish larvae was clearly separated from that of the commercial species by the Kuroshio front. However, a northward intrusion of the Kuroshio transported mesopelagic fish larvae onto the shelf, forming the BRE assemblage. Competition for prey between mesopelagic and commercial pelagic fish larvae would potentially occur if the intrusion is strong.

  8. Stakeholder participation in the management of North East Atlantic pelagic fish stocks

    DEFF Research Database (Denmark)

    Coers, Aukje; Raakjær, Jesper; Olesen, Christian

    2012-01-01

    well functioning management framework, which has lead to the situation that most pelagic fish stocks are harvested biologically sustainable. While a majority of Europe's fish stocks still need rebuilding, and the main aim accordingly is to reduce fishing mortality, the current focus for pelagic fish...... stocks is to improve the performance of already implemented Long Term Management plans in terms of their biological as well as social and economical objectives. This paper reflects upon experiences of the Pelagic Regional Advisory Council (PRAC) in its role as advisor to the EU institutions. Subsequently...... floor. For this reason, as well as the fact that they are usually widely distributed, researching and managing this dynamic group of fishes across the borders of many countries requires a unique approach. Fortunately, despite these complexities, policy makers have succeeded to establish a reasonably...

  9. Pelagic fish, particularly clupeoids, form the basis of many important ...

    African Journals Online (AJOL)

    spamer

    FORECASTING IN SOUTH AFRICAN PELAGIC FISHERIES MANAGEMENT: THE USE OF ... However, many current fisheries models have only short- term datasets ..... HILBORN, R. 1992 — Current and future trends in fisheries stock.

  10. Effectiveness of tori line use to reduce seabird bycatch in pelagic longline fishing

    Science.gov (United States)

    Domingo, Andrés; Abreu, Martin; Forselledo, Rodrigo; Yates, Oliver

    2017-01-01

    Industrial longline fisheries cause the death of large numbers of seabirds annually. Various mitigation measures have been proposed, including the use of tori lines. In this study the efficiency of a single tori line to reduce seabird bycatch was tested on pelagic longline vessels (25-37m length). Thirteen fishing trips were carried out in the area and season of the highest bycatch rates recorded in the southwest Atlantic (2009–2011). We deployed two treatments in random order: sets with a tori line and without a tori line (control treatment). The use of a tori line significantly reduced seabird bycatch rates. Forty three and seven birds were captured in the control (0.85 birds/1,000 hooks, n = 49 sets) and in the tori line treatment (0.13 birds/1,000 hooks, n = 51 sets), respectively. In 47% of the latter sets the tori line broke either because of entanglement with the longline gear or by tension. This diminished the tori line effectiveness; five of the seven captures during sets where a tori line was deployed were following ruptures. Nine additional trips were conducted with a tori line that was modified to reduce entanglements (2012–2016). Seven entanglements were recorded in 73 longline sets. The chance of a rupture on these trips was 4% (95% c.l. = 1–18%) of that during 2009–2011. This work shows that the use of a tori line reduces seabird bycatch in pelagic longline fisheries and is a practice suitable for medium size vessels (~25-40m length). Because the study area has historically very high bycatch rates at global level, this tori line design is potentially useful to reduce seabird bycatch in many medium size pelagic longline vessel fishing in the southern hemisphere. PMID:28886183

  11. Widespread kelp-derived carbon in pelagic and benthic nearshore fishes suggested by stable isotope analysis

    Science.gov (United States)

    von Biela, Vanessa R.; Newsome, Seth D.; Bodkin, James L.; Kruse, Gordon H.; Zimmerman, Christian E.

    2016-11-01

    Kelp forests provide habitat for diverse and abundant fish assemblages, but the extent to which kelp provides a source of energy to fish and other predators is unclear. To examine the use of kelp-derived energy by fishes we estimated the contribution of kelp- and phytoplankton-derived carbon using carbon (δ13C) and nitrogen (δ15N) isotopes measured in muscle tissue. Benthic-foraging kelp greenling (Hexagrammos decagrammus) and pelagic-foraging black rockfish (Sebastes melanops) were collected at eight sites spanning ∼35 to 60°N from the California Current (upwelling) to Alaska Coastal Current (downwelling) in the northeast Pacific Ocean. Muscle δ13C values were expected to be higher for fish tissue primarily derived from kelp, a benthic macroalgae, and lower for tissue primarily derived from phytoplankton, pelagic microalgae. Muscle δ13C values were higher in benthic-feeding kelp greenling than in pelagic-feeding black rockfish at seven of eight sites, indicating more kelp-derived carbon in greenling as expected. Estimates of kelp carbon contributions ranged from 36 to 89% in kelp greenling and 32 to 65% in black rockfish using carbon isotope mixing models. Isotopic evidence suggests that these two nearshore fishes routinely derive energy from kelp and phytoplankton, across coastal upwelling and downwelling systems. Thus, the foraging mode of nearshore predators has a small influence on their ultimate energy source as energy produced by benthic macroalgae and pelagic microalgae were incorporated in fish tissue regardless of feeding mode and suggest strong and widespread benthic-pelagic coupling. Widespread kelp contributions to benthic- and pelagic-feeding fishes suggests that kelp energy provides a benefit to nearshore fishes and highlights the potential for kelp and fish production to be linked.

  12. The use of pelagic fish as proxies of environmental contamination: a case study with sardine populations

    Directory of Open Access Journals (Sweden)

    Bruno Silva Nunes

    2015-12-01

    Full Text Available The use of bioindicators to analyze marine ecosystems contamination is often made difficult due to the absence of appropriate species. Pelagic fish species, captured by commercial fishing fleets around the world, can be successfully used to assess contaminant levels, by determining their body burden in specific compounds. However the study of biological responses elicited by such compounds, through the analysis of biomarkers, is highly dependent on the physiological and reproductive status of the organisms. Such confounding factors elicit seasonal fluctuations that difficult the extrapolation of data. Sardine (Sardina pilchardus is a marine species common in the North Atlantic Ocean, being easily available through commercial fisheries. The present work intended to explore the potential of this species in biomonitoring studies, by simultaneously using enzymatic biomarkers and condition indices determined in fish landed in three commercial harbors along the west coast of Portugal. This strategy allowed devising spatial and temporal patterns in the sardine metapopulation. Results evidenced significant variability in both biochemical and physiological profiles of the fish, which were coherent among all sampling sites. Throughout the year, large seasonal differences for most markers were reported, which were strongly linked to the reproductive cycle and its physiological consequences (acquisition of energy, mobilization of energy reserves, etc.. It was possible to conclude that seasonality acts as a strong factor underlying chronological physiological adaptations, influencing biochemical markers that are usually employed as indicators of contamination. These effects can limit the usefulness of such a biomarker approach unless seasonality is not accounted for, and if no background values are known from previous studies. In this sense, studies such as this are pivotal to establish a baseline for biomonitoring studies. Also, despite the difficulty in

  13. Dates and rates of major pelagic deep-sea fish radiations

    DEFF Research Database (Denmark)

    Poulsen, Jan Yde; Miya, Masaki; Kawaguchi, Akira

    2013-01-01

    view of actinopterygian phylogeny. Taxon sampling was chosen with special emphasis on recent results, that showed phylogeny and age estimates from nuclear evidence, allowing us to compare the ages of stem- and crown group nodes of all major deep-sea pelagic fish radiations. Two extreme extinction rates......The pelagic realm of the deep-sea is home to some of the most spectacular fishes in terms of morphological adaptations, a probable consequence of the distinct hostile living conditions in this poorly known habitat. Detecting speciation patterns in open ocean fishes is often complicated from...... sexual encounters, comparing species richness and habitat alone tells us little about successful speciation in the pelagic deep-sea environment. The last two decades has expanded our knowledge on teleostean phylogeny from molecular data, although comparing nuclear, mitochondrial and hundreds of years...

  14. Assessing the state of pelagic fish communities within an ecosystem approach and the European Marine Strategy Framework Directive

    NARCIS (Netherlands)

    Shephard, S.; Rindorf, A.; Dickey-Collas, M.; Hintzen, N.T.; Farnsworth, K.; Reid, D.G.

    2014-01-01

    Pelagic fish are key elements in marine foodwebs and thus comprise an important part of overall ecosystem health. We develop a suite of ecological indicators that track pelagic fish community state and evaluate state of specific objectives against Good Environmental Status (GES) criteria. Indicator

  15. Allometric relations and consequences for feeding in small pelagic fish in the Bay of Biscay

    KAUST Repository

    Bachiller, Eneko

    2012-11-21

    The body size of fish is an important factor in determining their biology and ecology, as predators eat prey smaller than themselves. Predator mouth size restricts the availability of possible prey. In this paper we provide the allometric relationships of eight common, small pelagic fish species in the Bay of Biscay. In addition, we describe the predator-prey size ratios for different species, and we determine changes in their ratio-based trophic-niche breadth with increasing body size. Results suggest that gape size does not totally determine the predator-prey size ratio distribution, but predators use the entire available prey size range, including the smallest. As they grow they simply incorporate larger prey as their increased gape size permits. Accordingly, a large degree of overlap was found in the diet composition in terms of size and predator-prey ratios, even between fish of different sizes. Of the species studied, only horse mackerels seem to be clearly specialized in relatively large prey. © 2012 International Council for the Exploration of the Sea.

  16. Feeding ecology of pelagic fish larvae and juveniles in slope waters of the Gulf of Mexico.

    Science.gov (United States)

    Wells, R J D; Rooker, J R

    2009-11-01

    Stable isotope ratios of carbon (delta13C) and nitrogen (delta15N) were used to investigate feeding patterns of larval and early juvenile pelagic fishes in slope waters of the Gulf of Mexico. Contribution of organic matter supplied to fishes and trophic position within this pelagic food web was estimated in 2007 and 2008 by comparing dietary signatures of the two main producers in this ecosystem: phytoplankton [based on particulate organic matter (POM)] and Sargassum spp. Stable isotope ratios of POM and pelagic Sargassum spp. were significantly different from one another with delta13C values of POM depleted by 3-6 per thousand and delta15N values enriched by 2 relative to Sargassum spp. Stable isotope ratios were significantly different among the five pelagic fishes examined: blue marlin Makaira nigricans, dolphinfish Coryphaena hippurus, pompano dolphinfish Coryphaena equiselis, sailfish Istiophorus platypterus and swordfish Xiphias gladius. Mean delta13C values ranged almost 2 among fishes and were most depleted in I. platypterus. In addition, mean delta15N values ranged 4-5 with highest mean values found for both C. hippurus and C. equiselis and the lowest mean value for M. nigricans during both years. Increasing delta13C or delta15N with standard length suggested that shifts in trophic position and diet occurred during early life for several species examined. Results of a two-source mixing model suggest approximately an equal contribution of organic matter by both sources (POM=55%; pelagic Sargassum spp.=45%) to the early life stages of pelagic fishes examined. Contribution of organic matter, however, varied among species, and sensitivity analyses indicated that organic source estimates changed from 2 to 13% for a delta(13)C fractionation change of +/-0.25 per thousand or a delta15N fractionation change of +/-1.0 per thousand relative to original fractionation values.

  17. Latitudinal variation in the recruitment dynamics of small pelagic fishes in the western North Pacific

    Science.gov (United States)

    Watanabe, Yoshiro

    2007-07-01

    The subarctic Oyashio Current flows south-westward and the subtropical Kuroshio Current flows north-eastward in the western North Pacific, converging in the waters off northern Japan to form the Kuroshio-Oyashio transition region. Some small pelagic fishes inhabit the subarctic or subtropical waters, and others seasonally migrate north and south across the major ocean fronts. Environmental conditions in the subarctic and transition waters are variable, whereas in the subtropical Kuroshio waters conditions are relatively stable. Latitudinally different environmental conditions may affect vital parameters and recruitment variability of small pelagic fishes inhabiting the various waters. Pacific saury Cololabis saira migrate seasonally from the Kuroshio to Oyashio waters and spawn in the transition waters in autumn and spring and in the Kuroshio waters in winter. During 1990-1999, the coefficients of variation (CVs) of daily growth rates (G) and instantaneous mortality coefficients (M) were large for larvae and juveniles spawned in the northern transition waters, but relatively small for those from the southern Kuroshio waters. The Pacific stock of chub mackerel Scomber japonicus spawns in the Kuroshio waters in spring and early summer and migrates to the subarctic Oyashio waters in summer for feeding, whereas the Tsushima Warm Current stock spawns in the East China Sea in spring and fish remain in the subtropical warm waters throughout their lifetime. The Pacific stock had CVs > 100% for the fish aged 0-5 during 1970-2002. In contrast, the Tsushima Warm Current stock had CVs of 34-40% during 1973-2002. Pacific herring Clupea pallasii, which inhabits subarctic waters, had CVs of 118-178% for the fish aged 3-8 y during 1910-1954. Japanese sardine Sardinops melanostictus, which spawn in the subtropical Kuroshio waters and migrate to the subarctic Oyashio waters in summer for feeding, had CVs > 120% for the fish aged 0-4 during 1976-2003. Contrasting with these subarctic

  18. Lake Roosevelt Fisheries Evaluation Program, Part C; Lake Roosevelt Pelagic Fish Study: Washington Department of Fish and Wildlife, 1998 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Baldwin, Casey; Polacek, Matt; Bonar, Scott

    2002-11-01

    Pelagic fishes, such as kokanee and rainbow trout, provide an important fishery in Lake Roosevelt; however, spawner returns and creel results have been below management goals in recent years. Our objective was to identify factors that potentially limit pelagic fish production in Lake Roosevelt including entrainment, food limitation, piscivory, and other abiotic factors. We estimated the ratio of total fish entrained through Grand Coulee Dam to the pelagic fish abundance for September and October, 1998. If the majority of these fish were pelagic species, then entrainment averaged 10-13% of pelagic fish abundance each month. This rate of entrainment could impose considerable losses to pelagic fish populations on an annual basis. Therefore, estimates of species composition of entrained fish will be important in upcoming years to estimate the proportion of stocked pelagic fish lost through the dam. Food was not limiting for kokanee or rainbow trout populations since growth rates were high and large zooplankton were present in the reservoir. Estimates of survival for kokanee were low (< 0.01 annual) and unknown for rainbow trout. We estimated that the 1997 standing stock biomass of large (>1.1 mm) Daphnia could have supported 0.08 annual survival by kokanee and rainbow trout before fish consumption would have exceeded available biomass during late winter and early spring. Therefore, if recruitment goals are met in the future there may be a bottleneck in food supply for pelagic planktivores. Walleye and northern pikeminnow were the primary piscivores of salmonids in 1996 and 1997. Predation on salmonid prey was rare for rainbow trout and not detected for burbot or smallmouth bass. Northern pikeminnow had the greatest individual potential as a salmonid predator due to their high consumptive demand; however, their overall impact was limited because of their low relative abundance. We modeled the predation impact of 273,524 walleye in 1996, and 39,075 northern pikeminnow in

  19. The Ecuadorian Artisanal Fishery for Large Pelagics: Species Composition and Spatio-Temporal Dynamics.

    Science.gov (United States)

    Martínez-Ortiz, Jimmy; Aires-da-Silva, Alexandre M; Lennert-Cody, Cleridy E; Maunder, Mark N

    2015-01-01

    The artisanal fisheries of Ecuador operate within one of the most dynamic and productive marine ecosystems of the world. This study investigates the catch composition of the Ecuadorian artisanal fishery for large pelagic fishes, including aspects of its spatio-temporal dynamics. The analyses of this study are based on the most extensive dataset available to date for this fishery: a total of 106,963 trip-landing inspection records collected at its five principal ports during 2008 ‒ 2012. Ecuadorian artisanal fisheries remove a substantial amount of biomass from the upper trophic-level predatory fish community of the eastern tropical Pacific Ocean. It is estimated that at least 135 thousand metric tons (mt) (about 15.5 million fish) were landed in the five principal ports during the study period. The great novelty of Ecuadorian artisanal fisheries is the "oceanic-artisanal" fleet component, which consists of mother-ship (nodriza) boats with their towed fiber-glass skiffs (fibras) operating with pelagic longlines. This fleet has fully expanded into oceanic waters as far offshore as 100°W, west of the Galapagos Archipelago. It is estimated that nodriza operations produce as much as 80% of the total catches of the artisanal fishery. The remainder is produced by independent fibras operating in inshore waters with pelagic longlines and/or surface gillnets. A multivariate regression tree analysis was used to investigate spatio-environmental effects on the nodriza fleet (n = 6,821 trips). The catch species composition of the nodriza fleet is strongly influenced by the northwesterly circulation of the Humboldt Current along the coast of Peru and its associated cold waters masses. The target species and longline gear-type used by nodrizas change seasonally with the incursion of cool waters (Coryphaena hippurus) dominates the catches. However, in warmer waters, the fishery changes to tuna-billfish-shark longline gear and the catch composition becomes much more diverse.

  20. Mercury content in commercial pelagic fish and its risk assessment in the Western Indian Ocean.

    Science.gov (United States)

    Kojadinovic, Jessica; Potier, Michel; Le Corre, Matthieu; Cosson, Richard P; Bustamante, Paco

    2006-08-01

    As top predators of pelagic food webs, large fish naturally bioaccumulate mercury (Hg). Determining Hg burdens in commercialized fish is essential considering the concern about effects of contaminants on human health and the legal thresholds that are therefore set for local consumption and/or exportation. Total Hg levels were measured in the muscular tissue of 183 fish of five commercially important species from the tropical zone of the Western Indian Ocean. All individuals were measured and sexed in order to study the impregnation of Hg with size and sex within each species. Values of Hg found in this part of the Indian Ocean were comparable to Hg in muscular tissue of the same species studied in other areas. The highest Hg levels were noted in Swordfish (Xiphias gladius) caught in waters surrounding Reunion Island (3.97+/-2.67 microg g(-1) dry weight). Following the Swordfish, in decreasing order of Hg content, were the Yellowfin Tuna (Thunnus albacares) and the Skipjack (Katsuwonus pelamis), then the Common Dolphinfish (Coryphaena hippurus) and the Wahoo (Acanthocybium solandri). In the North of the Mozambique Channel, Swordfish had higher Hg levels than Yellowfin Tunas, and Dolphinfish exhibited intermediate Hg levels. The size of a fish was a determining factor of its Hg burden, as was the species. Differences in size-normalized Hg levels were observed between the two study zones for Swordfish and Common Dolphinfish. Sex, in contrast, did not influence Hg levels suggesting that females and males have similar feeding habits. The muscular Hg levels presented here suggest that consumers of fish originating from the Western Indian Ocean should limit themselves to one Swordfish based meal per week, or one fish meal a day if they choose to eat tuna or Common Dolphinfish.

  1. Dates and rates of major pelagic deep-sea fish radiations

    DEFF Research Database (Denmark)

    Poulsen, Jan Yde; Miya, Masaki; Kawaguchi, Akira

    2013-01-01

    The pelagic realm of the deep-sea is home to some of the most spectacular fishes in terms of morphological adaptations, a probable consequence of the distinct hostile living conditions in this poorly known habitat. Detecting speciation patterns in open ocean fishes is often complicated from...... view of actinopterygian phylogeny. Taxon sampling was chosen with special emphasis on recent results, that showed phylogeny and age estimates from nuclear evidence, allowing us to compare the ages of stem- and crown group nodes of all major deep-sea pelagic fish radiations. Two extreme extinction rates...... were used to calculate the diversification rates of all major deep-sea fish radiations using the different phylogenetic hypotheses and associated estimates of divergence time. Two deep-sea radiations, the order Stomiiformes and the deep-sea Anglerfishes in the suborder Ceratoidei, were found to present...

  2. Use of classification trees to apportion single echo detections to species: Application to the pelagic fish community of Lake Superior

    Science.gov (United States)

    Yule, Daniel L.; Adams, Jean V.; Hrabik, Thomas R.; Vinson, Mark R.; Woiak, Zebadiah; Ahrenstroff, Tyler D.

    2013-01-01

    Acoustic methods are used to estimate the density of pelagic fish in large lakes with results of midwater trawling used to assign species composition. Apportionment in lakes having mixed species can be challenging because only a small fraction of the water sampled acoustically is sampled with trawl gear. Here we describe a new method where single echo detections (SEDs) are assigned to species based on classification tree models developed from catch data that separate species based on fish size and the spatial habitats they occupy. During the summer of 2011, we conducted a spatially-balanced lake-wide acoustic and midwater trawl survey of Lake Superior. A total of 51 sites in four bathymetric depth strata (0–30 m, 30–100 m, 100–200 m, and >200 m) were sampled. We developed classification tree models for each stratum and found fish length was the most important variable for separating species. To apply these trees to the acoustic data, we needed to identify a target strength to length (TS-to-L) relationship appropriate for all abundant Lake Superior pelagic species. We tested performance of 7 general (i.e., multi-species) relationships derived from three published studies. The best-performing relationship was identified by comparing predicted and observed catch compositions using a second independent Lake Superior data set. Once identified, the relationship was used to predict lengths of SEDs from the lake-wide survey, and the classification tree models were used to assign each SED to a species. Exotic rainbow smelt (Osmerus mordax) were the most common species at bathymetric depths 100 m (384 million; 6.0 kt). Cisco (Coregonus artedi) were widely distributed over all strata with their population estimated at 182 million (44 kt). The apportionment method we describe should be transferable to other large lakes provided fish are not tightly aggregated, and an appropriate TS-to-L relationship for abundant pelagic fish species can be determined.

  3. Larval assemblages of large and medium-sized pelagic species in the Straits of Florida

    Science.gov (United States)

    Richardson, David E.; Llopiz, Joel K.; Guigand, Cedric M.; Cowen, Robert K.

    2010-07-01

    Critical gaps in our understanding of the distributions, interactions, life histories and preferred habitats of large and medium-size pelagic fishes severely constrain the implementation of ecosystem-based, spatially structured fisheries management approaches. In particular, spawning distributions and the environmental characteristics associated with the early life stages are poorly documented. In this study, we consider the diversity, assemblages, and associated habitat of the larvae of large and medium-sized pelagic species collected during 2 years of monthly surveys across the Straits of Florida. In total, 36 taxa and 14,295 individuals were collected, with the highest diversity occurring during the summer and in the western, frontal region of the Florida Current. Only a few species (e.g. Thunnus obesus, T. alalunga, Tetrapturus pfluegeri) considered for this study were absent. Small scombrids (e.g. T. atlanticus, Katsuwonus pelamis, Auxis spp.) and gempylids dominated the catch and were orders of magnitude more abundant than many of the rare species (e.g. Thunnus thynnus,Kajikia albida). Both constrained (CCA) and unconstrained (NMDS) multivariate analyses revealed a number of species groupings including: (1) a summer Florida edge assemblage (e.g. Auxis spp., Euthynnus alleterattus, Istiophorus platypterus); (2) a summer offshore assemblage (e.g. Makaira nigricans, T. atlanticus, Ruvettus pretiosus, Lampris guttatus); (3) an ubiquitous assemblage (e.g. K. pelamis, Coryphaena hippurus, Xiphias gladius); and (4) a spring/winter assemblage that was widely dispersed in space (e.g. trachipterids). The primary environmental factors associated with these assemblages were sea-surface temperature (highest in summer-early fall), day length (highest in early summer), thermocline depth (shallowest on the Florida side) and fluorescence (highest on the Florida side). Overall, the results of this study provide insights into how a remarkable diversity of pelagic species

  4. The influence of depth on mercury levels in pelagic fishes and their prey.

    Science.gov (United States)

    Choy, C Anela; Popp, Brian N; Kaneko, J John; Drazen, Jeffrey C

    2009-08-18

    Mercury distribution in the oceans is controlled by complex biogeochemical cycles, resulting in retention of trace amounts of this metal in plants and animals. Inter- and intra-specific variations in mercury levels of predatory pelagic fish have been previously linked to size, age, trophic position, physical and chemical environmental parameters, and location of capture; however, considerable variation remains unexplained. In this paper, we focus on differences in ecology, depth of occurrence, and total mercury levels in 9 species of commercially important pelagic fish (Thunnus obesus, T. albacares, Katsuwonus pelamis, Xiphias gladius, Lampris guttatus, Coryphaena hippurus, Taractichthys steindachneri, Tetrapturus audax, and Lepidocybium flavobrunneum) and in numerous representatives (fishes, squids, and crustaceans) of their lower trophic level prey sampled from the central North Pacific Ocean. Results indicate that total mercury levels of predatory pelagic fishes and their prey increase with median depth of occurrence in the water column and mimic concentrations of dissolved organic mercury in seawater. Stomach content analysis results from this study and others indicate a greater occurrence of higher-mercury containing deeper-water prey organisms in the diets of the deeper-ranging predators, X. gladius, T. obesus, and L. guttatus. While present in trace amounts, dissolved organic mercury increases with depth in the water column suggesting that the mesopelagic habitat is a major entry point for mercury into marine food webs. These data suggest that a major determinant of mercury levels in oceanic predators is their depth of forage.

  5. Life cycle ecophysiology of small pelagic fish and climate-driven changes in populations

    Science.gov (United States)

    Peck, Myron A.; Reglero, Patricia; Takahashi, Motomitsu; Catalán, Ignacio A.

    2013-09-01

    Due to their population characteristics and trophodynamic role, small pelagic fishes are excellent bio-indicators of climate-driven changes in marine systems world-wide. We argue that making robust projections of future changes in the productivity and distribution of small pelagics will require a cause-and-effect understanding of historical changes based upon physiological principles. Here, we reviewed the ecophysiology of small pelagic (clupeiform) fishes including a matrix of abiotic and biotic extrinsic factors (e.g., temperature, salinity, light, and prey characteristics) and stage-specific vital rates: (1) adult spawning, (2) survival and development of eggs and yolk sac larvae, and (3) feeding and growth of larvae, post-larvae and juveniles. Emphasis was placed on species inhabiting Northwest Pacific and Northeast Atlantic (European) waters for which summary papers are particularly scarce compared to anchovy and sardine in upwelling systems. Our review revealed that thermal niches (optimal and sub-optimal ranges in temperatures) were species- and stage-specific but that temperature effects only partly explained observed changes in the distribution and/or productivity of populations in the Northwest Pacific and Northeast Atlantic; changes in temperature may be necessary but not sufficient to induce population-level shifts. Prey availability during the late larval and early juvenile period was a common, density-dependent mechanism linked to fluctuations in populations but recruitment mechanisms were system-specific suggesting that generalizations of climate drivers across systems should be avoided. We identified gaps in knowledge regarding basic elements of the growth physiology of each life stage that will require additional field and laboratory study. Avenues of research are recommended that will aid the development of models that provide more robust, physiological-based projections of the population dynamics of these and other small pelagic fish. In our

  6. Plastic ingestion by pelagic and demersal fish from the North Sea and Baltic Sea.

    Science.gov (United States)

    Rummel, Christoph D; Löder, Martin G J; Fricke, Nicolai F; Lang, Thomas; Griebeler, Eva-Maria; Janke, Michael; Gerdts, Gunnar

    2016-01-15

    Plastic ingestion by marine biota has been reported for a variety of different taxa. In this study, we investigated 290 gastrointestinal tracts of demersal (cod, dab and flounder) and pelagic fish species (herring and mackerel) from the North and Baltic Sea for the occurrence of plastic ingestion. In 5.5% of all investigated fishes, plastic particles were detected, with 74% of all particles being in the microplastic (ingestion was recorded, showing a significantly higher ingestion frequency in the pelagic feeders. The condition factor K was calculated to test differences in the fitness status between individuals with and without ingested plastic, but no direct effect was detected. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. HabitatSpace: Multidimensional Characterization of Pelagic Essential Fish Habitat

    Science.gov (United States)

    2010-06-01

    That area should be described in terms of ecological characteristics including biological, physical, and chemical parameters, location, and time... Ecologically , essential habitat includes structure or substrate that focuses distribution (e.g., coral reefs, marshes, or kelp beds) and other...feature. For example, seagrass (Fig. 1) is a typical habitat. It grows on the seafloor and is basically a 2-D substrate. Fish that rely on this

  8. The Ecuadorian Artisanal Fishery for Large Pelagics: Species Composition and Spatio-Temporal Dynamics.

    Directory of Open Access Journals (Sweden)

    Jimmy Martínez-Ortiz

    Full Text Available The artisanal fisheries of Ecuador operate within one of the most dynamic and productive marine ecosystems of the world. This study investigates the catch composition of the Ecuadorian artisanal fishery for large pelagic fishes, including aspects of its spatio-temporal dynamics. The analyses of this study are based on the most extensive dataset available to date for this fishery: a total of 106,963 trip-landing inspection records collected at its five principal ports during 2008 ‒ 2012. Ecuadorian artisanal fisheries remove a substantial amount of biomass from the upper trophic-level predatory fish community of the eastern tropical Pacific Ocean. It is estimated that at least 135 thousand metric tons (mt (about 15.5 million fish were landed in the five principal ports during the study period. The great novelty of Ecuadorian artisanal fisheries is the "oceanic-artisanal" fleet component, which consists of mother-ship (nodriza boats with their towed fiber-glass skiffs (fibras operating with pelagic longlines. This fleet has fully expanded into oceanic waters as far offshore as 100°W, west of the Galapagos Archipelago. It is estimated that nodriza operations produce as much as 80% of the total catches of the artisanal fishery. The remainder is produced by independent fibras operating in inshore waters with pelagic longlines and/or surface gillnets. A multivariate regression tree analysis was used to investigate spatio-environmental effects on the nodriza fleet (n = 6,821 trips. The catch species composition of the nodriza fleet is strongly influenced by the northwesterly circulation of the Humboldt Current along the coast of Peru and its associated cold waters masses. The target species and longline gear-type used by nodrizas change seasonally with the incursion of cool waters (< 25°C from the south and offshore. During this season, dolphinfish (Coryphaena hippurus dominates the catches. However, in warmer waters, the fishery changes to tuna

  9. The Ecuadorian Artisanal Fishery for Large Pelagics: Species Composition and Spatio-Temporal Dynamics

    Science.gov (United States)

    Martínez-Ortiz, Jimmy; Aires-da-Silva, Alexandre M.; Lennert-Cody, Cleridy E.; Maunder, Mark N.

    2015-01-01

    The artisanal fisheries of Ecuador operate within one of the most dynamic and productive marine ecosystems of the world. This study investigates the catch composition of the Ecuadorian artisanal fishery for large pelagic fishes, including aspects of its spatio-temporal dynamics. The analyses of this study are based on the most extensive dataset available to date for this fishery: a total of 106,963 trip-landing inspection records collected at its five principal ports during 2008 ‒ 2012. Ecuadorian artisanal fisheries remove a substantial amount of biomass from the upper trophic-level predatory fish community of the eastern tropical Pacific Ocean. It is estimated that at least 135 thousand metric tons (mt) (about 15.5 million fish) were landed in the five principal ports during the study period. The great novelty of Ecuadorian artisanal fisheries is the “oceanic-artisanal” fleet component, which consists of mother-ship (nodriza) boats with their towed fiber-glass skiffs (fibras) operating with pelagic longlines. This fleet has fully expanded into oceanic waters as far offshore as 100°W, west of the Galapagos Archipelago. It is estimated that nodriza operations produce as much as 80% of the total catches of the artisanal fishery. The remainder is produced by independent fibras operating in inshore waters with pelagic longlines and/or surface gillnets. A multivariate regression tree analysis was used to investigate spatio-environmental effects on the nodriza fleet (n = 6,821 trips). The catch species composition of the nodriza fleet is strongly influenced by the northwesterly circulation of the Humboldt Current along the coast of Peru and its associated cold waters masses. The target species and longline gear-type used by nodrizas change seasonally with the incursion of cool waters (< 25°C) from the south and offshore. During this season, dolphinfish (Coryphaena hippurus) dominates the catches. However, in warmer waters, the fishery changes to tuna

  10. Evolutionary origin of the Scombridae (tunas and mackerels: members of a paleogene adaptive radiation with 14 other pelagic fish families.

    Directory of Open Access Journals (Sweden)

    Masaki Miya

    Full Text Available Uncertainties surrounding the evolutionary origin of the epipelagic fish family Scombridae (tunas and mackerels are symptomatic of the difficulties in resolving suprafamilial relationships within Percomorpha, a hyperdiverse teleost radiation that contains approximately 17,000 species placed in 13 ill-defined orders and 269 families. Here we find that scombrids share a common ancestry with 14 families based on (i bioinformatic analyses using partial mitochondrial and nuclear gene sequences from all percomorphs deposited in GenBank (10,733 sequences and (ii subsequent mitogenomic analysis based on 57 species from those targeted 15 families and 67 outgroup taxa. Morphological heterogeneity among these 15 families is so extraordinary that they have been placed in six different perciform suborders. However, members of the 15 families are either coastal or oceanic pelagic in their ecology with diverse modes of life, suggesting that they represent a previously undetected adaptive radiation in the pelagic realm. Time-calibrated phylogenies imply that scombrids originated from a deep-ocean ancestor and began to radiate after the end-Cretaceous when large predatory epipelagic fishes were selective victims of the Cretaceous-Paleogene mass extinction. We name this clade of open-ocean fishes containing Scombridae "Pelagia" in reference to the common habitat preference that links the 15 families.

  11. Spatio-temporal patterns and environmental controls of small pelagic fish body condition from contrasted Mediterranean areas

    Science.gov (United States)

    Brosset, Pablo; Fromentin, Jean-Marc; Van Beveren, Elisabeth; Lloret, Josep; Marques, Virginie; Basilone, Gualtiero; Bonanno, Angelo; Carpi, Piera; Donato, Fortunata; Čikeš Keč, Vanja; De Felice, Andrea; Ferreri, Rosalia; Gašparević, Denis; Giráldez, Ana; Gücü, Ali; Iglesias, Magdalena; Leonori, Iole; Palomera, Isabel; Somarakis, Stylianos; Tičina, Vjekoslav; Torres, Pedro; Ventero, Ana; Zorica, Barbara; Ménard, Frédéric; Saraux, Claire

    2017-02-01

    Small pelagic fish are among the most ecologically and economically important marine fish species and are characterized by large fluctuations all over the world. In the Mediterranean Sea, low catches and biomass of anchovies and sardines have been described in some areas during the last decade, resulting in important fisheries crises. Therefore, we studied anchovy and sardine body condition variability, a key index of population health and its response to environmental and anthropogenic changes. Wide temporal and spatial patterns were investigated by analyzing separately data from scientific surveys and fisheries in eight Mediterranean areas between 1975 and 2015. Results showed that anchovy and sardine body condition as well as maximum size in some areas sharply decreased in most Mediterranean areas along years (except in the Northern Alboran Sea). Despite this general pattern, well-marked environmental differences between sub-regions were highlighted by several analyses and variations in body condition were not found to be homogeneous over all the Mediterranean Sea. Further, other analyses revealed that except for the Adriatic where major changes towards a lower body condition were concomitant with a decrease in river runoffs and chl-a concentration, no concomitant environmental regime shift was detected in other areas. Together, these analyses highlighted the current poor body condition of almost all small pelagic fish populations in the Mediterranean. Yet, global environmental indices could not explain the observed changes and the general decrease in condition might more likely come from regional environmental and/or anthropogenic (fishing) effects. A prolonged state of poor fish body condition, together with an observed reduced size and early age-at-maturity may have strong ecological, economic and social consequences all around the Mediterranean Sea.

  12. Toxic Metals in Pelagic, Benthic and Demersal Fish Species from Mediterranean FAO Zone 37.

    Science.gov (United States)

    Naccari, Clara; Cicero, Nicola; Ferrantelli, Vincenzo; Giangrosso, Giuseppe; Vella, Antonio; Macaluso, Andrea; Naccari, Francesco; Dugo, Giacomo

    2015-11-01

    Fish represents a nutrient-rich food but, at the same time, is one of the most important contributor to the dietary intake of heavy metals. The aim of this study was to assess residual levels of Pb, Cd and Hg in different species, caught from FAO zones 37 1.3 and 37 2.2, particularly small pelagic, benthic and demersal fishes. The results obtained showed the absence of toxic metal in fishes from FAO zone 37 1.3. Relating to FAO zone 37 2.2, instead, in all samples we observed the absence of Pb, small concentrations of Cd (0.081±0.022 mg/kg) and higher Hg residual levels (0.252±0.033 mg/kg). Particularly, the trend of Cd contamination was similar in all species whereas Hg showed high levels in demersal, intermediate in pelagic and low in benthic species. However, only Cd concentrations exceed the MRL in mackerel, mullet, sea-bream fishes, according to Regulation CE n. 629/2008 and n. 488/2014.

  13. Hydroacoustic estimates of abundance and spatial distribution of pelagic prey fishes in western Lake Superior

    Science.gov (United States)

    Mason, Doran M.; Johnson, Timothy B.; Harvey, Chris J.; Kitchell, James F.; Schram, Stephen T.; Bronte, Charles R.; Hoff, MIchael H.; Lozano, Stephen J.; Trebitz, Anett S.; Schreiner, Donald R.; Lamon, E. Conrad; Hrabik, Thomas R.

    2005-01-01

    Lake herring (Coregonus artedi) and rainbow smelt (Osmerus mordax) are a valuable prey resource for the recovering lake trout (Salvelinus namaycush) in Lake Superior. However, prey biomass may be insufficient to support the current predator demand. In August 1997, we assessed the abundance and spatial distribution of pelagic coregonines and rainbow smelt in western Lake Superior by combining a 120 kHz split beam acoustics system with midwater trawls. Coregonines comprised the majority of the midwater trawl catches and the length distributions for trawl caught fish coincided with estimated sizes of acoustic targets. Overall mean pelagic prey fish biomass was 15.56 kg ha−1 with the greatest fish biomass occurring in the Apostle Islands region (27.98 kg ha−1), followed by the Duluth Minnesota region (20.22 kg ha−1), and with the lowest biomass occurring in the open waters of western Lake Superior (9.46 kg ha−1). Biomass estimates from hydroacoustics were typically 2–134 times greater than estimates derived from spring bottom trawl surveys. Prey fish biomass for Lake Superior is about order of magnitude less than acoustic estimates for Lakes Michigan and Ontario. Discrepancies observed between bioenergetics-based estimates of predator consumption of coregonines and earlier coregonine biomass estimates may be accounted for by our hydroacoustic estimates.

  14. Remarkable vertical shift in residence depth links pelagic larval and demersal adult jellynose fish

    Science.gov (United States)

    Shiao, Jen-Chieh; Sui, Tsung-Da; Chang, Ni-Na; Chang, Chih-Wei

    2017-03-01

    Deep-sea fish show diverse migratory behaviors across depths at different life stages. The historical residence depths of jellynose fish Ateleopus japonicus and Ijimaia dofleini (Ateleopodidae) were reconstructed from otolith microstructures and isotopic compositions. δ18O values in the otolith core areas ranged from -0.5 to -1.3‰ among individuals, suggesting that larval and post-larval stages lived in the mixed layer (50-200 m). Otolith growth increment widths surged for 10-30 rings around 300-600 μm from the core, indicating a fast-growth phase during the early post-larval stage. Fish then migrated downward to 350-800 m depth at about 2 months of age, possibly during the post-larval metamorphosis to the juvenile. Otolith growth increments became narrower and otolith δ13C values increased from -5 to -1‰, suggesting a lower growth and metabolic rate when the fish experienced colder water during the downward migration. After arrival at the deepest waters, the fish then migrated upward to the continental margin or upper slopes where the adults persistently resided. A translucent otolith zone was formed after the residence depth shift from the deepest waters to shallower depths, indicating a transition from pelagic to bathydemersal life on the continental shelf or break. The down-and-up shift in residence depth of jellynose fish represents an indirect settlement process to the adult residence depth, which might be associated with a unique post-larval stage moving offshore before the downward migration. The results filled the gap of vertical distributions of jellynose fish from pelagic larvae near the sea surface to the bathydemersal adult dwelling on the continental shelf break.

  15. Effects of offshore wind power on the pelagic fish; Effekter av havsbaserad vindkraft paa pelagisk fisk

    Energy Technology Data Exchange (ETDEWEB)

    Axenrot, Thomas (SLU, Institutionen foer Akvatiska Resurser, Soetvattenlaboratoriet (Sweden)); Didrikas, Tomas (AquaBiota Water Research AB (Sweden); Stockholms universitet (Sweden))

    2012-02-15

    Marine wind parks are being planned for and built in coastal and shallow offshore areas in response to an increasing demand for renewable energy. Today's knowledge is limited about possible effects on fish from habitat change and generated underwater sound when wind parks are running. There may also be consequences for the fishery. Studies on fish hearing have shown that many fishes hear low frequency sound like that produced by wind turbines. This study consists of two parts. The first part of the study investigated pelagic fish abundance and spatial distribution at one wind park and two reference areas (200 m to 10 km distance from fundaments) at five different occasions from 2005 through 2007 in the Kalmar Sound of the Baltic Sea. The highest fish densities was found in the most remote reference area. The difference between areas was statistically significant for fish of the size groups 30-80 mm (stickleback), 80-140 mm (sprat, small herring) and 140-250 mm (adult herring). For fish >250 mm, representing cod and salmon, no statistically significant difference between areas was observed. For one group (sticklebacks) Area was significantly pointed out as the most important factor for the observed differences in fish density. No data on fish densities in the investigated areas were collected before the wind park (Utgrunden 1) was built which is a drawback to this part of the study. The second part of the study focused on possible effects of underwater sound generated by wind turbines on fish behaviour in the close vicinity of the fundaments (2-35 m distance). Stationary horizontal acoustics was used to estimate fish abundance and swimming speed in relation to turbine rotor speed and electricity production. The changes of abundance were not consistent and difficult to interpret. Fish swimming speed decreased with increasing turbine rotor speed and electricity production. However, it cannot be distinguished if this was an effect of sound emitted by wind turbines

  16. The distribution of Antarctic pelagic fish and larvae (CCAMLR division 58.4.1)

    Science.gov (United States)

    Hoddell, R. J.; Crossley, A. C.; Williams, R.; Hosie, G. W.

    2000-08-01

    Distribution patterns of pelagic fish, larvae and juveniles collected by RMT trawls during BROKE survey to CCAMLR Division 58.4.1 were investigated. Nearly 2000 individuals, weighing 1210 g, were collected from approximately 1.5 million m 3 of the upper 200 m of ocean, supporting the theory that Antarctic ichthyoplankton has low biomass. The collection consisted mainly of P. antarcticum larvae and juveniles and E. antarctica sub-adults, with a range of other notothenioid fish and myctophids. Three distinct biogeographic zones, with characteristic ichthyo- and zooplankton assemblages, were identified. The Oceanic Zone was dominated by myctophids and, in the western reaches, the paralepidid N. coatsi. The shelf break zone comprised of myctophids, and the juveniles of notothenioid fish. The shelf zone consisted of notothenioid juveniles and sub-adults. Characteristic water masses and associated zooplankton assemblages were found throughout these three zones. Analysis of fish stomach contents indicated feeding on locally abundant zooplankton taxa. There was niche-partitioning of prey taxa and size classes, between both sympatric species and between different ontogenetic stages. Fish distributions corresponded to known patterns, and extended the known geographic range of several species.

  17. Social aggregation in the pelagic zone with special reference to fish and invertebrates.

    Science.gov (United States)

    Ritz, David A; Hobday, Alistair J; Montgomery, John C; Ward, Ashley J W

    2011-01-01

    Aggregations of organisms, ranging from zooplankton to whales, are an extremely common phenomenon in the pelagic zone; perhaps the best known are fish schools. Social aggregation is a special category that refers to groups that self-organize and maintain cohesion to exploit benefits such as protection from predators, and location and capture of resources more effectively and with greater energy efficiency than could a solitary individual. In this review we explore general aggregation principles, with specific reference to pelagic organisms; describe a range of new technologies either designed for studying aggregations or that could potentially be exploited for this purpose; report on the insights gained from theoretical modelling; discuss the relationship between social aggregation and ocean management; and speculate on the impact of climate change. Examples of aggregation occur in all animal phyla. Among pelagic organisms, it is possible that repeated co-occurrence of stable pairs of individuals, which has been established for some schooling fish, is the likely precursor leading to networks of social interaction and more complex social behaviour. Social network analysis has added new insights into social behaviour and allows us to dissect aggregations and to examine how the constituent individuals interact with each other. This type of analysis is well advanced in pinnipeds and cetaceans, and work on fish is progressing. Detailed three-dimensional analysis of schools has proved to be difficult, especially at sea, but there has been some progress recently. The technological aids for studying social aggregation include video and acoustics, and have benefited from advances in digitization, miniaturization, motion analysis and computing power. New techniques permit three-dimensional tracking of thousands of individual animals within a single group which has allowed novel insights to within-group interactions. Approaches using theoretical modelling of aggregations have

  18. Effects of changing nutrient inputs on the ratio of small pelagic fish stock and phytoplankton biomass in the Black Sea

    Science.gov (United States)

    Yunev, Oleg A.; Velikova, Violeta; Carstensen, Jacob

    2017-10-01

    Significant increases in nitrogen and phosphorus inputs to the Black Sea in the second half of the 20th century caused eutrophication and drastically decreasing Si:N and Si:P ratios. Combined with climate change, overfishing of top predators and a huge outbreak of the non-indigenous ctenophore Mnemiopsis, the pelagic food web was strongly modified and its efficiency for channeling primary production to higher trophic levels substantially reduced. We used the ratio between small pelagic fish stock and phytoplankton biomass on the Danube shelf and in the open Black Sea to investigate long-term changes in food web functioning. The ratio had 1) highest values for the pre-eutrophication period when diatoms and copepods dominated the pelagic food web ('muscle food chain'), 2) decreased during the eutrophication period with stronger prevalence of autotrophic pico- and nanophytoplankton, bacteria, heterotrophic nanoflagellates, microzooplankton, Noctiluca and jellyfish ('jelly food chain' with increased importance of the microbial loop), 3) lowest values during the ecological crisis (1989-1992), when small pelagic fish stocks collapsed, and 4) increased after 1993, indicating that the ecosystem went out of the crisis and exhibited a trend of recovery. However, in the last period (1993-2008) the ratio remained close to values observed in the middle eutrophication phase, suggesting that the ecosystem was far from fully recovered. Since early 2000s, fluctuating pelagic fish stocks, with a tendency to decreasing fish landing again, have been observed in the Black Sea. Additionally, the quality of food for the small pelagic fish has deteriorated due to warming trends and the legacy of eutrophication, giving support for the 'jelly food chain', exhibiting low energy transfer and prevalence of organisms with high respiration rate and low nutritional value.

  19. Incidental catches of pelagic megafauna by the Dutch pelagic fleet in the Mauritanian Exclusive Economic Zone during the years 1999 - 2003

    NARCIS (Netherlands)

    Hofstede, ter R.; Zeeberg, J.J.; Haan, de D.; Couperus, A.S.; Mantingh, I.T.

    2004-01-01

    This report presents all registered catches of pelagic megafauna by the Dutch pelagic fleet in the Mauritanian Exclusive Economic Zone during the years 1999-2003. ‘By-catches’ incidentally include large species, notably cetaceans, sea turtles, sharks, rays, and some large pelagic fish such as swordf

  20. Body reserves mediate trade-offs between life-history traits: new insights from small pelagic fish reproduction.

    Science.gov (United States)

    Brosset, Pablo; Lloret, Josep; Muñoz, Marta; Fauvel, Christian; Van Beveren, Elisabeth; Marques, Virginie; Fromentin, Jean-Marc; Ménard, Frédéric; Saraux, Claire

    2016-10-01

    Limited resources in the environment prevent individuals from simultaneously maximizing all life-history traits, resulting in trade-offs. In particular, the cost of reproduction is well known to negatively affect energy investment in growth and maintenance. Here, we investigated these trade-offs during contrasting periods of high versus low fish size and body condition (before/after 2008) in the Gulf of Lions. Female reproductive allocation and performance in anchovy (Engraulis encrasicolus) and sardine (Sardina pilchardus) were examined based on morphometric historical data from the 1970s and from 2003 to 2015. Additionally, potential maternal effects on egg quantity and quality were examined in 2014/2015. After 2008, the gonadosomatic index increased for sardine and remained steady for anchovy, while a strong decline in mean length at first maturity indicated earlier maturation for both species. Regarding maternal effects, for both species egg quantity was positively linked to fish size but not to fish lipid reserves, while the egg quality was positively related to lipid reserves. Atresia prevalence and intensity were rather low regardless of fish condition and size. Finally, estimations of total annual numbers of eggs spawned indicated a sharp decrease for sardine since 2008 but a slight increase for anchovy during the last 5 years. This study revealed a biased allocation towards reproduction in small pelagic fish when confronted with a really low body condition. This highlights that fish can maintain high reproductive investment potentially at the cost of other traits which might explain the present disappearance of old and large individuals in the Gulf of Lions.

  1. Comparing nearshore benthic and pelagic prey as mercury sources to lake fish: the importance of prey quality and mercury content.

    Science.gov (United States)

    Karimi, Roxanne; Chen, Celia Y; Folt, Carol L

    2016-09-15

    Mercury (Hg) bioaccumulation in fish poses well-known health risks to wildlife and humans through fish consumption. Yet fish Hg concentrations are highly variable, and key factors driving this variability remain unclear. One little studied source of variation is the influence of habitat-specific feeding on Hg accumulation in lake fish. However, this is likely important because most lake fish feed in multiple habitats during their lives, and the Hg and caloric content of prey from different habitats can differ. This study used a three-pronged approach to investigate the extent to which habitat-specific prey determine differences in Hg bioaccumulation in fish. This study first compared Hg concentrations in common nearshore benthic invertebrates and pelagic zooplankton across five lakes and over the summer season in one lake, and found that pelagic zooplankton generally had higher Hg concentrations than most benthic taxa across lakes, and over a season in one lake. Second, using a bioenergetics model, the effects of prey caloric content from habitat-specific diets on fish growth and Hg accumulation were calculated. This model predicted that the consumption of benthic prey results in lower fish Hg concentrations due to higher prey caloric content and growth dilution (high weight gain relative to Hg from food), in addition to lower prey Hg levels. Third, using data from the literature, links between fish Hg content and the degree of benthivory, were examined, and showed that benthivory was associated with reduced Hg concentrations in lake fish. Taken together, these findings support the hypothesis that higher Hg content and lower caloric content make pelagic zooplankton prey greater sources of Hg for fish than nearshore benthic prey in lakes. Hence, habitat-specific foraging is likely to be a strong driver of variation in Hg levels within and between fish species.

  2. A Global View of Large-Scale Commercial Fishing

    Science.gov (United States)

    Kroodsma, D.

    2016-12-01

    Advances in big data processing and satellite technology, combined with the widespread adoption of Automatic Identification System (AIS) devices, now allow the monitoring of fishing activity at a global scale and in high resolution. We analyzed AIS data from more than 40,000 vessels from 2012-2015 to produce 0.1 degree global daily maps of apparent fishing effort. Vessels were matched to publically accessible fishing vessel registries and identified as fishing vessels through AIS Type 5 and Type 24 self-reported messages. Fishing vessels that broadcasted false locations in AIS data were excluded from the analysis. To model fishing pattern classification, a subset of fishing vessels were analyzed and specific movements were classified as "fishing" or "not fishing." A logistic regression model was fitted to these classifications using the following features: a vessel's average speed, the standard deviation of its speed, and the standard deviation of its course over a 12 hour time window. We then applied this model to the entire fishing vessel dataset and time normalized it to produce a global map of fishing hours. The resulting dataset allows for numerous new analyses. For instance, it can assist with monitoring apparent fishing activity in large pelagic marine protected areas and restricted gear use areas, or it can quantify how activity may be affected by seasonal or annual changes in biological productivity. This dataset is now published and freely available in Google's Earth Engine platform, available for researchers to answer a host of questions related to global fishing effort.

  3. Dual fuels: intra-annual variation in the relative importance of benthic and pelagic resources to maintenance, growth and reproduction in a generalist salmonid fish.

    Science.gov (United States)

    Hayden, Brian; Harrod, Chris; Kahilainen, Kimmo K

    2014-11-01

    Ecological systems are often characterized as stable entities. However, basal productivity in most ecosystems varies between seasons, particularly in subarctic and polar areas. How this variability affects higher trophic levels or entire food webs remains largely unknown, especially in these high-latitude regions. We undertook a year-long study of benthic (macroinvertebrate) and pelagic (zooplankton) resource availability, along with short (day/days: stomach content)-, medium (month: liver δ(13)C and δ(15)N isotopes)- and long-term (season: muscle δ(13)C and δ(15)N isotopes) assessments of resource use by a generalist fish, the European whitefish, in a deep, oligotrophic, subarctic lake in northern Europe. Due to the long ice-covered winter period, we expected to find general benthic reliance throughout the year, but also a seasonal importance of zooplankton to the diet, somatic growth and gonadal development of whitefish. Benthic and pelagic resource availability varied between seasons: peak littoral benthic macroinvertebrate density occurred in mid-winter, whereas maximum zooplankton density was observed in summer. Whitefish stomach content revealed a reliance on benthic prey items during winter and pelagic prey in summer. A seasonal shift from benthic to pelagic prey was evident in liver isotope ratios, but muscle isotope ratios indicated a year-round reliance on benthic macroinvertebrates. Whitefish activity levels as well as somatic and gonadal growth all peaked during the summer, coinciding with the zooplankton peak and the warmest water temperature. Stable isotopes of muscle consistently depicted the most important resource, benthic macroinvertebrates, whereas short-term indicators, that is, diet and stable isotopes of liver, revealed the seasonal significance of pelagic zooplankton for somatic growth and gonad development. Seasonal variability in resource availability strongly influences consumer growth and reproduction and may also be important in

  4. Dynamic height: A key variable for identifying the spawning habitat of small pelagic fishes

    Science.gov (United States)

    Asch, Rebecca G.; Checkley, David M., Jr.

    2013-01-01

    Small pelagic fishes off southern California exhibit interannual variations in the regions they occupy. An enhanced understanding of these fluctuations could improve fisheries management and predictions of fish's responses to climate change. We investigated dynamic height as a variable for identifying the spawning habitat of northern anchovy (Engraulis mordax), Pacific sardine (Sardinops sagax), and jack mackerel (Trachurus symmetricus). During cruises between 1998 and 2004, dynamic height was calculated from temperature and salinity profiles, while fish egg concentration was measured with obliquely towed bongo nets and the Continuous, Underway Fish Egg Sampler. Dynamic height ranged between 68 and 108 cm, with values increasing offshore. The greatest probability of encountering anchovy, sardine, and jack mackerel eggs occurred at dynamic heights of 79-83 cm, 84-89 cm, and 89-99 cm, respectively. Four mechanisms were proposed to explain how dynamic height affects egg distribution: (1) dynamic height is a proxy for upper water column temperature and salinity, which are known to influence spawning habitat. (2) Low dynamic heights are indicative of coastal upwelling, which increases primary and secondary productivity. (3) Egg concentration is greater at dynamic heights coincident with geostrophic currents that transport larvae to favorable habitats. (4) Eddies delineated by dynamic height contours retain eggs in productive habitats. To evaluate these mechanisms, a generalized linear model was constructed using dynamic height, temperature, salinity, chlorophyll, zooplankton volume, geostrophic currents, and eddies as independent variables. Dynamic height explained more variance than any other variable in models of sardine and anchovy spawning habitat. Together temperature, salinity, and chlorophyll accounted for 80-95% of the dynamic height effect, emphasizing the importance of the first two mechanisms. However, dynamic height remained statistically significant in the

  5. Global phylogeography of the dolphinfish (Coryphaena hippurus): the influence of large effective population size and recent dispersal on the divergence of a marine pelagic cosmopolitan species.

    Science.gov (United States)

    Díaz-Jaimes, P; Uribe-Alcocer, M; Rocha-Olivares, A; García-de-León, F J; Nortmoon, P; Durand, J D

    2010-12-01

    Pelagic fish that are distributed circumtropically are characterised by a low population structure level as a result of a high capacity for dispersion and large population sizes. Nevertheless, historical and contemporary processes, including past demographic and/or range expansions, secondary contact, dispersal, gene flow, and the achievement of large effective population sizes, may play a part in the detection of divergence signals, especially in the case of tropical pelagic species, whose distribution range depends strongly on the sea surface temperature. The connectivity and historical demography of Atlantic, Indian, Pacific and Mediterranean populations of dolphinfish (Coryphaena hippurus) was studied using partial sequences of the mitochondrial DNA NADH dehydrogenase subunit 1 (ND1). AMOVA analyses revealed significant inter-oceanic divergence with three phylogroups located in the Indo-Pacific, Eastern Atlantic, and Mediterranean Sea, the last one being the most divergent. However, it was not possible to clearly observe any genetic differentiation between the Indo-Pacific and Atlantic populations, as has been reported for most tropical pelagic species of tuna and billfishes. This supports the assumption of recent dispersal among basins facilitated by the actual continuous distribution of dolphinfish populations. Moreover, the lack of a divergence signal for populations separated by the Panamanian Isthmus reveals that genetic drift does not exert a strong influence on tropical pelagic species with large effective population sizes.

  6. The Distribution of Capture Fisheries Based Small Pelagic - Mackerel Fish Species In Balikpapan Waters, East Kalimantan

    Directory of Open Access Journals (Sweden)

    Said Abdusysyahid

    2014-04-01

    Full Text Available Normal 0 false false false IN X-NONE X-NONE In the utilization of common property resource, long term balance in aquaculture is difficult to maintain as people trying to maximize their profit leading to considerable extensification. The objective of this research was to analyze the number of stock, production, and effort of Mackerel fish (Scomberomorus commersonii resource based on bio-economic approach. Primary data was collected based on purposive sampling method where the respondents in this research were Small Pelagic fishers which determined deliberately due to specific consideration. Secondary data used in this research was obtained from several sources. Data production and effort (input or effort was arranged in a time sequence according to the type of fishing gears and their targets of fishery resource being studied and then determined the value of CPUE (catch per unit effort. Mathematically, the input gear to be standardized is calculated from fishing power index multiplies with input (effort of standardized gear. The result shows that the renewable capacity begins to decrease leading to a condition of biologically over fishing. Aside from that, the Mackerel fish resource in this area also experiences economically over fishing condition which indicated by higher economic calculation value and lower capture yield. /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New

  7. Divergence of brain and retinal anatomy and histology in pelagic antarctic notothenioid fishes of the sister taxa Dissostichus and Pleuragramma.

    Science.gov (United States)

    Eastman, Joseph T; Lannoo, Michael J

    2011-04-01

    The neutrally buoyant Antarctic fishes of the sister taxa Dissostichus (D. eleginoides and D. mawsoni) and Pleuragramma antarcticum diverged early in the notothenioid radiation and filled different niches in the pelagic realm of the developing Southern Ocean. To assess the influence of phylogenetic and ecological factors in shaping neural morphology in these taxa, we studied the anatomy and histology of the brains and retinae, and determined the proportional weights of brain regions. With the brain of the non-Antarctic sister taxon Eleginops maclovinus as plesiomorphic, statistically significant departures in the brains of the two Antarctic taxa include reduction of the corpus cerebelli and expansion of the mesencephalon and medulla. Compared to Eleginops, both species also have a relatively smaller telencephalon, although this is significant only in Dissostichus. There are a number of apomorphic features in the brain of Pleuragramma including reduced olfactory nerves and bulbs, an extremely small corpus cerebelli and an expanded mesencephalon. Although there is not a significant difference in the relative weights of the medulla in the two taxa, the prominence of the eminentia granularis and bulging cap-like appearance of the crista cerebellaris are distinctive in Pleuragramma. Brain histology of Dissostichus and Pleuragramma reflects typical perciform patterns and the two species of Dissostichus are histologically identical. Lateral compression in Pleuragramma and notable lobation in Dissostichus also contribute to differences between the taxa. Compression in Pleuragramma is attributable to convergence on an anchovy/herring body shape and to the relatively large brain in this small fish. The less prominent pattern of lobation of the telencephalon, inferior lobes and corpus cerebelli in Pleuragramma probably reflects underlying histology, specifically a reduction in cellularity of the neuropil in the nuclei and lobes. The retinal histology of Dissostichus and

  8. Spatial distribution and species composition of small pelagic fishes in the Gulf of California

    Directory of Open Access Journals (Sweden)

    Edgar Lanz

    2008-06-01

    Full Text Available Traditional regionalization methods in fisheries based on provinces or major fishing areas, includes large and arbitrary grids in which basic statistics or inferences on distribution or abundance are made. We describe a method for regionalization and analysis of fishing activities for small pelagic fisheries in the Gulf of California based on spatial patterns of landing and catch data in a Geographic Information System (GIS environment. A fisheries database from logbooks with spatial attributes from October 2002 to June 2007 was analyzed. Landings and catching data were transformed to a Weighted Region Index (WRI by using fuzzy logic operators. The WRI revealed fishing action centers characterized by areas with the highest WRI values, and a hierarchy for the relative importance of the regions was established. Guaymas, Desemboque de Caborca, Isla Patos, and Bahía San Rafael they were the most prominent ones. An analysis of the relative frequency of species composition showed that the Pacific sardine had an over 80 % abundance in the midriff islands, and remained as the most important in the upper gulf regions, while in the central part of the gulf, relative abundances of Pacific sardine and Northern anchovy were more balanced. Relative abundance of mackerel was significantly larger around Isla Patos than in any other place. Guaymas had the largest relative composition of Northern anchovy and the lowest values for Pacific sardine. Desemboque de Caborca showed the largest homogeneity in species relative composition. It is important to highlight that this results come from in situ data, while the results previously reported come from landing statistics by port. Therefore, the present method acknowledges the spatial differences of species by regions, additional to the traditional time series analysis. Rev. Biol. Trop. 56 (2: 575-590. Epub 2008 June 30.Los métodos tradicionales de regionalización en pesquerías, basados en provincias o grandes

  9. Intraguild predation between small pelagic fish in the Bay of Biscay: impact on anchovy (Engraulis encrasicolus L.) egg mortality

    KAUST Repository

    Bachiller, Eneko

    2015-05-12

    Small pelagic fish can play an important role in various ecosystems linking lower and upper trophic levels. Among the factor behind the observed inter-annual variations in small pelagic fish abundance, intra- and inter-specific trophic interactions could have a strong impact on the recruitment variability (e.g. anchovy). Egg cannibalism observed in anchovies has been postulated to be a mechanism that determines the upper limit of the population density and self-regulates the population abundance of the species. On the other hand, predation by other guild species is commonly considered as a regulation mechanism between competing species. This study provides empirical evidence of anchovy cannibalism and predation of the main small pelagic fish species on anchovy eggs and estimates the effect of intraguild predation on the anchovy egg mortality rate. Results show that, depending on the year (2008–2009), up to 33 % of the total anchovy egg mortality was the result of sardine predation and up to 4 % was the result of egg cannibalism together with predation by Atlantic and Atlantic Chub mackerel and sprat. Results also indicate that in the Bay of Biscay, fluctuations in the survival index of the early life stages of anchovy are likely to be attributable at least in part to egg cannibalism and especially to a high sardine predation on anchovy eggs. © 2015 Springer-Verlag Berlin Heidelberg

  10. Large, omega-3 rich, pelagic diatoms under Arctic sea ice: sources and implications for food webs.

    Science.gov (United States)

    Duerksen, Steven W; Thiemann, Gregory W; Budge, Suzanne M; Poulin, Michel; Niemi, Andrea; Michel, Christine

    2014-01-01

    Pelagic primary production in Arctic seas has traditionally been viewed as biologically insignificant until after the ice breakup. There is growing evidence however, that under-ice blooms of pelagic phytoplankton may be a recurrent occurrence. During the springs of 2011 and 2012, we found substantial numbers (201-5713 cells m-3) of the large centric diatom (diameter >250 µm) Coscinodiscus centralis under the sea ice in the Canadian Arctic Archipelago near Resolute Bay, Nunavut. The highest numbers of these pelagic diatoms were observed in Barrow Strait. Spatial patterns of fatty acid profiles and stable isotopes indicated two source populations for C. centralis: a western origin with low light conditions and high nutrients, and a northern origin with lower nutrient levels and higher irradiances. Fatty acid analysis revealed that pelagic diatoms had significantly higher levels of polyunsaturated fatty acids (mean ± SD: 50.3 ± 8.9%) compared to ice-associated producers (30.6 ± 10.3%) in our study area. In particular, C. centralis had significantly greater proportions of the long chain omega-3 fatty acid, eicosapentaenoic acid (EPA), than ice algae (24.4 ± 5.1% versus 13.7 ± 5.1%, respectively). Thus, C. centralis represented a significantly higher quality food source for local herbivores than ice algae, although feeding experiments did not show clear evidence of copepod grazing on C. centralis. Our results suggest that C. centralis are able to initiate growth under pack ice in this area and provide further evidence that biological productivity in ice-covered seas may be substantially higher than previously recognized.

  11. Comparative impacts of temperature and trade-offs on egg ecology of north Atlantic pelagic fish species

    DEFF Research Database (Denmark)

    Tsoukali, Stavroula; MacKenzie, Brian

    The early life history stages of fish are considered the most vulnerable and can be strongly affected by environmental variability, leading to population fluctuations. Temperature has a major role on development and mortality rates, with consequences for recruitment and overall stock productivity....... We collated development and survival data from publications on laboratory egg incubation experiments to investigate and compare the development, daily mortality and survival of fish eggs from pelagic species in the north Atlantic at different temperatures, and to investigate whether trade-offs exist...

  12. Transuranic concentrations in reef and pelagic fish from the Marshall Islands. [/sup 239/Pu, /sup 240/Pu

    Energy Technology Data Exchange (ETDEWEB)

    Noshkin, V.E.; Eagle, R.J.; Wong, K.M.; Jokela, T.A.

    1980-09-01

    Concentrations of /sup 239 + 240/Pu are reported in tissues of several species of reef and pelagic fish caught at 14 different atolls in the northern Marshall Islands. Several regularities that are species dependent are evident in the distribution of /sup 239 + 240/Pu among different body tissues. Concentrations in liver always exceeded those in bone and concentrations were lowest in the muscle of all fish analyzed. A progressive discrimination against /sup 239 + 240/Pu was observed at successive trophic levels at all atolls except Bikini and Enewetak, where it was difficult to conclude if any real difference exists between the average concentration factor for /sup 239 + 240/Pu among all fish, which include bottom feeding and grazing herbivores, bottom feeding carnivores, and pelagic carnivores from different atoll locations. The average concentration of /sup 239 + 240/Pu in the muscle of surgeonfish from Bikini and Enewetak was not significantly different from the average concentrations determined in these fish at the other, lesser contaminated atolls. Concentrations among all 3rd, 4th, and 5th trophic level species are highest at Bikini where higher environmental concentrations are found. The reasons for the anomalously low concentrations in herbivores from Bikini and Enewetak are not known.

  13. A new compilation of stomach content data for commercially important pelagic fish species in the northeast Atlantic

    Science.gov (United States)

    Pinnegar, J. K.; Goñi, N.; Trenkel, V. M.; Arrizabalaga, H.; Melle, W.; Keating, J.; Óskarsson, G.

    2015-02-01

    There is increasing demand for information on predator-prey interactions in the ocean as a result of legislative commitments aimed at achieving sustainable exploitation. However, comprehensive data sets are lacking for many fish species and this has hampered development of multispecies fisheries models and the formulation of effective food-web indicators. This work describes a new compilation of stomach content data for five pelagic fish species (herring, blue whiting, mackerel, albacore and bluefin tuna) sampled across the northeast Atlantic and submitted to the PANGAEA open-access data portal (www.pangaea.de). We provide detailed descriptions of sample origin and of the corresponding database structures. We describe the main results in terms of diet composition and predator-prey relationships. The feeding preferences of small pelagic fish (herring, blue whiting, mackerel) were sampled over a very broad geographic area within the North Atlantic basin, from Greenland in the west, to the Lofoten Islands in the east and from the Bay of Biscay northwards to the Arctic. This analysis revealed significant differences in the prey items selected in different parts of the region at different times of year. Tunas (albacore and bluefin) were sampled in the Bay of Biscay and Celtic Sea. Dominant prey items for these species varied by location, year and season. This data compilation exercise represents one of the largest and most wide-ranging ever attempted for pelagic fish in the North Atlantic. The earliest data included in the database were collected in 1864, whereas the most recent were collected in 2012. Data sets are available at doi:10.1594/PANGAEA.820041 and doi:10.1594/PANGAEA.826992.

  14. The influence of fish cage aquaculture on pelagic carbon flow and water chemistry in tidally dominated mangrove estuaries of peninsular Malaysia.

    Science.gov (United States)

    Alongi, D M; Chong, V C; Dixon, P; Sasekumar, A; Tirendi, F

    2003-05-01

    The impact of floating net cages culturing the seabass, Lates calcarifer, on planktonic processes and water chemistry in two heavily used mangrove estuaries in Malaysia was examined. Concentrations of dissolved inorganic and particulate nutrients were usually greater in cage vs. adjacent (approximately 100 m) non-cage waters, although most variability in water-column chemistry related to water depth and tides. There were few consistent differences in plankton abundance, production or respiration between cage and non-cage sites. Rates of primary production were low compared with rates of pelagic mineralization reflecting high suspended loads coupled with large inputs of organic matter from mangrove forests, fishing villages, fish cages, pig farms and other industries within the catchment. Our preliminary sampling did not reveal any large-scale eutrophication due to the cages. A crude estimate of the contribution of fish cage inputs to the estuaries shows that fish cages contribute only approximately 2% of C but greater percentages of N (32-36%) and P (83-99%) to these waters relative to phytoplankton and mangrove inputs. Isolating and detecting impacts of cage culture in such heavily used waterways--a situation typical of most mangrove estuaries in Southeast Asia--are constrained by a background of large, highly variable fluxes of organic material derived from extensive mangrove forests and other human activities.

  15. Development of a new multiple sampling trawl with autonomous opening/closing net control system for sampling juvenile pelagic fish

    Science.gov (United States)

    Oozeki, Yoshioki; Hu, Fuxiang; Tomatsu, Chiaki; Kubota, Hiroshi

    2012-03-01

    A new multiple layer sampling trawl with an autonomous net opening/closing control system was developed to sample pelagic juvenile fish quantitatively. The new trawl system, based on the Matsuda-Oozeki-Hu Trawl (MOHT), has a rigid-frame 3.3 m high and 2.35 m wide and five nets of 11.0 m length with a rectangular mouth of 2.22 m×1.81 m (4 m2 mouth area; large-scale prototype). A cambered V-shape depressor is hung below the frame and two bridles are attached at the midpoint of the side frames. A net-release controller is used, which not only controls the net release mechanism but also records the net depth, temperature and flow rate during net towing. The controller sends stored command signals to the net release mechanism as depth settings and/or time settings and does not require any commands from the surface through a conducting cable or by acoustic signals. Two other models were constructed before the construction of the large-scale prototype, which are a small-scale prototype (2 m2 mouth area) for testing the net release mechanism and a 1/4-scale model of the large-scale prototype for flume tank tests. Flume tank tests with the 1/4-scale model showed that the frame leaned forward at a tilt angle from 5 to 15 degrees at towing speeds from 0.8 to 1.4 m s-1. Opened nets closed smoothly and sequentially nets were completely opened when the trigger was released by the command. Net depth rarely changed even during changes in towing speed. Sea trials both by the small-scale and the large-scale prototype demonstrated the same towing characteristics expected from the flume tank tests. The newly developed multiple layer opening/closing MOHT (MOC-MOHT) is considered to be suitable for quantitative layer sampling of juvenile fish.

  16. Are tidal lagoons ecologically relevant to larval recruitment of small pelagic fish? An approach using nutritional condition and growth rate

    Science.gov (United States)

    Chícharo, M. A.; Amaral, A.; Faria, A.; Morais, P.; Mendes, C.; Piló, D.; Ben-Hamadou, R.; Chícharo, L.

    2012-10-01

    There are numerous studies dealing with larvae of Small Pelagic Fish (SPF), but only a few have actually addressed advanced larval phases. Temperate coastal lagoons are particularly understudied, due to the absence of standard method to capture advanced larval fish in these near shore shallow habitats. Accordingly, this study aims to describe abundances, nutritional condition and in situ growth of post-flexion (SPF) from the Ria Formosa, a tidal coastal lagoon in southern Portugal. The nutritional condition and in situ growth were determined through cohort analysis and standardized RNA:DNA ratio (sRD), complemented with feeding incidence (gut content) and fatty acids (FAs, trophic biomarkers) of postflexion larvae sampled sequentially with light traps, from spring 2005 to summer 2006. Simultaneously, environmental parameters such as water temperature, salinity, dissolved oxygen and chlorophyll a were measured. Post-larvae of SPF were captured through the year in important numbers. The dominant species were Sardina pilchardus (50.7%), Engraulis encrasicolus and Atherina presbyter (11.4%). These results are distinct from those based on adult/juvenile surveys or early planktonic phases in the Ria Formosa where clupeiformes were occasionally reported. Sardines were captured mainly in winter, spring and early summer and anchovies mainly during summer and autumn. Sand smelt, a resident species, was present throughout the year. In the early summer, the three species were present and during this period some diet overlapping occurred, the feeding incidence of the clupeiformes was very low, but atherinids always exhibited full guts reflecting the different gut morphology or indicating different life-cycle strategies. The bulk of the diet was mollusks, crustaceans and appendicularians, for sand smelts, sardines and anchovies, respectively. The results of FA analyses showed some contribution of phytoplankton to SPF in the area. All SPF exhibited higher condition (sRD) and

  17. A novel system for embryo-larval toxicity testing of pelagic fish: Applications for impact assessment of Deepwater Horizon crude oil.

    Science.gov (United States)

    Stieglitz, John D; Mager, Edward M; Hoenig, Ronald H; Alloy, Matthew; Esbaugh, Andrew J; Bodinier, Charlotte; Benetti, Daniel D; Roberts, Aaron P; Grosell, Martin

    2016-11-01

    Key differences in the developmental process of pelagic fish embryos, in comparison to embryos of standard test fish species, present challenges to obtaining sufficient control survival needed to successfully perform traditional toxicity testing bioassays. Many of these challenges relate to the change in buoyancy, from positive to negative, of pelagic fish embryos that occurs just prior to hatch. A novel exposure system, the pelagic embryo-larval exposure chamber (PELEC), has been developed to conduct successful bioassays on the early life stages (ELSs; embryos/larvae) of pelagic fish. Using this unique recirculating upwelling system, it was possible to significantly improve control survival in pelagic fish ELS bioassays compared to commonly used static exposure methods. Results demonstrate that control performance of mahi-mahi (Coryphaena hippurus) embryos in the PELEC system, measured as percent survival after 96-hrs, significantly outperformed agitated static exposure and static exposure systems. Similar significant improvements in 72-hr control survival were obtained with yellowfin tuna (Thunnus albacares). The PELEC system was subsequently used to test the effects of photo-induced toxicity of crude oil to mahi-mahi ELSs over the course of 96-hrs. Results indicate a greater than 9-fold increase in toxicity of Deepwater Horizon (DWH) crude oil during co-exposure to ambient sunlight compared to filtered ambient sunlight, revealing the importance of including natural sunlight in 96-hr DWH crude oil bioassays as well as the PELEC system's potential application in ecotoxicological assessments.

  18. Identifying pelagic ecosystem indicators for management

    DEFF Research Database (Denmark)

    Trenkel, Verena; Hintzen, Niels; Rindorf, Anna

    2013-01-01

    When exploiting fish populations under the ecosystem approach, aiming for MSY is not necessarily sufficient to ensure wider ecosystem sustainability. All of the large stocks of pelagic fish are managed through harvest control rules based on an MSY approach. Ensuring good environmental status...... will probably require further constraints to be imposed by management. Most of the current paradigm with regards to GES for fisheries has been based on demersal fish. Pelagic fisheries and fish are operationally and biologically respectively different. We use the example of applying the ecosystem approach...... to pelagic fisheries to further explore the setting of management objectives. The objectives were identified through a participatory process including industry, management, scientist and NGO representatives. These objectives were used to identify appropriate driver, pressure and state indicators. The links...

  19. Identifying pelagic ecosystem indicators for management

    DEFF Research Database (Denmark)

    Trenkel, Verena; Hintzen, Niels; Rindorf, Anna

    2013-01-01

    to pelagic fisheries to further explore the setting of management objectives. The objectives were identified through a participatory process including industry, management, scientist and NGO representatives. These objectives were used to identify appropriate driver, pressure and state indicators. The links......When exploiting fish populations under the ecosystem approach, aiming for MSY is not necessarily sufficient to ensure wider ecosystem sustainability. All of the large stocks of pelagic fish are managed through harvest control rules based on an MSY approach. Ensuring good environmental status...... will probably require further constraints to be imposed by management. Most of the current paradigm with regards to GES for fisheries has been based on demersal fish. Pelagic fisheries and fish are operationally and biologically respectively different. We use the example of applying the ecosystem approach...

  20. Status and trends of the major roundfish, flatfish, and pelagic fish stocks in the North Sea : Thirty-year overview

    DEFF Research Database (Denmark)

    Serchuk, F.M.; Kirkegaard, Eskild; Daan, N.

    1996-01-01

    Changes in the status of the major roundfish, flatfish, and pelagic stocks in the North Sea over the past 30 years are reviewed. Synopses are presented on trends in catches, fishing mortality, spawning-stock biomass, and recruitment for eight stocks (cod, haddock, whiting, saithe, plaice, sole......, herring, and mackerel), together with an evaluation of the current state of these resources and the most resent management advice provided by the ICES Advisory, Committee on Fishery Management. (C) 1996 International Council for the Exploration of the Sea...

  1. Genetic population structure of European sprat (Sprattus sprattus L.): differentiation across a steep environmental gradient in a small pelagic fish

    DEFF Research Database (Denmark)

    Limborg, Morten; Pedersen, Jes S.; Hansen, Jakob Hemmer

    2009-01-01

    locations in and around the North- and Baltic Sea area and from a geographically distant population from the Adriatic Sea. Analyses of nine microsatellite loci revealed a sharp genetic division separating samples from the Northeastern Atlantic and the Baltic Sea (pairwise θ = 0.019–0.035), concurring......Factors such as oceanographic retention, isolation by distance and secondary contact zones have, among others, been suggested to explain the low, but statistically significant, neutral population structure observed in many marine fishes. European sprat Sprattus sprattus is not known to display...... philopatric spawning behaviour or to exhibit local retention of eggs and larvae. It thus constitutes a good model for studying population structure in a characteristic small pelagic fish with high dispersal potential and an opportunistic life history. We analysed 931 specimens of sprat from nine spawning...

  2. 85 million years of pelagic ecosystem evolution: Pacific Ocean deep-sea ichthyolith records reveal fish community dynamics and a long-term decline in sharks

    Science.gov (United States)

    Sibert, E. C.; Norris, R. D.; Cuevas, J. M.; Graves, L. G.

    2015-12-01

    The structure and productivity of open ocean consumers has undergone major changes over the past 85 million years. Here, we present the first long-term detailed records of pelagic fish and sharks utilizing the record of ichthyoliths (teeth and dermal scales) from the deep Pacific Ocean. While the North and South Pacific Oceans show similar patterns throughout the 85 million year history, the North Pacific ichthyolith accumulation is significantly higher than the South Pacific, suggesting that the basin has been a more productive region for tens of millions of years. Fish and sharks were not abundant in the Pacific gyres until ~75 million years ago (Ma) suggesting that neither group was quantitatively important in oligotrophic pelagic food webs prior to the latest Cretaceous. Relative to ray-finned fish, sharks were common in the ancient ocean. Most ichthyolith assemblages have >50% shark dermal scales (denticles), but denticle abundance has been declining in both absolute and relative abundance since the Cretaceous-Paleogene (K/Pg) mass extinction. The accumulation rate of ichthyoliths of both sharks and ray-finned fish was highest in the Early Eocene, during the peak of the Cenozoic 'greenhouse' climate where production of shark dermal denticles and fish teeth increased almost five times over Paleocene production rates. Ichthyolith fluxes fell with cooler climates in the later Eocene and Oligocene, but fish production is almost always higher than in the Cretaceous and Paleocene reflecting the expanded ecological roles and importance of pelagic fish in marine ecosystems. Shark denticle production fell to less than half that of the Cretaceous by 20 Ma when it dropped abruptly to near-zero levels. Currently denticles make up sharks appear to be falling as major pelagic consumers over the Late Cretaceous and Cenozoic, and particularly over the past 20 Ma, perhaps reflecting demographic changes in shark and fish communities, or the rise of resource competition from

  3. Dolphinfish Bycatch in Spanish Mediterranean Large Pelagic Longline Fisheries, 2000–2010

    Directory of Open Access Journals (Sweden)

    David Macías

    2012-01-01

    Full Text Available The aim of this paper is to describe the dolphinfish bycatch rates in the longline fisheries of the Western Mediterranean and modelling the nominal bycatch abundance and distribution of dolphinfish from the Spanish Mediterranean as a function of technical, geographical, and seasonality factors. Our results indicate that the impact of the pelagic and semipelagic longline on the dolphinfish population is relatively low (1.083 fishes per 1000 hooks, in contrast with the greater effect on the target species population. We obtained a statistically significant logistic model, with the following factors: technical characteristics of the fishery, geographical location, and seasonality. Drifting surface longliners targeting albacore is the gear with the highest effect on Mediterranean dolphinfish population. The technical characteristics of the fishery and seasonality factors have an important role in explaining the absence or presence of dolphinfish bycatch in the different boat strata, gear types, and seasons. Moreover, sea surface temperature and lunar phases also present additional explanations. Lunar phase as SST has been frequently used as an explanatory variable affecting catch rates of dolphinfish.

  4. Impacts of hypoxia on the structure and processes in pelagic communities (zooplankton, macro-invertebrates and fish

    Directory of Open Access Journals (Sweden)

    W. Ekau

    2010-05-01

    Full Text Available Dissolved oxygen (DO concentration in the water column is an environmental parameter that is crucial for the successful development of many pelagic organisms. Hypoxia tolerance and threshold values are species- and stage-specific and can vary enormously. While some fish species may suffer from oxygen values of less than 3 mL O2 L−1 through impacted growth, development and behaviour, other organisms such as euphausiids may survive DO levels as low as 0.1 mL O2 L−1. A change in the average or the range of DO may have significant impacts on the survival of certain species and hence on the species composition in the ecosystem with consequent changes in trophic pathways and productivity.

    Evidence for the deleterious effects of oxygen depletion on pelagic species is scarce, particularly in terms of the effect of low oxygen on development, recruitment and patterns of migration and distribution. While planktonic organisms have to cope with variable DOs and exploit adaptive mechanisms, nektonic species may avoid areas of unfavourable DO and develop adapted migration strategies. Planktonic organisms may only be able to escape vertically, above or beneath the Oxygen Minimum Zone (OMZ. In shallow areas only the surface layer can serve as a refuge, but in deep waters many organisms have developed vertical migration strategies to use, pass through and cope with the OMZ.

    This paper elucidates the role of DO for different taxa in the pelagic realm and the consequences of low oxygen for foodweb structure and system productivity. We describe processes in two contrasting systems, the semi-enclosed Baltic Sea and the coastal upwelling system of the Benguela Current to demonstrate the consequences of increasing hypoxia on ecosystem functioning and services.

  5. Impacts of hypoxia on the structure and processes in the pelagic community (zooplankton, macro-invertebrates and fish

    Directory of Open Access Journals (Sweden)

    W. Ekau

    2009-05-01

    Full Text Available Dissolved oxygen (DO concentration in the water column is an environmental parameter that is crucial for the successful development of many pelagic organisms. Hypoxia tolerance and threshold values are species- and stage-specific and can vary enormously. While some fish species may suffer from oxygen values of less than 3 ml L−1 and show impact on growth, development and behaviour, other organisms such as euphausiids may survive DO levels as low as 0.1 ml L−1. A change in the average or the minimum or maximum DO in an area may have significant impacts on the survival of certain species and hence on the species composition in the ecosystem with consequent changes in trophic pathways and productivity.

    Evidence of the deleterious effects of oxygen depletion on species of the pelagic realm is scarce, particularly in terms of the effect of low oxygen on development, recruitment and patterns of migration and distribution. While planktonic organisms have to cope with different DOs and find adaptive mechanisms, nektonic species may avoid areas of inconvenient DO and develop adapted migrational strategies. Planktonic organisms may only be able to escape vertically, above or beneath the Oxygen Minimum Zone (OMZ. In shallow areas only the surface layer can serve as a refuge, in deep waters many organisms have developed vertical migration strategies to use, pass and cope with the OMZ.

    This paper elucidates the role of DO for different taxa in the pelagic realm and the consequences of low oxygen for foodweb structure and system productivity.

  6. Species composition and diversity of pelagic fishes based on a longline fishery catch in the North Pacific Ocean

    Institute of Scientific and Technical Information of China (English)

    ZHU Jiangfeng; DAI Xiaojie; CHEN Yong

    2011-01-01

    Evaluation of spatial-temporal variability of species composition and diversity in oceanic ecosystems is not easy because it is usually difficult to obtain sufficient data quantifying such variability.In this study, we examined pelagic species diversity indicators, species richness, Shannon-Wiener index of diversity and Hurlbert's species evenness, for fish assemblages from two areas (north and south) in the North Pacific Ocean (2°-12°N, 178°E-165°W) during May-July 2008. The assemblages were based on data collected by an onboard scientific observer during a commercial longline fishing trip. The species richness and Shannon-Wiener diversity index of fish assemblages in the northern area were slightly higher than those in the southern area, although these differences were not significant (t test,P>0.05). Non-parametric multidimensional scaling and analysis of similarities indicated that there were significant differences in fish assemblages between the two areas (P<0.01).

  7. Genetic structure of pelagic and littoral cichlid fishes from Lake Victoria.

    Directory of Open Access Journals (Sweden)

    Miyuki Takeda

    Full Text Available The approximately 700 species of cichlids found in Lake Victoria in East Africa are thought to have evolved over a short period of time, and they represent one of the largest known examples of adaptive radiation. To understand the processes that are driving this spectacular radiation, we must determine the present genetic structure of these species and elucidate how this structure relates to the ecological conditions that caused their adaptation. We analyzed the genetic structure of two pelagic and seven littoral species sampled from the southeast area of Lake Victoria using sequences from the mtDNA control region and 12 microsatellite loci as markers. Using a Bayesian model-based clustering method to analyze the microsatellite data, we separated these nine species into four groups: one group composed of pelagic species and another three groups composed mainly of rocky-shore species. Furthermore, we found significant levels of genetic variation between species within each group at both marker loci using analysis of molecular variance (AMOVA, although the nine species often shared mtDNA haplotypes. We also found significant levels of genetic variation between populations within species. These results suggest that initial groupings, some of which appear to have been related to habitat differences, as well as divergence between species within groups took place among the cichlid species of Lake Victoria.

  8. Habitat use and diel vertical migration of bigeye thresher shark: Overlap with pelagic longline fishing gear.

    Science.gov (United States)

    Coelho, Rui; Fernandez-Carvalho, Joana; Santos, Miguel N

    2015-12-01

    Pelagic longliners targeting swordfish and tunas in oceanic waters regularly capture sharks as bycatch, including currently protected species as the bigeye thresher, Alopias superciliosus. Fifteen bigeye threshers were tagged with pop-up satellite archival tags (PSATs) in 2012-2014 in the tropical northeast Atlantic, with successful transmissions received from 12 tags for a total of 907 tracking days. Marked diel vertical movements were recorded on all specimens, with most of the daytime spent in deeper colder water (mean depth = 353 m, SD = 73; mean temperature = 10.7 °C, SD = 1.8) and nighttime spent in warmer water closer to the surface (mean depth = 72 m, SD = 54; mean temperature = 21.9 °C, SD = 3.7). The operating depth of the pelagic longline gear was measured with Minilog Temperature and Depth Recorders (TDRs), and the overlap with habitat utilization was calculated. Overlap is taking place mainly during the night and is higher for juveniles. The results presented herein can be used as inputs for Ecological Risk Assessments for bigeye threshers captured in oceanic tuna fisheries, and serve as a basis for efficient management and conservation of this vulnerable shark species.

  9. Catchability of pelagic trawls for sampling deep-living nekton in the mid-North Atlantic

    OpenAIRE

    2011-01-01

    We use the material collected in summer 2004 from the Mid-Atlantic Ridge between Iceland the Azores with three pelagic trawls to estimate relative catchabilities for the common fish, cephalopod, decapod and jellyfish species. Catchability is defined as the ratio of numbers or weight caught between two trawls, standardised for towed distance. We estimate taxon-specific catchability coefficients for two large pelagic trawls with graded meshes, using a smaller pelagic trawl with uniform mesh siz...

  10. Role of the raw composition of pelagic fish muscle on the development of lipid oxidation and rancidity during storage.

    Science.gov (United States)

    Maestre, Rodrigo; Pazos, Manuel; Medina, Isabel

    2011-06-08

    The muscle composition of a pelagic fish species, Atlantic mackerel (Scomber scombrus), has been studied to determine the relationship with its susceptibility to develop lipid oxidation during chilled storage. For such an aim, the initial concentrations of the major components (water, total lipids, protein, and PUFAs) and minor pro-oxidant and antioxidant components (ascorbic acid, α-tocopherol, hemoglobin, total iron, LMW-iron, copper, and zinc) of different batches of mackerel were characterized. For the study, several batches of mackerel were caught during the spring and summer periods. The different batches were subjected to chilled storage, and the onset of lipid oxidation was statistically related with the initial muscle composition. Results showed significant compositional differences among the mackerel lots, especially for the muscle lipid content (2.83-9.50%). In a first step, a Pearson correlation test was used to check the influence of each component on the progress of lipid oxidation. Results showed a significant relationship between shelf life and water and total lipid contents. Multiple regression was performed to reveal the contribution of each component to the susceptibility to lipid oxidation. The model obtained combines the content of PUFAs, total iron, hemoglobin, and ascorbic acid. An accurate prediction of shelf life in terms of rancidity was achieved by the model created (R(2) = 0.9975). These results establish that the levels of endogenous pro-oxidants and antioxidants present in fish muscle together with the polyunsaturated lipids are relevant factors affecting the shelf life of mackerel muscle.

  11. Distribution, abundance and ecological relevance of pelagic fishes in the Lazarev Sea, Southern Ocean

    NARCIS (Netherlands)

    Florentino De Souza Silva, A.P.; Putte, van de A.P.; Siegel, V.; Pakhomov, E.A.; Franeker, van J.A.; Meesters, H.W.G.; Colckaert, F.A.M.

    2008-01-01

    The distribution and abundance of larval and postlarval fishes was investigated in the Lazarev Sea, Southern Ocean, in March and April 2004. The upper 200 m of the water column were sampled with an 8 m2 rectangular midwater trawl at 93 stations. The larval species community clustered in a diverse co

  12. Distribution, abundance and ecological relevance of pelagic fishes in the Lazarev Sea, Southern Ocean

    NARCIS (Netherlands)

    Flores, Hauke; de Putte, Anton P. Van; Siegel, Volker; Pakhomov, Evgeny A.; Van Franeker, Jan A.; Meesters, Hugo W. G.; Volckaert, Filip A. M.

    2008-01-01

    The distribution and abundance of larval and postlarval fishes was investigated in the Lazarev Sea, Southern Ocean, in March and April 2004. The upper 200 m of the water column were sampled with an 8 m(2) rectangular midwater trawl at 93 stations. The larval species community clustered in a diverse

  13. Gill net selectivity and catch rates of pelagic fish in tropical coastal ...

    African Journals Online (AJOL)

    STORAGESEVER

    2008-11-05

    Nov 5, 2008 ... gillnet selectivity of most tropical lagoon fish is poorly known. Knowledge of the ... continuous train of lagoons and creeks along the coast of Nigeria from the Republic of ..... favourability, since nutrients are flushed form inland and the catchement .... Fishery dynamics and present status of the yellowfin tuna ...

  14. Interactions Between the Cross-Shore Structure of Small Pelagic Fish Population, Offshore Industrial Fisheries and Near Shore Artisanal Fisheries: A Mathematical Approach.

    Science.gov (United States)

    Mchich, Rachid; Brochier, Timothée; Auger, Pierre; Brehmer, Patrice

    2016-12-01

    This work presents a mathematical model describing the interactions between the cross-shore structure of small pelagic fish population an their exploitation by coastal and offshore fisheries. The complete model is a system of seven ODE's governing three stocks of small pelagic fish population moving and growing between three zones. Two types of fishing fleets are inter-acting with the fish population, industrial boats, constrained to offshore area, and artisanal boats, operating from the shore. Two time scales were considered and we use aggregation methods that allow us to reduce the dimension of the model and to obtain an aggregated model, which is a four dimension one. The analysis of the aggregated model is performed. We discuss the possible equilibriums and their meaning in terms of fishery management. An interesting equilibrium state can be obtained for which we can expect coexistence and a stable equilibrium state between fish stocks and fishing efforts. Some identification parameters are also given in the discussion part of the model.

  15. Identifying pelagic fish eggs in the southeast Yucatan Peninsula using DNA barcodes.

    Science.gov (United States)

    Leyva-Cruz, E; Vásquez-Yeomans, L; Carrillo, L; Valdez-Moreno, M

    2016-12-01

    In the waters surrounding Banco Chinchorro in the Mexican Caribbean are spawning and nursery areas for many types of fish. In this natural environment, as opposed to under controlled laboratory conditions, it is almost impossible to link an individual egg to the adult that laid it. This makes identifying the species of the eggs difficult. However, DNA barcodes have made this easier. In the present study, 300 eggs were processed for molecular analysis, from which 139 sequences were obtained. We identified 42 taxa (33 species with their binomial names), 35 genera, and 24 families. The identified eggs included those from Ariomma melanum, which is the first recording of this species in the Mexican Caribbean. Eggs from economically important fish species were also identified, including frigate tuna (Auxis thazard), crevalle jack (Caranx hippos), common dolphinfish (Coryphaena hippurus), sailfish (Istiophorus platypterus), white marlin (Kajikia albida), skipjack tuna (Katsuwonus pelamis), blackfin tuna (Thunnus atlanticus), and swordfish (Xiphias gladius). We have also described new morphological characteristics and captured photographs for 21 species, as well as obtained new information about spawning locality and time for 16 species. This valuable information will provide the basis to develop more effective conservation measures for sustainable fisheries and protection of the Mesoamerican Barrier Reef System.

  16. IDENTIFICATION OF OCEANOGRAPHIC PARAMETERS FOR DETERMINING PELAGIC TUNA FISHING GROUND IN THE NORTH PAPUA WATERS USING MULTI-SENSOR SATELLITE DATA

    Directory of Open Access Journals (Sweden)

    VlNCENTIUS SlREGAR

    2006-01-01

    Full Text Available The North Papua waters as one of the important fi shing grounds in the world contribute approximately 75% of world production of pelagic tunas. These fishing grounds are still determined by hunting method. This method is time consuming and costly. However, in many areas determination of fishing ground using satellited data lias been applied by detecting the important oceanographic parameter of the presence of fish schooling such as, sea surface temperature and chlorophyl. Mostly these parameters are used integrat edly. The aim of this study is to assess the important oceanographic parameters detected from mu lti-sensor satellites (NO AA/AVHRR, Seawifs and Topex Poisedon for determining fishing ground of pelagic tunas in the North Papua waters at east season. The parameters include Sea Surface Temperature (STT, chlorophyl-a and currents. The ava ilability of data from optic sensor (Seawifs: chl-a and AVHRR: Thermal is limited by the presence of cloud cover. In that case, Topex Poseidon satellite data can be used to provide the currents data. The integration of data from multi-sensors increases the availability of the oceanographic parameters for prediction of the potential fishing zones in the study area.

  17. Modern state of the pelagic ecosystem of the Large Aral Sea

    Science.gov (United States)

    Arashkevich, E. G.; Nikishina, A. B.; Soloviev, K. A.; Zhitina, L. S.; Sergeeva, V. M.

    2009-04-01

    During the last five decades, zooplankton of the Aral Sea has been undergoing dramatic changes. Mineralization in the western Large Aral increased from 10 ppt in 1960 to 116 ppt and 211 ppt in the western and eastern basins, correspondingly, in 2008. Concurrently the crucial changes have been occurring in zooplankton community manifesting in the disappearance of most native species and significant decline of biodiversity of the pelagic community. During this period, the number of phytoplankton species dropped more than in order of magnitude. In June 2008, only 29 species were identified in the western basin of Aral Sea, Bacillariophyta - 17 species, Chlorophyta - 5 species, Cryptophyta, Dinophyta, and Cyanophyta - 2 species of each division, and one species of Flagellatae. The average concentration of phytoplankton in terms of number was 2.3*106 cells l-1, in terms of biomass 231 µg C l-1. In the eastern basin, 14 species of Bacillariophyta were found; the dominant species were Amphora coffeaeformis, Fragilaria brevistriata, and Navicula spp. Chlorophyta was presented by only unidentified species. The total number of phytoplankton was 0.9*106 cells l-1, biomass was 93 µg C l-1. Composition of phytoplankton community changed depending on the site and depth. In the eastern basin, where mineralization reached 211 ppt, the community was dominated by diatoms and green algae while in the western basin, with mineralization of 119 ppt, all divisions of algae were presented. The vertical distribution of phytoplankton reflected the light and temperature preferences of the different groups. Bacillariophyta, Chlorophyta, and Cryptophyta peaked at the 20 m depth with the temperature of about of 2°C and low irradiation. Warm-water and light-requiring Cyanophyta inhabited mainly the upper 5-m layer. The number of zooplankton species decreased from 42 species in 1971 to 1 species, the brine shrimp Artemia parthenogenetica, in 2008. Artemia, a typical resident of hypersaline

  18. Spatial, temporal, and habitat-related variation in abundance of pelagic fishes in the Gulf of Mexico: potential implications of the deepwater horizon oil spill.

    Directory of Open Access Journals (Sweden)

    Jay R Rooker

    Full Text Available Time-series data collected over a four-year period were used to characterize patterns of abundance for pelagic fishes in the northern Gulf of Mexico (GoM before (2007-2009 and after (2010 the Deepwater Horizon oil spill. Four numerically dominant pelagic species (blackfin tuna, blue marlin, dolphinfish, and sailfish were included in our assessment, and larval density of each species was lower in 2010 than any of the three years prior to the oil spill, although larval abundance in 2010 was often statistically similar to other years surveyed. To assess potential overlap between suitable habitat of pelagic fish larvae and surface oil, generalized additive models (GAMs were developed to evaluate the influence of ocean conditions on the abundance of larvae from 2007-2009. Explanatory variables from GAMs were then linked to environmental data from 2010 to predict the probability of occurrence for each species. The spatial extent of surface oil overlapped with early life habitat of each species, possibly indicating that the availability of high quality habitat was affected by the DH oil spill. Shifts in the distribution of spawning adults is another factor known to influence the abundance of larvae, and the spatial occurrence of a model pelagic predator (blue marlin was characterized over the same four-year period using electronic tags. The spatial extent of oil coincided with areas used by adult blue marlin from 2007-2009, and the occurrence of blue marlin in areas impacted by the DH oil spill was lower in 2010 relative to pre-spill years.

  19. Can pelagic forage fish and spawning cisco (Coregonus artedi) biomass in the western arm of Lake Superior be assessed with a single summer survey?

    Science.gov (United States)

    Yule, D.L.; Stockwell, J.D.; Schreiner, D.R.; Evrard, L.M.; Balge, M.; Hrabik, T.R.

    2009-01-01

    Management efforts to rehabilitate lake trout Salvelinus namaycush in Lake Superior have been successful and the recent increase in their numbers has led to interest in measuring biomass of pelagic prey fish species important to these predators. Lake Superior cisco Coregonus artedi currently support roe fisheries and determining the sustainability of these fisheries is an important management issue. We conducted acoustic and midwater trawl surveys of the western arm of Lake Superior during three periods: summer (July-August), October, and November 2006 to determine if a single survey can be timed to estimate biomass of both prey fish and spawning cisco. We evaluated our methods by comparing observed trawl catches of small (cisco increased substantially in November, while small bloater Coregonus hoyi biomass was lower. We compared our summer 2006 estimates of total fish biomass to the results of a summer survey in 1997 and obtained similar results. We conclude that the temporal window for obtaining biomass estimates of pelagic prey species in the western arm of Lake Superior is wide (July through October), but estimating spawning cisco abundance is best done with a November survey.

  20. 76 FR 17811 - Western Pacific Pelagic Fisheries; Prohibiting Purse Seine Fishing in the U.S. EEZ Around Guam...

    Science.gov (United States)

    2011-03-31

    ... troll fishery is vulnerable to potential catch competition and gear conflicts with the growing CNMI... this proposed rule. Although more recent troll, longline, and purse seine fishery information has... the CNMI pelagic fishery. CNMI's troll fleet consists primarily of vessels shorter than 24 ft (7.3...

  1. Interaction between spawning habitat and coastally steered circulation regulate larval fish retention in a large shallow temperate bay

    Science.gov (United States)

    Álvarez, Itziar; Catalán, Ignacio A.; Jordi, Antoni; Alemany, Francisco; Basterretxea, Gotzon

    2015-12-01

    Larval retention plays a fundamental role in the persistence of coastal fish assemblages. Here, we examine larval fish distribution and abundance patterns in Palma Bay, a large (˜20 km) wind-driven microtidal bay in the southern coast of Mallorca (Spain, NW Mediterranean Sea). Larval fish assemblage structure in the bay were analyzed during July 2010 and interpreted in the context of the observed circulation patterns, adult habitat distribution and spawning traits. Acoustic Doppler Current Profiler (ADCP) observations showed the presence of retentive flow patterns in the middle of the bay enhancing local larval accumulation and self-recruitment. In consequence, larval abundances were higher in this central part of the bay (˜40 m depth, mean abundance 607.6 ± 383 ind. 10 m-2) than along the coastal fringe (RDA) revealed differences between the larval fish assemblages in areas inside the bay, constituted by small pelagic and benthopelagic taxa (gobids, Chromis chromis and Serranus hepatus) and offshore larvae, mostly from meso and large pelagic fish. These larval fish assemblages were structured according to depth variations and zooplankton abundance, and remained relatively unmixed because of the circulation patterns in the mouth of the bay that uncouple its dynamics from alongshelf circulation. Even larvae of typically pelagic species that spawn close to the coast (Sardinella aurita, Auxis rochei) were associated with the retentive effect of the bay. Our study highlights the important role of coastal bays in the regulation of coastal fish population dynamics and as hotspots for the maintenance of diversity in the Mediterranean Sea.

  2. Temperature sensitivity of cardiac function in pelagic fishes with different vertical mobilities: yellowfin tuna (Thunnus albacares), bigeye tuna (Thunnus obesus), mahimahi (Coryphaena hippurus), and swordfish (Xiphias gladius).

    Science.gov (United States)

    Galli, Gina L J; Shiels, Holly A; Brill, Richard W

    2009-01-01

    We measured the temperature sensitivity, adrenergic sensitivity, and dependence on sarcoplasmic reticulum (SR) Ca(2+) of ventricular muscle from pelagic fishes with different vertical mobility patterns: bigeye tuna (Thunnus obesus), yellowfin tuna (Thunnus albacares), and mahimahi (Coryphaena hippurus) and a single specimen from swordfish (Xiphias gladius). Ventricular muscle from the bigeye tuna and mahimahi exhibited a biphasic response to an acute decrease in temperature (from 26 degrees to 7 degrees C); twitch force and kinetic parameters initially increased and then declined. The magnitude of this response was larger in the bigeye tuna than in the mahimahi. Under steady state conditions at 26 degrees C, inhibition of SR Ca(2+) release and reuptake with ryanodine and thapsigargin decreased twitch force and kinetic parameters, respectively, in the bigeye tuna only. However, the initial inotropy associated with decreasing temperature was abolished by SR inhibition in both the bigeye tuna and the mahimahi. Application of adrenaline completely reversed the effects of ryanodine and thapsigargin, but this effect was diminished at cold temperatures. In the yellowfin tuna, temperature and SR inhibition had minor effects on twitch force and kinetics, while adrenaline significantly increased these parameters. Limited data suggest that swordfish ventricular muscle responds to acute temperature reduction, SR inhibition, and adrenergic stimulation in a manner similar to that of bigeye tuna ventricular muscle. In aggregate, our results show that the temperature sensitivity, SR dependence, and adrenergic sensitivity of pelagic fish hearts are species specific and that these differences reflect species-specific vertical mobility patterns.

  3. 远洋金枪鱼围网渔船总布置特征%General Arrangement Features for Pelagic Fishing Boat of Tuna Purse Net

    Institute of Scientific and Technical Information of China (English)

    孙文志; 卢振义; 张维英; 李明; 刁有明

    2011-01-01

    在收集一些实船图纸资料,实船调查、总结和分析的基础上,阐述了远洋金枪鱼围网渔船总布置的基本原则及其特征,同时根据远洋金枪鱼围网渔船的渔捞作业特点,说明了渔捞设备布置形式和作业流程,以及"内胆式"浓盐水舱速冻作业流程及其特点.可为远洋金枪鱼围网渔船总布置设计提供参考.%The basic principles and features of general arrangement of pelagic tuna purse net are expounded based on collecting some drawing and deep investigation on existed ships. According to the operating characteristics of tuna purse net, the general form of fishing equipment and technological process are also presented and the quick-freezes operation technological process and their characteristics of brine cabin which form is lining are depicted. It provides a reference model for pelagic fishing boat of tuna purse net general arrangement design.

  4. Fish parasites in the Arctic deep-sea: Poor diversity in pelagic fish species vs. heavy parasite load in a demersal fish

    Science.gov (United States)

    Klimpel, Sven; Palm, Harry Wilhelm; Busch, Markus Wilhelm; Kellermanns, Esra; Rückert, Sonja

    2006-07-01

    A total of 219 deep-sea fishes belonging to five families were examined for the parasite fauna and stomach contents. The demersal fish Macrourus berglax, bathypelagic Bathylagus euryops, and mesopelagic Argentina silus, Borostomias antarcticus, Chauliodus sloani, and Lampanyctus macdonaldi were caught at 243-708 m trawling depth in the Greenland and the Irminger Sea in 2002. A total of 21 different parasite species, six Digenea, one Monogenea, two Cestoda, seven Nematoda, one Acanthocephala, and four Crustacea, were found. The parasite diversity in the meso- and bathypelagic environment was less diverse in comparison to the benthal. Macrourus berglax had the highest diversity (20 species), usually carrying 4-10 different parasite species (mean 7.1), whereas Bathylagus euryops harbored up to three and Argentina silus, Borostomias antarcticus, Chauliodus sloani and Lampanyctus macdonaldi each up to two species. Most Digenea, Cestoda, Nematoda, Acanthocephala, and Crustacea are known from a wide host range. Several of the encountered parasites occurred at a very low prevalence (<10%), indicating that the studied deep-sea fishes are most probably not instrumental to complete the parasite life cycles in the area of investigation. It is suggested that the lack of nutrients in the meso- and bathypelagial limits the abundance of potential first intermediate hosts of nematodes and cestodes, resulting in low infestation rates even of widely distributed, non-specific species. In contrast, the higher biomass in the benthic deep-sea environment increases the availability of potential intermediate hosts, such as molluscs for the digeneans, resulting in increased parasite diversity. Because many deep-sea fish have a generalistic feeding behavior, the observed different parasite diversity reflects a different depth range of the fish and not necessarily a specific fish feeding ecology.

  5. Pelagic larval duration and settlement size of a reef fish are spatially consistent, but post-settlement growth varies at the reef scale

    Science.gov (United States)

    Leahy, Susannah M.; Russ, Garry R.; Abesamis, Rene A.

    2015-12-01

    Recent research has demonstrated that, despite a pelagic larval stage, many coral reef fishes disperse over relatively small distances, leading to well-connected populations on scales of 0-30 km. Although variation in key biological characteristics has been explored on the scale of 100-1000 s of km, it has rarely been explored at the scale relevant to actual larval dispersal and population connectivity on ecological timescales. In this study, we surveyed the habitat and collected specimens ( n = 447) of juvenile butterflyfish, Chaetodon vagabundus, at nine sites along an 80-km stretch of coastline in the central Philippines to identify variation in key life history parameters at a spatial scale relevant to population connectivity. Mean pelagic larval duration (PLD) was 24.03 d (SE = 0.16 d), and settlement size was estimated to be 20.54 mm total length (TL; SE = 0.61 mm). Both traits were spatially consistent, although this PLD is considerably shorter than that reported elsewhere. In contrast, post-settlement daily growth rates, calculated from otolith increment widths from 1 to 50 d post-settlement, varied strongly across the study region. Elevated growth rates were associated with rocky habitats that this species is known to recruit to, but were strongly negatively correlated with macroalgal cover and exhibited negative density dependence with conspecific juveniles. Larger animals had lower early (first 50 d post-settlement) growth rates than smaller animals, even after accounting for seasonal variation in growth rates. Both VBGF and Gompertz models provided good fits to post-settlement size-at-age data ( n = 447 fish), but the VBGF's estimate of asymptotic length ( L ∞ = 168 mm) was more consistent with field observations of maximum fish length. Our findings indicate that larval characteristics are consistent at the spatial scale at which populations are likely well connected, but that site-level biological differences develop post-settlement, most likely as a

  6. Can small pelagic fish landings be used as predictors of high-frequency oceanographic fluctuations in the 1-2 El Niño region?

    Science.gov (United States)

    Ormaza-González, Franklin Isaac; Mora-Cervetto, Alejandra; María Bermúdez-Martínez, Raquel; Hurtado-Domínguez, Mario Armando; Raúl Peralta-Bravo, Manuel; Mariuxi Jurado-Maldonado, Viviana

    2016-08-01

    A group of small pelagic fish captured between 1981 and 2012 within El Niño area 1-2 by the Ecuadorian fleet was correlated with the oceanographic Multivariate ENSO Index (MEI), and the Oceanographic El Niño Index (ONI) referred to El Niño region 3-4. For the period 1981-2012, total landings correlated poorly with the indexes, but during 2000-2012 (cold PDO) they proved to have a 14-29 % association with both indexes; the negative slope of the curves suggested higher landing during cold events (La Niña) and also indicated a tendency to decrease at extreme values ( > 0.5 and 1.0 and manage these fisheries and to help the industry in long-term planning.

  7. Large number discrimination in newborn fish.

    Directory of Open Access Journals (Sweden)

    Laura Piffer

    Full Text Available Quantitative abilities have been reported in a wide range of species, including fish. Recent studies have shown that adult guppies (Poecilia reticulata can spontaneously select the larger number of conspecifics. In particular the evidence collected in literature suggest the existence of two distinct systems of number representation: a precise system up to 4 units, and an approximate system for larger numbers. Spontaneous numerical abilities, however, seem to be limited to 4 units at birth and it is currently unclear whether or not the large number system is absent during the first days of life. In the present study, we investigated whether newborn guppies can be trained to discriminate between large quantities. Subjects were required to discriminate between groups of dots with a 0.50 ratio (e.g., 7 vs. 14 in order to obtain a food reward. To dissociate the roles of number and continuous quantities that co-vary with numerical information (such as cumulative surface area, space and density, three different experiments were set up: in Exp. 1 number and continuous quantities were simultaneously available. In Exp. 2 we controlled for continuous quantities and only numerical information was available; in Exp. 3 numerical information was made irrelevant and only continuous quantities were available. Subjects successfully solved the tasks in Exp. 1 and 2, providing the first evidence of large number discrimination in newborn fish. No discrimination was found in experiment 3, meaning that number acuity is better than spatial acuity. A comparison with the onset of numerical abilities observed in shoal-choice tests suggests that training procedures can promote the development of numerical abilities in guppies.

  8. Early life history pelagic exposure profiles of selected commercially important fish species in the Gulf of Alaska

    Science.gov (United States)

    Doyle, Miriam J.; Mier, Kathryn L.

    2016-10-01

    A synthesis of nearly four decades of ichthyoplankton survey data from the Gulf of Alaska was undertaken to provide the most comprehensive information available on the early life history ecology of five focal species: Pacific Cod (Gadus macrocephalus), Walleye Pollock (Gadus chalcogrammus), Pacific Ocean Perch (Sebastes alutus), Sablefish (Anoplopoma fimbria), and Arrowtooth Flounder (Atheresthes stomias). This analysis of historical data, along with information from published studies, is presented here in the form of ecological reviews of the species during their planktonic phase. The reviews include descriptions of temporal and spatial patterns of exposure to the environment, and interpretation regarding associated sensitivities to environmental forcing. On a temporal scale, patterns in abundance of eggs and larvae are synthesized that characterize seasonal exposure to the pelagic environment, and interannual variation that is presumed to incorporate responses to long-term environmental forcing. Spatial patterns are synthesized to identify horizontal and vertical extent of egg and larval distributions, delineate areas of primary larval habitat, and illuminate egg and larval drift pathways. The observed patterns are discussed with respect to characterizing species early life history strategies, identifying long-term adaptations to the Gulf of Alaska environment, and associated resilience and vulnerability factors that may modulate early life responses to environmental forcing in this region. For each species, gaps in knowledge are identified and are concerned primarily with the period of transition between the larval and juvenile stage, and feeding habits and ecology across seasons, habitats and sub-intervals of early ontogeny. These early life history reviews advance our ecological understanding of the pelagic phase, and fine-tune our focus for the investigation of potential response mechanisms to environmental forcing at appropriate, species-specific temporal

  9. 76 FR 13330 - Western Pacific Pelagic Fisheries; Prohibiting Purse Seine Fishing in the U.S. EEZ Around Guam...

    Science.gov (United States)

    2011-03-11

    ... (troll, longline and purse seine) in the Mariana Archipelago. In addition, this action is intended to... potential impacts if purse seine fishing effort shifts to areas fished by domestic troll and longline... impacts to the CNMI troll fishery. If the number of CNMI-based longline vessels increases and move...

  10. Pelagic Fish and Seabird Inter-Relationships in the Central Tropical Pacific: Methods and Approaches to Study and Management

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — In conjunction with the NOAA Pacific Islands Regional Office, Marine Conservation Instituteconducted a three‐day expert workshop in Honolulu, HI to set a framework...

  11. Pelagic Dealer Commercial Landings Monitoring (HMS Dealers)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains summarized pounds of select pelagic fish species bought by selected federally permitted seafood dealers in the SE Region of the US mainland....

  12. Maximum swimming speeds of sailfish and three other large marine predatory fish species based on muscle contraction time and stride length

    DEFF Research Database (Denmark)

    Svendsen, Morten B S; Domenici, Paolo; Marras, Stefano;

    2016-01-01

    , and three other large marine pelagic predatory fish species, by measuring the twitch contraction time of anaerobic swimming muscle. The highest estimated maximum swimming speeds were found in sailfish (8.3±1.4 m s(-1)), followed by barracuda (6.2±1.0 m s(-1)), little tunny (5.6±0.2 m s(-1)) and dorado (4...

  13. Genetic Structure in a Small Pelagic Fish Coincides with a Marine Protected Area: Seascape Genetics in Patagonian Fjords.

    Science.gov (United States)

    Canales-Aguirre, Cristian B; Ferrada-Fuentes, Sandra; Galleguillos, Ricardo; Hernández, Cristián E

    2016-01-01

    Marine environmental variables can play an important role in promoting population genetic differentiation in marine organisms. Although fjord ecosystems have attracted much attention due to the great oscillation of environmental variables that produce heterogeneous habitats, species inhabiting this kind of ecosystem have received less attention. In this study, we used Sprattus fuegensis, a small pelagic species that populates the inner waters of the continental shelf, channels and fjords of Chilean Patagonia and Argentina, as a model species to test whether environmental variables of fjords relate to population genetic structure. A total of 282 individuals were analyzed from Chilean Patagonia with eight microsatellite loci. Bayesian and non-Bayesian analyses were conducted to describe the genetic variability of S. fuegensis and whether it shows spatial genetic structure. Results showed two well-differentiated genetic clusters along the Chilean Patagonia distribution (i.e. inside the embayment area called TicToc, and the rest of the fjords), but no spatial isolation by distance (IBD) pattern was found with a Mantel test analysis. Temperature and nitrate were correlated to the expected heterozygosities and explained the allelic frequency variation of data in the redundancy analyses. These results suggest that the singular genetic differences found in S. fuegensis from inside TicToc Bay (East of the Corcovado Gulf) are the result of larvae retention bya combination of oceanographic mesoscale processes (i.e. the west wind drift current reaches the continental shelf exactly in this zone), and the local geographical configuration (i.e. embayment area, islands, archipelagos). We propose that these features generated an isolated area in the Patagonian fjords that promoted genetic differentiation by drift and a singular biodiversity, adding support to the existence of the largest marine protected area (MPA) of continental Chile, which is the Tic-Toc MPA.

  14. Large River Monitoring Forum Fish Assemblage Database 2016

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Large River Monitoring Forum compiled fish assemblage data for five large rivers in the U.S. as a part of a coordinated effort to compare and contract river...

  15. Structure of deep-sea pelagic fish assemblages in relation to the Mid-Atlantic Ridge (45° 50°N)

    Science.gov (United States)

    Fock, Heino O.; Pusch, Christian; Ehrich, Siegfried

    2004-07-01

    Pelagic fishes from depths of 250 to 3200 m from 45°N to 50°N were sampled during a mid-Atlantic cruise in 1982. These clustered into 6 assemblages, which were related to the Mid-Atlantic Ridge, the continental shelf edge and oceanic habitats. Spatial distribution of clusters coincided with SST and surface chlorophyll patterns. Cluster distribution further coincided with published mid-depth hydrography indicating that hydrographic recirculation features were an important determinant of community structure. Over the ridge, Melamphaidae, Serrivomeridae, Stomiidae and Centrolophidae increased in abundance. Horizontally, the myctophid Benthosema glaciale indicated the transition from temperate-subtropical to temperate-subarctic waters. The gadid Micromesistius poutassou and the alepocephalid Xenodermichthys copei were characteristic species for the shallow shelf edge assemblage. Vertically, extended depth ranges were stated for assemblages above MAR and the southern leg, as indicated for the species Gonostoma bathyphilum, and Schedophilus medusophagus. This was further tested for the saccopharyngid Saccopharynx ampullaceus. The increase of gelatinous plankton feeders over the ridge, in particular for S. medusophagus, is discussed with respect to a probable increase of gelatinous plankton abundance in the area considered. An error model was developed to address the contamination problem with respect to non-closing devices.

  16. Preservation Obscures Pelagic Deep-Sea Fish Diversity: Doubling the Number of Sole-Bearing Opisthoproctids and Resurrection of the Genus Monacoa (Opisthoproctidae, Argentiniformes).

    Science.gov (United States)

    Poulsen, Jan Yde; Sado, Tetsuya; Hahn, Christoph; Byrkjedal, Ingvar; Moku, Masatoshi; Miya, Masaki

    2016-01-01

    The family Opisthoproctidae (barreleyes) constitutes one of the most peculiar looking and unknown deep-sea fish groups in terms of taxonomy and specialized adaptations. All the species in the family are united by the possession of tubular eyes, with one distinct lineage exhibiting also drastic shortening of the body. Two new species of the mesopelagic opisthoproctid mirrorbelly genus Monacoa are described based on pigmentation patterns of the "sole"-a unique vertebrate structure used in the reflection and control of bioluminescence in most short-bodied forms. Different pigmentation patterns of the soles, previously noted as intraspecific variations based on preserved specimens, are here shown species-specific and likely used for communication in addition to counter-illumination of down-welling sunlight. The genus Monacoa is resurrected from Opisthoproctus based on extensive morphological synaphomorphies pertaining to the anal fin and snout. Doubling the species diversity within sole-bearing opisthoproctids, including recognition of two genera, is unambiguously supported by mitogenomic DNA sequence data. Regular fixation with formalin and alcohol preservation is shown problematic concerning the retention of species-specific pigmentation patterns. Examination or photos of fresh material before formalin fixation is shown paramount for correct species recognition of sole-bearing opisthoproctids-a relatively unknown issue concerning species diversity in the deep-sea pelagic realm.

  17. Inter-annual cascade effect on marine food web: A benthic pathway lagging nutrient supply to pelagic fish stock.

    Science.gov (United States)

    Fernandes, Lohengrin Dias de Almeida; Fagundes Netto, Eduardo Barros; Coutinho, Ricardo

    2017-01-01

    Currently, spatial and temporal changes in nutrients availability, marine planktonic, and fish communities are best described on a shorter than inter-annual (seasonal) scale, primarily because the simultaneous year-to-year variations in physical, chemical, and biological parameters are very complex. The limited availability of time series datasets furnishing simultaneous evaluations of temperature, nutrients, plankton, and fish have limited our ability to describe and to predict variability related to short-term process, as species-specific phenology and environmental seasonality. In the present study, we combine a computational time series analysis on a 15-year (1995-2009) weekly-sampled time series (high-resolution long-term time series, 780 weeks) with an Autoregressive Distributed Lag Model to track non-seasonal changes in 10 potentially related parameters: sea surface temperature, nutrient concentrations (NO2, NO3, NH4 and PO4), phytoplankton biomass (as in situ chlorophyll a biomass), meroplankton (barnacle and mussel larvae), and fish abundance (Mugil liza and Caranx latus). Our data demonstrate for the first time that highly intense and frequent upwelling years initiate a huge energy flux that is not fully transmitted through classical size-structured food web by bottom-up stimulus but through additional ontogenetic steps. A delayed inter-annual sequential effect from phytoplankton up to top predators as carnivorous fishes is expected if most of energy is trapped into benthic filter feeding organisms and their larval forms. These sequential events can explain major changes in ecosystem food web that were not predicted in previous short-term models.

  18. Pacific Remote Islands MNM: Initial Survey Instructions for Pelagic Wildlife

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The estimated millions of seabirds breeding at national wildlife refuges in the central Pacific Ocean are primarily pelagic feeders that obtain the fish and squid...

  19. Overfishing of small pelagic fishes increases trophic overlap between immature and mature striped dolphins in the Mediterranean Sea.

    Science.gov (United States)

    Gómez-Campos, Encarna; Borrell, Assumpció; Cardona, Luis; Forcada, Jaume; Aguilar, Alex

    2011-01-01

    The interactions among diet, ecology, physiology, and biochemistry affect N and C stable isotope signatures in animal tissues. Here, we examined if ecological segregation among animals in relation to sex and age existed by analyzing the signatures of δ(15)N and δ(13)C in the muscle of Western Mediterranean striped dolphins. Moreover, we used a Bayesian mixing model to study diet composition and investigated potential dietary changes over the last two decades in this population. For this, we compared isotope signatures in samples of stranded dolphins obtained during two epizootic events occurring in 1990 and 2007-2008. Mean δ(13)C values for females and males were not significantly different, but age-related variation indicated δ(13)C enrichment in both sexes, suggesting that females and males most likely fed in the same general areas, increasing their consumption of benthic prey with age. Enrichment of δ(15)N was only observed in females, suggesting a preference for larger or higher trophic level prey than males, which could reflect different nutritional requirements. δ(13)C values showed no temporal variation, although the mean δ(15)N signature decreased from 1990 to 2007-2008, which could indicate a dietary shift in the striped dolphin over the last two decades. The results of SIAR indicated that in 1990, hake and sardine together contributed to 60% on the diet of immature striped dolphins, and close to 90% for mature striped dolphins. Conversely, the diet of both groups in 2007-2008 was more diverse, as hake and sardine contributed to less than 40% of the entire diet. These results suggest a dietary change that was possibly related to changes in food availability, which is consistent with the depletion of sardine stocks by fishing.

  20. Overfishing of small pelagic fishes increases trophic overlap between immature and mature striped dolphins in the Mediterranean Sea.

    Directory of Open Access Journals (Sweden)

    Encarna Gómez-Campos

    Full Text Available The interactions among diet, ecology, physiology, and biochemistry affect N and C stable isotope signatures in animal tissues. Here, we examined if ecological segregation among animals in relation to sex and age existed by analyzing the signatures of δ(15N and δ(13C in the muscle of Western Mediterranean striped dolphins. Moreover, we used a Bayesian mixing model to study diet composition and investigated potential dietary changes over the last two decades in this population. For this, we compared isotope signatures in samples of stranded dolphins obtained during two epizootic events occurring in 1990 and 2007-2008. Mean δ(13C values for females and males were not significantly different, but age-related variation indicated δ(13C enrichment in both sexes, suggesting that females and males most likely fed in the same general areas, increasing their consumption of benthic prey with age. Enrichment of δ(15N was only observed in females, suggesting a preference for larger or higher trophic level prey than males, which could reflect different nutritional requirements. δ(13C values showed no temporal variation, although the mean δ(15N signature decreased from 1990 to 2007-2008, which could indicate a dietary shift in the striped dolphin over the last two decades. The results of SIAR indicated that in 1990, hake and sardine together contributed to 60% on the diet of immature striped dolphins, and close to 90% for mature striped dolphins. Conversely, the diet of both groups in 2007-2008 was more diverse, as hake and sardine contributed to less than 40% of the entire diet. These results suggest a dietary change that was possibly related to changes in food availability, which is consistent with the depletion of sardine stocks by fishing.

  1. Comparative ecology of widely distributed pelagic fish species in the North Atlantic: Implications for modelling climate and fisheries impacts

    DEFF Research Database (Denmark)

    Trenkel, V.M.; Huse, G.; MacKenzie, Brian

    2014-01-01

    scombrus), capelin (Mallotus villosus), blue whiting (Micromesistius poutassou), and horse mackerel (Trachurus trachurus), which have distributions extending beyond the continental shelf and predominantly occur on both sides of the North Atlantic. We also include albacore (Thunnus alalunga), bluefin tuna...... (Thunnus thynnus), swordfish (Xiphias gladius), and blue marlin (Makaira nigricans), which, by contrast, show large-scale migrations at the basin scale. We focus on the links between life history processes and the environment, horizontal and vertical distribution, spatial structure and trophic role. Many...

  2. Ecological traits influencing range expansion across large oceanic dispersal barriers: insights from tropical Atlantic reef fishes.

    Science.gov (United States)

    Luiz, Osmar J; Madin, Joshua S; Robertson, D Ross; Rocha, Luiz A; Wirtz, Peter; Floeter, Sergio R

    2012-03-01

    How do biogeographically different provinces arise in response to oceanic barriers to dispersal? Here, we analyse how traits related to the pelagic dispersal and adult biology of 985 tropical reef fish species correlate with their establishing populations on both sides of two Atlantic marine barriers: the Mid-Atlantic Barrier (MAB) and the Amazon-Orinoco Plume (AOP). Generalized linear mixed-effects models indicate that predictors for successful barrier crossing are the ability to raft with flotsam for the deep-water MAB, non-reef habitat usage for the freshwater and sediment-rich AOP, and large adult-size and large latitudinal-range for both barriers. Variation in larval-development mode, often thought to be broadly related to larval-dispersal potential, is not a significant predictor in either case. Many more species of greater taxonomic diversity cross the AOP than the MAB. Rafters readily cross both barriers but represent a much smaller proportion of AOP crossers than MAB crossers. Successful establishment after crossing both barriers may be facilitated by broad environmental tolerance associated with large body size and wide latitudinal-range. These results highlight the need to look beyond larval-dispersal potential and assess adult-biology traits when assessing determinants of successful movements across marine barriers.

  3. The feediIlg biology of four predatory reef fishes off the south ...

    African Journals Online (AJOL)

    authors recorded only four positively identified fish prey species while a large .... Petrus rupestris. Petrus rupestris is a large demersal carnivore associated with ..... False Bay and possible effects of pelagic purse-seining on their food supply. Fish. .... Food and feeding ecology of piscivorous fishes at Lake St Lucia, Zululand.

  4. Major correlates of mercury in small fish and common loons (Gavia immer) across four large study areas in Canada.

    Science.gov (United States)

    Scheuhammer, A M; Lord, S I; Wayland, M; Burgess, N M; Champoux, L; Elliott, J E

    2016-03-01

    We investigated mercury (Hg) concentrations in small fish (mainly yellow perch, Perca flavescens; ∼60% of fish collected) and in blood of common loons (Gavia immer) that prey upon them during the breeding season on lakes in 4 large, widely separated study areas in Canada (>13 lakes per study area; total number of lakes = 93). Although surface sediments from lakes near a base metal smelter in Flin Flon, Manitoba had the highest Hg concentrations, perch and other small fish and blood of common loon chicks sampled from these same lakes had low Hg concentrations similar to those from uncontaminated reference lakes. Multiple regression modeling with AIC analysis indicated that lake pH was by far the most important single factor influencing perch Hg concentrations in lakes across the four study areas (R(2) = 0.29). The best model was a three-variable model (pH + alkalinity + sediment Se; Wi = 0.61, R(2) = 0.85). A single-variable model (fish Hg) best explained among-lake variability in loon chick blood Hg (Wi = 0.17; R(2) = 0.53). From a toxicological risk perspective, all lakes posing a potential Hg health risk for perch and possibly other small pelagic fish species (where mean fish muscle Hg concentrations exceeded 2.4 μg/g dry wt.), and for breeding common loons (where mean fish muscle Hg concentrations exceeded 0.8 μg/g dry wt., and loon chick blood Hg exceeded 1.4 μg/g dry wt.) had pH < 6.7 and were located in eastern Canada.

  5. Fall 2011 Small Pelagics Survey (PC1108, EK60)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Objectives of the Fall 2011 Small Pelagics Survey were to sample the waters of the northern Gulf of Mexico less than 500 meters deep with 90-ft high opening fish...

  6. Fall 2010 Small Pelagics Survey (PC1006, EK60)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Objectives of the Fall 2010 Small Pelagics Survey were to sample the waters of the northern Gulf of Mexico less than 500 meters deep with 90-ft high opening fish...

  7. Predicting the Presence of Large Fish through Benthic Geomorphic Features

    Science.gov (United States)

    Knuth, F.; Sautter, L.; Levine, N. S.; Kracker, L.

    2013-12-01

    Marine Protected Areas are critical in sustaining the resilience of fish populations to commercial fishing operations. Using acoustic data to survey these areas promises efficiency, accuracy, and minimal environmental impact. In July, 2013, the NOAA Ship Pisces collected bathymetric, backscatter and water column data for 10 proposed MPA sites along the U.S. Southeast Atlantic continental shelf. A total of 205 km2 of seafloor were mapped between Mayport, FL and Wilmington, NC, using the SIMRAD ME70 and EK60 echosounder systems. These data were processed in Caris HIPS, QPS FMGT, MATLAB and ArcGIS. The backscatter and bathymetry reveal various benthic geomorphic features, including flat sand, rippled sand, and rugose hard bottom. Water column data directly above highly rugose hardbottom contains the greatest counts for large fish populations. Using spatial statistics, such as a geographically weighted regression model, we aim to identify features of the benthic profile, including rugosity, curvature and slope, that can predict the presence of large fish. The success of this approach will greatly expedite fishery surveys, minimize operational cost and aid in making timely management decisions.

  8. The response of the North Sea demersal fish community to changing fishing pressure as seen through the prism of the large fish indicator

    NARCIS (Netherlands)

    Stamoulis, Antonios; Torreele, Els

    2016-01-01

    The large fish indicator (LFI) is a size-based indicator of fish community state. In the North Sea, the LFI is already established as the fish community's Ecological Quality Objective (OSPAR-EcoQO). The LFI has also been proposed as an indicator for food webs and for monitoring of biodiversity in

  9. Mercury in the pelagic food web of Lake Champlain.

    Science.gov (United States)

    Miller, Eric K; Chen, Celia; Kamman, Neil; Shanley, James; Chalmers, Ann; Jackson, Brian; Taylor, Vivien; Smeltzer, Eric; Stangel, Pete; Shambaugh, Angela

    2012-04-01

    Lake Champlain continues to experience mercury contamination resulting in public advisories to limit human consumption of top trophic level fish such as walleye. Prior research suggested that mercury levels in biota could be modified by differences in ecosystem productivity as well as mercury loadings. We investigated relationships between mercury in different trophic levels in Lake Champlain. We measured inorganic and methyl mercury in water, seston, and two size fractions of zooplankton from 13 sites representing a range of nutrient loading conditions and productivity. Biomass varied significantly across lake segments in all measured ecosystem compartments in response to significant differences in nutrient levels. Local environmental factors such as alkalinity influenced the partitioning of mercury between water and seston. Mercury incorporation into biota was influenced by the biomass and mercury content of different ecosystem strata. Pelagic fish tissue mercury was a function of fish length and the size of the mercury pool associated with large zooplankton. We used these observations to parameterize a model of mercury transfers in the Lake Champlain food web that accounts for ecosystem productivity effects. Simulations using the mercury trophic transfer model suggest that reductions of 25-75% in summertime dissolved eplimnetic total mercury will likely allow fish tissue mercury concentrations to drop to the target level of 0.3 μg g(-1) in a 40-cm fish in all lake segments. Changes in nutrient loading and ecosystem productivity in eutrophic segments may delay any response to reduced dissolved mercury and may result in increases in fish tissue mercury.

  10. Long-term, Ecosystem-Scale Changes in the Southern Benguela Marine Pelagic Social-Ecological System: Interaction of Natural and Human Drivers

    Directory of Open Access Journals (Sweden)

    Astrid Jarre

    2013-12-01

    Full Text Available South Africa's small pelagics fishery is currently the largest in volume and second largest in value in the southern Benguela. It exploits short-lived, small pelagic fishes such as anchovy (for reduction into fish meal and oil and sardine (for reduction as well as human consumption through canned products, and to a lesser extent redeye round herring and mesopelagics, largely for reduction. We explore the recent history (1940s to present of the social-ecological system around this fishery. The natural subsystem, at the scales of the ocean environment and the ecosystem, is characterized by high interannual and documented decadal-scale variability. We characterize the human social subsystem at the scales of the fishing industry, legislation, and west coast fishing towns, and demonstrate interdependencies between the natural and social subsystems by following system-scale changes. The pelagic fishing industry has evolved to deal with variability through consolidation, diversification, and range expansion. Legislation has increasingly looked for conservation of the resource while ensuring economic viability of the industry, and hence factory- and vessel-related jobs. Fishing communities under apartheid stayed largely dependent on company-generated infrastructure, combining seasonal employment in the fishing factories with inshore fishing, targeting rock lobster and line fish. While the pelagic industry persisted and communities survived, the resource base for both offshore and inshore fisheries gradually eroded. The advent of democracy in the mid-1990s brought allocation of long-term fishing rights to individuals or companies under conditions of depleted inshore resources aggravated by a shift in the distribution of pelagic fish away from the west coast towards the Cape south coast in the second half of the 1990s. The resultant loss of employment and fishing rights in the inshore has generated community coping strategies that include poaching and

  11. 福建省主要海湾浮性鱼卵和仔稚鱼的种类组成与丰度分布%Composition of species and distribution of abundance of pelagic fish eggs, larvae and juveniles in main bays of Fujian

    Institute of Scientific and Technical Information of China (English)

    张跃平

    2011-01-01

    根据2007年8月至2009年10月期间在福建省主要海湾的调查资料,对其浮性鱼卵和仔稚鱼的种类组成与数量分布特点进行初步研究和探讨.结果表明,本调查海域共出现鱼卵和仔稚鱼68种,隶属于29科,主要是近海中上层鱼类、浅海底层鱼类和港湾河口型鱼类3个生态类型.各站鱼卵总平均丰度是497.5粒/网,仔稚鱼总平均丰度50.8个/网.优势种明显,占总量比例大;不同季节和不同海湾的种类数相差不大;数量平面分布呈现不同季节不同海湾差别较大,规律性不强,偶然性大等特点.%Many coastal constructing projects in Fujian seriously impact fishery resources in sea bays. Distributions of species and abundances of fish eggs, larvae and juveniles, which are very sensitive to environmental change, are important parameters in assessment of fishery resources; however, there are scant data at present. According to the instructions of The Specification for Marine Monitoring, part 7: Ecological survey of offshore pollution and biological monitoring, 62 stations in the main bays of Fujian were included in the survey of pelagic fish eggs, larvae and juveniles from August 2007 to October 2009. A total of 30 844 fish eggs and 3 150 larvae and juveniles were obtained. Using the survey data, the distributions of species and abundances of pelagic fish eggs, larvae and juveniles are discussed in this paper. The results show 68 species, belonging to 29 families, which can be classified into three eco-types: epipelagic and mesopelagic fish, shallow-water benthic fish, and estuarine fish. The total mean abundance of fish eggs is 497.5 ind/net, and that of larvae and juveniles is 50.8 indt/net. Dominant species account for a large proportion of the total number of individuals. The number of species is similar for different seasons and bays. The abundance distribution differs for different seasons and bays, and is irregular and random. The data can be used to guide

  12. You can swim but you can't hide: the global status and conservation of oceanic pelagic sharks and rays

    OpenAIRE

    Dulvy, N. K.; Baum, J.K.; Clarke, S; Compagno, L.J.V.; Cortes, E.; Domingo, A.; Fordham, S.; Fowler, S; Francis, M.P.; Gibson, C; Martinez, J.; Musick, J A; Soldo, A; Stevens, J D; Valenti, S.

    2008-01-01

    1. Fishing spans all oceans and the impact on ocean predators such as sharks and rays is largely unknown. A lack of data and complicated jurisdictional issues present particular challenges for assessing and conserving high seas biodiversity. It is clear, however, that pelagic sharks and rays of the open ocean are subject to high and often unrestricted levels of mortality from bycatch and targeted fisheries for their meat and valuable fins. 2. These species exhibit a wide range of life-history...

  13. The importance of benthic-pelagic coupling for marine ecosystem functioning in a changing world

    DEFF Research Database (Denmark)

    Griffiths, Jennifer R.; Kadin, Martina; Nascimento, Francisco J. A.

    2017-01-01

    and function is strongly affected by anthropogenic pressures, however there are large gaps in our understanding of the responses of inorganic nutrient and organic matter fluxes between benthic habitats and the water column. We illustrate the varied nature of physical and biological benthic-pelagic coupling...... processes and their potential sensitivity to three anthropogenic pressures - climate change, nutrient loading, and fishing - using the Baltic Sea as a case study, and summarize current knowledge on the exchange of inorganic nutrients and organic material between habitats. Traditionally measured benthic......-pelagic coupling processes (e.g. nutrient exchange and sedimentation of organic material) are to some extent quantifiable but the magnitude and variability of biological processes are rarely assessed, preventing quantitative comparisons. Changing oxygen conditions will continue to have widespread effects...

  14. Elucidating fishing effects in a large-predator dominated system: The case of Darwin and Wolf Islands (Galápagos)

    Science.gov (United States)

    Ruiz, Diego J.; Banks, Stuart; Wolff, Matthias

    2016-01-01

    Fifty years of artisanal fishing history in Galápagos characterized by boom and bust of resources has changed the natural marine community structure close to fishing ports in the Galápagos Marine Reserve. Nonetheless, the remote Darwin and Wolf Islands are still in a "near natural state" harboring high species richness unique for the archipelago and high biomass. Marine life that aggregates to the pinnacles linked to the wider oceanic seascape makes them interesting and unique systems in terms of community structure and study of on-shore/offshore trophic interactions. Although > 200 km from local fishing ports the two islands also support an artisanal fishery targeting large demersal predators of high trophic levels. They are areas prioritized for conservation actions by Galápagos National Park, and local non-governmental organizations given their natural heritage importance, value to local fishers and revenue from dive tourism attracted by the promise of large marine predator aggregations such as sharks. Given that catch data upon which to base conservation recommendations is sparse it is difficult to accurately estimate present day fishing trends in Darwin and Wolf. We used a trophic steady-state model that connects benthic and pelagic communities to assess the potential effects of a change in fishing intensity in the two islands system. A predator-prey matrix was built using the Ecopath with Ecosim (EwE) software with total biomass estimated at 937 t km- 2. Large fish aggregations accounted for 19%, primary producers for 9.0% and non-fish (seabirds, marine mammals and sea turtles) for less than 0.1% of the total living biomass. The total system size in terms of overall flows was 16,652 t km- 2 year- 1, four times larger than a generic seamount model but smaller than that modeled for a Galápagos upwelling system based upon the western Bolivar Channel region. Consumption and respiration dominated the flows in the system (53.4 and 31.8% respectively). The

  15. Life histories, salinity zones, and sublethal contributions of contaminants to pelagic fish declines illustrated with a case study of San Francisco Estuary, California, USA

    Science.gov (United States)

    Brooks, Marjorie L.; Fleishman, Erica; Brown, Larry R.; Lehman, Peggy W.; Werner, Inge; Scholz, Nathaniel; Michelmore, Carys; Loworn, James R.; Johnson, Michael L.; Schlenk, Daniel

    2012-01-01

    Human effects on estuaries are often associated with major decreases in abundance of aquatic species. However, remediation priorities are difficult to identify when declines result from multiple stressors with interacting sublethal effects. The San Francisco Estuary offers a useful case study of the potential role of contaminants in declines of organisms because the waters of its delta chronically violate legal water quality standards; however, direct effects of contaminants on fish species are rarely observed. Lack of direct lethality in the field has prevented consensus that contaminants may be one of the major drivers of coincident but unexplained declines of fishes with differing life histories and habitats (anadromous, brackish, and freshwater). Our review of available evidence indicates that examining the effects of contaminants and other stressors on specific life stages in different seasons and salinity zones of the estuary is critical to identifying how several interacting stressors could contribute to a general syndrome of declines. Moreover, warming water temperatures of the magnitude projected by climate models increase metabolic rates of ectotherms, and can hasten elimination of some contaminants. However, for other pollutants, concurrent increases in respiratory rate or food intake result in higher doses per unit time without changes in the contaminant concentrations in the water. Food limitation and energetic costs of osmoregulating under altered salinities further limit the amount of energy available to fish; this energy must be redirected from growth and reproduction toward pollutant avoidance, enzymatic detoxification, or elimination. Because all of these processes require energy, bioenergetics methods are promising for evaluating effects of sublethal contaminants in the presence of other stressors, and for informing remediation. Predictive models that evaluate the direct and indirect effects of contaminants will be possible when data become

  16. Abundance and distribution of Arctic cod (Boreogadus saida) and other pelagic fishes over the U.S. Continental Shelf of the Northern Bering and Chukchi Seas

    Science.gov (United States)

    De Robertis, Alex; Taylor, Kevin; Wilson, Christopher D.; Farley, Edward V.

    2017-01-01

    We conducted acoustic-trawl (AT) surveys of the northern Bering and Chukchi Seas during ice-free periods in 2012 and 2013. The mixed species assemblages in the study area required refinement of standard AT survey methods, and adjustment of trawl catches for the effects of trawl selectivity. Sensitivity analyses indicate that the AT abundance estimates are relatively robust to the assumptions of the analysis. These surveys indicate that midwater fishes are dominated by age-0 Arctic cod (Boreogadus saida), age-0 saffron cod (Eleginus gracilis), capelin (Mallotus villosus), and Pacific herring (Clupea pallasii). In both years, age-0 Arctic cod were distributed principally ≥69.5 °N, age-0 saffron cod were abundant in coastal areas between 66.5 and 69.5 °N, and Pacific herring were distributed south of 67 °N. These three fishes exhibited consistent associations with temperature, salinity and bottom depth: e.g., age-0 Arctic cod were abundant at lower mean water column temperatures than saffron cod. In contrast, capelin were distributed throughout the study area, and were not consistently associated with environmental measures. There was a geographic trend in body length, with smaller Arctic cod, saffron cod and capelin in northern areas, but smaller herring in the south. Arctic cod, saffron cod, herring and capelin were all >2 times more abundant in 2013 than 2012. Sizeable populations of age-0 Arctic cod were observed in the northern Chukchi Sea, which suggests that this area is an important nursery ground. However, relatively few older Arctic cod were observed in this and other surveys of the area, which suggests that either overwinter mortality of age-0 Arctic cod is high, and/or these fish are not retained on the Chukchi shelf.

  17. Contrasting time trends of organic contaminants in Antarctic pelagic and benthic food webs

    NARCIS (Netherlands)

    Brink, van den N.W.; Riddle, M.J.; Heuvel-Greve, van den M.J.; Franeker, van J.A.

    2011-01-01

    We demonstrate that pelagic Antarctic seabirds show significant decreases in concentrations of some persistent organic pollutants. Trends in Adélie penguins and Southern fulmars fit in a general pattern revealed by a broad literature review. Downward trends are also visible in pelagic fish, contrast

  18. Demonstration of a fully-coupled end-to-end model for small pelagic fish using sardine and anchovy in the California Current

    Science.gov (United States)

    Rose, Kenneth A.; Fiechter, Jerome; Curchitser, Enrique N.; Hedstrom, Kate; Bernal, Miguel; Creekmore, Sean; Haynie, Alan; Ito, Shin-ichi; Lluch-Cota, Salvador; Megrey, Bernard A.; Edwards, Chris A.; Checkley, Dave; Koslow, Tony; McClatchie, Sam; Werner, Francisco; MacCall, Alec; Agostini, Vera

    2015-11-01

    We describe and document an end-to-end model of anchovy and sardine population dynamics in the California Current as a proof of principle that such coupled models can be developed and implemented. The end-to-end model is 3-dimensional, time-varying, and multispecies, and consists of four coupled submodels: hydrodynamics, Eulerian nutrient-phytoplankton-zooplankton (NPZ), an individual-based full life cycle anchovy and sardine submodel, and an agent-based fishing fleet submodel. A predator roughly mimicking albacore was included as individuals that consumed anchovy and sardine. All submodels were coded within the ROMS open-source community model, and used the same resolution spatial grid and were all solved simultaneously to allow for possible feedbacks among the submodels. We used a super-individual approach and solved the coupled models on a distributed memory parallel computer, both of which created challenging but resolvable bookkeeping challenges. The anchovy and sardine growth, mortality, reproduction, and movement, and the fishing fleet submodel, were each calibrated using simplified grids before being inserted into the full end-to-end model. An historical simulation of 1959-2008 was performed, and the latter 45 years analyzed. Sea surface height (SSH) and sea surface temperature (SST) for the historical simulation showed strong horizontal gradients and multi-year scale temporal oscillations related to various climate indices (PDO, NPGO), and both showed responses to ENSO variability. Simulated total phytoplankton was lower during strong El Nino events and higher for the strong 1999 La Nina event. The three zooplankton groups generally corresponded to the spatial and temporal variation in simulated total phytoplankton. Simulated biomasses of anchovy and sardine were within the historical range of observed biomasses but predicted biomasses showed much less inter-annual variation. Anomalies of annual biomasses of anchovy and sardine showed a switch in the mid

  19. 云雾混合计算改进远洋渔船物联网系统通讯质量%Improving communication quality of internet of things for pelagic fishing vessel by blended fog computing and cloud computing

    Institute of Scientific and Technical Information of China (English)

    杨劲松; 虞丽娟; 凌培亮; 陈成明; 夏俊

    2014-01-01

    远洋渔船上不断增加的船载智能设备和传感器增大了对网络通讯带宽和流量的要求,目前船岸间通讯的高昂费用和带宽限制成为整个系统的瓶颈。该文在远洋渔船作业系统中引入云雾混合计算架构。研究以云计算为基本架构,采用面向服务的构架,提供可靠和安全的数据存储中心,降低了对用户端的设备要求,利于不同设备间的数据与应用共享;同时,利用船载设备的计算和存储能力,采用雾计算架构的设备固件更新分发机制获取最少必要固件资源后在船载网络内部进行推送和更新,并利用船载传感网络雾计算模型在船载网络内部存储和压缩传感器环境数据,以降低船岸之间的数据通讯量。研究证明,云雾混合计算架构在保证船岸数据信息交互一体化的同时明显降低了对数据通讯带宽的要求,减少了网络流量。在测试期内,开富号各计算节点及传感设备固件更新文件数据量降低为传统架构的15.13%,传感器发往云端的报文数据量降低为传统架构的4.75%。参考卫星宽带流量套餐费用计算(1 MB费用约为10美元,2014年标准),在该时间段内,仅“开富号”一条船舶约节约7500美元,每年能节约通讯费36000美元,具有一定的经济效益。研究实践证明云雾混合计算有利于改善远洋渔船物联网系统通讯质量。%The communication bandwidth from pelagic fishing vessel to shore was unable to cope with the increasing needs of smart devices and sensors on vessel. Fog computing and cloud computing were combined to solve this problem effectively in operating system of pelagic fishing vessel. Cloud computing could be used as the basic framework of system. Fog computing could be used as model in the local area network and sensor network on vessel. This mixed computing architectures could effectively play the advantages of each other and have a

  20. Environmental factors affecting large-bodied coral reef fish assemblages in the Mariana Archipelago.

    Directory of Open Access Journals (Sweden)

    Benjamin L Richards

    Full Text Available Large-bodied reef fishes represent an economically and ecologically important segment of the coral reef fish assemblage. Many of these individuals supply the bulk of the reproductive output for their population and have a disproportionate effect on their environment (e.g. as apex predators or bioeroding herbivores. Large-bodied reef fishes also tend to be at greatest risk of overfishing, and their loss can result in a myriad of either cascading (direct or indirect trophic and other effects. While many studies have investigated habitat characteristics affecting populations of small-bodied reef fishes, few have explored the relationship between large-bodied species and their environment. Here, we describe the distribution of the large-bodied reef fishes in the Mariana Archipelago with an emphasis on the environmental factors associated with their distribution. Of the factors considered in this study, a negative association with human population density showed the highest relative influence on the distribution of large-bodied reef fishes; however, depth, water temperature, and distance to deep water also were important. These findings provide new information on the ecology of large-bodied reef fishes can inform discussions concerning essential fish habitat and ecosystem-based management for these species and highlight important knowledge gaps worthy of additional research.

  1. Quantifying pelagic-benthic coupling in the North Sea: Are we asking the right question?

    DEFF Research Database (Denmark)

    Richardson, K.; Cedhagen, T.

    2002-01-01

    fished region such as the North Sea where deployment of sediment traps or bottom mounted cameras or samplers is difficult. Thus, there are relatively few sites in the North Sea for which good data are available for describing pelagic-benthic (or near shore-offsbore) coupling and considerable effort...... of energy and nutrients. We argue that foraminiferans may deserve more study in this respect. Their large numbers in combination with structural and physiological adaptations suggest that these organisms may be of greater importance than other meiofaunal organisms of comparative size and abundance....

  2. Native fish conservation areas: A vision for large-scale conservation of native fish communities

    Science.gov (United States)

    Williams, Jack E.; Williams, Richard N.; Thurow, Russell F.; Elwell, Leah; Philipp, David P.; Harris, Fred A.; Kershner, Jeffrey L.; Martinez, Patrick J.; Miller, Dirk; Reeves, Gordon H.; Frissell, Christopher A.; Sedell, James R.

    2011-01-01

    The status of freshwater fishes continues to decline despite substantial conservation efforts to reverse this trend and recover threatened and endangered aquatic species. Lack of success is partially due to working at smaller spatial scales and focusing on habitats and species that are already degraded. Protecting entire watersheds and aquatic communities, which we term "native fish conservation areas" (NFCAs), would complement existing conservation efforts by protecting intact aquatic communities while allowing compatible uses. Four critical elements need to be met within a NFCA: (1) maintain processes that create habitat complexity, diversity, and connectivity; (2) nurture all of the life history stages of the fishes being protected; (3) include a long-term enough watershed to provide long-term persistence of native fish populations; and (4) provide management that is sustainable over time. We describe how a network of protected watersheds could be created that would anchor aquatic conservation needs in river basins across the country.

  3. As multiple fish species in large marine ecosystems are harvested ...

    African Journals Online (AJOL)

    CMPTMAC10

    culling to increase fish available for human harvesting ... species to develop positive surplus production invari- ... Whole-ecosystem foodweb models, specifically the dynamic model ECOSIM, contain specific ... of younger animals, would unrealistically overestimate ..... sidered to have sufficient weight to have reproductive.

  4. 76 FR 29718 - Western Pacific Pelagic Fisheries; American Samoa Longline Gear Modifications To Reduce Turtle...

    Science.gov (United States)

    2011-05-23

    ... bigeye tunas. The fishery also takes wahoo, oilfish, blue marlin, blue sharks, and other pelagic fish... turtles (Chelonia mydas), which are listed as threatened under the Endangered Species Act. Most of...

  5. A review of the small pelagics fishery resources of the Dutch Caribbean and adjacent areas

    NARCIS (Netherlands)

    Couperus, A.S.; Beek, van I.J.M.; Debrot, A.O.; Fassler, S.M.M.; Gastauer, S.

    2015-01-01

    This deskstudy gives a review of small pelagic fish species and fisheries in the Dutch Caribbean, specifically species which distributions exceed the national boundaries and where international cooperation in research and management is required.

  6. Southeast Alaska ESI: FISH (Fish Polygons)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains biological resource data for estuarine, benthic, and pelagic fish in Southeast Alaska. Vector polygons in this data set represent locations of...

  7. American Samoa ESI: FISH (Fish Polygons)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains sensitive biological resource data for reef, pelagic, benthic, and estuarine fish species in American Samoa. Vector polygons in this data set...

  8. Competition for shelter in a high-diversity system: structure use by large reef fishes

    Science.gov (United States)

    Kerry, J. T.; Bellwood, D. R.

    2016-03-01

    Competition among large reef fishes for shelter beneath tabular structures provides a rare opportunity to study competition in a species-rich environment. The system permits a detailed study of localised competition with major implications for coral reefs with respect to human impacts including climate change. Using underwater video cameras, this study examined competition among 30 species of large reef fishes (from nine families) for access to shelter provided by 26 tabular structures, which may be the highest reported diversity of vertebrates competing for a single resource. Mean concentrations of fishes under tabular structures were also among the highest biomass recorded on reefs (4.71 kg m-2). A generated dominance hierarchy for the occupation of shelter appeared to be primarily driven by the size of fishes. In contrast to previous studies, fishes higher in the hierarchy tended to exhibit the lowest levels of aggression. However, size difference between fishes was found to be strongly negatively correlated with the proportion of aggressive interactions ( R 2 = 0.971, P concerns about future shifts in the structure of large reef fish communities as corals are lost. This is particularly concerning given the critical functional roles played by certain species of large reef fishes that utilise tabular structure for shelter and which occupy the lower ranks of the dominance hierarchy.

  9. The functional role of tabular structures for large reef fishes: avoiding predators or solar irradiance?

    Science.gov (United States)

    Kerry, J. T.; Bellwood, D. R.

    2015-06-01

    Large reef fishes may often be seen sheltering under tabular structures on coral reefs. There are two principle explanations for this behaviour: avoidance of predation or avoidance of solar irradiance. This study sought supporting evidence to distinguish between these two explanations by examining the usage of tabular structures on a shallow mid-shelf reef of the Great Barrier Reef at midday and sunset. If predation avoidance is most important, usage should increase towards sunset; conversely, if avoidance of solar radiation is most important, more fishes should use cover at midday. Underwater video observations revealed that tabular structures were extensively used by large reef fishes at midday, being characterised by numerous species, especially Lutjanidae and Haemulidae. In contrast, at sunset, tabular structures were used by significantly fewer large reef fishes, being characterised mostly by species of unicornfish ( Naso spp.). Resident times of fishes using tabular structures were also significantly longer at midday (28:06 ± 5:55 min) than at sunset (07:47 ± 2:19 min). The results suggest that the primary function of tabular structures for large reef fishes is the avoidance of solar irradiance. This suggestion is supported by the position of fishes when sheltering. The majority of large reef fishes were found to shelter under the lip of tabular structure, facing outwards. This behaviour is thought to allow protection from harmful downwelling UV-B irradiance while allowing the fish to retain photopic vision and survey more of the surrounding area. These findings help to explain the importance of tabular structures for large reef fishes on coral reefs, potentially providing a valuable energetic refuge from solar irradiance.

  10. Interacting effects of discharge and channel morphology on transport of semibuoyant fish eggs in large, altered river systems.

    Directory of Open Access Journals (Sweden)

    Thomas A Worthington

    Full Text Available Habitat fragmentation and flow regulation are significant factors related to the decline and extinction of freshwater biota. Pelagic-broadcast spawning cyprinids require moving water and some length of unfragmented stream to complete their life cycle. However, it is unknown how discharge and habitat features interact at multiple spatial scales to alter the transport of semi-buoyant fish eggs. Our objective was to assess the relationship between downstream drift of semi-buoyant egg surrogates (gellan beads and discharge and habitat complexity. We quantified transport time of a known quantity of beads using 2-3 sampling devices at each of seven locations on the North Canadian and Canadian rivers. Transport time was assessed based on median capture time (time at which 50% of beads were captured and sampling period (time period when 2.5% and 97.5% of beads were captured. Habitat complexity was assessed by calculating width∶depth ratios at each site, and several habitat metrics determined using analyses of aerial photographs. Median time of egg capture was negatively correlated to site discharge. The temporal extent of the sampling period at each site was negatively correlated to both site discharge and habitat-patch dispersion. Our results highlight the role of discharge in driving transport times, but also indicate that higher dispersion of habitat patches relates to increased retention of beads within the river. These results could be used to target restoration activities or prioritize water use to create and maintain habitat complexity within large, fragmented river systems.

  11. Percentage of microbeads in pelagic microplastics within Japanese coastal waters.

    Science.gov (United States)

    Isobe, Atsuhiko

    2016-09-15

    To compare the quantity of microbeads with the quantity of pelagic microplastics potentially degraded in the marine environment, samples were collected in coastal waters of Japan using neuston nets. Pelagic spherical microbeads were collected in the size range below 0.8mm at 9 of the 26 stations surveyed. The number of pelagic microbeads smaller than 0.8mm accounted for 9.7% of all microplastics collected at these 9 stations. This relatively large percentage results from a decrease in the abundance of microplastics smaller than 0.8mm in the upper ocean, as well as the regular loading of new microbeads from land areas, in this size range. In general, microbeads in personal care and cosmetic products are not always spherical, but rather are often a variety of irregular shapes. It is thus likely that this percentage is a conservative estimate, because of the irregular shapes of the remaining pelagic microbeads.

  12. Restoring piscivorous fish populations in the Laurentian Great Lakes causes seabird dietary change

    Science.gov (United States)

    Hebert, C.E.; Weseloh, D.V.C.; Idrissi, A.; Arts, M.T.; O'Gorman, R.; Gorman, O.T.; Locke, B.; Madenjian, C.P.; Roseman, E.F.

    2008-01-01

    Ecosystem change often affects the structure of aquatic communities thereby regulating how much and by what pathways energy and critical nutrients flow through food webs. The availability of energy and essential nutrients to top predators such as seabirds that rely on resources near the water's surface will be affected by changes in pelagic prey abundance. Here, we present results from analysis of a 25-year data set documenting dietary change in a predatory seabird from the Laurentian Great Lakes. We reveal significant declines in trophic position and alterations in energy and nutrient flow over time. Temporal changes in seabird diet tracked decreases in pelagic prey fish abundance. As pelagic prey abundance declined, birds consumed less aquatic prey and more terrestrial food. This pattern was consistent across all five large lake ecosystems. Declines in prey fish abundance may have primarily been the result of predation by stocked piscivorous fishes, but other lake-specific factors were likely also important. Natural resource management activities can have unintended consequences for nontarget ecosystem components. Reductions in pelagic prey abundance have reduced the capacity of the Great Lakes to support the energetic requirements of surface-feeding seabirds. In an environment characterized by increasingly limited pelagic fish resources, they are being offered a Hobsonian choice: switch to less nutritious terrestrial prey or go hungry. ?? 2008 by the Ecological Society of America.

  13. California Pelagic Longline Fishery

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains catch and effort, landings, and observer data from longline vessels fishing in the North Pacific outside the U.S. west coast EEZ. Logbooks and...

  14. Selective exploitation of large pike Esox lucius-Effects on mercury concentrations in fish populations

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Chhatra Mani [Department of Ecology and Natural Resource Management, Norwegian University of Life Sciences, P.O. Box 5003, 1432 As (Norway)], E-mail: chhatra.sharma@gmail.com; Borgstrom, Reidar [Department of Ecology and Natural Resource Management, Norwegian University of Life Sciences, P.O. Box 5003, 1432 As (Norway)], E-mail: reidar.borgstrom@umb.no; Huitfeldt, Jorgen Sinkaberg [Department of Ecology and Natural Resource Management, Norwegian University of Life Sciences, P.O. Box 5003, 1432 As (Norway)], E-mail: jhu@wang.no; Rosseland, Bjorn Olav [Department of Ecology and Natural Resource Management, Norwegian University of Life Sciences, P.O. Box 5003, 1432 As (Norway)], E-mail: bjorn.rosseland@umb.no

    2008-07-25

    The present study outlines two main trends of mercury transfer patterns through the fish community: 1) the Hg concentrations increase with increase in the trophic level, with top predators having the highest concentrations, and 2) a fast growth rate may dilute the concentrations of Hg in fish muscle tissue (growth biodilution). In 2004, an extensive reduction in number of large pike (Esox lucius L.), was initiated by selective gillnet fishing in Lake Arungen, Norway, in order to increase the pike recruitment due to an expected reduction in cannibalism. In this connection, total mercury (THg) concentrations in the fish community were studied both before (2003) and after (2005) the removal of large pike. The {delta}{sup 15}N signatures and stomach content analyses indicated that pike and perch (Perca fluviatilis L.) occupied the highest trophic position, while roach (Rutilus rutilus (L.)) was at the lower level, and rudd (Scardinius erythrophthalmus L.) at the lowest. The piscivores, pike and perch, had the highest concentrations of THg. The biomagnification rate of THg through the food web in the fish community was 0.163 ( per mille{delta}{sup 15}N), with the highest uptake rate (0.232) in perch. A significant decrease in THg concentrations was found in all fish species in 2005 compared to 2003. Removal of the top predators in an Hg contaminated lake might thus be an important management tool for reducing Hg levels in fish, thereby reducing health risk to humans.

  15. Selective exploitation of large pike Esox lucius--effects on mercury concentrations in fish populations.

    Science.gov (United States)

    Sharma, Chhatra Mani; Borgstrøm, Reidar; Huitfeldt, Jørgen Sinkaberg; Rosseland, Bjørn Olav

    2008-07-25

    The present study outlines two main trends of mercury transfer patterns through the fish community: 1) the Hg concentrations increase with increase in the trophic level, with top predators having the highest concentrations, and 2) a fast growth rate may dilute the concentrations of Hg in fish muscle tissue (growth biodilution). In 2004, an extensive reduction in number of large pike (Esox lucius L.), was initiated by selective gillnet fishing in Lake Arungen, Norway, in order to increase the pike recruitment due to an expected reduction in cannibalism. In this connection, total mercury (THg) concentrations in the fish community were studied both before (2003) and after (2005) the removal of large pike. The delta(15)N signatures and stomach content analyses indicated that pike and perch (Perca fluviatilis L.) occupied the highest trophic position, while roach (Rutilus rutilus (L.)) was at the lower level, and rudd (Scardinius erythrophthalmus L.) at the lowest. The piscivores, pike and perch, had the highest concentrations of THg. The biomagnification rate of THg through the food web in the fish community was 0.163 (per thousand delta(15)N), with the highest uptake rate (0.232) in perch. A significant decrease in THg concentrations was found in all fish species in 2005 compared to 2003. Removal of the top predators in an Hg contaminated lake might thus be an important management tool for reducing Hg levels in fish, thereby reducing health risk to humans.

  16. Influence of a large dam on the longitudinal patterns of fish assemblages in Qingyi Stream.

    Science.gov (United States)

    Sui, Xiao-Yun; Lu, Zhi; Yan, Yun-Zhi; Chen, Yi-Feng; Jia, Yin-Tao

    2014-09-01

    Using seasonally collected data (2009-2010) from 15 sampling sites that represent first- to fifth-order streams within the Qingyi watershed, we examined the spatio-temporal patterns of fish assemblages along two longitudinal gradients to explore the effects of a large dam on fish assemblages at the watershed scale. No significant variation was observed in either species richness or assemblage structure across seasons. Species richness significantly varied according to stream order and gradient. Dam construction appeared to decrease species richness upstream substantially, while a significant decrease between gradients only occurred within fourth-order streams. Along the gradient without the large dam, fish assemblage structures presented distinct separation between two neighboring stream orders, with the exception of fourth-order versus fifth-order streams. However, the gradient disrupted by a large dam displayed the opposite pattern in the spatial variation of fish assemblages related with stream orders. Significant between-gradient differences in fish assemblage structures were only observed within fourth-order streams. Species distributions were determined by local habitat environmental factors, including elevation, substrate, water depth, current discharge, wetted width, and conductivity. Our results suggested that dam construction might alter the longitudinal pattern in fish species richness and assemblage structure in Qingyi Stream, despite the localized nature of the ecological effect of dams.

  17. Trophic structure of pelagic species in the northwestern Mediterranean Sea

    Science.gov (United States)

    Albo-Puigserver, Marta; Navarro, Joan; Coll, Marta; Layman, Craig A.; Palomera, Isabel

    2016-11-01

    Ecological knowledge of food web interactions within pelagic marine communities is often limited, impairing our capabilities to manage these ecologically and economically important marine fish species. Here we used stable isotope analyses to investigate trophic interactions in the pelagic ecosystem of the northwestern Mediterranean Sea during 2012 and 2013. Our results suggest that European sardine, Sardina pilchardus, and anchovy, Engraulis encrasicolus, are consumers located at relatively low levels of the pelagic food web. Unexpectedly, the round sardinella, Sardinella aurita, appeared to be located at a higher trophic level than the other small pelagic fish species, although previous studies found similarity in their diets. Isotope data suggested that trophic niches of species within the genera Trachurus spp. and Scomber spp., were distinct. Atlantic bonito Sarda sarda, European hake Merluccius merluccius and European squid Loligo vulgaris, appeared to feed at higher trophic levels than other species. Despite some intraspecific seasonal variability for some species, community trophic structure appeared relatively stable through the year. These data provide an important step for developing models of food web dynamics in the northwestern Mediterranean Sea.

  18. Medusivorous fishes, a review

    NARCIS (Netherlands)

    Ates, R.M.L.

    1988-01-01

    A preliminary review is presented of fish species having consumed pelagic Cnidaria (Scyphozoa and Hydrozoa) as well as Ctenophora. Quantitative data are scarce. Knowledge of morphological and physiological adaptations of fishes foraging on gelatinous plankton is almost non-existent. Many fish specie

  19. Medusivorous fishes, a review

    OpenAIRE

    Ates, R.M.L.

    1988-01-01

    A preliminary review is presented of fish species having consumed pelagic Cnidaria (Scyphozoa and Hydrozoa) as well as Ctenophora. Quantitative data are scarce. Knowledge of morphological and physiological adaptations of fishes foraging on gelatinous plankton is almost non-existent. Many fish species consume medusae and some reasons to suspect that there are even more that do so, are discussed.

  20. Medusivorous fishes, a review

    NARCIS (Netherlands)

    Ates, R.M.L.

    1988-01-01

    A preliminary review is presented of fish species having consumed pelagic Cnidaria (Scyphozoa and Hydrozoa) as well as Ctenophora. Quantitative data are scarce. Knowledge of morphological and physiological adaptations of fishes foraging on gelatinous plankton is almost non-existent. Many fish

  1. 77 FR 75896 - Atlantic Highly Migratory Species; 2013 Atlantic Shark Commercial Fishing Season

    Science.gov (United States)

    2012-12-26

    ... Species; 2013 Atlantic Shark Commercial Fishing Season AGENCY: National Marine Fisheries Service (NMFS... the Atlantic commercial shark fisheries (sandbar sharks, non-sandbar large coastal sharks, blue sharks, porbeagle sharks, and pelagic sharks (other than porbeagle and blue sharks), non-blacknose small...

  2. Contribution of anadromous fish to the diet of European catfish in a large river system

    Science.gov (United States)

    Syväranta, Jari; Cucherousset, Julien; Kopp, Dorothée; Martino, Aurélia; Céréghino, Régis; Santoul, Frédéric

    2009-05-01

    Many anadromous fish species, when migrating from the sea to spawn in fresh waters, can potentially be a valuable prey for larger predatory fish, thereby efficiently linking these two ecosystems. Here, we assess the contribution of anadromous fish to the diet of European catfish ( Silurus glanis) in a large river system (Garonne, southwestern France) using stable isotope analysis and allis shad ( Alosa alosa) as an example of anadromous fish. Allis shad caught in the Garonne had a very distinct marine δ13C value, over 8‰ higher after lipid extraction compared to the mean δ13C value of all other potential freshwater prey fish. The δ13C values of European catfish varied considerably between these two extremes and some individuals were clearly specializing on freshwater prey, whereas others specialized on anadromous fish. The mean contribution of anadromous fish to the entire European catfish population was estimated to be between 53% and 65%, depending on the fractionation factor used for δ13C.

  3. Fish habitat selection in a large hydropeaking river: Strong individual and temporal variations revealed by telemetry.

    Science.gov (United States)

    Capra, Hervé; Plichard, Laura; Bergé, Julien; Pella, Hervé; Ovidio, Michaël; McNeil, Eric; Lamouroux, Nicolas

    2017-02-01

    Modeling individual fish habitat selection in highly variable environments such as hydropeaking rivers is required for guiding efficient management decisions. We analyzed fish microhabitat selection in the heterogeneous hydraulic and thermal conditions (modeled in two-dimensions) of a reach of the large hydropeaking Rhône River locally warmed by the cooling system of a nuclear power plant. We used modern fixed acoustic telemetry techniques to survey 18 fish individuals (five barbels, six catfishes, seven chubs) signaling their position every 3s over a three-month period. Fish habitat selection depended on combinations of current microhabitat hydraulics (e.g. velocity, depth), past microhabitat hydraulics (e.g. dewatering risk or maximum velocities during the past 15days) and to a lesser extent substrate and temperature. Mixed-effects habitat selection models indicated that individual effects were often stronger than specific effects. In the Rhône, fish individuals appear to memorize spatial and temporal environmental changes and to adopt a "least constraining" habitat selection. Avoiding fast-flowing midstream habitats, fish generally live along the banks in areas where the dewatering risk is high. When discharge decreases, however, they select higher velocities but avoid both dewatering areas and very fast-flowing midstream habitats. Although consistent with the available knowledge on static fish habitat selection, our quantitative results demonstrate temporal variations in habitat selection, depending on individual behavior and environmental history. Their generality could be further tested using comparative experiments in different environmental configurations.

  4. Fish navigation of large dams emerges from their modulation of flow field experience.

    Science.gov (United States)

    Goodwin, R Andrew; Politano, Marcela; Garvin, Justin W; Nestler, John M; Hay, Duncan; Anderson, James J; Weber, Larry J; Dimperio, Eric; Smith, David L; Timko, Mark

    2014-04-08

    Navigating obstacles is innate to fish in rivers, but fragmentation of the world's rivers by more than 50,000 large dams threatens many of the fish migrations these waterways support. One limitation to mitigating the impacts of dams on fish is that we have a poor understanding of why some fish enter routes engineered for their safe travel around the dam but others pass through more dangerous routes. To understand fish movement through hydropower dam environments, we combine a computational fluid dynamics model of the flow field at a dam and a behavioral model in which simulated fish adjust swim orientation and speed to modulate their experience to water acceleration and pressure (depth). We fit the model to data on the passage of juvenile Pacific salmonids (Oncorhynchus spp.) at seven dams in the Columbia/Snake River system. Our findings from reproducing observed fish movement and passage patterns across 47 flow field conditions sampled over 14 y emphasize the role of experience and perception in the decision making of animals that can inform opportunities and limitations in living resources management and engineering design.

  5. A novel artificial fish swarm algorithm for solving large-scale reliability-redundancy application problem.

    Science.gov (United States)

    He, Qiang; Hu, Xiangtao; Ren, Hong; Zhang, Hongqi

    2015-11-01

    A novel artificial fish swarm algorithm (NAFSA) is proposed for solving large-scale reliability-redundancy allocation problem (RAP). In NAFSA, the social behaviors of fish swarm are classified in three ways: foraging behavior, reproductive behavior, and random behavior. The foraging behavior designs two position-updating strategies. And, the selection and crossover operators are applied to define the reproductive ability of an artificial fish. For the random behavior, which is essentially a mutation strategy, the basic cloud generator is used as the mutation operator. Finally, numerical results of four benchmark problems and a large-scale RAP are reported and compared. NAFSA shows good performance in terms of computational accuracy and computational efficiency for large scale RAP.

  6. A phylogenetic analysis of egg size, clutch size, spawning mode, adult body size, and latitude in reef fishes

    Science.gov (United States)

    Kasimatis, Katja; Riginos, Cynthia

    2016-06-01

    Theoretical treatments of egg size in fishes suggest that constraints on reproductive output should create trade-offs between the size and number of eggs produced per spawn. For marine reef fishes, the observation of distinct reproductive care strategies (demersal guarding, egg scattering, and pelagic spawning) has additionally prompted speculation that these strategies reflect alternative fitness optima with selection on egg size differing by reproductive mode and perhaps latitude. Here, we aggregate data from 278 reef fish species and test whether clutch size, reproductive care, adult body size, and latitudinal bands (i.e., tropical, subtropical, and temperate) predict egg size, using a statistically unified framework that accounts for phylogenetic correlations among traits. We find no inverse relationship between species egg size and clutch size, but rather that egg size differs by reproductive mode (mean volume for demersal eggs = 1.22 mm3, scattered eggs = 0.18 mm3, pelagic eggs = 0.52 mm3) and that clutch size is strongly correlated with adult body size. Larger eggs were found in temperate species compared with tropical species in both demersal guarders and pelagic spawners, but this difference was not strong when accounting for phylogenetic correlations, suggesting that differences in species composition underlies regional differences in egg size. In summary, demersal guarders are generally small fishes with small clutch sizes that produce large eggs. Pelagic spawners and egg scatterers are variable in adult and clutch size. Although pelagic spawned eggs are variable in size, those of scatterers are consistently small.

  7. Nearshore energy subsidies support Lake Michigan fishes and invertebrates following major changes in food web structure

    Science.gov (United States)

    Turschak, Benjamin A; Bunnell, David B.; Czesny, Sergiusz J.; Höök, Tomas O.; Janssen, John; Warner, David M.; Bootsma, Harvey A

    2014-01-01

    Aquatic food webs that incorporate multiple energy channels (e.g. nearshore benthic or pelagic) with varying productivity and turnover rates convey stability to biological communities by providing multiple independent energy sources. Within the Lake Michigan food web, invasive dreissenid mussels have caused rapid changes to food web structure and potentially altered the channels through which consumers acquire energy. We used stable C and N isotopes to determine how Lake Michigan food web structure has changed in the past decade, coincident with the expansion of dreissenid mussels, decreased pelagic phytoplankton production and increased nearshore benthic algal production. Fish and invertebrate samples collected from sites around Lake Michigan were analyzed to determine taxa-specific 13C:12C (delta 13C) and 15N:14N (delta 15N) ratios. Sampling took place during two distinct periods, 2002-2003 and 2010-2012, that spanned the period of dreissenid expansion, and included nearshore, pelagic and profundal fish and invertebrate taxa. Magnitude and direction of the 13C shift indicated significantly greater reliance upon nearshore benthic energy sources among nearly all fish taxa as well as profundal invertebrates. Although the mechanisms underlying this 13C shift likely varied among species, possible causes include the transport of benthic algal production to offshore waters and an increased reliance on nearshore prey items. Delta 15N shifts were more variable and of smaller magnitude across taxa although declines in delta 15N among some pelagic fishes may indicate a shift to alternative prey resources. Lake Michigan fishes and invertebrates appear to have responded to dreissenid induced changes in nutrient and energy pathways by switching from pelagic to alternative nearshore energy subsidies. Although large shifts in energy allocation (i.e. pelagic to nearshore benthic) resulting from invasive species appear to have affected total production at upper trophic

  8. Pelagic nekton abundance and distribution in the northern Sacramento–San Joaquin Delta, California

    Science.gov (United States)

    Feyrer, Frederick; Slater, Steven B.; Portz, Donald E.; Odom, Darren; Morgan-King, Tara L.; Brown, Larry R.

    2017-01-01

    Knowledge of the habitats occupied by species is fundamental for the development of effective conservation and management actions. The collapse of pelagic fish species in the Sacramento–San Joaquin Delta, California, has triggered a need to better understand factors that drive their distribution and abundance. A study was conducted in summer–fall 2014 in an attempt to identify physical and biological habitat conditions that drive the abundance and distribution of pelagic species in the northern region of the system. The study was conducted in the three largest channels in the northern Sacramento–San Joaquin Delta by dimension, volume, and flow capacity. The pelagic community was dominated by three nonnative species, Siberian prawn Exopalaemon modestus, which comprised 56% of the total number of organisms, and two fish species, Threadfin Shad Dorosoma petenense and Mississippi Silversides Menidia audens, which together comprised 43% of the total number of organisms. Total fish and total shrimp abundance were sensitive to the most extreme values of turbidity and temperature encountered and positively associated with total zooplankton biomass. The results suggested that habitat conditions in terminal channels, historically a common feature on the landscape, support higher abundances of pelagic species and zooplankton than open-ended channels. These results provide resource managers with useful information on the habitat associations of pelagic species and on how the future distribution and abundance of pelagic species will likely change in response to climate or other ecological factors.

  9. Challenges in developing fish-based ecological assessment methods for large foodplain rivers

    NARCIS (Netherlands)

    Leeuw, de J.J.; Buijse, A.D.; Haidvogl, G.; Lapinska, M.

    2007-01-01

    Large European floodplain rivers have a great diversity in habitats and fish fauna, but tend to be heavily modified. The complexity of these river systems and their multiple human impacts pose considerable challenges for assessment of their ecological status. This paper discusses: (1) the

  10. On some ecological and faunistic pecularities of fish parasites in large oligotrophic lakes of Karelia

    Directory of Open Access Journals (Sweden)

    Rumjantsev Yevgeny

    2014-11-01

    Full Text Available The ecological and faunistic pecularities of parasite fauna of fishes in large oligotrophic lakes of Karelia were studied. These lakes belong typologically to different classes. The presence of glacial species of parasites in Onega Lake and sea relict representatives in Ladoga lake is shown.

  11. Maximum swimming speeds of sailfish and three other large marine predatory fish species based on muscle contraction time and stride length: a myth revisited

    Directory of Open Access Journals (Sweden)

    Morten B. S. Svendsen

    2016-10-01

    Full Text Available Billfishes are considered to be among the fastest swimmers in the oceans. Previous studies have estimated maximum speed of sailfish and black marlin at around 35 m s−1 but theoretical work on cavitation predicts that such extreme speed is unlikely. Here we investigated maximum speed of sailfish, and three other large marine pelagic predatory fish species, by measuring the twitch contraction time of anaerobic swimming muscle. The highest estimated maximum swimming speeds were found in sailfish (8.3±1.4 m s−1, followed by barracuda (6.2±1.0 m s−1, little tunny (5.6±0.2 m s−1 and dorado (4.0±0.9 m s−1; although size-corrected performance was highest in little tunny and lowest in sailfish. Contrary to previously reported estimates, our results suggest that sailfish are incapable of exceeding swimming speeds of 10-15 m s−1, which corresponds to the speed at which cavitation is predicted to occur, with destructive consequences for fin tissues.

  12. Maximum swimming speeds of sailfish and three other large marine predatory fish species based on muscle contraction time and stride length: a myth revisited

    Science.gov (United States)

    Svendsen, Morten B. S.; Domenici, Paolo; Marras, Stefano; Krause, Jens; Boswell, Kevin M.; Rodriguez-Pinto, Ivan; Wilson, Alexander D. M.; Kurvers, Ralf H. J. M.; Viblanc, Paul E.; Finger, Jean S.; Steffensen, John F.

    2016-01-01

    ABSTRACT Billfishes are considered to be among the fastest swimmers in the oceans. Previous studies have estimated maximum speed of sailfish and black marlin at around 35 m s−1 but theoretical work on cavitation predicts that such extreme speed is unlikely. Here we investigated maximum speed of sailfish, and three other large marine pelagic predatory fish species, by measuring the twitch contraction time of anaerobic swimming muscle. The highest estimated maximum swimming speeds were found in sailfish (8.3±1.4 m s−1), followed by barracuda (6.2±1.0 m s−1), little tunny (5.6±0.2 m s−1) and dorado (4.0±0.9 m s−1); although size-corrected performance was highest in little tunny and lowest in sailfish. Contrary to previously reported estimates, our results suggest that sailfish are incapable of exceeding swimming speeds of 10-15 m s−1, which corresponds to the speed at which cavitation is predicted to occur, with destructive consequences for fin tissues. PMID:27543056

  13. What makes pelagic copepods so successful?

    DEFF Research Database (Denmark)

    Kiørboe, Thomas

    2011-01-01

    Three features that are unique or almost unique to pelagic copepods among zooplankton may account for their numerical dominance in the pelagic realm of the oceans: (i) the torpedo-shaped body, the sensory armed antennules and the ‘gearing’ of the muscle motor make pelagic copepods very efficient...

  14. Olfaction Contributes to Pelagic Navigation in a Coastal Shark.

    Science.gov (United States)

    Nosal, Andrew P; Chao, Yi; Farrara, John D; Chai, Fei; Hastings, Philip A

    2016-01-01

    How animals navigate the constantly moving and visually uniform pelagic realm, often along straight paths between distant sites, is an enduring mystery. The mechanisms enabling pelagic navigation in cartilaginous fishes are particularly understudied. We used shoreward navigation by leopard sharks (Triakis semifasciata) as a model system to test whether olfaction contributes to pelagic navigation. Leopard sharks were captured alongshore, transported 9 km offshore, released, and acoustically tracked for approximately 4 h each until the transmitter released. Eleven sharks were rendered anosmic (nares occluded with cotton wool soaked in petroleum jelly); fifteen were sham controls. Mean swimming depth was 28.7 m. On average, tracks of control sharks ended 62.6% closer to shore, following relatively straight paths that were significantly directed over spatial scales exceeding 1600 m. In contrast, tracks of anosmic sharks ended 37.2% closer to shore, following significantly more tortuous paths that approximated correlated random walks. These results held after swimming paths were adjusted for current drift. This is the first study to demonstrate experimentally that olfaction contributes to pelagic navigation in sharks, likely mediated by chemical gradients as has been hypothesized for birds. Given the similarities between the fluid three-dimensional chemical atmosphere and ocean, further research comparing swimming and flying animals may lead to a unifying paradigm explaining their extraordinary navigational abilities.

  15. The paradox of pelagic food webs in the northern Bering Sea—I. Seabird food habits

    Science.gov (United States)

    Springer, Alan M.; Murphy, Edward C.; Roseneau, David G.; McRoy, C. Peter; Cooper, Brian A.

    1987-08-01

    Two distinct environmental settings in the Bering Strait region of the northern Bering Sea lead to characteristic pathways of energy flow through primarily pelagic food webs to avian consumers. In Norton Sound, a large, shallow embayment on the northeastern coast, the physical environment is dominated by the discharge of the Yukon River and by a large seasonal temperature signal. Seabirds breeding at Bluff, the largest colony in Norton Sound, number in the order of 5 × 10 4 and require 1.2 × 10 6 g C d -1. Two piscivorous species constitute the bulk of all seabirds there and are supported by a pelagic food web typical of the coastal zone of the Bering and Chukchi seas. This food web also is present around St. Lawrence Island, on the northwestern shelf, and is important to at least one species of seabird there. In addition, and generally more important, St. Lawrence Island is in a biologically rich environment resulting from the northward flow of water that originates along the continental shelf break of the Bering Sea. This flow apparently accounts for the unexpected presence of oceanic zooplankton and a diversity of forage fishes on the shallow northern shelf that support an abundant and taxonomically rich avifauna. In comparison to Norton Sound, breeding seabirds on St. Lawrence Island number in the order of 2 × 10 6, with planktivores consuming about 8 × 10 6 g C d -1 and piscivores consuming about 16 × 10 6 g C d -1.

  16. Long-term fish monitoring in large rivers: Utility of “benchmarking” across basins

    Science.gov (United States)

    Ward, David L.; Casper, Andrew F.; Counihan, Timothy D.; Bayer, Jennifer M.; Waite, Ian R.; Kosovich, John J.; Chapman, Colin; Irwin, Elise R.; Sauer, Jennifer S.; Ickes, Brian; McKerrow, Alexa

    2017-01-01

    In business, benchmarking is a widely used practice of comparing your own business processes to those of other comparable companies and incorporating identified best practices to improve performance. Biologists and resource managers designing and conducting monitoring programs for fish in large river systems tend to focus on single river basins or segments of large rivers, missing opportunities to learn from those conducting fish monitoring in other rivers. We briefly examine five long-term fish monitoring programs in large rivers in the United States (Colorado, Columbia, Mississippi, Illinois, and Tallapoosa rivers) and identify opportunities for learning across programs by detailing best monitoring practices and why these practices were chosen. Although monitoring objectives, methods, and program maturity differ between each river system, examples from these five case studies illustrate the important role that long-term monitoring programs play in interpreting temporal and spatial shifts in fish populations for both established objectives and newly emerging questions. We suggest that deliberate efforts to develop a broader collaborative network through benchmarking will facilitate sharing of ideas and development of more effective monitoring programs.

  17. Trace elements in oceanic pelagic communities in the western Indian Ocean.

    Science.gov (United States)

    Bodin, Nathalie; Lesperance, Dora; Albert, Rona; Hollanda, Stephanie; Michaud, Philippe; Degroote, Maxime; Churlaud, Carine; Bustamante, Paco

    2017-05-01

    The mineral composition of target and non-target pelagic fish caught by purse-seiners and longliners in the western-central Indian Ocean was determined. From the 10 essential elements analysed, selenium and zinc showed the highest concentrations in swordfish and blue marlin while Indian mackerel appeared as a good source of copper, iron and chrome. All catch had levels of lead and cadmium, two toxic elements, below the maximum sanitary limits. Although some concerns were raised regarding mercury concentrations in the largest species (wahoo, swordfish and blue marlin), molar ratios of mercury and selenium indicate that all oceanic pelagic fish from the western-central Indian Ocean are safe for human consumption. This study also gives insights on the relationships between the levels of essential and toxic elements in fish muscle and the size, trophic position and diet sources of the studied pelagic species.

  18. Guam and the Northern Mariana Islands ESI: FISH (Fish Polygons)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains sensitive biological resource data for reef, pelagic, benthic, and estuarine fish species in Guam and the Northern Mariana Islands. Vector...

  19. Towards an integrated forecasting system for pelagic fisheries

    Directory of Open Access Journals (Sweden)

    A. Christensen

    2012-03-01

    Full Text Available First results of a coupled modeling and forecasting system for the pelagic fisheries are being presented. The system consists currently of three mathematically fundamentally different model subsystems: POLCOMS-ERSEM providing the physical-biogeochemical environment implemented in the domain of the North-West European shelf and the SPAM model which describes sandeel stocks in the North Sea. The third component, the SLAM model, connects POLCOMS-ERSEM and SPAM by computing the physical-biological interaction. Our major experience by the coupling model subsystems is that well-defined and generic model interfaces are very important for a successful and extendable coupled model framework. The integrated approach, simulating ecosystem dynamics from physics to fish, allows for analysis of the pathways in the ecosystem to investigate the propagation of changes in the ocean climate and lower trophic levels to quantify the impacts on the higher trophic level, in this case the sandeel population, demonstrated here on the base of hindcast data. The coupled forecasting system is tested for some typical scientific questions appearing in spatial fish stock management and marine spatial planning, including determination of local and basin scale maximum sustainable yield, stock connectivity and source/sink structure. Our presented simulations indicate that sandeels stocks are currently exploited close to the maximum sustainable yield, but large uncertainty is associated with determining stock maximum sustainable yield due to stock eigen dynamics and climatic variability. Our statistical ensemble simulations indicates that the predictive horizon set by climate interannual variability is 2–6 yr, after which only an asymptotic probability distribution of stock properties, like biomass, are predictable.

  20. Identification document for large by-catch species in the Mauritanian Exclusive Economic Zone

    NARCIS (Netherlands)

    Hofstede, ter R.

    2003-01-01

    The coastal waters of Mauritania (Northwest Africa) contain large numbers of pelagic fish such as sardinella, sardine, mackerel and horse mackerel. Freezer-trawlers from the European Union (EU), mainly of Dutch origin, have exploited these resources since 1996. In 1998 the Dutch ship owners commissi

  1. Identification document for large by-catch species in the Mauritanian Exclusive Economic Zone

    NARCIS (Netherlands)

    Hofstede, ter R.

    2003-01-01

    The coastal waters of Mauritania (Northwest Africa) contain large numbers of pelagic fish such as sardinella, sardine, mackerel and horse mackerel. Freezer-trawlers from the European Union (EU), mainly of Dutch origin, have exploited these resources since 1996. In 1998 the Dutch ship owners

  2. Contrasting time trends of organic contaminants in Antarctic pelagic and benthic food webs.

    Science.gov (United States)

    van den Brink, Nico W; Riddle, Martin J; van den Heuvel-Greve, Martine; van Franeker, Jan Andries

    2011-01-01

    We demonstrate that pelagic Antarctic seabirds show significant decreases in concentrations of some persistent organic pollutants. Trends in Adélie penguins and Southern fulmars fit in a general pattern revealed by a broad literature review. Downward trends are also visible in pelagic fish, contrasting sharply with steady or increasing concentrations in Antarctic benthic organisms. Transfer of contaminants between Antarctic pelagic and benthic food webs is associated with seasonal sea-ice dynamics which may influence the balance between the final receptors of contaminants under different climatic conditions. This complicates the predictability of future trends of emerging compounds in the Antarctic ecosystem, such as of the brominated compounds that we detected in Antarctic petrels. The discrepancy in trends between pelagic and benthic organisms shows that Antarctic biota are still final receptors of globally released organic contaminants and it remains questionable whether the total environmental burden of contaminants in the Antarctic ecosystem is declining.

  3. Incidental catches of pelagic megafauna by the EU pelagic fleet in the Mauritanian exclusive economic zone during the year 2001 : results extracted from the scientific observer program

    NARCIS (Netherlands)

    Hofstede, ter R.

    2003-01-01

    The joint project between the Netherlands Institute for Fisheries Research (RIVO) and the Mauritanian Institute for Oceanography and Fisheries Research (IMROP) has been initiated in 1998 in order to strengthen Mauritania’s capacity for research on stocks of small pelagic fish. Part of this project i

  4. Patterns of interactions of a large fish-parasite network in a tropical floodplain.

    Science.gov (United States)

    Lima, Dilermando P; Giacomini, Henrique C; Takemoto, Ricardo M; Agostinho, Angelo A; Bini, Luis M

    2012-07-01

    1. Describing and explaining the structure of species interaction networks is of paramount importance for community ecology. Yet much has to be learned about the mechanisms responsible for major patterns, such as nestedness and modularity in different kinds of systems, of which large and diverse networks are a still underrepresented and scarcely studied fraction. 2. We assembled information on fishes and their parasites living in a large floodplain of key ecological importance for freshwater ecosystems in the Paraná River basin in South America. The resulting fish-parasite network containing 72 and 324 species of fishes and parasites, respectively, was analysed to investigate the patterns of nestedness and modularity as related to fish and parasite features. 3. Nestedness was found in the entire network and among endoparasites, multiple-host life cycle parasites and native hosts, but not in networks of ectoparasites, single-host life cycle parasites and non-native fishes. All networks were significantly modular. Taxonomy was the major host's attribute influencing both nestedness and modularity: more closely related host species tended to be associated with more nested parasite compositions and had greater chance of belonging to the same network module. Nevertheless, host abundance had a positive relationship with nestedness when only native host species pairs of the same network module were considered for analysis. 4. These results highlight the importance of evolutionary history of hosts in linking patterns of nestedness and formation of modules in the network. They also show that functional attributes of parasites (i.e. parasitism mode and life cycle) and origin of host populations (i.e. natives versus non-natives) are crucial to define the relative contribution of these two network properties and their dependence on other ecological factors (e.g. host abundance), with potential implications for community dynamics and stability.

  5. Temporal Patterns of Larval Fish Occurrence in a Large Subtropical River.

    Directory of Open Access Journals (Sweden)

    Fangmin Shuai

    Full Text Available Knowledge of temporal patterns of larval fish occurrence is limited in south China, despite its ecological importance. This research examines the annual and seasonal patterns of fish larval presence in the large subtropical Pearl River. Data is based on samples collected every two days, from 2006 to 2013. In total, 45 taxa representing 13 families and eight orders were sampled. The dominant larval family was Cyprinidae, accounting for 27 taxa. Squaliobarbus curriculus was the most abundant species, followed by Megalobrama terminalis, Xenocypris davidi, Cirrhinus molitorella, Hemiculter leuscisculus and Squalidus argentatus. Fish larvae abundances varied significantly throughout the seasons (multivariate analyses: Cluster, SIMPROF and ANOSIM. The greatest numbers occurred between May and September, peaking from June through August, which corresponds to the reproductive season. In this study, redundancy analysis was used to describe the relationship between fish larval abundance and associated environmental factors. Mean water temperature, river discharge, atmospheric pressure, maximum temperature and precipitation play important roles in larval occurrence patterns. According to seasonal variations, fish larvae occurrence is mainly affected by water temperature. It was also noted that the occurrence of Salanx reevesii and Cyprinus carpio larvae is associated with higher dissolved oxygen (DO concentrations, higher atmospheric pressure and lower water temperatures which occur in the spring. On the other hand, M. terminalis, X. davidi, and C. molitorella are associated with high precipitation, high river discharge, low atmospheric pressure and low DO concentrations which featured during the summer months. S. curriculus also peaks in the summer and is associated with peak water temperatures and minimum NH3-N concentrations. Rhinogobius giurinus occur when higher atmospheric pressure, lower precipitation and lower river discharges occur in the autumn

  6. Population structure and adaptation in fishes

    DEFF Research Database (Denmark)

    Limborg, Morten

    Marine fishes represent a valuable resource for the global economy and food consumption. Accordingly, many species experience high levels of exploitation necessitating effective management plans. However, long term sustainability may be jeopardized from insufficient knowledge about intra-specific......Marine fishes represent a valuable resource for the global economy and food consumption. Accordingly, many species experience high levels of exploitation necessitating effective management plans. However, long term sustainability may be jeopardized from insufficient knowledge about intra......-specific population structure and adaptive divergence. The large population sizes and high migration rates common to most marine fishes impede the differentiating effect of genetic drift, having led to expectations of no population structure and that the occurrence of local adaptation should be rare in these species....... Comprehensive genetic analyses on the small pelagic fish European sprat (Sprattus sprattus) revealed significant population structure throughout its distribution with an overall pattern of reduced connectivity across environmental transition zones. Population structure reflected both historical separations over...

  7. Patterns of habitat segregation among large fishes in a Venezuelan floodplain river

    Directory of Open Access Journals (Sweden)

    Craig A. Layman

    Full Text Available Distribution and abundance of large fishes (SL>100 mm in the río Cinaruco, a floodplain river in the Venezuelan llanos, were examined by gill net sampling in four habitat types: sand banks, backwater creeks, floodplain lagoons, and river channel. Sampling was standardized using nets (25 m x 2 m of three mesh sizes set for 24-h periods. Based on data from >10,000 hours of gill netting over three years, there were significant differences in assemblage composition among the four habitats. Pair-wise comparisons suggested differences in assemblage composition between all pairs of habitats except creeks and lagoons. Differences in assemblage composition likely arose from species-specific habitat affinities. For example, 21 taxa were collected from both creeks and lagoons, but not from sand banks or the main river channel; each of these 21 taxa were associated with particular features characteristic of creeks and lagoons (e.g. abundant detritus. Assemblage structure also could be influenced by predation or other biological interactions, but mechanistic experiments are needed to evaluate this hypothesis. Assemblage composition was highly variable within all habitat types, likely the result of spatial and temporal heterogeneity associated with seasonal hydrology. Long distance migrations by prochilodontids and other taxa contributed to higher CPUE during the rising-water period of May 2002. Data from this study will provide a baseline to assess changes in the abundance and distribution of large-bodied fishes in response to increasing impacts from illegal commercial fishing in this region.

  8. Preliminary Research on the Potential Effects of Gulf Stream Energy Turbines on Rates of Productivity and Nutrient Cycling in Pelagic Sargassum Communities

    Science.gov (United States)

    Dubbs, L. L.; Piehler, M.

    2014-12-01

    Sargassum is an important and protected genus of pelagic macroalgae that serves as habitat for numerous bacteria, fungi, invertebrates, fish, and sea turtles. Sargassum and its associated communities are also a significant source of carbon, nitrogen, and phosphorus to the otherwise deficient oligotrophic pelagic waters of the Atlantic Ocean. The densest concentration of pelagic Sargassum, primarily comprised of Sargassum natans and S. fluitans, is found in the North Atlantic Central Gyre of the Sargasso Sea, but large quantities are also found in the waters of the continental shelf of the southeastern United States and especially the western edge of the Florida Current/Gulf Stream, including off the coast of North Carolina. This western edge of the Gulf Stream off the North Carolina coast is also of interest for renewable current energy exploration and development because of the constant flow of the Gulf Stream current in close proximity to land at this location, which presents a potential source of substantial baseload power for the east coast of the United States. Marine hydrokinetic turbines placed in the Gulf Stream will likely be placed at depths of 30 to 50 m below the surface of the water, far removed from buoyant Sargassum that floats at the surface of the water and associated fish assemblages that extend to a depth of 3 m. Nonetheless, Gulf Stream turbines may influence the functional roles of Sargassum and its epibionts because the wakes generated by turbines will change turbulence conditions in the water column, which are in turn likely to affect nutrient cycling and productivity. Our research begins to examine how alterations of the Sargassum environment presented by increased turbulence will affect the productivity, nitrogen fixation, and organic matter fluxes of Sargassum macroalgae and their associated epibiotic communities. We have conducted field and laboratory experiments aimed at quantifying the influence of increased turbulence on the

  9. Dispersal capacity predicts both population genetic structure and species richness in reef fishes.

    Science.gov (United States)

    Riginos, Cynthia; Buckley, Yvonne M; Blomberg, Simon P; Treml, Eric A

    2014-07-01

    Dispersal is a fundamental species characteristic that should directly affect both rates of gene flow among spatially distributed populations and opportunities for speciation. Yet no single trait associated with dispersal has been demonstrated to affect both micro- and macroevolutionary patterns of diversity across a diverse biological assemblage. Here, we examine patterns of genetic differentiation and species richness in reef fishes, an assemblage of over 7,000 species comprising approximately one-third of the extant bony fishes and over one-tenth of living vertebrates. In reef fishes, dispersal occurs primarily during a planktonic larval stage. There are two major reproductive and parental investment syndromes among reef fishes, and the differences between them have implications for dispersal: (1) benthic guarding fishes lay negatively buoyant eggs, typically guarded by the male parent, and from these eggs hatch large, strongly swimming larvae; in contrast, (2) pelagic spawning fishes release small floating eggs directly into the water column, which drift unprotected before small weakly swimming larvae hatch. Using phylogenetic comparative methods, we show that benthic guarders have significantly greater population structure than pelagic spawners and additionally that taxonomic families of benthic guarders are more species rich than families of pelagic spawners. Our findings provide a compelling case for the continuity between micro- and macroevolutionary processes of biological diversification and underscore the importance of dispersal-related traits in influencing the mode and tempo of evolution.

  10. Incidence and patterns of ALK FISH abnormalities seen in a large unselected series of lung carcinomas

    Directory of Open Access Journals (Sweden)

    Dai Zunyan

    2012-12-01

    Full Text Available Abstract Background Anaplastic lymphoma receptor tyrosine kinase (ALK gene rearrangements have been reported in 2-13% of patients with non-small cell lung cancer (NSCLC. Patients with ALK rearrangements do not respond to EGFR-specific tyrosine kinase inhibitors (TKIs; however, they do benefit from small molecule inhibitors targeting ALK. Results In this study, fluorescence in situ hybridization (FISH using a break-apart probe for the ALK gene was performed on formalin fixed paraffin-embedded tissue to determine the incidence of ALK rearrangements and hybridization patterns in a large unselected cohort of 1387 patients with a referred diagnosis of non-small cell lung cancer (1011 of these patients had a histologic diagnosis of adenocarcinoma. The abnormal FISH signal patterns varied from a single split signal to complex patterns. Among 49 abnormal samples (49/1387, 3.5%, 32 had 1 to 3 split signals. Fifteen samples had deletions of the green 5′ end of the ALK signal, and 1 of these 15 samples showed amplification of the orange 3′ end of the ALK signal. Two patients showed a deletion of the 3′ALK signal. Thirty eight of these 49 samples (38/1011, 3.7% were among the 1011 patients with confirmed adenocarcinoma. Five of 8 patients with ALK rearrangements detected by FISH were confirmed to have EML4-ALK fusions by multiplex RT-PCR. Among the 45 ALK-rearranged samples tested, only 1 EGFR mutation (T790M was detected. Two KRAS mutations were detected among 24 ALK-rearranged samples tested. Conclusions In a large unselected series, the frequency of ALK gene rearrangement detected by FISH was approximately 3.5% of lung carcinoma, and 3.7% of patients with lung adenocarcinoma, with variant signal patterns frequently detected. Rare cases with coexisting KRAS and EGFR mutations were seen.

  11. Bycatch and release of pelagic megafauna in industrial trawler fisheries off Northwest Africa

    NARCIS (Netherlands)

    Zeeberg, J.J.; Corten, A.A.H.M.; Graaf, de E.

    2006-01-01

    The accidental capture of large animals such as sharks, manta rays, sea turtles, and dolphins in pelagic trawler fisheries remains controversial because it threatens biological diversity in many biogeographical regions, including the subtropical eastern North Atlantic. Bycatch rates observed during

  12. Bycatch and release of pelagic megafauna in industrial trawler fisheries off Northwest Africa

    NARCIS (Netherlands)

    Zeeberg, J.J.; Corten, A.A.H.M.; Graaf, de E.

    2006-01-01

    The accidental capture of large animals such as sharks, manta rays, sea turtles, and dolphins in pelagic trawler fisheries remains controversial because it threatens biological diversity in many biogeographical regions, including the subtropical eastern North Atlantic. Bycatch rates observed during

  13. Climate change and control of the southeastern Bering Sea pelagic ecosystem

    Science.gov (United States)

    Hunt, George L., Jr.; Stabeno, Phyllis; Walters, Gary; Sinclair, Elizabeth; Brodeur, Richard D.; Napp, Jeffery M.; Bond, Nicholas A.

    2002-12-01

    We propose a new hypothesis, the Oscillating Control Hypothesis (OCH), which predicts that pelagic ecosystem function in the southeastern Bering Sea will alternate between primarily bottom-up control in cold regimes and primarily top-down control in warm regimes. The timing of spring primary production is determined predominately by the timing of ice retreat. Late ice retreat (late March or later) leads to an early, ice-associated bloom in cold water (e.g., 1995, 1997, 1999), whereas no ice, or early ice retreat before mid-March, leads to an open-water bloom in May or June in warm water (e.g., 1996, 1998, 2000). Zooplankton populations are not closely coupled to the spring bloom, but are sensitive to water temperature. In years when the spring bloom occurs in cold water, low temperatures limit the production of zooplankton, the survival of larval/juvenile fish, and their recruitment into the populations of species of large piscivorous fish, such as walleye pollock ( Theragra chalcogramma), Pacific cod ( Gadus macrocephalus) and arrowtooth flounder ( Atheresthes stomias). When continued over decadal scales, this will lead to bottom-up limitation and a decreased biomass of piscivorous fish. Alternatively, in periods when the bloom occurs in warm water, zooplankton populations should grow rapidly, providing plentiful prey for larval and juvenile fish. Abundant zooplankton will support strong recruitment of fish and will lead to abundant predatory fish that control forage fish, including, in the case of pollock, their own juveniles. Piscivorous marine birds and pinnipeds may achieve higher production of young and survival in cold regimes, when there is less competition from large piscivorous fish for cold-water forage fish such as capelin ( Mallotus villosus). Piscivorous seabirds and pinnipeds also may be expected to have high productivity in periods of transition from cold regimes to warm regimes, when young of large predatory species of fish are numerous enough to

  14. Fishing

    Institute of Scientific and Technical Information of China (English)

    姜群山

    2002-01-01

    @@ Last Saturday my cousin (表兄) came to my home. We were very happy to see each other. We decided that the next day we went to fish. We got up very early that day. When we left home,the moon could still be seen in the sky.

  15. Aggregation of organic matter by pelagic tunicates

    Energy Technology Data Exchange (ETDEWEB)

    Pomeroy, L.R. (Univ. of Georgia, Athens); Deibel, D.

    1980-07-01

    Three genera of pelagic tunicates were fed concentrates of natural seston and an axenic diatom culture. Fresh and up to 4-day-old feces resemble flocculent organic aggregates containing populations of microorganisms, as described from highly productive parts of the ocean, and older feces resemble the nearly sterile flocculent aggregates which are ubiquitous in surface waters. Fresh feces consist of partially digested phytoplankton and other inclusions in an amorphous gelatinous matrix. After 18 to 36 h, a population of large bacteria develops in the matrix and in some of the remains of phytoplankton contained in the feces. From 48 to 96 h, protozoan populations arise which consume the bacteria and sometimes the remains of the phytoplankton in the feces. Thereafter only a sparse population of microorganisms remains, and the particles begin to fragment. Water samples taken in or below dense populations of salps and doliolids contained greater numbers of flocculent aggregates than did samples from adjacent stations.

  16. Large-amplitude undulatory fish swimming: fluid mechanics coupled to internal mechanics.

    Science.gov (United States)

    Pedley, T J; Hill, S J

    1999-12-01

    The load against which the swimming muscles contract, during the undulatory swimming of a fish, is composed principally of hydrodynamic pressure forces and body inertia. In the past this has been analysed, through an equation for bending moments, for small-amplitude swimming, using Lighthill's elongated-body theory and a 'vortex-ring panel method', respectively, to compute the hydrodynamic forces. Those models are outlined in this review, and a summary is given of recent work on large-amplitude swimming that has (a) extended the bending moment equation to large amplitude, which involves the introduction of a new (though probably usually small) term, and (b) developed a large-amplitude vortex-ring panel method. The latter requires computation of the wake, which rolls up into concentrated vortex rings and filaments, and has a significant effect on the pressure on the body. Application is principally made to the saithe (Pollachius virens). The calculations confirm that the wave of muscle activation travels down the fish much more rapidly than the wave of bending.

  17. Vulnerability of the Oceanic Whitetip Shark to Pelagic Longline Fisheries.

    Science.gov (United States)

    Tolotti, Mariana Travassos; Bach, Pascal; Hazin, Fábio; Travassos, Paulo; Dagorn, Laurent

    2015-01-01

    A combination of fisheries dependent and independent data was used to assess the vulnerability of the oceanic whitetip shark to pelagic longline fisheries. The Brazilian tuna longline fleet, operating in the equatorial and southwestern Atlantic, is used as a case study. Fisheries dependent data include information from logbooks (from 1999 to 2011) and on-board observers (2004 to 2010), totaling 65,277 pelagic longline sets. Fisheries independent data were obtained from 8 oceanic whitetip sharks tagged with pop-up satellite archival tags in the area where longline fleet operated. Deployment periods varied from 60 to 178 days between 2010 and 2012. Tagging and pop-up sites were relatively close to each other, although individuals tended to travel long distances before returning to the tagging area. Some degree of site fidelity was observed. High utilization hotspots of tagged sharks fell inside the area under strongest fishing pressure. Despite the small sample size, a positive correlation between tag recorded information and catch data was detected. All sharks exhibited a strong preference for the warm and shallow waters of the mixed layer, spending on average more than 70% of the time above the thermocline and 95% above 120 m. Results indicate that the removal of shallow hooks on longline gear might be an efficient mitigation measure to reduce the bycatch of this pelagic shark species. The work also highlights the potential of tagging experiments to provide essential information for the development of spatio-temporal management measures.

  18. Vulnerability of the Oceanic Whitetip Shark to Pelagic Longline Fisheries

    Science.gov (United States)

    Tolotti, Mariana Travassos; Bach, Pascal; Hazin, Fábio; Travassos, Paulo; Dagorn, Laurent

    2015-01-01

    A combination of fisheries dependent and independent data was used to assess the vulnerability of the oceanic whitetip shark to pelagic longline fisheries. The Brazilian tuna longline fleet, operating in the equatorial and southwestern Atlantic, is used as a case study. Fisheries dependent data include information from logbooks (from 1999 to 2011) and on-board observers (2004 to 2010), totaling 65,277 pelagic longline sets. Fisheries independent data were obtained from 8 oceanic whitetip sharks tagged with pop-up satellite archival tags in the area where longline fleet operated. Deployment periods varied from 60 to 178 days between 2010 and 2012. Tagging and pop-up sites were relatively close to each other, although individuals tended to travel long distances before returning to the tagging area. Some degree of site fidelity was observed. High utilization hotspots of tagged sharks fell inside the area under strongest fishing pressure. Despite the small sample size, a positive correlation between tag recorded information and catch data was detected. All sharks exhibited a strong preference for the warm and shallow waters of the mixed layer, spending on average more than 70% of the time above the thermocline and 95% above 120 m. Results indicate that the removal of shallow hooks on longline gear might be an efficient mitigation measure to reduce the bycatch of this pelagic shark species. The work also highlights the potential of tagging experiments to provide essential information for the development of spatio-temporal management measures. PMID:26492091

  19. Vulnerability of the Oceanic Whitetip Shark to Pelagic Longline Fisheries.

    Directory of Open Access Journals (Sweden)

    Mariana Travassos Tolotti

    Full Text Available A combination of fisheries dependent and independent data was used to assess the vulnerability of the oceanic whitetip shark to pelagic longline fisheries. The Brazilian tuna longline fleet, operating in the equatorial and southwestern Atlantic, is used as a case study. Fisheries dependent data include information from logbooks (from 1999 to 2011 and on-board observers (2004 to 2010, totaling 65,277 pelagic longline sets. Fisheries independent data were obtained from 8 oceanic whitetip sharks tagged with pop-up satellite archival tags in the area where longline fleet operated. Deployment periods varied from 60 to 178 days between 2010 and 2012. Tagging and pop-up sites were relatively close to each other, although individuals tended to travel long distances before returning to the tagging area. Some degree of site fidelity was observed. High utilization hotspots of tagged sharks fell inside the area under strongest fishing pressure. Despite the small sample size, a positive correlation between tag recorded information and catch data was detected. All sharks exhibited a strong preference for the warm and shallow waters of the mixed layer, spending on average more than 70% of the time above the thermocline and 95% above 120 m. Results indicate that the removal of shallow hooks on longline gear might be an efficient mitigation measure to reduce the bycatch of this pelagic shark species. The work also highlights the potential of tagging experiments to provide essential information for the development of spatio-temporal management measures.

  20. Analysis of reproductive patterns of fishes from three Large Marine Ecosystems

    Directory of Open Access Journals (Sweden)

    Isaac eTrindade-Santos

    2015-06-01

    Full Text Available Fish reproductive biology plays an important role for fishery management, especially in developing countries. The aim of this study was to compile all available information and analyze reproduction patterns of marine fishes in three Large Marine Ecosystems (LMEs: North, East, and South Brazil Shelves. We tested the hypothesis that the onset and duration of spawning season differ among these three LMEs; compared the ratio between length at first maturity and asymptotic length with the global trend observed; analyzed sex ratios; and tested whether females allocate more energy into reproduction than males. The following data were compiled from published sources and ‘grey’ literature: sex ratio, spawning season, gonadosomatic indices (GSI, and length at first maturity (Lm. The reproductive load was estimated as Lm/L∞. The median extension of the spawning season in the North, East, and South Brazil Shelves were 6.5, 6.0 and 5.0 months, respectively, with higher frequency during austral summer in South Brazil. Marine fishes from these three LMEs can be grouped in summer and non-summer spawners. About ninety six percent of the cases the reproductive load was between 0.3 and 0.8, which is slightly shifted toward smaller values, compared with the global range of 0.4-0.9. Gonadosomatic indices for females were higher. Contrary to some expectations, there is seasonality in the reproduction of tropical fishes. However, seasonality is stronger in southern populations. Size at first maturity is not efficiently used as a tool for fisheries management in the ecosystems analyzed.

  1. Shift in a large river fish assemblage: body-size and trophic structure dynamics.

    Directory of Open Access Journals (Sweden)

    Kyle J Broadway

    Full Text Available As the intensity and speed of environmental change increase at both local and global scales it is imperative that we gain a better understanding of the ecological implications of community shifts. While there has been substantial progress toward understanding the drivers and subsequent responses of community change (e.g. lake trophic state, the ecological impacts of food web changes are far less understood. We analyzed Wabash River fish assemblage data collected from 1974-2008, to evaluate temporal variation in body-size structure and functional group composition. Two parameters derived from annual community size-spectra were our major response variables: (1 the regression slope is an index of ecological efficiency and predator-prey biomass ratios, and (2 spectral elevation (regression midpoint height is a proxy for food web capacity. We detected a large assemblage shift, over at least a seven year period, defined by dramatic changes in abundance (measured as catch-per-unit-effort of the dominant functional feeding groups among two time periods; from an assemblage dominated by planktivore-omnivores to benthic invertivores. There was a concurrent increase in ecological efficiency (slopes increased over time following the shift associated with an increase in large-bodied low trophic level fish. Food web capacity remained relatively stable with no clear temporal trends. Thus, increased ecological efficiency occurred simultaneous to a compensatory response that shifted biomass among functional feeding groups.

  2. Large scale dynamics of the Persistent Turning Walker model of fish behavior

    CERN Document Server

    Degond, Pierre

    2007-01-01

    This paper considers a new model of individual displacement, based on fish motion, the so-called Persistent Turning Walker (PTW) model, which involves an Ornstein-Uhlenbeck process on the curvature of the particle trajectory. The goal is to show that its large time and space scale dynamics is of diffusive type, and to provide an analytic expression of the diffusion coefficient. Two methods are investigated. In the first one, we compute the large time asymptotics of the variance of the individual stochastic trajectories. The second method is based on a diffusion approximation of the kinetic formulation of these stochastic trajectories. The kinetic model is a Fokker-Planck type equation posed in an extended phase-space involving the curvature among the kinetic variables. We show that both methods lead to the same value of the diffusion constant. We present some numerical simulations to illustrate the theoretical results.

  3. Replacement of Dietary Fish Oil with Vegetable Oils Improves the Growth and Flesh Quality of Large Yellow Croaker (Larmichthys crocea)

    Institute of Scientific and Technical Information of China (English)

    DUAN Qingyuan; MAI Kangsen; SHENTU Jikang; AI Qinghui; ZHONG Huiying; JIANG Yujian; ZHANG Lu; ZHANG Chunxiao; GUO Sitong

    2014-01-01

    We investigated the effect of the replacement of dietary fish oil with vegetable oils on the growth and flesh quality of large yellow croaker (Larmichthys crocea). The basal diet (FO) was formulated to contain 66.5%fish meal and 6.4%menhaden fish oil;whereas the other 3 experimental diets were formulated by replacing the fish oil with 50%soybean oil (SO50), 100%soybean oil (SO100) and 100%palm oil (PO100), respectively. The 4 diets were randomly assigned to 4 floating sea cages (3.0 m × 3.0 m × 3.0 m), and each was stocked with 250 fish individuals with an initial average weight of 245.29 g ± 7.45 g. The fish were fed to apparent sa-tiation twice a day at 5:00 and 17:00, respectively, for 12 weeks. Experimental analysis showed that the specific growth rate of fish fed SO50 or PO100 were significantly higher than that of fish fed FO or SO100 (P0.05). Compared to FO diet, SO50, SO100 and PO100 diets led to substantial decreases in the liquid loss and wa-ter loss from fresh fillets (1 d, 4℃) (P<0.05). Similarly, thiobarbituric acid reactive substance (TBARS) values of fillets under dif-ferent storage conditions (1 d, 4℃;7 d, 4℃;4 weeks,-20℃;8 weeks,-20℃) decreased significantly after partial or complete re-placement of fish oil with vegetable oils. These findings indicated that the growth performance and selected flesh quality properties (liquid holding capacity and TBARS value) of large yellow croaker were substantially improved by replacing dietary fish oil with vegetable oils.

  4. The role of marine protected areas in conserving highly mobile pelagic species

    OpenAIRE

    Curnick, D. J.

    2016-01-01

    In this thesis I assess the efficacy of large no-take marine protected areas (MPAs), known as marine reserves, in safeguarding mobile pelagic predators. The creation of reserves excludes fisheries, so while removing a pressure, it also removes a key source of data on pelagic predators. Therefore, I also evaluate two fisheries-independent monitoring techniques: telemetry and camera trapping. I use the British Indian Ocean Territory (BIOT) marine reserve as a case study. In Chapter 2 I assess t...

  5. The origin and initial rise of pelagic cephalopods in the Ordovician.

    Directory of Open Access Journals (Sweden)

    Björn Kröger

    Full Text Available BACKGROUND: During the Ordovician the global diversity increased dramatically at family, genus and species levels. Partially the diversification is explained by an increased nutrient, and phytoplankton availability in the open water. Cephalopods are among the top predators of today's open oceans. Their Ordovician occurrences, diversity evolution and abundance pattern potentially provides information on the evolution of the pelagic food chain. METHODOLOGY/PRINCIPAL FINDINGS: We reconstructed the cephalopod departure from originally exclusively neritic habitats into the pelagic zone by the compilation of occurrence data in offshore paleoenvironments from the Paleobiology Database, and from own data, by evidence of the functional morphology, and the taphonomy of selected cephalopod faunas. The occurrence data show, that cephalopod associations in offshore depositional settings and black shales are characterized by a specific composition, often dominated by orthocerids and lituitids. The siphuncle and conch form of these cephalopods indicate a dominant lifestyle as pelagic, vertical migrants. The frequency distribution of conch sizes and the pattern of epibionts indicate an autochthonous origin of the majority of orthocerid and lituitid shells. The consistent concentration of these cephalopods in deep subtidal sediments, starting from the middle Tremadocian indicates the occupation of the pelagic zone early in the Early Ordovician and a subsequent diversification which peaked during the Darriwilian. CONCLUSIONS/SIGNIFICANCE: The exploitation of the pelagic realm started synchronously in several independent invertebrate clades during the latest Cambrian to Middle Ordovician. The initial rise and diversification of pelagic cephalopods during the Early and Middle Ordovician indicates the establishment of a pelagic food chain sustainable enough for the development of a diverse fauna of large predators. The earliest pelagic cephalopods were slowly

  6. Unexpected hydrogen isotope variation in oceanic pelagic seabirds

    Science.gov (United States)

    Ostrom, Peggy H.; Wiley, Anne E.; Rossman, Sam; Stricker, Craig A.; James, Helen F.

    2014-01-01

    Hydrogen isotopes have significantly enhanced our understanding of the biogeography of migratory animals. The basis for this methodology lies in predictable, continental patterns of precipitation δD values that are often reflected in an organism's tissues. δD variation is not expected for oceanic pelagic organisms whose dietary hydrogen (water and organic hydrogen in prey) is transferred up the food web from an isotopically homogeneous water source. We report a 142% range in the δD values of flight feathers from the Hawaiian petrel (Pterodroma sandwichensis), an oceanic pelagic North Pacific species, and inquire about the source of that variation. We show δD variation between and within four other oceanic pelagic species: Newell's shearwater (Puffinus auricularis newellii), Black-footed albatross (Phoebastria nigripes), Laysan albatross (Phoebastria immutabilis) and Buller's shearwater (Puffinus bulleri). The similarity between muscle δD values of hatch-year Hawaiian petrels and their prey suggests that trophic fractionation does not influence δD values of muscle. We hypothesize that isotopic discrimination is associated with water loss during salt excretion through salt glands. Salt load differs between seabirds that consume isosmotic squid and crustaceans and those that feed on hyposmotic teleost fish. In support of the salt gland hypothesis, we show an inverse relationship between δD and percent teleost fish in diet for three seabird species. Our results demonstrate the utility of δD in the study of oceanic consumers, while also contributing to a better understanding of δD systematics, the basis for one of the most commonly utilized isotope tools in avian ecology.

  7. Unexpected hydrogen isotope variation in oceanic pelagic seabirds.

    Science.gov (United States)

    Ostrom, Peggy H; Wiley, Anne E; Rossman, Sam; Stricker, Craig A; James, Helen F

    2014-08-01

    Hydrogen isotopes have significantly enhanced our understanding of the biogeography of migratory animals. The basis for this methodology lies in predictable, continental patterns of precipitation δD values that are often reflected in an organism's tissues. δD variation is not expected for oceanic pelagic organisms whose dietary hydrogen (water and organic hydrogen in prey) is transferred up the food web from an isotopically homogeneous water source. We report a 142‰ range in the δD values of flight feathers from the Hawaiian petrel (Pterodroma sandwichensis), an oceanic pelagic North Pacific species, and inquire about the source of that variation. We show δD variation between and within four other oceanic pelagic species: Newell's shearwater (Puffinus auricularis newellii), Black-footed albatross (Phoebastria nigripes), Laysan albatross (Phoebastria immutabilis) and Buller's shearwater (Puffinus bulleri). The similarity between muscle δD values of hatch-year Hawaiian petrels and their prey suggests that trophic fractionation does not influence δD values of muscle. We hypothesize that isotopic discrimination is associated with water loss during salt excretion through salt glands. Salt load differs between seabirds that consume isosmotic squid and crustaceans and those that feed on hyposmotic teleost fish. In support of the salt gland hypothesis, we show an inverse relationship between δD and percent teleost fish in diet for three seabird species. Our results demonstrate the utility of δD in the study of oceanic consumers, while also contributing to a better understanding of δD systematics, the basis for one of the most commonly utilized isotope tools in avian ecology.

  8. A Habitat Model for Fish Communities in Large Streams and Small Rivers

    Directory of Open Access Journals (Sweden)

    Mark B. Bain

    2012-01-01

    Full Text Available Habitat has become one of the fundamentals for managing the environment. We report on synthesis of 30 habitat models for fish species that inhabit large streams and small rivers. Our protocol for integration of many species-level habitat models was to form a robust, general model that reflected the most common characteristics of the reviewed models. Eleven habitat variables were most commonly used in habitat models, and they were grouped by water quality, reproduction, and food and cover. The developed relations defined acceptable and optimal conditions for each habitat variable. Water quality variables were mid-summer water temperature, dissolved oxygen, pH, and turbidity. Other structural habitat variables were identified: riffle and pool velocity, riffle depth, and percent of the stream area with cover and pools. We conclude that it is feasible to consolidate species-level habitat models for fish that inhabit the same waterway type. Given the similarity among species models, our specification set will closely approximate the needs and optimal conditions of many species. These eleven variables can serve as design specifications for rehabilitating streams and small rivers in human dominated settings.

  9. Movements of diadromous fish in large unregulated tropical rivers inferred from geochemical tracers.

    Science.gov (United States)

    Walther, Benjamin D; Dempster, Tim; Letnic, Mike; McCulloch, Malcolm T

    2011-04-06

    Patterns of migration and habitat use in diadromous fishes can be highly variable among individuals. Most investigations into diadromous movement patterns have been restricted to populations in regulated rivers, and little information exists for those in unregulated catchments. We quantified movements of migratory barramundi Lates calcarifer (Bloch) in two large unregulated rivers in northern Australia using both elemental (Sr/Ba) and isotope ((87)Sr/(86)Sr) ratios in aragonitic ear stones, or otoliths. Chemical life history profiles indicated significant individual variation in habitat use, particularly among chemically distinct freshwater habitats within a catchment. A global zoning algorithm was used to quantify distinct changes in chemical signatures across profiles. This algorithm identified between 2 and 6 distinct chemical habitats in individual profiles, indicating variable movement among habitats. Profiles of (87)Sr/(86)Sr ratios were notably distinct among individuals, with highly radiogenic values recorded in some otoliths. This variation suggested that fish made full use of habitats across the entire catchment basin. Our results show that unrestricted movement among freshwater habitats is an important component of diadromous life histories for populations in unregulated systems.

  10. Effects of fishing rope strength on the severity of large whale entanglements.

    Science.gov (United States)

    Knowlton, Amy R; Robbins, Jooke; Landry, Scott; McKenna, Henry A; Kraus, Scott D; Werner, Timothy B

    2016-04-01

    Entanglement in fixed fishing gear affects whales worldwide. In the United States, deaths of North Atlantic right (Eubalaena glacialis) and humpback whales (Megaptera novaeangliae) have exceeded management limits for decades. We examined live and dead whales entangled in fishing gear along the U.S. East Coast and the Canadian Maritimes from 1994 to 2010. We recorded whale species, age, and injury severity and determined rope polymer type, breaking strength, and diameter of the fishing gear. For the 132 retrieved ropes from 70 cases, tested breaking strength range was 0.80-39.63 kN (kiloNewtons) and the mean was 11.64 kN (SD 8.29), which is 26% lower than strength at manufacture (range 2.89-53.38 kN, mean = 15.70 kN [9.89]). Median rope diameter was 9.5 mm. Right and humpback whales were found in ropes with significantly stronger breaking strengths at time of manufacture than minke whales (Balaenoptera acuturostrata) (19.30, 17.13, and 10.47 mean kN, respectively). Adult right whales were found in stronger ropes (mean 34.09 kN) than juvenile right whales (mean 15.33 kN) and than all humpback whale age classes (mean 17.37 kN). For right whales, severity of injuries increased since the mid 1980s, possibly due to changes in rope manufacturing in the mid 1990s that resulted in production of stronger ropes at the same diameter. Our results suggest that broad adoption of ropes with breaking strengths of ≤ 7.56 kN (≤ 1700 lbsf) could reduce the number of life-threatening entanglements for large whales by at least 72%, and yet could provide sufficient strength to withstand the routine forces involved in many fishing operations. A reduction of this magnitude would achieve nearly all the mitigation legally required for U.S. stocks of North Atlantic right and humpback whales. Ropes with reduced breaking strength should be developed and tested to determine the feasibility of their use in a variety of fisheries.

  11. Long-term GPS tracking of ocean sunfish Mola mola offers a new direction in fish monitoring.

    Directory of Open Access Journals (Sweden)

    David W Sims

    Full Text Available Satellite tracking of large pelagic fish provides insights on free-ranging behaviour, distributions and population structuring. Up to now, such fish have been tracked remotely using two principal methods: direct positioning of transmitters by Argos polar-orbiting satellites, and satellite relay of tag-derived light-level data for post hoc track reconstruction. Error fields associated with positions determined by these methods range from hundreds of metres to hundreds of kilometres. However, low spatial accuracy of tracks masks important details, such as foraging patterns. Here we use a fast-acquisition global positioning system (Fastloc GPS tag with remote data retrieval to track long-term movements, in near real time and position accuracy of <70 m, of the world's largest bony fish, the ocean sunfish Mola mola. Search-like movements occurred over at least three distinct spatial scales. At fine scales, sunfish spent longer in highly localised areas with faster, straighter excursions between them. These 'stopovers' during long-distance movement appear consistent with finding and exploiting food patches. This demonstrates the feasibility of GPS tagging to provide tracks of unparalleled accuracy for monitoring movements of large pelagic fish, and with nearly four times as many locations obtained by the GPS tag than by a conventional Argos transmitter. The results signal the potential of GPS-tagged pelagic fish that surface regularly to be detectors of resource 'hotspots' in the blue ocean and provides a new capability for understanding large pelagic fish behaviour and habitat use that is relevant to ocean management and species conservation.

  12. Spatial and temporal changes in the Barents Sea pelagic compartment during the recent warming

    Science.gov (United States)

    Eriksen, Elena; Skjoldal, Hein Rune; Gjøsæter, Harald; Primicerio, Raul

    2017-02-01

    The Barents Sea has experienced substantial warming over the last few decades with expansion of relatively warm Atlantic water and reduction in sea ice. Based on a review of relevant literature and additional analyses, we report changes in the pelagic compartment associated with this warming using data from autumn surveys (acoustic capelin, 0-group fish, and ecosystem surveys). We estimated biomass for 25 components of the pelagic community, including macroplankton, 0-group fish, and juvenile and adult pelagic fish, were examined for spatial and temporal variation over the period 1993-2013. The estimated total biomass of the investigated pelagic compartment, not including mesozooplankton, ranged between about 6 and 30 million tonnes wet weight with an average of 17 million tonnes over the 21-years period. Krill was the dominant biomass component (63%), whereas pelagic fish (capelin, polar cod and herring) made up 26% and 0-group fish 11% of the biomass on average. The spatial distribution of biomass showed a broad-scale pattern reflecting differences in distribution of the main pelagic fishes (capelin in the north, polar cod in the east, and herring in the south) and transport of krill and 0-group fish with the Atlantic water flowing into the southern Barents Sea. Dividing the Barents Sea into six regions, the highest average biomass values were found in the Southwestern and South-Central subareas (about 4 million tonnes in each), with krill as the main component. Biomass was also high in the North-Central subarea (about 3 million tonnes) where capelin was the major contributor. The total estimated biomass of the pelagic compartment remained relatively stable during each of two main periods (before and after 2004), but increased by a factor of two from around 11 million tonnes in the first to around 23 million tonnes in the last period. The pronounced increase reflected the warming between the relatively cold 1990s and the warmer 2000s and was driven mainly by an

  13. Total mercury levels in commercial fish species from Italian fishery and aquaculture.

    Science.gov (United States)

    Di Lena, Gabriella; Casini, Irene; Caproni, Roberto; Fusari, Andrea; Orban, Elena

    2017-01-29

    Total mercury levels were measured in 42 commercial fish species caught off the Central Adriatic and Tyrrhenian coasts of Italy and in 6 aquaculture species. The study on wild fish covered species differing in living habitat and trophic level. The study on farmed fish covered marine and freshwater species from intensive and extensive aquaculture and their feed. Mercury levels were analysed by thermal decomposition-amalgamation-atomic absorption spectrophotometry. Total mercury concentrations in the muscle of wild fish showed a high variability among species (0.025-2.20 mg kg(-1) wet weight). The lowest levels were detected in low trophic-level demersal and pelagic-neritic fish and in young individuals of high trophic-level species. Levels exceeding the European Commission limits were found in large-size specimens of high trophic-level pelagic and demersal species. Fish from intensive farming showed low levels of total mercury (0.008-0.251 mg kg(-1)). Fish from extensive rearing showed variable contamination levels, depending on the area of provenience. An estimation of the human intake of mercury associated to the consumption of the studied fish and its comparison with the tolerable weekly intake is provided.

  14. Rapid communication: experimental evidence that juvenile pelagic jacks (Carangidae) respond behaviorally to DMSP.

    Science.gov (United States)

    Debose, Jennifer L; Nevitt, Gabrielle A; Dittman, Andrew H

    2010-03-01

    Dimethylsulfoniopropionate (DMSP) is produced by marine algae and released during foraging activity by zooplankton and fish. Pelagic fishes depend on patchily distributed foraging opportunities, and DMSP may be an important signaling molecule for these events. We have previously shown that the abundance of carangid jacks is positively associated with elevated DMSP levels over coral reefs in the Gulf of Mexico, suggesting that these fishes may use spatial and temporal variation in DMSP to locate foraging opportunities. Here, we extend this work by demonstrating that juveniles of two species of pelagic jack, crevalle jack, Caranx hippos, and bluefin trevally, C. melampygus, detect and respond to DMSP in a flow-through tank in the laboratory. Juveniles of these species showed elevated swimming activity in response to ecologically relevant concentrations of DMSP (10(-9) M). These results provide further evidence that this chemical may serve as a chemosensory cue for carangid species.

  15. 物联网智慧服务系统架构及在远洋渔船中的应用%The architecture of smart service system based on IOT and its application on pelagic fishing vessel

    Institute of Scientific and Technical Information of China (English)

    虞丽娟; 凌培亮; 杨劲松; 曹守启; 陈成明

    2013-01-01

    计算环境的变化使得服务化正成为当今信息社会各类资源共享的主要商业模式,信息系统也完成了从以企业自身为中心专注内部管理的管理信息系统向以客户为中心关注整个供应链的ERP系统的演变,物联网时代的到来,使得新型的基于物联网的信息系统呼之欲出.从远洋渔船及其作业系统需求出发,以面向服务的架构SOA为指导,提出并构建了远洋渔船物联网智慧服务系统,探讨基于新型物联网智慧服务系统的开放式服务构件架构模型及系统功能;由于实际应用中,系统的服务构件关系的表达和管理往往比较复杂,服务构件间的冗余及整体关系难于掌握,论述了基于Petri网的系统中各构件服务关系动态表达方法,该方法能增强使用者对服务构件库的整体掌握能力,便于发现服务构件间的求解冲突与冗余,并提供了直观的服务构件的组合配置图示机制,提高了系统智能,发挥了SOA架构的优势.同时进行了实验仿真,证明了方法的可靠性.%The change of the computing environment makes the servitization become the main business model of all kinds of the resource sharing in the modern informationized society. The information system has accomplished the evolution from enterprise-oriented MIS focusing on the internal management to the client-oriented ERP concerning the whole supply chain. The arrival of the Internet of Things (IOT) summons the new type of information systems based on IOT. Founded on the requirements of pelagic vessel and its operating system, this paper discussed the architecture model of open service component architecture model based on the new-type IOT smart service system and its systemic function. In the practical application, the relational representation and management of system service components are grossly complicated while the redundancy and overall relationship between the service components are troublesome to be

  16. Linking fish and fluid behavior: Results from a physical model of turbulence and bioenergetics around large wood in rivers

    Science.gov (United States)

    Tullos, D. D.; Walter, C.

    2013-12-01

    The re-introduction of large woody debris into streams and rivers for restoration purposes is rapidly growing, yet detailed, quantitative study linking the hydraulics around and fish use of large wood is lacking. This presentation summarizes the methods and results of a 1:1 scale physical model of a meander and a full channel jam, including observations of the flow field and fish behavior around the wood. Velocity measurements were made with an array of ADVs at 0.1m spacing. The flow field was analyzed to map hydraulic regions around the wood and characterize the location, circulation patterns, turbulent length scales, and turbulence intensities of dominant flow structures. Underwater videogrammetry was conducted using wild, juvenile steelhead and coho to 1) identify patches of salmonid use of the wood, 2) establish orientation of the fish relative to the flow field, 3) document tailbeat frequencies and focal point velocities, and 4) investigate the percent of time fish expend avoiding predation, foraging, and resting in regions of hydraulic refuge under and around the wood. Results indicate that four primary flow fields develop. In the first, flow is concentrated in a jet through the wood structure, where downstream velocities, turbulence intensities, and total energy are highest. Downstream of the wood, flow expansion results in three hydraulic regions, characterized by a) a large eddy of length scale equivalent to approximately one-half of the wetted channel width, b) a lower velocity, downstream oriented core, and c) an interface of strong hydraulic gradients between the eddy and downstream flow. Fish were predominantly observed in two locations. As expected, fish generally avoided the jet directly, but were observed seeking cover under a log located in an area of rapid flow on the downstream portion of the jet. The fish were also observed hiding and resting in the eddy downstream of the log, with little to no evidence of the expected movement into higher

  17. Small estuarine fishes feed on large trematode cercariae: Lab and field investigations

    Science.gov (United States)

    Kaplan, A.T.; Rebhal, S.; Lafferty, K.D.; Kuris, A.M.

    2009-01-01

    In aquatic ecosystems, dense populations of snails can shed millions of digenean trematode cercariae every day. These short-lived, free-living larvae are rich in energy and present a potential resource for consumers. We investigated whether estuarine fishes eat cercariae shed by trematodes of the estuarine snail Cerithidea californica. In aquaria we presented cercariae from 10 native trematode species to 6 species of native estuarine fishes. Many of these fishes readily engorged on cercariae. To determine if fishes ate cercariae in the field, we collected the most common fish species, Fundulus parvipinnis (California killifish), from shallow water on rising tides when snails shed cercariae. Of 61 killifish, 3 had recognizable cercariae in their gut. Because cercariae are common in this estuary, they could be frequent sources of energy for small fishes. In turn, predation on cercariae by fishes (and other predators) could also reduce the transmission success of trematodes. ?? 2009 American Society of Parasitologists.

  18. Long-term impact of bottom trawling on pelagic-benthic coupling in the southern North Sea (German Bight)

    Science.gov (United States)

    Friedrich, Jana; van Beusekom, Justus E. E.; Neumann, Andreas; Naderipour, Celine; Janssen, Felix; Ahmerkamp, Soeren; Holtappels, Moritz; Schueckel, Ulrike

    2016-04-01

    were measured on sandy (permeable) and silty (diffusive) sediments, whereas significant differences of microbial O2 uptake were observed indeed between permeable and diffusive sediments. Nevertheless, when considering the multitude of different methods, we found that benthic respiration over the season seemed to be governed mainly by settling of fresh organic matter during calm periods and its rapid turnover in a region where strong tidal and wind-forced currents distribute suspended particles over large areas. Summer pelagic respiration rates were an order of magnitude higher then benthic rates, and account for 88-93% of total respiration, which represents 79-98% of pelagic primary production. Our measurements of benthic respiration account for 7-12% of the total in the German Bight, which is lower compared to earlier studies. Strong tidal and wind-forced currents along with the lack of complex three-dimensional biogenic structures seem to prevent settling of suspended matter and foster resuspension, thereby supporting pelagic turnover processes. Hence, we assume that benthic turnover might have been higher before systematic bottom trawling destroyed the bottom hydrobiological regime. Today, due to the strong current regime in the German Bight, the pelagic system appears to be a largely closed system of production and respiration, with comparably little for export to the benthic system due to absence of biogenic structures. References Callaway R, Engelhard GH, Dann J, Cotter J, Rumohr H (2007) One century of North Sea epibenthos and fishing: comparison between 1902-1912, 1982-1985 and 2000. Marine Ecology Progress Series 346, 27-43. Christiansen S (2009) Towards good environmental status - A network of marine protected areas for the North Sea. In: Lutter S (ed) WWF Germany, Fankfurt/Main Emeis K-C, van Beusekom J, Callies U, Ebinghaus R, Kannen A, Kraus G, Kröncke I, Lenhart H, Lorkowski I, Matthias V, Möllmann C, Pätsch J, Scharfe M, Thomas H, Weisse R, Zorita E

  19. Pelagic life and depth: coastal physical features in West Africa shape the genetic structure of the Bonga Shad, Ethmalosa fimbriata.

    Directory of Open Access Journals (Sweden)

    Jean-Dominique Durand

    Full Text Available The bonga shad, Ethmalosa fimbriata, is a West African pelagic species still abundant in most habitats of its distribution range and thought to be only recently affected by anthropogenic pressure (habitat destruction or fishing pressure. Its presence in a wide range of coastal habitats characterised by different hydrodynamic processes, represents a case study useful for evaluating the importance of physical structure of the west African shoreline on the genetic structure of a small pelagic species. To investigate this question, the genetic diversity of E. fimbriata was assessed at both regional and species range scales, using mitochondrial (mt and nuclear DNA markers. Whereas only three panmictic units were identified with mtDNA at the large spatial scale, nuclear genetic markers (EPIC: exon-primed intron-crossing indicated a more complex genetic pattern at the regional scale. In the northern-most section of shad's distribution range, up to 4 distinct units were identified. Bayesian inference as well as spatial autocorrelation methods provided evidence that gene flow is impeded by the presence of deep-water areas near the coastline (restricting the width of the coastal shelf, such as the Cap Timiris and the Kayar canyons in Mauritania and Senegal, respectively. The added discriminatory power provided by the use of EPIC markers proved to be essential to detect the influence of more subtle, contemporary processes (e.g. gene flow, barriers, etc. acting within the glacial refuges identified previously by mtDNA.

  20. North Pacific Pelagic Seabird Database (NPPSD)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The North Pacific Pelagic Seabird Database (NPPSD) was created in 2005 to consolidate data on the oceanic distribution of marine bird species in the North Pacific....

  1. Nutrient reduction and climate change cause a potential shift from pelagic to benthic pathways in a eutrophic marine ecosystem

    DEFF Research Database (Denmark)

    Lindegren, Martin; Blenckner, T.; Stenseth, N.C.

    2012-01-01

    for the occurrence of regime shifts and the relative importance of multiple drivers, e.g., climate change, eutrophication and commercial fishing on ecosystem dynamics and trophic pathways. Using multivariate statistics and nonlinear regression on a comprehensive data set, covering abiotic factors and biotic...... large and abrupt changes, i.e., trophic cascades and ecological regime shifts, which once having occurred may prove potentially irreversible. In this study, we investigate the state and regulatory pathways of the Kattegat; a eutrophied and heavily exploited marine ecosystem, specifically testing...... variables across all trophic levels, we here propose a potential regime shift from pelagic to benthic regulatory pathways; a possible first sign of recovery from eutrophication likely triggered by drastic nutrient reductions (involving both nitrogen and phosphorus), in combination with climate...

  2. Quantifying fish assemblages in large, offshore marine protected areas: an Australian case study.

    Directory of Open Access Journals (Sweden)

    Nicole A Hill

    Full Text Available As the number of marine protected areas (MPAs increases globally, so does the need to assess if MPAs are meeting their management goals. Integral to this assessment is usually a long-term biological monitoring program, which can be difficult to develop for large and remote areas that have little available fine-scale habitat and biological data. This is the situation for many MPAs within the newly declared Australian Commonwealth Marine Reserve (CMR network which covers approximately 3.1 million km2 of continental shelf, slope, and abyssal habitat, much of which is remote and difficult to access. A detailed inventory of the species, types of assemblages present and their spatial distribution within individual MPAs is required prior to developing monitoring programs to measure the impact of management strategies. Here we use a spatially-balanced survey design and non-extractive baited video observations to quantitatively document the fish assemblages within the continental shelf area (a multiple use zone, IUCN VI of the Flinders Marine Reserve, within the Southeast marine region. We identified distinct demersal fish assemblages, quantified assemblage relationships with environmental gradients (primarily depth and habitat type, and described their spatial distribution across a variety of reef and sediment habitats. Baited videos recorded a range of species from multiple trophic levels, including species of commercial and recreational interest. The majority of species, whilst found commonly along the southern or south-eastern coasts of Australia, are endemic to Australia, highlighting the global significance of this region. Species richness was greater on habitats containing some reef and declined with increasing depth. The trophic breath of species in assemblages was also greater in shallow waters. We discuss the utility of our approach for establishing inventories when little prior knowledge is available and how such an approach may inform future

  3. The community structure of over-wintering larval and small juvenile fish in a large estuary

    Science.gov (United States)

    Munk, Peter; Cardinale, Massimiliano; Casini, Michele; Rudolphi, Ann-Christin

    2014-02-01

    The Skagerrak and Kattegat are estuarine straits of high hydrographical and ecological diversity, situated between the saline waters of the North Sea and the brackish waters of the Baltic Sea. These sustain important nursery grounds of many fish species, of which several overwinter during the larval and early juvenile stages. In order to give more insight into the communities of the overwintering ichthyoplankton in estuarine areas, we examine an annual series of observations from a standard survey carried out 1992-2010. Species differences and annual variability in distributions and abundances are described, and linkages between ichthyoplankton abundances and corresponding hydrographical information are analysed by GAM methods. Communities were dominated by herring, gobies, butterfish, sprat, pipefishes, lemon sole and European eel (i.e. glass eel), and all the sampled species showed large annual fluctuations in abundances. The species showed quite specific patterns of distribution although species assemblages with common distributional characteristics were identified. Within these assemblages, the ichthyoplankton abundances showed linkage to environmental characteristics described by bottom-depth and surface temperature and salinity. Hence the study points to a significant structuring of overwintering ichthyoplankton communities in large estuaries, based on the species habitat choice and its response to physical gradients.

  4. Comparative movements of four large fish species in a lowland river.

    Science.gov (United States)

    Koehn, J D; Nicol, S J

    2016-04-01

    A multi-year radio-telemetry data set was used to comparatively examine the concurrent movements of the adults of three large-bodied Australian native freshwater fishes (Murray cod Maccullochella peelii, trout cod Maccullochella macquariensis and golden perch Macquaria ambigua) and the introduced carp Cyprinus carpio. The study was conducted over a reach scale in the regulated Murray River in south-eastern Australia. Differences were identified in the movements among these species. The predominant behaviour was the use of small movements (1 km) did occur, the frequency varied considerably among species. Large-scale movements were least evident for M. macquariensis and more common for M. ambigua and C. carpio with these two species also having a greater propensity to change locations. Macquaria ambigua displayed the largest movements and more M. ambigua moved on a 'continual' basis. Although a degree of site fidelity was evident for all species, the highest levels were exhibited by M. macquariensis and M. peelii. Homing was also evident to some degree in all species, but was greatest for M. peelii.

  5. Large mesopelagic fishes biomass and trophic efficiency in the open ocean.

    KAUST Repository

    Irigoien, Xabier

    2014-01-01

    With a current estimate of ~1,000 million tons, mesopelagic fishes likely dominate the world total fishes biomass. However, recent acoustic observations show that mesopelagic fishes biomass could be significantly larger than the current estimate. Here we combine modelling and a sensitivity analysis of the acoustic observations from the Malaspina 2010 Circumnavigation Expedition to show that the previous estimate needs to be revised to at least one order of magnitude higher. We show that there is a close relationship between the open ocean fishes biomass and primary production, and that the energy transfer efficiency from phytoplankton to mesopelagic fishes in the open ocean is higher than what is typically assumed. Our results indicate that the role of mesopelagic fishes in oceanic ecosystems and global ocean biogeochemical cycles needs to be revised as they may be respiring ~10% of the primary production in deep waters.

  6. Aleutian Islands Coastal Resources Inventory and Environmental Sensitivity Maps: FISH (Fish Polygons)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains biological resource data for estuarine, benthic, and pelagic fish in the Aleutian Islands, Alaska. Vector polygons in this data set represent...

  7. A New model to forecast fishing ground ofScomber japonicus in the Yellow Sea and East China Sea

    Institute of Scientific and Technical Information of China (English)

    GAO Feng; CHEN Xinjun; GUAN Wenjiang; LI Gang

    2016-01-01

    The pelagic species is closely related to the marine environmental factors, and establishment of forecasting model of fishing ground with high accuracy is an important content for pelagic fishery. The chub mackerel (Scomber japonicus) in the Yellow Sea and East China Sea is an important fishing target for Chinese lighting purse seine fishery. Based on the fishery data from China’s mainland large-type lighting purse seine fishery for chub mackerel during the period of 2003 to 2010 and the environmental data including sea surface temperature (SST), gradient of the sea surface temperature (GSST), sea surface height (SSH) and geostrophic velocity (GV), we attempt to establish one new forecasting model of fishing ground based on boosted regression trees. In this study, the fishing areas with fishing effort is considered as one fishing ground, and the areas with no fishing ground are randomly selected from a background field, in which the fishing areas have no records in the logbooks. The performance of the forecasting model of fishing ground is evaluated with the testing data from the actual fishing data in 2011. The results show that the forecasting model of fishing ground has a high prediction performance, and the area under receiver operating curve (AUC) attains 0.897. The predicted fishing grounds are coincided with the actual fishing locations in 2011, and the movement route is also the same as the shift of fishing vessels, which indicates that this forecasting model based on the boosted regression trees can be used to effectively forecast the fishing ground of chub mackerel in the Yellow Sea and East China Sea.

  8. Effects of landscape and riparian condition on a fish index of biotic integrity in a large southeastern Brazil river

    Science.gov (United States)

    Environmental conditions of a large river in southeastern Brazil were assessed by evaluating fish assemblage structure (index of biotic integrity, IBI), landscape use (forest, pasture, urban area, and tributary water) and riparian condition. A survey of the 338 km-long middle rea...

  9. The importance of flooded terrestrial habitats for larval fish in a semi-natural large floodplain (Volga, Russian Federation)

    NARCIS (Netherlands)

    Gorski, Konrad; Leeuw, De Joep; Winter, Hendrik; Khoruzhaya, Victoria; Boldyrev, Vasily; Vekhov, Dmitry; Nagelkerke, Leo

    2016-01-01

    We assessed the importance of flooded terrestrial habitats for fish larvae in a semi-natural large floodplain (Volga, Russian Federation) by comparing abundances at the shoreline of permanent waterbodies with flooded terrestrial habitats. We found that overall larval abundance at the shoreline of

  10. CUDA based Level Set Method for 3D Reconstruction of Fishes from Large Acoustic Data

    DEFF Research Database (Denmark)

    Sharma, Ojaswa; Anton, François

    2009-01-01

    Acoustic images present views of underwater dynamics, even in high depths. With multi-beam echo sounders (SONARs), it is possible to capture series of 2D high resolution acoustic images. 3D reconstruction of the water column and subsequent estimation of fish abundance and fish species...

  11. The global susceptibility of coastal forage fish to competition by large jellyfish

    DEFF Research Database (Denmark)

    Schnedler-Meyer, Nicolas Azaña; Mariani, Patrizio; Kiørboe, Thomas

    2016-01-01

    , but the lack of both good quality data and a robust theoretical framework have prevented general global analyses. Here, we present a general mechanistic food web model that considers fundamental differences in feeding modes and predation pressure between fish and jellyfish. The model predicts forage fish...

  12. Systematics and biogeography of Sternarchellini (Gymnotiformes: Apteronotidae: Diversification of electric fishes in large Amazonian rivers

    Directory of Open Access Journals (Sweden)

    Stephen J. Ivanyisky III

    Full Text Available The Sternarchellini (Gymnotiformes, Apteronotidae is a clade of 10 electric fish species that inhabit deep river channels of the Amazon and Orinoco basins, attain moderate adult body sizes (15-50 cm TL, and have a predatory life style. Here we trace the evolutionary origin and diversification of Sternarchellini using standard phylogenetic and biogeographic procedures and a dataset of 70 morphological characters. The main results are: 1 the genus Sternarchellaincludes both species currently assigned to the genus Magosternarchus; and 2 neither of the multi-species assemblages of Sternarchellini in the Amazon and Orinoco basins are monophyletic. Historical biogeographic analysis suggests that sternarchelline evolution was linked to the large-scale river capture event that formed the modern Amazon and Orinoco basins, i.e. the Late Miocene rise of the Vaupes structural arch and concomitant breaching of the Purus structural arch. This event is hypothesized to have contributed to formation of the modern sternarchelline species, and to the formation of the modern basin-wide sternarchelline species assemblages. The results indicate that cladogenesis (speciation and anagenesis (adaptive evolution were decoupled processes in the evolution of Sternarchellini.

  13. Efficient trawl avoidance by mesopelagic fishes causes large underestimation of their biomass

    KAUST Repository

    Kaartvedt, Stein

    2012-06-07

    Mesopelagic fishes occur in all the world’s oceans, but their abundance and consequently their ecological significance remains uncertain. The current global estimate based on net sampling prior to 1980 suggests a global abundance of one gigatonne (109 t) wet weight. Here we report novel evidence of efficient avoidance of such sampling by the most common myctophid fish in the Northern Atlantic, i.e. Benthosema glaciale. We reason that similar avoidance of nets may explain consistently higher acoustic abundance estimates of mesopelagic fish from different parts of the world’s oceans. It appears that mesopelagic fish abundance may be underestimated by one order of magnitude, suggesting that the role of mesopelagic fish in the oceans might need to be revised.

  14. Large-scale assessment of Mediterranean marine protected areas effects on fish assemblages.

    Science.gov (United States)

    Guidetti, Paolo; Baiata, Pasquale; Ballesteros, Enric; Di Franco, Antonio; Hereu, Bernat; Macpherson, Enrique; Micheli, Fiorenza; Pais, Antonio; Panzalis, Pieraugusto; Rosenberg, Andrew A; Zabala, Mikel; Sala, Enric

    2014-01-01

    Marine protected areas (MPAs) were acknowledged globally as effective tools to mitigate the threats to oceans caused by fishing. Several studies assessed the effectiveness of individual MPAs in protecting fish assemblages, but regional assessments of multiple MPAs are scarce. Moreover, empirical evidence on the role of MPAs in contrasting the propagation of non-indigenous-species (NIS) and thermophilic species (ThS) is missing. We simultaneously investigated here the role of MPAs in reversing the effects of overfishing and in limiting the spread of NIS and ThS. The Mediterranean Sea was selected as study area as it is a region where 1) MPAs are numerous, 2) fishing has affected species and ecosystems, and 3) the arrival of NIS and the northward expansion of ThS took place. Fish surveys were done in well-enforced no-take MPAs (HP), partially-protected MPAs (IP) and fished areas (F) at 30 locations across the Mediterranean. Significantly higher fish biomass was found in HP compared to IP MPAs and F. Along a recovery trajectory from F to HP MPAs, IP were similar to F, showing that just well enforced MPAs triggers an effective recovery. Within HP MPAs, trophic structure of fish assemblages resembled a top-heavy biomass pyramid. Although the functional structure of fish assemblages was consistent among HP MPAs, species driving the recovery in HP MPAs differed among locations: this suggests that the recovery trajectories in HP MPAs are likely to be functionally similar (i.e., represented by predictable changes in trophic groups, especially fish predators), but the specific composition of the resulting assemblages may depend on local conditions. Our study did not show any effect of MPAs on NIS and ThS. These results may help provide more robust expectations, at proper regional scale, about the effects of new MPAs that may be established in the Mediterranean Sea and other ecoregions worldwide.

  15. Large-scale assessment of Mediterranean marine protected areas effects on fish assemblages.

    Directory of Open Access Journals (Sweden)

    Paolo Guidetti

    Full Text Available Marine protected areas (MPAs were acknowledged globally as effective tools to mitigate the threats to oceans caused by fishing. Several studies assessed the effectiveness of individual MPAs in protecting fish assemblages, but regional assessments of multiple MPAs are scarce. Moreover, empirical evidence on the role of MPAs in contrasting the propagation of non-indigenous-species (NIS and thermophilic species (ThS is missing. We simultaneously investigated here the role of MPAs in reversing the effects of overfishing and in limiting the spread of NIS and ThS. The Mediterranean Sea was selected as study area as it is a region where 1 MPAs are numerous, 2 fishing has affected species and ecosystems, and 3 the arrival of NIS and the northward expansion of ThS took place. Fish surveys were done in well-enforced no-take MPAs (HP, partially-protected MPAs (IP and fished areas (F at 30 locations across the Mediterranean. Significantly higher fish biomass was found in HP compared to IP MPAs and F. Along a recovery trajectory from F to HP MPAs, IP were similar to F, showing that just well enforced MPAs triggers an effective recovery. Within HP MPAs, trophic structure of fish assemblages resembled a top-heavy biomass pyramid. Although the functional structure of fish assemblages was consistent among HP MPAs, species driving the recovery in HP MPAs differed among locations: this suggests that the recovery trajectories in HP MPAs are likely to be functionally similar (i.e., represented by predictable changes in trophic groups, especially fish predators, but the specific composition of the resulting assemblages may depend on local conditions. Our study did not show any effect of MPAs on NIS and ThS. These results may help provide more robust expectations, at proper regional scale, about the effects of new MPAs that may be established in the Mediterranean Sea and other ecoregions worldwide.

  16. Towards an integrated forecasting system for pelagic fisheries

    DEFF Research Database (Denmark)

    Christensen, Asbjørn; Butenschön, Momme; Gürkan, Zeren

    First results of a coupled modelling and forecasting system for pelagic fisheries are presented. The system consists of three mathematically fundamentally different model subsystems: POLCOMSERSEM provides the physical–biogeochemical environment in the northwest European shelf, the Sandeel...... Population Analysis Model describes sandeel stocks in the North Sea, and the Sandeel Larval Analysis Model connects POLCOMS‐ERSEM and SPAM by computing the physical–biological interaction. Our main findings by coupling model subsystems is that well‐defined and generic model interfaces are very important...... for a successful and extendable coupled model framework. The integrated approach, simulating ecosystem dynamics from physics to fish, allows analysis of the pathways in the ecosystem to investigate the propagation of changes in the ocean climate and lower trophic levels to quantify the impacts on the higher...

  17. Towards an integrated forecasting system for pelagic fisheries

    DEFF Research Database (Denmark)

    Christensen, Asbjørn; Butenschön, Momme; Gürkan, Zeren

    2012-01-01

    First results of a coupled modelling and forecasting system for pelagic fisheries are presented. The system consists of three mathematically fundamentally different model subsystems: POLCOMSERSEM provides the physical–biogeochemical environment in the northwest European shelf, the Sandeel...... Population Analysis Model describes sandeel stocks in the North Sea, and the Sandeel Larval Analysis Model connects POLCOMS‐ERSEM and SPAM by computing the physical–biological interaction. Our main findings by coupling model subsystems is that well‐defined and generic model interfaces are very important...... for a successful and extendable coupled model framework. The integrated approach, simulating ecosystem dynamics from physics to fish, allows analysis of the pathways in the ecosystem to investigate the propagation of changes in the ocean climate and lower trophic levels to quantify the impacts on the higher...

  18. Large Recovery of Fish Biomass in a No-Take Marine Reserve

    Science.gov (United States)

    Aburto-Oropeza, Octavio; Erisman, Brad; Galland, Grantly R.; Mascareñas-Osorio, Ismael; Sala, Enric; Ezcurra, Exequiel

    2011-01-01

    No-take marine reserves are effective management tools used to restore fish biomass and community structure in areas depleted by overfishing. Cabo Pulmo National Park (CPNP) was created in 1995 and is the only well enforced no-take area in the Gulf of California, Mexico, mostly because of widespread support from the local community. In 1999, four years after the establishment of the reserve, there were no significant differences in fish biomass between CPNP (0.75 t ha−1 on average) and other marine protected areas or open access areas in the Gulf of California. By 2009, total fish biomass at CPNP had increased to 4.24 t ha−1 (absolute biomass increase of 3.49 t ha−1, or 463%), and the biomass of top predators and carnivores increased by 11 and 4 times, respectively. However, fish biomass did not change significantly in other marine protected areas or open access areas over the same time period. The absolute increase in fish biomass at CPNP within a decade is the largest measured in a marine reserve worldwide, and it is likely due to a combination of social (strong community leadership, social cohesion, effective enforcement) and ecological factors. The recovery of fish biomass inside CPNP has resulted in significant economic benefits, indicating that community-managed marine reserves are a viable solution to unsustainable coastal development and fisheries collapse in the Gulf of California and elsewhere. PMID:21858183

  19. Large recovery of fish biomass in a no-take marine reserve.

    Directory of Open Access Journals (Sweden)

    Octavio Aburto-Oropeza

    Full Text Available No-take marine reserves are effective management tools used to restore fish biomass and community structure in areas depleted by overfishing. Cabo Pulmo National Park (CPNP was created in 1995 and is the only well enforced no-take area in the Gulf of California, Mexico, mostly because of widespread support from the local community. In 1999, four years after the establishment of the reserve, there were no significant differences in fish biomass between CPNP (0.75 t ha(-1 on average and other marine protected areas or open access areas in the Gulf of California. By 2009, total fish biomass at CPNP had increased to 4.24 t ha(-1 (absolute biomass increase of 3.49 t ha(-1, or 463%, and the biomass of top predators and carnivores increased by 11 and 4 times, respectively. However, fish biomass did not change significantly in other marine protected areas or open access areas over the same time period. The absolute increase in fish biomass at CPNP within a decade is the largest measured in a marine reserve worldwide, and it is likely due to a combination of social (strong community leadership, social cohesion, effective enforcement and ecological factors. The recovery of fish biomass inside CPNP has resulted in significant economic benefits, indicating that community-managed marine reserves are a viable solution to unsustainable coastal development and fisheries collapse in the Gulf of California and elsewhere.

  20. Vertical migrations of a deep-sea fish and its prey.

    Directory of Open Access Journals (Sweden)

    Pedro Afonso

    Full Text Available It has been speculated that some deep-sea fishes can display large vertical migrations and likely doing so to explore the full suite of benthopelagic food resources, especially the pelagic organisms of the deep scattering layer (DSL. This would help explain the success of fishes residing at seamounts and the increased biodiversity found in these features of the open ocean. We combined active plus passive acoustic telemetry of blackspot seabream with in situ environmental and biological (backscattering data collection at a seamount to verify if its behaviour is dominated by vertical movements as a response to temporal changes in environmental conditions and pelagic prey availability. We found that seabream extensively migrate up and down the water column, that these patterns are cyclic both in short-term (tidal, diel as well as long-term (seasonal scales, and that they partially match the availability of potential DSL prey components. Furthermore, the emerging pattern points to a more complex spatial behaviour than previously anticipated, suggesting a seasonal switch in the diel behaviour mode (benthic vs. pelagic of seabream, which may reflect an adaptation to differences in prey availability. This study is the first to document the fine scale three-dimensional behaviour of a deep-sea fish residing at seamounts.

  1. Patterns of habitat segregation among large fishes in a Venezuelan floodplain river

    Directory of Open Access Journals (Sweden)

    Craig A. Layman

    2005-03-01

    Full Text Available Distribution and abundance of large fishes (SL>100 mm in the río Cinaruco, a floodplain river in the Venezuelan llanos, were examined by gill net sampling in four habitat types: sand banks, backwater creeks, floodplain lagoons, and river channel. Sampling was standardized using nets (25 m x 2 m of three mesh sizes set for 24-h periods. Based on data from >10,000 hours of gill netting over three years, there were significant differences in assemblage composition among the four habitats. Pair-wise comparisons suggested differences in assemblage composition between all pairs of habitats except creeks and lagoons. Differences in assemblage composition likely arose from species-specific habitat affinities. For example, 21 taxa were collected from both creeks and lagoons, but not from sand banks or the main river channel; each of these 21 taxa were associated with particular features characteristic of creeks and lagoons (e.g. abundant detritus. Assemblage structure also could be influenced by predation or other biological interactions, but mechanistic experiments are needed to evaluate this hypothesis. Assemblage composition was highly variable within all habitat types, likely the result of spatial and temporal heterogeneity associated with seasonal hydrology. Long distance migrations by prochilodontids and other taxa contributed to higher CPUE during the rising-water period of May 2002. Data from this study will provide a baseline to assess changes in the abundance and distribution of large-bodied fishes in response to increasing impacts from illegal commercial fishing in this region.A distribuição e abundância de grandes peixes (SL>100 mm no rio Cinaruco, um rio com uma planície inundação nos llanos da Venezuela, foram examinadas através de amostragens por redes de espera em quatro habitats: bancos de areia, riachos, lagoas da planície de inundação e o canal do rio. As amostragens foram padronizadas usando-se redes de espera (25 m x 2 m

  2. Effects of fish protein hydrolysate on growth performance and humoral immune response in large yellow croaker (Pseudosciaena crocea R.)

    Institute of Scientific and Technical Information of China (English)

    Hong-gang TANG; Tian-xing WU; Zhan-yu ZHAO; Xiao-dong PAN

    2008-01-01

    We investigated the effects of fish protein hydrolysate (FPH) on growth performance and humoral immune response of the large yellow croaker (Pseudosciaena crocea R.). One thousand and two hundred large yellow croakers [initial average weight: (162.75±23.85) g] were divided into four groups and reared in floating sea cages (3 m×3 m×3 m). The animals were fed with 4 diets: basal diet only (control) or diets supplemented with 5%, 10% and 15% (w/w) FPH. The results show that dietary FPH levels significantly influenced the growth and immunity of the large yellow croaker. Compared with the control group, total weight gain (TWG) in all treatment groups, relative weight gain (RWG) and specific growth rate (SGR) in fish fed with diets supplemerited with 10% and 15% FPH were significantly increased (P<0.05). Similar results were observed in immune parameters [lysozyme activity, serum complements, immunoglobulin M (IgM)]. Lysozyme activity, complement C4 and IgM were also significantly increased (P<0.05) in fish fed with diets supplemented with 10% and 15% FPH, while complement C3 level was significantly increased (P<0.05) in all treatment groups. In general, with the supplementation of FPH, particularly at dose of 10%,the growth performance and immunity of the large yellow croaker can be improved effectively.

  3. Deep vision: an in-trawl stereo camera makes a step forward in monitoring the pelagic community.

    Directory of Open Access Journals (Sweden)

    Melanie J Underwood

    Full Text Available Ecosystem surveys are carried out annually in the Barents Sea by Russia and Norway to monitor the spatial distribution of ecosystem components and to study population dynamics. One component of the survey is mapping the upper pelagic zone using a trawl towed at several depths. However, the current technique with a single codend does not provide fine-scale spatial data needed to directly study species overlaps. An in-trawl camera system, Deep Vision, was mounted in front of the codend in order to acquire continuous images of all organisms passing. It was possible to identify and quantify of most young-of-the-year fish (e.g. Gadus morhua, Boreogadus saida and Reinhardtius hippoglossoides and zooplankton, including Ctenophora, which are usually damaged in the codend. The system showed potential for measuring the length of small organisms and also recorded the vertical and horizontal positions where individuals were imaged. Young-of-the-year fish were difficult to identify when passing the camera at maximum range and to quantify during high densities. In addition, a large number of fish with damaged opercula were observed passing the Deep Vision camera during heaving; suggesting individuals had become entangled in meshes farther forward in the trawl. This indicates that unknown numbers of fish are probably lost in forward sections of the trawl and that the heaving procedure may influence the number of fish entering the codend, with implications for abundance indices and understanding population dynamics. This study suggests modifications to the Deep Vision and the trawl to increase our understanding of the population dynamics.

  4. A Large-Scale Pattern of Ontogenetic Shape Change in Ray-Finned Fishes.

    Directory of Open Access Journals (Sweden)

    Hilary R Katz

    Full Text Available Fishes exhibit a remarkable diversity of body shape as adults; however, it is unknown whether this diversity is reflected in larval stage morphology. Here we investigate the relationship between larval and adult body shape as expressed by body elongation. We surveyed a broad range of ray-finned fish species and compared body shape at larval and adult stages. Analysis shows that the vast majority of fish are more elongate at the larval stage than at the adult stage, and that adults display greater interspecies variation than larvae. We found that the superorder Elompomorpha is unique because many species within the group do not follow the observed elongation trends. These results indicate that much of the diversity observed in adults is achieved in post-larval stages. We suggest that larval morphology is subject to common constraints across the phylogeny.

  5. Benthic life in the pelagic: Aggregate encounter and degradation rates by pelagic harpacticoid copepods

    DEFF Research Database (Denmark)

    Koski, Marja; Kiørboe, Thomas; Takahashi, K.

    2005-01-01

    We measured field abundances, feeding rates, swimming behavior, and particle colonization of two harpacticoids, the pelagic Microsetella norvegica and the semibenthic Amonardia normanni, to examine (1) if aggregates have a significant role in harpacticoid nutrition and (2) if harpacticoids...

  6. Large-scale spatial and interspecies differences in trace elements and stable isotopes in marine wild fish from Chinese waters

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Wei [Key Laboratory of Marine Bio-resources Sustainable Utilization, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301 (China); Graduate School, Chinese Academy of Sciences, Beijing 100049 (China); Wang, Wen-Xiong, E-mail: wwang@ust.hk [Division of Life Science, HKUST, Clear Water Bay, Kowloon (Hong Kong)

    2012-05-15

    Highlights: Black-Right-Pointing-Pointer A large-scale study on trace element levels in marine wild fish from Chinese waters. Black-Right-Pointing-Pointer Spatial variation found for Al, As, Cd, Cr, Fe, Ni, Pb, but not for Ag, Cu, Mo, Se and Zn. Black-Right-Pointing-Pointer The Pearl River Estuary contained the highest concentrations of Al, Cr, Ni, and Pb. Black-Right-Pointing-Pointer No biomagnification occurred for any of the trace elements studied in marine fish. Black-Right-Pointing-Pointer No obvious health risk from the intake of trace elements through fish consumption. - Abstract: We conducted a large scale investigation of twelve trace element levels and stable isotopes ({delta}{sup 13}C and {delta}{sup 15}N) in twenty-nine marine wild fish species collected from Chinese coastal waters. Trace element levels varied significantly with species. Clear spatial variations were found for Al, As, Cd, Cr, Fe, Ni, and Pb, whereas Ag, Cu, Mo, Se and Zn did not show much spatial variation. The Pearl River Estuary contained the highest concentrations of Al, Cr, Ni, and Pb, whereas the most southern waters (Haikou) contained the lowest concentrations of Al, Fe, and Pb. There was no correlation between log-transformed trace elements concentrations and {delta}{sup 15}N values or {delta}{sup 13}C values, indicating no biomagnification among these trace elements. The calculated hazard quotients (HQ) of 10 elements were less than 1, thus there was no obvious health risk from the intake of trace elements through marine wild fish consumption.

  7. Spatial patterns and scale-dependent relationships between macrozooplankton and fish in the Bay of Biscay: an acoustic study

    KAUST Repository

    Lezama-Ochoa, A

    2011-10-20

    Macrozooplankton plays a key role in pelagic ecosystems as a link between lower trophic levels and fish. However, although its ecological role is usually considered in polar ecosystems, it is rarely considered in temperate ones. To obtain comprehensive information on the macrozooplankton distribution in the Bay of Biscay we adapted a bi-frequency acoustic method developed for the Humboldt Current system. This method can be used to extract continuous and simultaneous high-resolution information on the spatiotemporal patterns of biomass distributions of macrozooplankton and pelagic fish throughout the diel cycle. The 2 distributions were mapped using geostatistical techniques. We applied kriging with external drifts, which accounts for both diel and across-shore changes in macrozooplankton biomass. We then used a cross-variogram to determine the scale-dependent relationships between macrozooplankton and fish. The results show how macrozooplankton and fish are distributed according to the different ecological domains (coast, shelf, shelf-break and offshore) along the Spanish and French coasts. Specific macrozooplankton hotspots were observed, but macrozooplankton was generally more abundant offshore than inshore, whereas fish showed the opposite trend. This pattern was confirmed by the aggregation sizes, which increased towards oceanic waters for macrozooplankton and decreased for fish. Finally, the correlation between fish and macrozooplankton was positive on a small scale (<30 nautical miles) and negative on a large scale (>30 nautical miles).

  8. Impact on demersal fish of a large-scale and deep sand extraction site with ecosystem-based landscaped sandbars

    Science.gov (United States)

    de Jong, Maarten F.; Baptist, Martin J.; van Hal, Ralf; de Boois, Ingeborg J.; Lindeboom, Han J.; Hoekstra, Piet

    2014-06-01

    For the seaward harbour extension of the Port of Rotterdam in the Netherlands, approximately 220 million m3 sand was extracted between 2009 and 2013. In order to decrease the surface area of direct impact, the authorities permitted deep sand extraction, down to 20 m below the seabed. Biological and physical impacts of large-scale and deep sand extraction are still being investigated and largely unknown. For this reason, we investigated the colonization of demersal fish in a deep sand extraction site. Two sandbars were artificially created by selective dredging, copying naturally occurring meso-scale bedforms to increase habitat heterogeneity and increasing post-dredging benthic and demersal fish species richness and biomass. Significant differences in demersal fish species assemblages in the sand extraction site were associated with variables such as water depth, median grain size, fraction of very fine sand, biomass of white furrow shell (Abra alba) and time after the cessation of sand extraction. Large quantities of undigested crushed white furrow shell fragments were found in all stomachs and intestines of plaice (Pleuronectes platessa), indicating that it is an important prey item. One and two years after cessation, a significant 20-fold increase in demersal fish biomass was observed in deep parts of the extraction site. In the troughs of a landscaped sandbar however, a significant drop in biomass down to reference levels and a significant change in species assemblage was observed two years after cessation. The fish assemblage at the crests of the sandbars differed significantly from the troughs with tub gurnard (Chelidonichthys lucerna) being a Dufrêne-Legendre indicator species of the crests. This is a first indication of the applicability of landscaping techniques to induce heterogeneity of the seabed although it remains difficult to draw a strong conclusion due the lack of replication in the experiment. A new ecological equilibrium is not reached after 2

  9. Trends in spatio-temporal distribution of Peruvian anchovy and other small pelagic fish biomass from 1966-2009 Tendencias espacio-temporales en la distribución de la biomasa de anchoveta peruana y de otros peces pelágicos pequenos entre 1966 y 2009

    Directory of Open Access Journals (Sweden)

    Mariano Gutiérrez

    2012-09-01

    Full Text Available Changes in abundance and distribution of anchovy and other species of pelagic fish of the Northern Humboldt Current System (NHCS are driven by environmental forcing variations in different time and spatial scales between the coastal 'cold' ecosystem and the 'warm' oceanic one. Data to study these fluctuations have come mostly from the fishery to show how anchovy (Engraulis ringens increases when sardine (Sardinops sagax declines and vice versa. However, using acoustic data on latitudinal biomass we show that other species as mackerel (Scomber japonicus and jack mackerel (Trachurus murphyi also follow the same opposed trend, then the fishery data hides the true dimension of the balance of abundance among species. Based on Hovmoller diagrams we scrutinized the changes in interannual latitudinal acoustic biomass, landings and influence of El Nino events from 1966 to 2009 in order to describe: 1 how the anchovy decadal distribution pattern moved from south to north since the 1960's; 2 how there have been produced concomitant changes in the latitudinal abundance and distribution of other species such as sardine, jack mackerel and mackerel before, during and after El Nino events; and 3 what was the overall effect of the succession of El Nino events on all these pelagic species. We concluded that: a every El Nino event has had an effect on the expansion or contraction of pelagic species distribution and abundance, with different latitudinal effects; and b the El Nino 1997-98 did not trigger but accelerated a decline phase on the abundance of sardine, jack mackerel and mackerel by a reduction of their ideal habitat due to an expansion of the coastal ecosystem caused by a shallower location of the upper limit of the Oxygen Minimum Zone (OMZ These findings observed using past data might be taken into consideration for fishery management purposes when considering future scenarios.Los cambios en la abundancia y distribución de anchoveta y de otras especies

  10. Long-term aggregation of larval fish siblings during dispersal along an open coast.

    Science.gov (United States)

    Ottmann, Daniel; Grorud-Colvert, Kirsten; Sard, Nicholas M; Huntington, Brittany E; Banks, Michael A; Sponaugle, Su

    2016-12-06

    Pelagic dispersal of most benthic marine organisms is a fundamental driver of population distribution and persistence and is thought to lead to highly mixed populations. However, the mechanisms driving dispersal pathways of larvae along open coastlines are largely unknown. To examine the degree to which early stages can remain spatially coherent during dispersal, we measured genetic relatedness within a large pulse of newly recruited splitnose rockfish (Sebastes diploproa), a live-bearing fish whose offspring settle along the US Pacific Northwest coast after spending up to a year in the pelagic environment. A total of 11.6% of the recruits in a single recruitment pulse were siblings, providing the first evidence for persistent aggregation throughout a long dispersal period. Such protracted aggregation has profound implications for our understanding of larval dispersal, population connectivity, and gene flow within demersal marine populations.

  11. Transport and dispersal of fish eggs and larvae are important ...

    African Journals Online (AJOL)

    denise

    populations. ... sume that fish with pelagic eggs and larvae will spawn ... with highest concentrations deeper than 20 m, indicates active movement out of the layer moving ...... KING, D. P. F. 1977a — Influence of temperature, dissolved oxygen.

  12. Simulations of the social organization of large schools of fish whose perception is obstructed

    NARCIS (Netherlands)

    Kunz, Hanspeter; Hemelrijk, Charlotte K.

    2012-01-01

    Individual-based models have shown that simple interactions among moving individuals (repulsion, attraction and alignment) result in travelling schools that resemble those of real fish. In most models individuals interact with all neighbours within sensory range which usually includes almost all the

  13. Gulf Watch Alaska Forage Fish Component: Fish Morph data in Prince William Sound, Alaska 2012-2015

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — These data are part of the Gulf Watch Alaska (GWA) long term monitoring program, pelagic monitoring component. This dataset contains fish morph data from summer...

  14. systems, pelagic fish of the southern Benguela are dominated by ...

    African Journals Online (AJOL)

    denise

    Occupancy of this mid-trophic level position by a small number of species .... rates of prey digestion, gut passage times or codend feeding (James 1987). ...... NAPIER, I. R. 1993 — The organic carbon content of gravel bed herring spawning ...

  15. Aromatic hydrocarbon pathology in fish following a large spill into the Nemadji River, Wisconsin, USA

    Science.gov (United States)

    Caldwell, C.A.

    1997-01-01

    On June 30, 1992, a train accident resulted in a rail car releasing 114,000 L of a complex mixture of aromatic hydrocarbons into the Nemadji River, a tributary of Lake Superior near Superior, Wisconsin (Table 1). Although the majority of the spilled material evaporated, damage to aquatic life was extensive. Several thousand fishes were killed and an inestimable number were exposed to low concentrations (exposure to determine the extent of injury when compared to fishes collected from the reference site. The liver, spleen, gill, and head kidney were examined for histopathology. Blood was collected to determine the severity of liver damage reflected by the presence of the serum enzymes (aspartate aminotransferase, alanine aminotransferase, and d - glutamyl transferase).

  16. Fish diets in a freshwater-deprived semiarid estuary (The Coorong, Australia) as inferred by stable isotope analysis

    Science.gov (United States)

    Lamontagne, S.; Deegan, B. M.; Aldridge, K. T.; Brookes, J. D.; Geddes, M. C.

    2016-09-01

    In 2007, high rates of water extraction combined with a regional drought stopped freshwater discharge to the Coorong, a ∼120 km estuarine and coastal lagoon system at the outlet of the River Murray (Australia). The sources of organic matter sustaining the Coorong food web in the absence of river-borne organic matter and nutrient inputs were evaluated by measuring δ13C, δ15N and δ34S in large-bodied fish and their prey. In general, the δ34S of the food web (mean = 11.3‰; range = 4.32-18.9‰) suggested a comparable contribution from autochthonous pelagic (∼21‰) and benthic (organisms (-20 to -9.2‰) was also consistent with a dominant contribution from autochtonous sources to the food web. A Bayesian mixing model framework (SIMMR) was used to estimate the diet of large-bodied fish for statistically-determined prey groups based on their similarity in isotopic composition. Argyrosomus japonicus preyed primarily on Fish Group 1 (small pelagic fish like galaxiids and Hyperlophus vittatus), Rhombosolea tapirina on Invertebrate Group 2 (polychaetes like Capitella spp.) but Acanthopagrus butcheri fed on a wide variety of fish and invertebrate groups. A partial switch in diet to other prey groups suggested larger Ar. japonicus fed on larger prey, such as crabs and adult Aldrichetta forsteri. Despite being numerically abundant at the time, Fish Group 2 (benthic species) was a relatively low proportion of large-bodied fish diets. This probably reflected the tendency of some salt-tolerant members of this group (such as Atherinosoma microstoma) to prefer hypersaline habitats, which the large-bodied fish avoided. As the heavily preyed-on Fish Group 1 included species with a marine component to their life-cycle, marine productivity may also help to maintain this estuarine ecosystem in the absence of river-borne organic matter inputs.

  17. Improved management of small pelagic fisheries through seasonal climate prediction.

    Science.gov (United States)

    Tommasi, Désirée; Stock, Charles A; Pegion, Kathleen; Vecchi, Gabriel A; Methot, Richard D; Alexander, Michael A; Checkley, David M

    2017-03-01

    Populations of small pelagic fish are strongly influenced by climate. The inability of managers to anticipate environment-driven fluctuations in stock productivity or distribution can lead to overfishing and stock collapses, inflexible management regulations inducing shifts in the functional response to human predators, lost opportunities to harvest populations, bankruptcies in the fishing industry, and loss of resilience in the human food supply. Recent advances in dynamical global climate prediction systems allow for sea surface temperature (SST) anomaly predictions at a seasonal scale over many shelf ecosystems. Here we assess the utility of SST predictions at this "fishery relevant" scale to inform management, using Pacific sardine as a case study. The value of SST anomaly predictions to management was quantified under four harvest guidelines (HGs) differing in their level of integration of SST data and predictions. The HG that incorporated stock biomass forecasts informed by skillful SST predictions led to increases in stock biomass and yield, and reductions in the probability of yield and biomass falling below socioeconomic or ecologically acceptable levels. However, to mitigate the risk of collapse in the event of an erroneous forecast, it was important to combine such forecast-informed harvest controls with additional harvest restrictions at low biomass. © 2016 by the Ecological Society of America.

  18. Liver lesions in demersal fishes near a large ocean outfall on the San Pedro Shelf, California.

    Science.gov (United States)

    Basmadjian, Edward; Perkins, Edwin M; Phillips, Charles R; Heilprin, Daniel J; Watts, Susan D; Diener, Douglas R; Myers, Mark S; Koerner, Kelly A; Mengel, Michael J; Robertson, George; Armstrong, Jeffrey L; Lissner, Andrew L; Frank, Victoria L

    2008-03-01

    The prevalence of toxicopathic liver lesions in demersal fish on the San Pedro Shelf, California was determined for a 15-year period (1988-2003). Fish livers were sampled at fixed locations as part of the Orange County Sanitation Districts (OCSD) ocean monitoring program. Histopathological examination of selected fish liver tissues was studied to determine whether the wastewater discharge had affected fish health. The prevalence of toxicopathic lesion classes neoplasms (NEO), preneoplastic foci of cellular alteration (FCA), and hydropic vacuolation (HYDVAC) varied among species and locations. For all species sampled, severe lesions occurred in 6.2% of the fish examined (n=7,694). HYDVAC (4.1%) was the most common toxicopathic lesion type followed by FCA (1.4%) and NEO (0.7%). HYDVAC occurred only in white croaker (Genyonemus lineatus), accounting for 84.8% of the toxicopathic lesions for this species. Prevalence of HYDVAC, NEO, and FCA in white croaker was 15.2, 2.0, and 0.7%, respectively. The prevalence of HYDVAC and NEO in white croaker increased with age and size but there was no sexual difference. A linear regression model was used for hypothesis testing to account for significant differences in fish size (and age for croakers) at the different sampling locations. This analysis showed that for HYDVAC there was no spatial or location effect for lesion rate or size/age of onset. For NEO, the model predicted that white croaker near the wastewater outfall may acquire these lesions at a smaller size/younger age, and at a higher rate, than at other sites. However, this result may be biased due to the unequal size frequency distributions and the low prevalence of NEO in white croaker at the different sampling sites. Bigmouth sole (Hippoglossina stomata) had a prevalence of FCA and NEO of 1.3 and 0.35%, respectively, but the prevalence and distribution of lesions was too few for statistical testing. There was no sexual difference for lesion prevalence in hornyhead

  19. Patterns of variability in early-life traits of fishes depend on spatial scale of analysis.

    Science.gov (United States)

    Di Franco, Antonio; Guidetti, Paolo

    2011-06-23

    Estimates of early-life traits of fishes (e.g. pelagic larval duration (PLD) and spawning date) are essential for investigating and assessing patterns of population connectivity. Such estimates are available for a large number of both tropical and temperate fish species, but few studies have assessed their variability in space, especially across multiple scales. The present study, where a Mediterranean fish (i.e. the white seabream Diplodus sargus sargus) was used as a model, shows that spawning date and PLD are spatially more variable at a scale of kilometres than at a scale of tens to hundreds of kilometres. This study indicates the importance of considering spatial variability of early-life traits of fishes in order to properly delineate connectivity patterns at larval stages (e.g. by means of Lagrangian simulations), thus providing strategically useful information on connectivity and relevant management goals (e.g. the creation of networks of marine reserves).

  20. Fuzzy robust path tracking strategy of an active pelagic trawl system with coordinated ship and winch regulation

    Institute of Scientific and Technical Information of China (English)

    陈英龙; 周华; 赵勇刚; 侯交义

    2014-01-01

    A fuzzy robust path tracking strategy of an active pelagic trawl system with ship and winch regulation is proposed. First, nonlinear mathematic model of the pelagic trawl system was derived using Lagrange equation and further simplified as a low order model for the convenience of controller design. Then, an active path tracking strategy of pelagic trawl system was investigated to improve the catching efficiency of the target fish near the sea bottom. By means of the active tracking control, the pelagic trawl net can be positioned dynamically to follow a specified trajectory via the coordinated winch and ship regulation. In addition, considering the system nonlinearities, modeling uncertainties and the unknown exogenous disturbance of the trawl system model, a nonlinear robust H2/H∞controller based on Takagi-Sugeno (T-S) fuzzy model was presented, and the simulation comparison with linear robust H2/H∞controller and PID method was conducted for the validation of the nonlinear fuzzy robust controller. The nonlinear simulation results show that the average tracking error is 0.4 m for the fuzzy robust H2/H∞control and 125.8 m for the vertical and horizontal displacement, respectively, which is much smaller than linear H2/H∞ controller and the PID controller. The investigation results illustrate that the fuzzy robust controller is effective for the active path tracking control of the pelagic trawl system.

  1. Catch of pelagic hauls in Mediterranean acoustic surveys: Is it the same between day and night?

    Directory of Open Access Journals (Sweden)

    Athanassios Machias

    2013-03-01

    Full Text Available Fish sampling is a critical aspect of acoustic surveys, because it is directly related to the “transformation” of echo into species biomass and subsequently affects the accuracy of acoustic estimates. In the present study, we investigated the differences between day and night sampling in a the catch composition through certain diversity indices and b the length frequency distribution of anchovy and sardine using catch data of pelagic hauls collected from four different regions of the European Mediterranean waters. In addition, the possible bias in trawl efficiency due to sampling time and the possible error introduced in acoustic estimates were investigated. No statistically significant differences were found between day and night in any of the parameters examined. The results showed that a more flexible strategy can be adopted to reduce the duration and the cost of acoustic sampling for small pelagic species. The advantages and disadvantages of the two sampling strategies are discussed.

  2. Fish community responses to green tides in shallow estuarine and coastal areas

    Science.gov (United States)

    Le Luherne, E.; Réveillac, E.; Ponsero, A.; Sturbois, A.; Ballu, S.; Perdriau, M.; Le Pape, O.

    2016-06-01

    All over the world, numerous bays and estuarine systems that are known to shelter essential fish habitats are experiencing proliferations of green macroalgae known as green tides. Although the processes that enhance green tides in response to nutrient enrichment are well known, their consequences for ecological communities -especially for ichthyofauna- remain poorly studied. To estimate these consequences, this analysis focused on the two types of shallow systems that are experiencing green tides: sandy beaches and estuarine mudflats. In these two systems, macroalgae proliferation and fish community were surveyed along seasonal cycles at control and impacted sites that shared similar physico-chemical parameters and sediment structure. To analyse the consequences of green tides on the fish community, a Before-After Control-Impact approach was used. This approach reveals no difference between fish communities at the control and impacted sites before the macroalgal bloom. Then, it underlines an influence of green tides on the fish community, and this influence varies according to the composition, density and duration of the macroalgal bloom. Indeed, when intertidal systems experienced short proliferation and/or weak density, green tides did not seem to impact the fish community. However, when green macroalgae proliferated in large quantities and/or when the proliferation lasted for long periods, the fish community was significantly affected. These modifications in the fish community led to a significant decrease in fish species diversity and density until fish disappeared from impacted sites at high proliferations. Furthermore, the response of fish species to green tides differed according to their functional guilds. Negative consequences for benthic and marine juvenile fish species were beginning at low proliferations, whereas for pelagic fish species they occurred only at high proliferations. Thus, green tides significantly affect fish habitat suitability because

  3. Diversity of planktonic fish larvae along a latitudinal gradient in the Eastern Atlantic Ocean estimated through DNA barcodes

    Directory of Open Access Journals (Sweden)

    Alba Ardura

    2016-10-01

    Full Text Available Mid-trophic pelagic fish are essential components of marine ecosystems because they represent the link between plankton and higher predators. Moreover, they are the basis of the most important fisheries resources; for example, in African waters. In this study, we have sampled pelagic fish larvae in the Eastern Atlantic Ocean along a latitudinal gradient between 37°N and 2°S. We have employed Bongo nets for plankton sampling and sorted visually fish and fish larvae. Using the cytochrome oxidase I gene (COI as a DNA barcode, we have identified 44 OTUs down to species level that correspond to 14 families, with Myctophidae being the most abundant. A few species were cosmopolitan and others latitude-specific, as was expected. The latitudinal pattern of diversity did not exhibit a temperate-tropical cline; instead, it was likely correlated with environmental conditions with a decline in low-oxygen zones. Importantly, gaps and inconsistencies in reference DNA databases impeded accurate identification to the species level of 49% of the individuals. Fish sampled from tropical latitudes and some orders, such as Perciformes, Myctophiformes and Stomiiformes, were largely unidentified due to incomplete references. Some larvae were identified based on morphology and COI analysis for comparing time and costs employed from each methodology. These results suggest the need of reinforcing DNA barcoding reference datasets of Atlantic bathypelagic tropical fish that, as main prey of top predators, are crucial for ecosystem-based management of fisheries resources.

  4. Diversity of planktonic fish larvae along a latitudinal gradient in the Eastern Atlantic Ocean estimated through DNA barcodes

    Science.gov (United States)

    Morote, Elvira; Kochzius, Marc; Garcia-Vazquez, Eva

    2016-01-01

    Mid-trophic pelagic fish are essential components of marine ecosystems because they represent the link between plankton and higher predators. Moreover, they are the basis of the most important fisheries resources; for example, in African waters. In this study, we have sampled pelagic fish larvae in the Eastern Atlantic Ocean along a latitudinal gradient between 37°N and 2°S. We have employed Bongo nets for plankton sampling and sorted visually fish and fish larvae. Using the cytochrome oxidase I gene (COI) as a DNA barcode, we have identified 44 OTUs down to species level that correspond to 14 families, with Myctophidae being the most abundant. A few species were cosmopolitan and others latitude-specific, as was expected. The latitudinal pattern of diversity did not exhibit a temperate-tropical cline; instead, it was likely correlated with environmental conditions with a decline in low-oxygen zones. Importantly, gaps and inconsistencies in reference DNA databases impeded accurate identification to the species level of 49% of the individuals. Fish sampled from tropical latitudes and some orders, such as Perciformes, Myctophiformes and Stomiiformes, were largely unidentified due to incomplete references. Some larvae were identified based on morphology and COI analysis for comparing time and costs employed from each methodology. These results suggest the need of reinforcing DNA barcoding reference datasets of Atlantic bathypelagic tropical fish that, as main prey of top predators, are crucial for ecosystem-based management of fisheries resources. PMID:27761307

  5. A comparison of two sampling designs for fish assemblage assessment in a large river

    Science.gov (United States)

    Kiraly, Ian A.; Coghlan Jr., Stephen M.; Zydlewski, Joseph; Hayes, Daniel

    2014-01-01

    We compared the efficiency of stratified random and fixed-station sampling designs to characterize fish assemblages in anticipation of dam removal on the Penobscot River, the largest river in Maine. We used boat electrofishing methods in both sampling designs. Multiple 500-m transects were selected randomly and electrofished in each of nine strata within the stratified random sampling design. Within the fixed-station design, up to 11 transects (1,000 m) were electrofished, all of which had been sampled previously. In total, 88 km of shoreline were electrofished during summer and fall in 2010 and 2011, and 45,874 individuals of 34 fish species were captured. Species-accumulation and dissimilarity curve analyses indicated that all sampling effort, other than fall 2011 under the fixed-station design, provided repeatable estimates of total species richness and proportional abundances. Overall, our sampling designs were similar in precision and efficiency for sampling fish assemblages. The fixed-station design was negatively biased for estimating the abundance of species such as Common Shiner Luxilus cornutus and Fallfish Semotilus corporalis and was positively biased for estimating biomass for species such as White Sucker Catostomus commersonii and Atlantic Salmon Salmo salar. However, we found no significant differences between the designs for proportional catch and biomass per unit effort, except in fall 2011. The difference observed in fall 2011 was due to limitations on the number and location of fixed sites that could be sampled, rather than an inherent bias within the design. Given the results from sampling in the Penobscot River, application of the stratified random design is preferable to the fixed-station design due to less potential for bias caused by varying sampling effort, such as what occurred in the fall 2011 fixed-station sample or due to purposeful site selection.

  6. Using environmental DNA to census marine fishes in a large mesocosm.

    Directory of Open Access Journals (Sweden)

    Ryan P Kelly

    Full Text Available The ocean is a soup of its resident species' genetic material, cast off in the forms of metabolic waste, shed skin cells, or damaged tissue. Sampling this environmental DNA (eDNA is a potentially powerful means of assessing whole biological communities, a significant advance over the manual methods of environmental sampling that have historically dominated marine ecology and related fields. Here, we estimate the vertebrate fauna in a 4.5-million-liter mesocosm aquarium tank at the Monterey Bay Aquarium of known species composition by sequencing the eDNA from its constituent seawater. We find that it is generally possible to detect mitochondrial DNA of bony fishes sufficient to identify organisms to taxonomic family- or genus-level using a 106 bp fragment of the 12S ribosomal gene. Within bony fishes, we observe a low false-negative detection rate, although we did not detect the cartilaginous fishes or sea turtles present with this fragment. We find that the rank abundance of recovered eDNA sequences correlates with the abundance of corresponding species' biomass in the mesocosm, but the data in hand do not allow us to develop a quantitative relationship between biomass and eDNA abundance. Finally, we find a low false-positive rate for detection of exogenous eDNA, and we were able to diagnose non-native species' tissue in the food used to maintain the mesocosm, underscoring the sensitivity of eDNA as a technique for community-level ecological surveys. We conclude that eDNA has substantial potential to become a core tool for environmental monitoring, but that a variety of challenges remain before reliable quantitative assessments of ecological communities in the field become possible.

  7. Mercury in South Carolina fishes, USA.

    Science.gov (United States)

    Glover, James B; Domino, Marisa E; Altman, Kenneth C; Dillman, James W; Castleberry, William S; Eidson, Jeannie P; Mattocks, Micheal

    2010-04-01

    The South Carolina Department of Health and Environmental Control has collected, processed, and analyzed fish tissue total mercury (Hg) since 1976. For this study, skin-on-filet data from 1993 to 2007 were examined to determine biotic, spatial and temporal trends in tissue Hg levels for SC fishes. Because of the relatively high number of tissue Hg values below the analytical detection limits interval censored regression and censored least absolute deviations were used to construct several models to characterize trends. Large pelagic, piscivorous fish species, such as bowfin (Amia calva Linnaeus 1766), had higher levels of tissue Hg than smaller omnivorous species. Estuarine species had relatively low levels of tissue Hg compared to freshwater species, while two large open ocean species, king mackerel (Scomberomorus cavalla Cuvier 1829) and swordfish (Xiphias gladius Linnaeus 1758), had higher tissue Hg readings. For a given fish species, length was an important predictor of tissue Hg with larger individuals having higher levels than smaller individuals. The USEPA Level III ecoregion and water body type from where the fishes were collected were important in predicting the levels of tissue Hg. The Middle Atlantic Coastal Plain ecoregion had fishes with the highest levels of tissue Hg, while the Piedmont and Southern Coastal Plain ecoregions had the lowest. For a given ecoregion, large reservoirs and regulated rivers had fish with lower levels of tissue Hg than unregulated rivers. For reservoirs, the size of the impoundment was a significant predictor of tissue mercury with small reservoirs having higher levels of tissue mercury than large reservoirs. Landuse and water chemistry accounted for differences seen in fish of various ecoregions and waterbody types. Sampling locations associated with a high percentage of wetland area had fish with high levels of tissue Hg. Correlation analysis showed a strong positive relationship between tissue Hg levels and water column

  8. Modeling energy flow in a large Neotropical reservoir: a tool do evaluate fishing and stability

    Directory of Open Access Journals (Sweden)

    Ronaldo Angelini

    Full Text Available Recently, there is an increasing perception that the ecosystem approach gives important insights to support fisheries stock assessment and management. This paper aims to quantify energy flows in the Itaipu Reservoir (Brazil and to simulate increase of the fishing effort of some species, using Ecopath with Ecosim software, which could allow inferences on stability. Therefore, two steady-state Itaipu models were built (1983-87 and 1988-92. Results showed that: a there are no differences between models, and results on aging trends do not vary over time indicating that fishery does not alter the ecosystem as a whole; b results of fisheries simulations are approximate to mono-specific stock assessment for the same species and periods; c many authors believe that tropical ecosystems are environments where biotic and abiotic oscillations are annual and sometimes unexpected, but the results found for the Itaipu Reservoir indicate that stability was met after 16 years.

  9. Persistent disturbance by commercial navigation afters the relative abundance of channel-dwelling fishes in a large river

    Science.gov (United States)

    Gutreuter, S.; Vallazza, J.M.; Knights, B.C.

    2006-01-01

    We provide the first evidence for chronic effects of disturbance by commercial vessels on the spatial distribution and abundance of fishes in the channels of a large river. Most of the world's large rivers are intensively managed to satisfy increasing demands for commercial shipping, but little research has been conducted to identify and alleviate any adverse consequences of commercial navigation. We used a combination of a gradient sampling design incorporating quasicontrol areas with Akaike's information criterion (AIC)-weighted model averaging to estimate effects of disturbances by commercial vessels on fishes in the upper Mississippi River. Species density, which mainly measured species evenness, decreased with increasing disturbance frequency. The most abundant species - gizzard shad (Dorosoma cepedianum) and freshwater drum (Aplodinotus grunniens) - and the less abundant shovelnose sturgeon (Scaphirhynchus platorhynchus) and flathead catfish (Pylodictis olivaris) were seemingly unaffected by traffic disturbance. In contrast, the relative abundance of the toothed herrings (Hiodon spp.), redhorses (Moxostoma spp.), buffaloes (Ictiobus spp.), channel catfish (Ictalurus punctatus), sauger (Sander canadensis), and white bass (Morone chrysops) decreased with increasing traffic in the navigation channel. We hypothesized that the combination of alteration of hydraulic features within navigation channels and rehabilitation of secondary channels might benefit channel-dependent species. ?? 2006 NRC.

  10. Pelagic Charter Boat Patrons (1999-2001)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This study describes several aspects of the charter fishing experience, including patrons' motivations for coming to Hawaii and going charter fishing, their related...

  11. Fishing and Fish Consumption in the Swahili Communities of East Africa, 700–1400 CE

    Directory of Open Access Journals (Sweden)

    Eréndira M. Quintana Morales

    2014-08-01

    Full Text Available Historical and archaeological records of consumption practices indicate that people living along the Swahili coast relied largely on fish for subsistence; however, little research has been done to explore how aquatic subsistence strategies varied among different settlements in the region, both spatially and chronologically. Such questions are particularly interesting, as the communities were largely urban, and relied on fish for the bulk of their protein consumption. We compared evidence of subsistence strategies and exploited fish habitats in two Swahili regions that represent different maritime landscapes. Because particular fish species generally inhabit different sections of the marine environment, the composition of these species at each site can be used to estimate the variable exploitation of these habitats. Overall, the analysed samples showed a heavy exploitation of fish found around coral reefs, but with varying proportions of other exploited habitats, such as estuary, mangrove, sandy/muddy, and outer reef zones. The general pattern indicates that samples from offshore islands have higher representations of fish from coral/rocky habitats while samples from near-shore islands show a lower reliance on coral species. Over time there is an increase at certain sites in the exploitation of oceanic and pelagic fish that coincides with the more frequent consumption of domesticated bovids. We discuss the historical and environmental implications of these variable patterns of aquatic subsistence strategies along the East African coastline, and propose that there is a close link between their ability to exploit these marine resources, their success as urban settlements, and the development of feasting rituals.

  12. Assessing juvenile native fish demographic responses to a steady flow experiment in a large regulated river

    Science.gov (United States)

    Finch, Colton G.; Pine, William E.; Yackulic, Charles B.; Dodrill, Michael J.; Yard, Michael D.; Gerig, Brandon S.; Coggins,, Lewis G.; Korman, Josh

    2016-01-01

    The Colorado River below Glen Canyon Dam, Arizona, is part of an adaptive management programme which optimizes dam operations to improve various resources in the downstream ecosystem within Grand Canyon. Understanding how populations of federally endangered humpback chub Gila cypha respond to these dam operations is a high priority. Here, we test hypotheses concerning temporal variation in juvenile humpback chub apparent survival rates and abundance by comparing estimates between hydropeaking and steady discharge regimes over a 3-year period (July 2009–July 2012). The most supported model ignored flow type (steady vs hydropeaking) and estimated a declining trend in daily apparent survival rate across years (99.90%, 99.79% and 99.67% for 2009, 2010 and 2011, respectively). Corresponding abundance of juvenile humpback chub increased temporally; open population model estimates ranged from 615 to 2802 individuals/km, and closed model estimates ranged from 94 to 1515 individuals/km. These changes in apparent survival and abundance may reflect broader trends, or simply represent inter-annual variation. Important findings include (i) juvenile humpback chub are currently surviving and recruiting in the mainstem Colorado River with increasing abundance; (ii) apparent survival does not benefit from steady fall discharges from Glen Canyon Dam; and (iii) direct assessment of demographic parameters for juvenile endangered fish are possible and can rapidly inform management actions in regulated rivers.

  13. Recruitment of coastal fishes and oceanographic variability in central California

    Science.gov (United States)

    Wilson, J. R.; Broitman, B. R.; Caselle, J. E.; Wendt, D. E.

    2008-09-01

    Recruitment of pelagic larval fishes to the nearshore environment is dependent on a suite of biological and physical processes operating at many spatial and temporal scales. Nearshore circulation processes associated with coastal upwelling are widely upheld as major determinants of year class strength for many rockfishes ( Sebastes spp.), but the mechanism by which these processes drive recruitment is largely unknown. We used Standard Monitoring Units for the Recruitment of Fishes (SMURFs) to monitor recruitment of two rockfish complexes ( Sebastes spp.) and cabezon ( Scorpaenichthys marmoratus) from March to September of 2004 and 2005 at 3 sites along the central California coast. We examined the relationship between recruitment of these fishes and measurements of oceanographic variability associated with upwelling dynamics, including in situ water temperature, AVHRR sea surface temperature, the Bakun upwelling index, and an index of alongshore surface water transport. We found that rockfish comprising the KCGB complex ( Sebastes atrovirens, Sebastes caurinus, Sebastes carnatus, Sebastes chrysomelas) recruit during early summer, while fishes of the BYO complex ( Sebastes melanops, Sebastes flavidus, Sebastes serranoides), as well as cabezon recruit during late summer. Our results provide limited support for an association between the arrival of juvenile pelagic rockfish and cabezon to the nearshore environment and physical processes related to upwelling and relaxation. Beyond the limitations of our bimonthly sampling scheme, the lack of a clear pattern may be related to the near absence of upwelling-relaxation cycles along this stretch of coast during these two study periods. Moreover, the settlement and recruitment of nearshore fishes may be closely tied to processes occurring earlier in the larval stage.

  14. 舟山远洋渔业发展状况及其对策研究%Development Conditions and Countermeasures Study about Pelagic Fishery in Zhoushan

    Institute of Scientific and Technical Information of China (English)

    涂德贤; 苗振清; 俞存根; 陈斌

    2015-01-01

    Zhoushan is the pioneer of pelagic fishery industry in China, pelagic fishery is an important part of fisheries, is the new growth point of fishery economy in Zhoushan. After the development of thirty years, the scale of Zhoushan pelagic fishery industry growing, industry momentum of development fine, is strong city of China's pelagic fishery field. In this paper, basing on research about the development condition and operating status of pelagic fish-ery in Zhoushan, aiming at the existing problems, we put forward some countermeasures and suggestions to promote the healthy and sustainable development of Zhoushan pelagic fishery.%舟山是开展我国远洋渔业事业的先锋者,远洋渔业是舟山渔业重要组成部分,是舟山渔业经济新的增长点。经过30年的发展,舟山远洋渔业产业规模不断壮大、行业发展势头良好,是我国远洋渔业领域强市。本文在对舟山远洋渔业的发展概况及经营现状研究基础上,针对存在的问题提出推动舟山远洋渔业健康持续发展的对策建议。

  15. Acoustic measures of the abundance and size of pelagic planktivores in Lake Michigan

    Science.gov (United States)

    Brandt, Stephen B.; Mason, Doran M.; Patrick, E. Vincent; Argyle, Ray L.; Wells, L.; Unger, Philip A.; Stewart, Donald J.

    1991-01-01

    Based on acoustic data taken at night and vertically stratified by bottom depth (3–110 m only), the total number (± 95% Cl) of pelagic fishes in Lake Michigan was 43.4 ± 10.1 x 109 or 226.0 ± 55.2 kt in spring (mean density 0.7–3.8 fish·m-2 or 1.6–12.8 ga·m-2) and 115.8 ± 18.3 x 109 or 313.2 ± 74.3 kt in late summer, 1987 (mean density 1.1–7.0 fish·m-2 or 3.0–13.2 g·m-2); approximately 30% of this increase in numbers (35% of biomass) occurred within Green Bay. Abundance estimates from horizontally stratified (by water column depth) data were within 9-11% of vertically stratified estimates during spring but over 20% higher during summer. By extrapolation to all water depths, we estimated total pelagic biomass as 274.6 kt for spring and 410.8 kt for summer. During both seasons, smaller fishes were nearer to the surface and nearer shore than larger individuals, and acoustic measures of size approximated the sizes of fishes caught in trawls. Bioenergetic model simulations suggest that 60% of the available production of alewife (Alosa pseudoharengus) was either consumed by stocked salmonines (52.9%) or commercially harvested (7.1%) in 1987. Underwater acoustics proved a valuable tool for lakewide assessments of fish abundances in the Great Lakes.

  16. Historical ecology and the conservation of large, hermaphroditic fishes in Pacific Coast kelp forest ecosystems

    Science.gov (United States)

    Braje, Todd J.; Rick, Torben C.; Szpak, Paul; Newsome, Seth D.; McCain, Joseph M.; Elliott Smith, Emma A.; Glassow, Michael; Hamilton, Scott L.

    2017-01-01

    The intensive commercial exploitation of California sheephead (Semicossyphus pulcher) has become a complex, multimillion-dollar industry. The fishery is of concern because of high harvest levels and potential indirect impacts of sheephead removals on the structure and function of kelp forest ecosystems. California sheephead are protogynous hermaphrodites that, as predators of sea urchins and other invertebrates, are critical components of kelp forest ecosystems in the northeast Pacific. Overfishing can trigger trophic cascades and widespread ecological dysfunction when other urchin predators are also lost from the system. Little is known about the ecology and abundance of sheephead before commercial exploitation. Lack of a historical perspective creates a gap for evaluating fisheries management measures and marine reserves that seek to rebuild sheephead populations to historical baseline conditions. We use population abundance and size structure data from the zooarchaeological record, in concert with isotopic data, to evaluate the long-term health and viability of sheephead fisheries in southern California. Our results indicate that the importance of sheephead to the diet of native Chumash people varied spatially across the Channel Islands, reflecting modern biogeographic patterns. Comparing ancient (~10,000 calibrated years before the present to 1825 CE) and modern samples, we observed variability and significant declines in the relative abundance of sheephead, reductions in size frequency distributions, and shifts in the dietary niche between ancient and modern collections. These results highlight how size-selective fishing can alter the ecological role of key predators and how zooarchaeological data can inform fisheries management by establishing historical baselines that aid future conservation. PMID:28164155

  17. Temporal and Spatial Distribution of Catches of Tiger Sharks, Galeocerdo cuvier, in the Pelagic Longline Fishery Around the Hawaiian Islands

    OpenAIRE

    Jeffrey J Polovina; Lau, Boulderson B.

    1993-01-01

    Thirty-five tiger sharks, Galeocerdo cuvier, have been reported caught in pelagic longline gearfrom 25 to 265 n.mi. off the Hawaiian Archipelago during December 1990-May 1993. Fifteen sharks were caught farther than 50 n.mi. offshore, indicating that tiger sharks do occur well offshore and removed from benthic topography. About 89% of the sharks were caught during October-March, while only 56% of the fishing effort occurred during that period.

  18. Vulnerability of oceanic sharks as pelagic longline bycatch

    Directory of Open Access Journals (Sweden)

    A.J. Gallagher

    2014-08-01

    Full Text Available Bycatch (the unintentional catch of non-target species or sizes is consistently ranked as one of the greatest threats to marine fish populations; yet species-specific rates of bycatch survival are rarely considered in risk assessments. Regulations often require that bycatch of threatened species be released; but, if animals are already dead, their release serves no conservation purpose. We examined the survival of 12 shark species caught as bycatch in the US Atlantic pelagic longline fishery. Shark survival was evaluated in relation to fishery target (swordfish versus tuna and four operational, environmental, and biological variables to evaluate the underlying mechanisms affecting mortality. Survival estimates ranged from 33% (night shark to 97% (tiger shark with seven of the 12 species being significantly affected by at least one variable. We placed our survival results within a framework that assessed each species’ relative vulnerability by integrating survival estimates with reproductive potential and found that the bigeye thresher, dusky, night, and scalloped hammerhead shark exhibited the highest vulnerabilities to bycatch. We suggest that considering ecological and biological traits of species shows promise for designing effective conservation measures, whereas techniques that reduce fisheries interactions in the first place may be the best strategy for highly vulnerable species.

  19. Defining a pelagic typology of the eastern English Channel

    Science.gov (United States)

    Delavenne, Juliette; Marchal, Paul; Vaz, Sandrine

    2013-01-01

    Classifying marine habitats is a growing research field and is of increasing interest to spatial planners and managers. Most studies have predominantly focused on the seabed to determine benthic habitat types, and only limited attention has been paid to the water column. Classification projects aim at identifying candidate management units for the application of various regional or national regulations such as the European Water Framework Directive. Here, we propose a seasonal classification of the water column in the eastern English Channel, which we validated with biological data. For the three tested compartments, phytoplankton, zooplankton and pelagic fishes, the validation results were satisfactory, with recall values (i.e. percentage of observations correctly assigned in a given water type) ranging from 0.5 to 1. This validation was a crucial step to verify that the proposed typology was ecologically relevant and to use it as a biodiversity surrogate in management and conservation plans. Because management plans are generally set on an annual rather than a seasonal basis, we also produced a "multi-seasonal" typology encompassing seasonal variability, which can be used as an appropriate all year round description of the water column attributes in the eastern English Channel. The "multi-seasonal" typology reflected the relative stability of the French waters and the central part of the eastern English Channel and the strongest variability of the English coastal waters and the Dover strait.

  20. FISH ASSEMBLAGES IN NORTHERN GULF OF MEXICO ESTUARIES: LARGE SCALE ECOLOGICAL CHARACTERIZATION

    Science.gov (United States)

    Abstract for American Fisheries Society Annual Meeting.We are using trawl data from >100 estuaries, bayous, and coastal lagoons of the EMAP Louisianan Province to develop indicators of ecological condition over large geographic scales. Our primary goal is to enhance the s...

  1. Seasonal changes in the δ13C and δ15N signatures of the Lago Maggiore pelagic food web

    Directory of Open Access Journals (Sweden)

    Marina MANCA

    2011-08-01

    Full Text Available Seasonal variation in the relative contributions of littoral and pelagic food sources to the diets of open-water zooplankton and subsequent changes in their trophic positions were investigated with carbon and nitrogen Stable Isotope Analysis (SIA. We selected three open water stations as truly pelagic, but also influenced by littoral and riverine carbon sources. During each of the four seasons, integrated pelagic zooplankton samples were collected over 0-50 m depth intervals at each site along with seston in the size range 1.2-76 μm. In addition, vertical temperature profiles were measured. Littoral benthos from three sites along the main longitudinal axis of the lake was sampled to serve as a reference for tracing Lago Maggiore's littoral carbon isotopic signature. Among stations differences in δ13C and δ15N signatures of the different components of the pelagic food web, from seston to predatory zooplankton, were statistically non significant, thus confirming that allochthonous input may become important only after exceptional rainfall events. Changes in the δ13C pelagic baseline mirrored mean water temperature (0-50 m seasonal changes. Similarly to Lake Geneva, they were likely driven by changes in carbon sources for phytoplankton growth during stratification and vertical water mixing. Differently from what observed for the other taxa, the role of littoral food sources was far from negligible (>50% for diaptomids during winter and spring. We do not know however, whether such a result could be at least partially attributed to the heavy infestation by algal epibionts, or was consequent to the fact that these zooplankters may carry littoral carbon to the pelagial via horizontal migration. In winter, Bythotrephes longimanus was able to prey on Cyclops, thus occupying a trophic position comparable to that of planktivorous fish. Such a result confirms an ability of this visual, invertebrate predator to compete with young zooplanktivorous fish

  2. Estuarine refugia and fish responses to a large anoxic, hydrogen sulphide, “black tide” event in the adjacent marine environment

    Science.gov (United States)

    Lamberth, S. J.; Branch, G. M.; Clark, B. M.

    2010-01-01

    The fish fauna of the Berg River Estuary was sampled from the mouth to 40 km upstream using a small-meshed seine-net before (summer 1993), during (summer 1994) and after (summer 1996) a low-oxygen, hydrogen sulphide "black tide" event that caused a mass mortality of fish in St Helena Bay. These data were compared to determine how the species composition, abundance and distribution of the fish fauna of the Berg River Estuary differed before, during and after the event as well as to ascertain which species, if any, found refuge in the estuary. The overall catch-per-unit-effort of 1637 fish.haul -1 during the event was almost double the 932 fish.haul -1 and 643 fish.haul -1 in the years before and after respectively. All the fish recorded alive in the estuary during the event were species known to have some degree of estuarine association. No representatives of the purely marine species found dead on the adjacent shoreline were recorded live in the estuary during the event. Of the 10 estuarine-associated species sampled, 5 extended their range and/or modal peaks of abundance further upstream during the event. One species, Liza richardsonii, was abundant enough to examine its size distribution in different breaches of the estuary. Large/adult fish were concentrated further upstream than small/juvenile fish, which appeared to be unable to escape tidal currents and were concentrated at the edge of the low-oxygen front. Collectively this circumstantial evidence indicates that (1) fish used the Berg Estuary as a refuge from low-oxygen conditions in the marine environment during the "black tide" event, and (2) the ability to secure refuge in the estuary was restricted to species described as "estuarine-associated" or "estuarine-dependent".

  3. The Gulf of Cádiz pelagic ecosystem: A review

    Science.gov (United States)

    García Lafuente, Jesús; Ruiz, Javier

    2007-08-01

    The Gulf of Cádiz, strategically situated between the North Atlantic Ocean and the Mediterranean Sea, has been the focus of attention of a few oceanographic studies dealing with the deep circulation in order to understand the dynamics of the dense plume of Mediterranean water. Much less attention has been paid to the surface pelagic layer which holds important living resources of commercial and ecological interest. This overview summarizes the recent advances that have been made concerning the regional oceanography of the northern half of this important basin from an interdisciplinary point of view. Probably the most relevant oceanographic feature of the basin is its strong seasonality, which is linked to the meteorologically-induced seasonality of the eastern boundary current system of the North Atlantic. The prominent cape Santa Maria divides the continental shelf off the southern Iberian Peninsula in two shelves of different shape that hold different oceanographic processes, which in turn determine the characteristics of the pelagic ecosystem. Mass and energy inputs from land as well as tidally-driven processes makes the wider eastern shelf be more productive while the narrower western shelf, cut by a sharp submarine canyon, is under the influence of the almost-permanent upwelling spot off cape San Vicente. Under easterlies, the west-going, warm coastal countercurrent that is observed in the eastern shelf may invade the western shelf thus connecting biologically both shelves in an east-to-west direction. Westerlies induce generalised upwelling off the southern Iberia Peninsula, which adds to the almost-permanent one off cape San Vicente and generates an upwelling jet that moves eastwards. Cape Santa Maria may deflect this flow by generating a cold filament that extends southward and diverts water from the western shelf to the open ocean. This pattern of circulation hampers the biological connection between shelves in the west-to-east direction, which is

  4. Oxygen: a fundamental property regulating pelagic ecosystem structure in the coastal southeastern tropical Pacific.

    Directory of Open Access Journals (Sweden)

    Arnaud Bertrand

    Full Text Available BACKGROUND: In the southeastern tropical Pacific anchovy (Engraulis ringens and sardine (Sardinops sagax abundance have recently fluctuated on multidecadal scales and food and temperature have been proposed as the key parameters explaining these changes. However, ecological and paleoecological studies, and the fact that anchovies and sardines are favored differently in other regions, raise questions about the role of temperature. Here we investigate the role of oxygen in structuring fish populations in the Peruvian upwelling ecosystem that has evolved over anoxic conditions and is one of the world's most productive ecosystems in terms of forage fish. This study is particularly relevant given that the distribution of oxygen in the ocean is changing with uncertain consequences. METHODOLOGY/PRINCIPAL FINDINGS: A comprehensive data set is used to show how oxygen concentration and oxycline depth affect the abundance and distribution of pelagic fish. We show that the effects of oxygen on anchovy and sardine are opposite. Anchovy flourishes under relatively low oxygen conditions while sardine avoid periods/areas with low oxygen concentration and restricted habitat. Oxygen consumption, trophic structure and habitat compression play a fundamental role in fish dynamics in this important ecosystem. CONCLUSIONS/SIGNIFICANCE: For the ocean off Peru we suggest that a key process, the need to breathe, has been neglected previously. Inclusion of this missing piece allows the development of a comprehensive conceptual model of pelagic fish populations and change in an ocean ecosystem impacted by low oxygen. Should current trends in oxygen in the ocean continue similar effects may be evident in other coastal upwelling ecosystems.

  5. Poor transferability of species distribution models for a pelagic predator, the grey petrel, indicates contrasting habitat preferences across ocean basins.

    Directory of Open Access Journals (Sweden)

    Leigh G Torres

    Full Text Available Species distribution models (SDMs are increasingly applied in conservation management to predict suitable habitat for poorly known populations. High predictive performance of SDMs is evident in validations performed within the model calibration area (interpolation, but few studies have assessed SDM transferability to novel areas (extrapolation, particularly across large spatial scales or pelagic ecosystems. We performed rigorous SDM validation tests on distribution data from three populations of a long-ranging marine predator, the grey petrel Procellaria cinerea, to assess model transferability across the Southern Hemisphere (25-65°S. Oceanographic data were combined with tracks of grey petrels from two remote sub-Antarctic islands (Antipodes and Kerguelen using boosted regression trees to generate three SDMs: one for each island population, and a combined model. The predictive performance of these models was assessed using withheld tracking data from within the model calibration areas (interpolation, and from a third population, Marion Island (extrapolation. Predictive performance was assessed using k-fold cross validation and point biserial correlation. The two population-specific SDMs included the same predictor variables and suggested birds responded to the same broad-scale oceanographic influences. However, all model validation tests, including of the combined model, determined strong interpolation but weak extrapolation capabilities. These results indicate that habitat use reflects both its availability and bird preferences, such that the realized distribution patterns differ for each population. The spatial predictions by the three SDMs were compared with tracking data and fishing effort to demonstrate the conservation pitfalls of extrapolating SDMs outside calibration regions. This exercise revealed that SDM predictions would have led to an underestimate of overlap with fishing effort and potentially misinformed bycatch mitigation

  6. Positive Darwinian selection in the singularly large taste receptor gene family of an 'ancient' fish, Latimeria chalumnae.

    Science.gov (United States)

    Syed, Adnan S; Korsching, Sigrun I

    2014-08-05

    Chemical senses are one of the foremost means by which organisms make sense of their environment, among them the olfactory and gustatory sense of vertebrates and arthropods. Both senses use large repertoires of receptors to achieve perception of complex chemosensory stimuli. High evolutionary dynamics of some olfactory and gustatory receptor gene families result in considerable variance of chemosensory perception between species. Interestingly, both ora/v1r genes and the closely related t2r genes constitute small and rather conserved families in teleost fish, but show rapid evolution and large species differences in tetrapods. To understand this transition, chemosensory gene repertoires of earlier diverging members of the tetrapod lineage, i.e. lobe-finned fish such as Latimeria would be of high interest. We report here the complete T2R repertoire of Latimeria chalumnae, using thorough data mining and extensive phylogenetic analysis. Eighty t2r genes were identified, by far the largest family reported for any species so far. The genomic neighborhood of t2r genes is enriched in repeat elements, which may have facilitated the extensive gene duplication events resulting in such a large family. Examination of non-synonymous vs. synonymous substitution rates (dN/dS) suggests pronounced positive Darwinian selection in Latimeria T2Rs, conceivably ensuring efficient neo-functionalization of newly born t2r genes. Notably, both traits, positive selection and enrichment of repeat elements in the genomic neighborhood, are absent in the twenty v1r genes of Latimeria. Sequence divergence in Latimeria T2Rs and V1Rs is high, reminescent of the corresponding teleost families. Some conserved sequence motifs of Latimeria T2Rs and V1Rs are shared with the respective teleost but not tetrapod genes, consistent with a potential role of such motifs in detection of aquatic chemosensory stimuli. The singularly large T2R repertoire of Latimeria may have been generated by facilitating local

  7. Patterns and drivers of fish community assembly in a large marine ecosystem

    DEFF Research Database (Denmark)

    Pécuchet, Lauréne; Törnroos, Anna; Lindegren, Martin

    2016-01-01

    shaping community composition. However, community composition in the eastern part, an area beyond the steep decline in salinity, was characterized by fewer species with largely different trait characteristics, indicating that community assembly is also affected by biotic interactions. Our results add......The presence and survival of the species in a community depend on their abilities to maximize fitness in a given environment. The study of the processes that control survival and co‑existence, termed ‘assembly rules’, follows various mechanisms, primarily related to biotic or abiotic factors....... To determine assembly rules, ecological similarities of co-occurring species are often investigated. This can be evaluated using trait-based indices summarizing the species’ niches in a given community. In order to investigate the underlying processes shaping community assembly in marine ecosystems, we...

  8. Evidence of a Shift in the Littoral Fish Community of the Sacramento-San Joaquin Delta

    National Research Council Canada - National Science Library

    Mahardja, Brian; Farruggia, Mary Jade; Schreier, Brian; Sommer, Ted

    2017-01-01

    .... Over the past two decades, the Sacramento-San Joaquin Delta (Delta) in California, USA, saw a severe decline in pelagic fishes, a shift in zooplankton community composition, and a rapid expansion of invasive aquatic vegetation...

  9. Abrupt transitions of the top-down controlled Black Sea pelagic ecosystem during 1960 2000: Evidence for regime-shifts under strong fishery exploitation and nutrient enrichment modulated by climate-induced variations

    Science.gov (United States)

    Oguz, Temel; Gilbert, Denis

    2007-02-01

    Functioning of the Black Sea ecosystem has profoundly changed since the early 1970s under cumulative effects of excessive nutrient enrichment, strong cooling/warming, over-exploitation of pelagic fish stocks, and population outbreak of gelatinous carnivores. Applying a set of criteria to the long-term (1960-2000) ecological time-series data, the present study demonstrates that the Black Sea ecosystem was reorganised during this transition phase in different forms of top-down controlled food web structure through successive regime-shifts of distinct ecological properties. The Secchi disc depth, oxic-anoxic interface zone, dissolved oxygen and hydrogen sulphide concentrations also exhibit abrupt transition between their alternate regimes, and indicate tight coupling between the lower trophic food web structure and the biogeochemical pump in terms of regime-shift events. The first shift, in 1973-1974, marks a switch from large predatory fish to small planktivore fish-controlled system, which persisted until 1989 in the form of increasing small pelagic and phytoplankton biomass and decreasing zooplankton biomass. The increase in phytoplankton biomass is further supported by a bottom-up contribution due to the cumulative response to high anthropogenic nutrient load and the concurrent shift of the physical system to the "cold climate regime" following its ˜20-year persistence in the "warm climate regime". The end of the 1980s signifies the depletion of small planktivores and the transition to a gelatinous carnivore-controlled system. By the end of the 1990s, small planktivore populations take over control of the system again. Concomitantly, their top-down pressure when combined with diminishing anthropogenic nutrient load and more limited nutrient supply into the surface waters due to stabilizing effects of relatively warm winter conditions switched the "high production" regime of phytoplankton to its background "low production" regime. The Black Sea regime

  10. Bentho-pelagic divergence of cichlid feeding architecture was prodigious and consistent during multiple adaptive radiations within African rift-lakes.

    Directory of Open Access Journals (Sweden)

    W James Cooper

    Full Text Available BACKGROUND: How particular changes in functional morphology can repeatedly promote ecological diversification is an active area of evolutionary investigation. The African rift-lake cichlids offer a calibrated time series of the most dramatic adaptive radiations of vertebrate trophic morphology yet described, and the replicate nature of these events provides a unique opportunity to test whether common changes in functional morphology have repeatedly facilitated their ecological success. METHODOLOGY/PRINCIPAL FINDINGS: Specimens from 87 genera of cichlid fishes endemic to Lakes Tanganyka, Malawi and Victoria were dissected in order to examine the functional morphology of cichlid feeding. We quantified shape using geometric morphometrics and compared patterns of morphological diversity using a series of analytical tests. The primary axes of divergence were conserved among all three radiations, and the most prevalent changes involved the size of the preorbital region of the skull. Even the fishes from the youngest of these lakes (Victoria, which exhibit the lowest amount of skull shape disparity, have undergone extensive preorbital evolution relative to other craniofacial traits. Such changes have large effects on feeding biomechanics, and can promote expansion into a wide array of niches along a bentho-pelagic ecomorphological axis. CONCLUSIONS/SIGNIFICANCE: Here we show that specific changes in trophic anatomy have evolved repeatedly in the African rift lakes, and our results suggest that simple morphological alterations that have large ecological consequences are likely to constitute critical components of adaptive radiations in functional morphology. Such shifts may precede more complex shape changes as lineages diversify into unoccupied niches. The data presented here, combined with observations of other fish lineages, suggest that the preorbital region represents an evolutionary module that can respond quickly to natural selection when fishes

  11. [New settlers comb jellies Mnemiopsis leidyi (A. Agassiz) and Beroe ovata Mayer 1912 and their influence on the pelagic ecosystem of the northeastern part of the Black Sea].

    Science.gov (United States)

    Shiganova, T A; Musaeva, E I; Bulgakova, Iu V; Mirzoian, Z A; MartynIuk, M L

    2003-01-01

    We analyzed the condition of pelagic ecosystem of northeastern Black Sea influenced by expansion of a new settler Beroe ovata in 1999-2001. Expansion of B. ovata considerably decreased the population of another new settler Mnemiopsis leidyi that deformed the Black Sea ecosystem for over a decade. Reduction of M. leidyi population limited its influence on the ecosystem and, consequently, we observed reestablishment of the main components of the Black Sea pelagic ecosystem--zooplankton and fish, their spawn and larvae. The relationship between annual and seasonal variability of the population and biomass of the both new settlers M. leidyi and B. ovata are discussed.

  12. Low fertilization rates in a pelagic copepod caused by sexual selection?

    DEFF Research Database (Denmark)

    Ceballos, Sara; Sichlau, Mie Hylstofte; Heuschele, Jan;

    2014-01-01

    random mating. Such low fertilization rates are normally related to environmental factors such as poor food or low densities, which we could not confirm in our experiment. Male density was negatively related to fertilization rate, and a large fraction of males did not mate in laboratory incubations. We...... therefore suggest that sexual selection, through mate choice or male–male competition could account for low fertilization rates of females in populations of pelagic copepods during some periods of the year...

  13. A large new subset of TRIM genes highly diversified by duplication and positive selection in teleost fish

    Directory of Open Access Journals (Sweden)

    Herbomel Philippe

    2009-02-01

    Full Text Available Abstract Background In mammals, the members of the tripartite motif (TRIM protein family are involved in various cellular processes including innate immunity against viral infection. Viruses exert strong selective pressures on the defense system. Accordingly, antiviral TRIMs have diversified highly through gene expansion, positive selection and alternative splicing. Characterizing immune TRIMs in other vertebrates may enlighten their complex evolution. Results We describe here a large new subfamily of TRIMs in teleosts, called finTRIMs, identified in rainbow trout as virus-induced transcripts. FinTRIMs are formed of nearly identical RING/B-box regions and C-termini of variable length; the long variants include a B30.2 domain. The zebrafish genome harbors a striking diversity of finTRIMs, with 84 genes distributed in clusters on different chromosomes. A phylogenetic analysis revealed different subsets suggesting lineage-specific diversification events. Accordingly, the number of fintrim genes varies greatly among fish species. Conserved syntenies were observed only for the oldest fintrims. The closest mammalian relatives are trim16 and trim25, but they are not true orthologs. The B30.2 domain of zebrafish finTRIMs evolved under strong positive selection. The positions under positive selection are remarkably congruent in finTRIMs and in mammalian antiviral TRIM5α, concentrated within a viral recognition motif in mammals. The B30.2 domains most closely related to finTRIM are found among NOD-like receptors (NLR, indicating that the evolution of TRIMs and NLRs was intertwined by exon shuffling. Conclusion The diversity, evolution, and features of finTRIMs suggest an important role in fish innate immunity; this would make them the first TRIMs involved in immunity identified outside mammals.

  14. Roosting ecology and the evolution of pelage markings in bats.

    Science.gov (United States)

    Santana, Sharlene E; Dial, Thomas O; Eiting, Thomas P; Alfaro, Michael E

    2011-01-01

    Multiple lineages of bats have evolved striking facial and body pelage makings, including spots, stripes and countershading. Although researchers have hypothesized that these markings mainly evolved for crypsis, this idea has never been tested in a quantitative and comparative context. We present the first comparative study integrating data on roosting ecology (roost type and colony size) and pelage coloration patterns across bats, and explore the hypothesis that the evolution of bat pelage markings is associated with roosting ecologies that benefit from crypsis. We find that lineages that roost in the vegetation have evolved pelage markings, especially stripes and neck collars, which may function in crypsis through disruptive coloration and a type of countershading that might be unique to bats. We also demonstrate that lineages that live in larger colonies and are larger in size tend not to have pelage markings, possibly because of reduced predation pressures due to the predator dilution effect and a lower number of potential predators. Although social functions for pelage color patterns are also possible, our work provides strong support for the idea that roosting ecology has driven the evolution of pelage markings in bats.

  15. Roosting ecology and the evolution of pelage markings in bats.

    Directory of Open Access Journals (Sweden)

    Sharlene E Santana

    Full Text Available Multiple lineages of bats have evolved striking facial and body pelage makings, including spots, stripes and countershading. Although researchers have hypothesized that these markings mainly evolved for crypsis, this idea has never been tested in a quantitative and comparative context. We present the first comparative study integrating data on roosting ecology (roost type and colony size and pelage coloration patterns across bats, and explore the hypothesis that the evolution of bat pelage markings is associated with roosting ecologies that benefit from crypsis. We find that lineages that roost in the vegetation have evolved pelage markings, especially stripes and neck collars, which may function in crypsis through disruptive coloration and a type of countershading that might be unique to bats. We also demonstrate that lineages that live in larger colonies and are larger in size tend not to have pelage markings, possibly because of reduced predation pressures due to the predator dilution effect and a lower number of potential predators. Although social functions for pelage color patterns are also possible, our work provides strong support for the idea that roosting ecology has driven the evolution of pelage markings in bats.

  16. Do human activities influence survival and orientation abilities of larval fishes in the ocean?

    Science.gov (United States)

    Siebeck, Ulrike E; O'Connor, Jack; Braun, Christoph; Leis, Jeffrey M

    2015-01-01

    The larval stages of most marine fishes spend days to weeks in the pelagic environment, where they must find food and avoid predators in order to survive. Some fish only spend part of their life history in the pelagic environment before returning to their adult habitat, for example, a coral reef. The sensory systems of larval fish develop rapidly during the first few days of their lives, and here we concentrate on the various sensory cues the fish have available to them for survival in the pelagic environment. We focus on the larvae of reef fishes because most is known about them. We also review the major threats caused by human activities that have been identified to have worldwide impact and evaluate how these threats may impact larval-fish survival and orientation abilities. Many human activities negatively affect larval-fish sensory systems or the cues the fish need to detect. Ultimately, this could lead to decreased numbers of larvae surviving to settlement, and, therefore, to decreased abundance of adult fishes. Although we focus on species wherein the larvae and adults occupy different habitats (pelagic and demersal, respectively), it is important to acknowledge that the potential anthropogenic effects we identify may also apply to larvae of species like tuna and herring, where both larvae and adults are pelagic. © 2014 International Society of Zoological Sciences, Institute of Zoology/Chinese Academy of Sciences and Wiley Publishing Asia Pty Ltd.

  17. Diets and trophic-guild structure of a diverse fish assemblage in Chesapeake Bay, U.S.A.

    Science.gov (United States)

    Buchheister, A; Latour, R J

    2015-03-01

    Dietary habits and trophic-guild structure were examined in a fish assemblage (47 species) of the Chesapeake Bay estuary, U.S.A., using 10 years of data from >25 000 fish stomachs. The assemblage was comprised of 10 statistically significant trophic guilds that were principally differentiated by the relative amounts of Mysida, Bivalvia, Polychaeta, Teleostei and other Crustacea in the diets. These guilds were broadly aggregated into five trophic categories: piscivores, zooplanktivores, benthivores, crustacivores and miscellaneous consumers. Food web structure was largely dictated by gradients in habitat (benthic to pelagic) and prey size. Size classes within piscivorous species were more likely to be classified into different guilds, reflecting stronger dietary changes through ontogeny relative to benthivores and other guilds. Relative to predator species and predator size, the month of sampling had negligible effects on dietary differences within the assemblage. A majority of sampled fishes derived most of their nutrition from non-pelagic prey sources, suggesting a strong coupling of fish production to benthic and demersal food resources. Mysida (predominantly the opossum shrimp Neomysis americana) contributed substantially to the diets of over 25% of the sampled predator groups, indicating that this species is a critical, but underappreciated, node in the Chesapeake Bay food web.

  18. Size-related mortality due to gnathiid isopod micropredation correlates with settlement size in coral reef fishes

    Science.gov (United States)

    Grutter, A. S.; Blomberg, S. P.; Fargher, B.; Kuris, A. M.; McCormick, M. I.; Warner, R. R.

    2017-06-01

    The transition between the planktonic and the benthic habitat is a critical period for the larvae of many demersal marine organisms. Understanding the potential constraints on the timing of this habitat transition, called settlement, is important to understanding their biology. Size-specific mortality can set the limits on lifestyle and help explain ontogenetic habitat shifts. We examined whether size-based mortality risks after settlement may include micropredation by ectoparasites by testing whether survival of settlement-stage fish varies with fish size when exposed to a reef-associated micropredator. Fish (14 species) were exposed to one blood-sucking gnathiid isopod overnight, with appropriate controls; gnathiid feeding success and survival, and fish mortality were recorded relative to fish size. After adjusting for fish relatedness, we found the relationship between fish mortality and size differed with gnathiid exposure: for gnathiid-exposed fish, the mean mortality of the smallest fish was much higher (57%) than unexposed controls (10%), and decreased to 0% for fish >12 mm standard length (SL); mortality was almost nil in controls. Thus, a predicted optimal size to switch habitat and reduce mortality risk from micropredation should be >12 mm SL. We then asked what species might be at greater risk and if the steep increase in survival at 12 mm SL might coincide with settlement at larger sizes among fishes. Across 102 other species (32 families), 61% settled at ≥12 mm SL. After adjusting for relatedness, mean fish settlement size was 15.0 mm and this was not significantly different from 12 mm. Thus, settlement size clusters around the minimum fish size threshold our gnathiid experiment predicted would be large enough to survive a gnathiid encounter. These results suggest micropredators may contribute to size-selective mortality during settlement processes and are consistent with the hypothesis that the pelagic phase provides fish an escape from certain

  19. Groups travel further: pelagic metamorphosis and polyp clustering allow higher dispersal potential in sun coral propagules

    Science.gov (United States)

    Mizrahi, Damián; Navarrete, Sergio A.; Flores, Augusto A. V.

    2014-06-01

    We report that planulae produced by Tubastraea coccinea can metamorphose and aggregate in groups of up to eight polyps in the water column, without previous settlement on benthic substrate. We also evaluated the survival of propagules to test whether different levels of aggregation allowed for longer planktonic life and, therefore, higher dispersal potential. Our results show that pelagic polyps live longer than planulae, probably because they can feed and meet the presumably high-energy demands of swimming. Clusters of two or more individuals lived longer than solitary polyps. However, mortality did not differ between small (2-3 polyps) and large (4-8 polyps) clusters, suggesting the existence of an upper limit to cluster size. Most swimming clusters (80 %) remained alive after 6 months, suggesting that pelagic metamorphosis and cluster formation can be a key life-history feature increasing dispersal potential, population connectivity, and the colonization of new habitats in this invasive species.

  20. Observations on inshore and pelagic Dolphins on the South-Eastern Cape coast of South Africa

    Directory of Open Access Journals (Sweden)

    G. S Saayman

    1972-01-01

    Full Text Available The occurrence, size and seaward distribution of schools of inshore and pelagic dolphins is described for three study areas on the south-eastern Cape coast (Algoa Bay; the Tsitsikama Coastal National Park and Plettenberg Bay. Inshore dolphins {Tursiops and Sousa sp. frequented the coastline in relatively small schools whereas pelagic dolphins {Delphinus delphis and Stenella caeruleoalba occurred in very large schools far out to sea. Different ecological zones were used by Sousa for feeding and for social behaviour and maintenance activities. The frequency of occurrence of Sousa at Plettenberg Bay was not affected by seasonal fluctuations in sea surface temperatures. The role of dolphins as predators and their implication in the regulation of the ecosystem of the Tsitsikama Coastal National Park is discussed.

  1. Coexistence of fish species in a large lowland river: food niche partitioning between small-sized percids, cyprinids and sticklebacks in submersed macrophytes.

    Directory of Open Access Journals (Sweden)

    Małgorzata Dukowska

    Full Text Available In the spring and summer of each year, large patches of submersed aquatic macrophytes overgrow the bottom of the alluvial Warta River downstream of a large dam reservoir owing to water management practices. Environmental variables, macroinvertebrates (zoobenthos and epiphytic fauna, zooplankton and fish abundance and biomass were assessed at this biologically productive habitat to learn intraseasonal dynamics of food types, and their occurrence in the gut contents of small-sized roach, dace, perch, ruffe and three-spined stickleback. Gut fullness coefficient, niche breadth and niche overlap indicated how the fishes coexist in the macrophytes. Chironomidae dominated in the diet of the percids. However, ruffe consumed mostly benthic chironomids, while perch epiphytic chironomids and zooplankton. The diet of dace resembled that in fast flowing water although this rheophilic species occurred at unusual density there. The generalist roach displayed the lowest gut fullness coefficient values and widest niche breadth; consequently, intraspecific rather than interspecific competition decided the fate of roach. Three-spined stickleback differed from the other fishes by consuming epiphytic simuliids and fish eggs. The diet overlap between fishes reaching higher gut fullness coefficient values was rather low when the food associated with the submersed aquatic macrophytes was most abundant; this is congruent with the niche overlap hypothesis that maximal tolerable niche overlap can be higher in less intensely competitive conditions.

  2. Coexistence of fish species in a large lowland river: food niche partitioning between small-sized percids, cyprinids and sticklebacks in submersed macrophytes.

    Science.gov (United States)

    Dukowska, Małgorzata; Grzybkowska, Maria

    2014-01-01

    In the spring and summer of each year, large patches of submersed aquatic macrophytes overgrow the bottom of the alluvial Warta River downstream of a large dam reservoir owing to water management practices. Environmental variables, macroinvertebrates (zoobenthos and epiphytic fauna, zooplankton) and fish abundance and biomass were assessed at this biologically productive habitat to learn intraseasonal dynamics of food types, and their occurrence in the gut contents of small-sized roach, dace, perch, ruffe and three-spined stickleback. Gut fullness coefficient, niche breadth and niche overlap indicated how the fishes coexist in the macrophytes. Chironomidae dominated in the diet of the percids. However, ruffe consumed mostly benthic chironomids, while perch epiphytic chironomids and zooplankton. The diet of dace resembled that in fast flowing water although this rheophilic species occurred at unusual density there. The generalist roach displayed the lowest gut fullness coefficient values and widest niche breadth; consequently, intraspecific rather than interspecific competition decided the fate of roach. Three-spined stickleback differed from the other fishes by consuming epiphytic simuliids and fish eggs. The diet overlap between fishes reaching higher gut fullness coefficient values was rather low when the food associated with the submersed aquatic macrophytes was most abundant; this is congruent with the niche overlap hypothesis that maximal tolerable niche overlap can be higher in less intensely competitive conditions.

  3. Habitat loss as the main cause of the slow recovery of fish faunas of regulated large rivers in Europe: The transversal floodplain gradient

    NARCIS (Netherlands)

    Aarts, B.G.W.; Brink, F.W.B. van den; Nienhuis, P.H.

    2004-01-01

    In large European rivers the chemical water quality has improved markedly in recent decades, yet the recovery of the fish fauna is not proceeding accordingly. Important causes are the loss of habitats in the main river channels and their floodplains, and the diminished hydrological connectivity betw

  4. Oxidative stability during storage of fish oil from filleting by-products of rainbow trout (Oncorhynchus mykiss) is largely independent of the processing and production temperature

    DEFF Research Database (Denmark)

    Honold, Philipp; Nouard, Marie-Louise; Jacobsen, Charlotte

    2016-01-01

    Rainbow trout (Oncorhynchus mykiss) is the main fish species produced in Danish fresh water farming. Large amounts of fileting by-products like heads, bones, tails (HBT), and intestines are produced when rainbow trout is processed to smoked rainbow trout filets. The filleting by-products can...

  5. The status of limnophilic fish and the need for conservation in floodplains along the lower Rhine, a large regulated river

    NARCIS (Netherlands)

    Grift, R.E.; Buijse, A.D.; Van Geest, G.J.

    2006-01-01

    Recovery of the fish community of the river Rhine focussed mainly on the return of migratory species, in particular the Atlantic Salmon, Salmo salar, and to a lesser extent on rheophilic fish species. Several limnophilic species that characterize remote parts of the floodplains are, however, also en

  6. High resolution study of the spatial distributions of abyssal fishes by autonomous underwater vehicle

    Science.gov (United States)

    Milligan, R. J.; Morris, K. J.; Bett, B. J.; Durden, J. M.; Jones, D. O. B.; Robert, K.; Ruhl, H. A.; Bailey, D. M.

    2016-05-01

    On abyssal plains, demersal fish are believed to play an important role in transferring energy across the seafloor and between the pelagic and benthic realms. However, little is known about their spatial distributions, making it difficult to quantify their ecological significance. To address this, we employed an autonomous underwater vehicle to conduct an exceptionally large photographic survey of fish distributions on the Porcupine Abyssal Plain (NE Atlantic, 4850 m water depth) encompassing two spatial scales (1–10 km2) on and adjacent to a small abyssal hill (240 m elevation). The spatial distributions of the total fish fauna and that of the two dominant morphotypes (Coryphaenoides sp. 1 and C. profundicolus) appeared to be random, a result contrary to common expectation but consistent with previous predictions for these fishes. We estimated total fish density on the abyssal plain to be 723 individuals km‑2 (95% CI: 601–844). This estimate is higher, and likely more precise, than prior estimates from trawl catch and baited camera techniques (152 and 188 individuals km‑2 respectively). We detected no significant difference in fish density between abyssal hill and plain, nor did we detect any evidence for the existence of fish aggregations at any spatial scale assessed.

  7. Small fishes crossed a large mountain range: Quaternary stream capture events and freshwater fishes on both sides of the Taebaek Mountains.

    Science.gov (United States)

    Kim, Daemin; Hirt, M Vincent; Simons, Andrew M; Won, Yong-Jin

    2016-08-31

    The Taebaek Mountains in South Korea serves as the most apparent biogeographic barrier for South Korean freshwater fishes, resulting in two distinct ichthyofaunal assemblages on the eastern (East/Japan Sea slope) and western (Yellow Sea and Korea Strait slopes) sides of the mountain range. Of nearly 100 species of native primary freshwater fishes in South Korea, only 18 species occur naturally on both sides of the mountain range. Interestingly, there are five rheophilic species (Phoxinus phoxinus, Coreoleuciscus splendidus, Ladislavia taczanowskii, Iksookimia koreensis and Koreocobitis rotundicaudata) found on both sides of the Taebaek Mountains that are geographically restricted to the Osip River (and several neighboring rivers, for L. taczanowskii and I. koreensis) on the eastern side of the mountain range. The Osip River and its neighboring rivers also shared a rheophilic freshwater fish, Liobagrus mediadiposalis, with the Nakdong River on the western side of the mountain range. We assessed historical biogeographic hypotheses on the presence of these rheophilic fishes, utilizing DNA sequence data from the mitochondrial cytochrome b gene. Results of our divergence time estimation indicate that ichthyofaunal transfers into the Osip River (and several neighboring rivers in East Sea slope) have occurred from the Han (Yellow Sea slope) and Nakdong (Korea Strait slope) rivers since the late-Pleistocene. The inferred divergence times for the ichthyofaunal transfer across the Taebaek Mountains were consistent with the timing of hypothesized multiple reactivations of the Osip River Fault (late-Pleistocene), suggesting that the Osip River Fault reactivations may have caused stream capture events, followed by ichthyofaunal transfer, not only between the Osip and Nakdong rivers, but also between the Osip and Han rivers. This article is protected by copyright. All rights reserved.

  8. 2014 Small Pelagics Survey (GU1406, EK60)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Objectives of the 2013 Small Pelagics Acoustic/Trawl Survey were to sample the northern Gulf of Mexico with a 90-ft high opening trawl to facilitate assessments of...

  9. Thermal properties of the pelages of selected African ungulates

    African Journals Online (AJOL)

    lower heat load at the surface of the skin than similarly insulated dark coats. ... different pelages showed that measurements on the midflank region, halfway between the spinal ...... Ph.D. thesis, University of Cape Town. BIRKEBAK, R.C. 1966.

  10. Global Tagging of Pelagic Predators (GTOPP) Animal Tracking Data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These data (updated daily) are from the Global Tagging of Pelagic Predators (GTOPP) program. Begun as one of the field projects in the international Census of Marine...

  11. Distribution of pelagic harpacticoid copepods from the Indian ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Haridas, P.; Rao, T.S.S.

    Pelagic harpacticoid copepods have been studied from the International Indian Ocean Expedition collections. Macrosetella gracilis and Miracia efferata were the most common species of harpacticoids with high densities near land masses. Other three...

  12. Postrelease survival, vertical and horizontal movements, and thermal habitats of five species of pelagic sharks in the central Pacific Ocean

    DEFF Research Database (Denmark)

    Musyl, Michael K.; Brill, Richard W.; Curran, Daniel S.

    2011-01-01

    and the current study (n=78 reporting PSATs) indicated that the summary effect of postrelease mortality for blue sharks was 15% (95% CI, 8.5-25.1%) and suggested that catch-and-release in longline fisheries can be a viable management tool to protect parental biomass in shark populations. Pelagic sharks displayed......]) in the central Pacific Ocean to determine speciesspecific movement patterns and survival rates after release from longline fishing gear. Only a single postrelease mortality could be unequivocally documented: a male blue shark which succumbed seven days after release. Meta-analysis of published reports...... species-specific depth and temperature ranges, although with significant individual temporal and spatial variability in vertical movement patterns, which were also punctuated by stochastic events (e.g., El Nino-Southern Oscillation). Pelagic species can be separated into three broad groups based...

  13. Postrelease survival, vertical and horizontal movements, and thermal habitats of five species of pelagic sharks in the central Pacific Ocean

    DEFF Research Database (Denmark)

    Musyl, Michael K.; Brill, Richard W.; Curran, Daniel S.

    2011-01-01

    From 2001 to 2006, 71 pop-up satellite archival tags (PSATs) were deployed on five species of pelagic shark (blue shark [Prionace glauca]; shortfin mako [Isurus oxyrinchus]; silky shark [Carcharhinus falciformis]; oceanic whitetip shark [C. longimanus]; and bigeye thresher [Alopias superciliosus......]) in the central Pacific Ocean to determine speciesspecific movement patterns and survival rates after release from longline fishing gear. Only a single postrelease mortality could be unequivocally documented: a male blue shark which succumbed seven days after release. Meta-analysis of published reports...... and the current study (n=78 reporting PSATs) indicated that the summary effect of postrelease mortality for blue sharks was 15% (95% CI, 8.5-25.1%) and suggested that catch-and-release in longline fisheries can be a viable management tool to protect parental biomass in shark populations. Pelagic sharks displayed...

  14. Pelagic sea snakes dehydrate at sea

    Science.gov (United States)

    Lillywhite, Harvey B.; Sheehy, Coleman M.; Brischoux, François; Grech, Alana

    2014-01-01

    Secondarily marine vertebrates are thought to live independently of fresh water. Here, we demonstrate a paradigm shift for the widely distributed pelagic sea snake, Hydrophis (Pelamis) platurus, which dehydrates at sea and spends a significant part of its life in a dehydrated state corresponding to seasonal drought. Snakes that are captured following prolonged periods without rainfall have lower body water content, lower body condition and increased tendencies to drink fresh water than do snakes that are captured following seasonal periods of high rainfall. These animals do not drink seawater and must rehydrate by drinking from a freshwater lens that forms on the ocean surface during heavy precipitation. The new data based on field studies indicate unequivocally that this marine vertebrate dehydrates at sea where individuals may live in a dehydrated state for possibly six to seven months at a time. This information provides new insights for understanding water requirements of sea snakes, reasons for recent declines and extinctions of sea snakes and more accurate prediction for how changing patterns of precipitation might affect these and other secondarily marine vertebrates living in tropical oceans. PMID:24648228

  15. Pelagic sea snakes dehydrate at sea.

    Science.gov (United States)

    Lillywhite, Harvey B; Sheehy, Coleman M; Brischoux, François; Grech, Alana

    2014-05-07

    Secondarily marine vertebrates are thought to live independently of fresh water. Here, we demonstrate a paradigm shift for the widely distributed pelagic sea snake, Hydrophis (Pelamis) platurus, which dehydrates at sea and spends a significant part of its life in a dehydrated state corresponding to seasonal drought. Snakes that are captured following prolonged periods without rainfall have lower body water content, lower body condition and increased tendencies to drink fresh water than do snakes that are captured following seasonal periods of high rainfall. These animals do not drink seawater and must rehydrate by drinking from a freshwater lens that forms on the ocean surface during heavy precipitation. The new data based on field studies indicate unequivocally that this marine vertebrate dehydrates at sea where individuals may live in a dehydrated state for possibly six to seven months at a time. This information provides new insights for understanding water requirements of sea snakes, reasons for recent declines and extinctions of sea snakes and more accurate prediction for how changing patterns of precipitation might affect these and other secondarily marine vertebrates living in tropical oceans.

  16. A large outbreak of scombroid fish poisoning associated with eating yellowfin tuna (Thunnus albacares) at a military mass catering in Dakar, Senegal.

    Science.gov (United States)

    Demoncheaux, J-P; Michel, R; Mazenot, C; Duflos, G; Iacini, C; de Laval, F; Delaval, F; Saware, E M; Renard, J-C

    2012-06-01

    On 26 November 2010, an outbreak of scombroid fish poisoning occurred in the French Armed Forces in Dakar, Senegal. This chemical intoxication, due to high histamine concentration in fish, is often mistaken for an allergic reaction. A case-control study was undertaken including the 71 cases and 78 randomly selected controls among lunch attendees. The usual symptoms for scombroid fish poisoning were observed in cases, i.e. flushing (85.9%), headache (83.1%), rapid/weak pulse (59.1%) and diarrhoea (47.9%). Symptoms occurred from within a few minutes to up to 3 h following the meal. Most patients quickly recovered with antihistamine and/or symptomatic treatment. Tuna was the only food item positively associated with illness (odds ratio 36.3, 95% confidence interval 6.3-210.0), with the risk of illness increasing with the quantity of fish consumed. No bacterial contamination was found in leftover food, but histamine concentration in tuna was found to be 4900 mg/kg, almost 50-fold higher than the concentration allowed by European regulations. This report is unique because of the large size of the case series - to our knowledge, the largest event of scombroid fish poisoning ever reported - and the chemical and bacteriological analyses results obtained on leftover food.

  17. Increased oceanic microplastic debris enhances oviposition in an endemic pelagic insect

    Science.gov (United States)

    Goldstein, Miriam C.; Rosenberg, Marci; Cheng, Lanna

    2012-01-01

    Plastic pollution in the form of small particles (diameter less than 5 mm)—termed ‘microplastic’—has been observed in many parts of the world ocean. They are known to interact with biota on the individual level, e.g. through ingestion, but their population-level impacts are largely unknown. One potential mechanism for microplastic-induced alteration of pelagic ecosystems is through the introduction of hard-substrate habitat to ecosystems where it is naturally rare. Here, we show that microplastic concentrations in the North Pacific Subtropical Gyre (NPSG) have increased by two orders of magnitude in the past four decades, and that this increase has released the pelagic insect Halobates sericeus from substrate limitation for oviposition. High concentrations of microplastic in the NPSG resulted in a positive correlation between H. sericeus and microplastic, and an overall increase in H. sericeus egg densities. Predation on H. sericeus eggs and recent hatchlings may facilitate the transfer of energy between pelagic- and substrate-associated assemblages. The dynamics of hard-substrate-associated organisms may be important to understanding the ecological impacts of oceanic microplastic pollution. PMID:22573831

  18. Beyond the vent: New perspectives on hydrothermal plumes and pelagic biology

    Science.gov (United States)

    Phillips, Brennan T.

    2017-03-01

    Submarine hydrothermal vent fields introduce buoyant plumes of chemically altered seawater to the deep-sea water column. Chemoautotrophic microbes exploit this energy source, facilitating seafloor-based primary production that evidence suggests may transfer to pelagic consumers. While most hydrothermal plumes have relatively small volumes, there are recent examples of large-scale plume events associated with periods of eruptive activity, which have had a pronounced effect on water-column biology. This correlation suggests that hydrothermal plumes may have influenced basin-scale ocean chemistry during periods of increased submarine volcanism during the Phanerozoic eon. This paper synthesizes a growing body of scientific evidence supporting the hypothesis that hydrothermal plumes are the energetic basis of unique deep-sea pelagic food webs. While many important questions remain concerning the biology of hydrothermal plumes, this discussion is not present in ongoing management efforts related to seafloor massive sulfide (SMS) mining. Increased research efforts, focused on high-resolution surveys of midwater biology relative to plume structures, are recommended to establish baseline conditions and monitor the impact of future mining-based disturbances to the pelagic biosphere.

  19. The influence of oceanographic processes on pelagic-benthic coupling in polar regions: A benthic perspective

    Science.gov (United States)

    Grebmeier, Jacqueline M.; Barry, James P.

    1991-08-01

    Benthic community abundance and biomass in polar marine systems is directly influenced by food supply from the overlying water column. Variability in hydrographic regimes, ice coverage, light, water column temperature and pelagic food web structure limit the amount of organic carbon reaching the benthos. Data from the high Arctic and Antarctic indicate that a large percentage of surface-produced organic matter is consumed by both macro- and micro-zooplankton as well as recycled in the water column via the microbial loop. This results in food-limited regimes for the underlying benthos. The few exceptions are nearshore continental shelf systems, such as in the Bering and Chukchi Seas in the western Arctic and portions of the Canadian Archipelago and Barents Sea in the eastern Arctic, where high benthic abundance and biomass occurs due to a tight coupling between water column primary production and benthic secondary production. A major difference between the Antarctic and Arctic is that the nearshore deep Antarctic is characterized by relatively high benthic abundance and biomass despite low water column production, suggesting that stability, low disturbance levels and cold temperatures enable benthic organisms to grow larger than in the Arctic. Both physical and biological disturbance levels are high in the marginal seas of the Arctic may directly influence benthic productivity. The relationship between primary production and sedimentation of organic material to the benthos is nonlinear due to its dependence on the role of the pelagic food web. Therefore, in this review we will only discuss the pelagic system with respect to how it impacts the net food supply reachig the benthos. A major objective of this review paper is demonstrate the influence of oceanographic processes on pelagic-benthic coupling in polar regions from a "bottom-up" perspective, using benthic studies from various regions in both the Arctic and Antarctic. Similarities and differences in

  20. Benthic and pelagic pathways of methylmercury bioaccumulation in estuarine food webs of the northeast United States.

    Science.gov (United States)

    Chen, Celia Y; Borsuk, Mark E; Bugge, Deenie M; Hollweg, Terill; Balcom, Prentiss H; Ward, Darren M; Williams, Jason; Mason, Robert P

    2014-01-01

    Methylmercury (MeHg) is a contaminant of global concern that bioaccumulates and bioamagnifies in marine food webs. Lower trophic level fauna are important conduits of MeHg from sediment and water to estuarine and coastal fish harvested for human consumption. However, the sources and pathways of MeHg to these coastal fisheries are poorly known particularly the potential for transfer of MeHg from the sediment to biotic compartments. Across a broad gradient of human land impacts, we analyzed MeHg concentrations in food webs at ten estuarine sites in the Northeast US (from the Hackensack Meadowlands, NJ to the Gulf of Maine). MeHg concentrations in water column particulate material, but not in sediments, were predictive of MeHg concentrations in fish (killifish and Atlantic silversides). Moreover, MeHg concentrations were higher in pelagic fauna than in benthic-feeding fauna suggesting that MeHg delivery to the water column from methylation sites from within or outside of the estuary may be an important driver of MeHg bioaccumulation in estuarine pelagic food webs. In contrast, bulk sediment MeHg concentrations were only predictive of concentrations of MeHg in the infaunal worms. Our results across a broad gradient of sites demonstrate that the pathways of MeHg to lower trophic level estuarine organisms are distinctly different between benthic deposit feeders and forage fish. Thus, even in systems with contaminated sediments, transfer of MeHg into estuarine food webs maybe driven more by the efficiency of processes that determine MeHg input and bioavailability in the water column.

  1. Benthic and pelagic pathways of methylmercury bioaccumulation in estuarine food webs of the northeast United States.

    Directory of Open Access Journals (Sweden)

    Celia Y Chen

    Full Text Available Methylmercury (MeHg is a contaminant of global concern that bioaccumulates and bioamagnifies in marine food webs. Lower trophic level fauna are important conduits of MeHg from sediment and water to estuarine and coastal fish harvested for human consumption. However, the sources and pathways of MeHg to these coastal fisheries are poorly known particularly the potential for transfer of MeHg from the sediment to biotic compartments. Across a broad gradient of human land impacts, we analyzed MeHg concentrations in food webs at ten estuarine sites in the Northeast US (from the Hackensack Meadowlands, NJ to the Gulf of Maine. MeHg concentrations in water column particulate material, but not in sediments, were predictive of MeHg concentrations in fish (killifish and Atlantic silversides. Moreover, MeHg concentrations were higher in pelagic fauna than in benthic-feeding fauna suggesting that MeHg delivery to the water column from methylation sites from within or outside of the estuary may be an important driver of MeHg bioaccumulation in estuarine pelagic food webs. In contrast, bulk sediment MeHg concentrations were only predictive of concentrations of MeHg in the infaunal worms. Our results across a broad gradient of sites demonstrate that the pathways of MeHg to lower trophic level estuarine organisms are distinctly different between benthic deposit feeders and forage fish. Thus, even in systems with contaminated sediments, transfer of MeHg into estuarine food webs maybe driven more by the efficiency of processes that determine MeHg input and bioavailability in the water column.

  2. Metal concentration in water, sediment and four fish species from Lake Titicaca reveals a large-scale environmental concern.

    Science.gov (United States)

    Monroy, Mario; Maceda-Veiga, Alberto; de Sostoa, Adolfo

    2014-07-15

    Although intensive mining activity and urban sewage discharge are major sources of metal inputs to Lake Titicaca, the risk posed by metal pollution to wildlife and human populations has been poorly studied. In this study we compared the concentrations of Cu, Zn, Cd, Hg, Pb, Co, and Fe in water, sediment, and two tissues (liver and muscle) of four fish species (Odontesthes bonariensis, Orestias luteus, Orestias agassii, and Trichomycterus rivulatus) across important fishery areas in Lake Titicaca. The concentration of Pb in water at the discharge sites of the main rivers and of most elements, with the exception of Co and Fe, in all fish collected in this study exceeded the safety thresholds established by international legislation. The highest metal concentrations were observed in benthopelagic species, and liver tissue was identified as the main depository for all metals with the exception of mercury. The metal bioaccumulation pattern in fish was weakly related to the metal concentrations in the environment with the exception of Hg at the most polluted location, partly explained by the different metabolic role of essential and non-essential elements and the influence of other factors such as species' ecology and individual traits in the bioaccumulation of most metals. As metal pollution extended across the study area and high metal concentrations were detected in all four fish species, we urge the authorities to enforce legislation for water and fish consumption and to evaluate the effects of metal pollution on fish health.

  3. Influence of ocean winds on the pelagic ecosystem in upwelling regions.

    Science.gov (United States)

    Rykaczewski, Ryan R; Checkley, David M

    2008-02-12

    Upwelling of nutrient-rich, subsurface water sustains high productivity in the ocean's eastern boundary currents. These ecosystems support a rate of fish harvest nearly 100 times the global mean and account for >20% of the world's marine fish catch. Environmental variability is thought to be the major cause of the decadal-scale biomass fluctuations characteristic of fish populations in these regions, but the mechanisms relating atmospheric physics to fish production remain unexplained. Two atmospheric conditions induce different types of upwelling in these ecosystems: coastal, alongshore wind stress, resulting in rapid upwelling (with high vertical velocity, w); and wind-stress curl, resulting in slower upwelling (low w). We show that the level of wind-stress curl has increased and that production of Pacific sardine (Sardinops sagax) varies with wind-stress curl over the past six decades. The extent of isopycnal shoaling, nutricline depth, and chlorophyll concentration in the upper ocean also correlate positively with wind-stress curl. The size structure of plankton assemblages is related to the rate of wind-forced upwelling, and sardine feed efficiently on small plankters generated by slow upwelling. Upwelling rate is a fundamental determinant of the biological structure and production in coastal pelagic ecosystems, and future changes in the magnitude and spatial gradient of wind stress may have important and differing effects on these ecosystems. Understanding of the biological mechanisms relating fisheries production to environmental variability is essential for wise management of marine resources under a changing climate.

  4. STUDY ON OCEANGRAFHIC AND WEATHER CONDITIONS RELATED TO THE ABUNDANCE OF SMALL PELAGIC FISHERY IN NATUNA SEA USING REMOTE SENSING DATA

    Directory of Open Access Journals (Sweden)

    Teguh Prayogo

    2012-11-01

    Full Text Available Indonesian waters have abundance of natural resources; the potential of small pelagic fish in Natuna Sea and SouthChina Sea have not been optimized yet explores. Unfortunately, it was caused by lacking in the data of environmentalconditions that have been changed and the information of appropriate fishing ground. Hence, dynamical oceanographicinformation and weather condition is necessary to optimize small pelagic fish exploitation.Research location in Natuna Sea and its surrounding with geographical position is 08°N–03°S; 103°–111°E. Theoceanographic condition representative by monthly SST, Chl-a, SSH that derived from satellite data and Dipole ModeIndex for 2002-2007 from FRCGC website. Monthly wind data is variable for weather condition. Small pelagic fishabundance representative by annual fish production (2002-2005 and monthly Catch Per Unit Effort (CPUE ofGoldstripe sardinella, Bigeye scad and Indian scad (2006. It was data collected from Directorate General of CaptureFisheries (Ministry of Marine Affairs and Fisheries and daily fishing operation (2007 used to calculate match-up ratiothat was collected from Pemangkat fishing port in West Kalimantan. Research process consists of image processing,descriptive correlation analysis and GIS analysis to predict fishing ground map and match-up ratio calculation.Result of this research is the annual fish catch production of Bigeye scad and Indian scad (2002-2005 is tend toincrease and the monthly CPUE of both species is high during SE Monsoon (May-Sep that is condition contrarily in NWMonsoon (Nov-Apr. Meanwhile, the annual fish catch production of Goldstripe sardinella production is tend to decreasefrom 2002-2005, it has CPUE is high in early SE Monsoon (May. During the SE Monsoon (May-Sep when DM Index ispositive (+ the Indian scad and Bigeye scad production is high, for Goldstripe sardinella the fish production is highwhen DM Index is positive (+ in May. The accuracy of prediction map of

  5. The replacement of fish oil with refined coconut oil in the diet of large rainbow trout (Oncorhynchus mykiss

    Directory of Open Access Journals (Sweden)

    Marco Maxia

    2010-01-01

    Full Text Available Three hundred rainbow trout (242.9 ± 6.9 g were randomly assigned to 12 fibreglass tanks (25 fish/tank. The fish were fed, for 231 days (feeding level: 0.74 % average bw, four experimental diets, containing increasing levels of coconut oil: diet A 0 %, diet B 6 %; diet C 12 % and diet D 13 %, as replacements of herring oil and cod liver oil. Weight gains of fish were > 3 g d-1 and FCR lower than 1.5, for all treatments. No significant difference was observed in the main car- cass traits and whole body composition, but whole fish energy content significantly increased in fish fed diet D (10.68 KJ g-1. Different dietary fatty acid profiles had significant effects on the rainbow trout muscle contents of C10:0, C12:0, C14:0, total n-3, and the main ratios: SFA/USFA; DHA/EPA; DHA/AA, n-3/n-6, but not on total fatty acids content of the muscle.

  6. Assessment of Heavy Metals in Water, Sediment, and Fishes of a Large Tropical Hydroelectric Dam in Sarawak, Malaysia

    Directory of Open Access Journals (Sweden)

    Siong Fong Sim

    2016-01-01

    Full Text Available Bakun Hydroelectric Dam in Sarawak is one of the world highest concrete rock filled dams. This paper reports the heavy metals concentrations in water, sediment, and fishes of Bakun Dam. Water and sediment samples were collected from 11 stations and 6 fish species were caught. The samples were digested with open acid digestion and the metals contents were analysed using an atomic absorption spectrophotometer and mercury analyser. The method was validated based on certified reference materials. A higher concentration of Fe and Mn was detected in downstream water with significant longitudinal variation. Cu, Zn, and Hg were present in trace amount. All elements analysed were consistently found in sediment with no risk of contamination. For fish, Hemibagrus planiceps was characterised by higher affinity for Hg accumulation. The concentrations detected in all fish species were within the permissible guideline of 0.5 mg/kg. The health risk assessment suggested that Barbonymus schwanenfeldii, Puntioplites waandersii, Cyclocheilichthys apogon, and Hemibagrus planiceps were characterised by hazard index > 1 implying possible adverse effects. The amount of fish recommended for adults and children was in the range of 500–775 g/week and 33–135 g/week, respectively.

  7. Modeling the Hook Depth Distribution of Pelagic Longlining in the Equatorial Area of Indian Ocean

    Institute of Scientific and Technical Information of China (English)

    SONG Liming; LI Jie; GAO Panfeng; ZHOU Ji; XU Liuxiong

    2012-01-01

    A survey was conducted in the equatorial area of Indian Ocean for a better understanding of the dynamics of hook depth distribution of pelagic longline fishery.We determined the relationship between hook depth and vertical shear of current coefficiency,wind speed,hook position code,sine of wind angle,sine of angle of attack and weight of messenger weight.We identified the hook depth models by the analysis of covariance with a general linear model.The results showed that the wind effect on the hook depth can be ignored from October to November in the survey area; the surface current effect on the hook depth can be ignored; the equatorial undercurrent is the key factor for the hook depth in Indian Ocean; and there is a negative correlation between the hook depth and vertical shear of current and angle of attack.It was also found that the deeper the hook was set,the higher hook depth shoaling was.The proposed model improves the accuracy of the prediction of hook depth,which can be used to estimate the vertical distribution of pelagic fish in water column.

  8. Climate Change Impacts to North Pacific Pelagic Habitat Are Projected to Lower Carrying Capacity

    Science.gov (United States)

    Woodworth-Jefcoats, P. A.; Polovina, J. J.; Drazen, J.

    2016-02-01

    We use output from a suite of CMIP5 earth system models to explore the impacts of climate change on marine fisheries over the 21st century. Ocean temperatures from both the historical and RCP 8.5 projections are integrated over the upper 200 m of the water column to characterize thermal habitat in the epipelagic realm. We find that across all models the projected temperature increases lead to a redistribution of thermal habitat: temperatures that currently represent the majority of North Pacific pelagic habitat are replaced by temperatures several degrees warmer. Additionally, all models project the emergence of new thermal habitat that exceeds present-day maximum temperatures. Spatially, present-day thermal habitat retreats northward and contracts eastward as warmer habitat in the southern and western North Pacific expands. In addition to these changes in thermal habitat, zooplankton densities are projected to decline across much of the North Pacific. Taken together, warming temperatures and declining zooplankton densities create the potential for mismatches in metabolic demand and supply through the 21st century. We find that carrying capacity for tropical tunas and other commercially valuable pelagic fish may be especially vulnerable to the impacts of climate change. The waters projected to see the greatest redistribution of thermal habitat and greatest declines in zooplankton densities are primarily those targeted by the Hawaii-based and international longline fleets. Fishery managers around the North Pacific will need to incorporate these impacts of climate change into future management strategies.

  9. Ocean acidification alters the otoliths of a pantropical fish species with implications for sensory function.

    Science.gov (United States)

    Bignami, Sean; Enochs, Ian C; Manzello, Derek P; Sponaugle, Su; Cowen, Robert K

    2013-04-30

    Ocean acidification affects a wide diversity of marine organisms and is of particular concern for vulnerable larval stages critical to population replenishment and connectivity. Whereas it is well known that ocean acidification will negatively affect a range of calcareous taxa, the study of fishes is more limited in both depth of understanding and diversity of study species. We used new 3D microcomputed tomography to conduct in situ analysis of the impact of ocean acidification on otolith (ear stone) size and density of larval cobia (Rachycentron canadum), a large, economically important, pantropical fish species that shares many life history traits with a diversity of high-value, tropical pelagic fishes. We show that 2,100 μatm partial pressure of carbon dioxide (pCO2) significantly increased not only otolith size (up to 49% greater volume and 58% greater relative mass) but also otolith density (6% higher). Estimated relative mass in 800 μatm pCO2 treatments was 14% greater, and there was a similar but nonsignificant trend for otolith size. Using a modeling approach, we demonstrate that these changes could affect auditory sensitivity including a ∼50% increase in hearing range at 2,100 μatm pCO2, which may alter the perception of auditory information by larval cobia in a high-CO2 ocean. Our results indicate that ocean acidification has a graded effect on cobia otoliths, with the potential to substantially influence the dispersal, survival, and recruitment of a pelagic fish species. These results have important implications for population maintenance/replenishment, connectivity, and conservation efforts for other valuable fish stocks that are already being deleteriously impacted by overfishing.

  10. Arcane epipelagic fishes of the subtropical North Pacific and factors associated with their distribution

    Science.gov (United States)

    McKinnell, Skip; Seki, Michael P.

    2017-01-01

    In 1992, a moratorium was declared by the United Nations General Assembly to end the practice of large-scale pelagic driftnet fishing. During two years leading up to the moratorium, three scientific research and fishery observer programs involving Canada, Japan, Korea, China-Taipei and the United States had collected significant amounts of information about the distribution and abundance of the epipelagic fauna in the subtropical North Pacific Ocean. The pan-regional distributions of the fishes in 1990 and 1991, most of which were taken as bycatch in 9910 fishing operations (357,150 km of driftnet) are described. More species were observed per fishing operation in 1991 than in 1990. Principal coordinate analysis of the incidence of the commonly caught fish species was used to show that, except for an anomaly in the region of the Shatsky Rise (165°E), the composition of the catch changed from the coast of Japan across more than 6000 km to the eastern boundary of the fishery (145°W). The analysis suggested that the fish species composition changed rather little with increasing latitude within the southern part of the domain (25-35°N), before changing more rapidly north of the Kuroshio Extension region to a more subarctic, transition zone fauna.

  11. Higher mass-independent isotope fractionation of methylmercury in the pelagic food web of Lake Baikal (Russia).

    Science.gov (United States)

    Perrot, Vincent; Pastukhov, Mikhail V; Epov, Vladimir N; Husted, Søren; Donard, Olivier F X; Amouroux, David

    2012-06-01

    Mercury undergoes several transformations that influence its stable isotope composition during a number of environmental and biological processes. Measurements of Hg isotopic mass-dependent (MDF) and mass-independent fractionation (MIF) in food webs may therefore help to identify major sources and processes leading to significant bioaccumulation of methylmercury (MeHg). In this work, δ(13)C, δ(15)N, concentration of Hg species (MeHg, inorganic Hg), and stable isotopic composition of Hg were determined at different trophic levels of the remote and pristine Lake Baikal ecosystem. Muscle of seals and different fish as well as amphipods, zooplankton, and phytoplankton were specifically investigated. MDF during trophic transfer of MeHg leading to enrichment of heavier isotopes in the predators was clearly established by δ(202)Hg measurements in the pelagic prey-predator system (carnivorous sculpins and top-predator seals). Despite the low concentrations of Hg in the ecosystem, the pelagic food web reveals very high MIF Δ(199)Hg (3.15-6.65‰) in comparison to coastal fish (0.26-1.65‰) and most previous studies in aquatic organisms. Trophic transfer does not influence MIF signature since similar Δ(199)Hg was observed in sculpins (4.59 ± 0.55‰) and seal muscles (4.62 ± 0.60‰). The MIF is suggested to be mainly controlled by specific physical and biogeochemical characteristics of the water column. The higher level of MIF in pelagic fish of Lake Baikal is mainly due to the bioaccumulation of residual MeHg that is efficiently turned over and photodemethylated in deep oligotrophic and stationary (i.e., long residence time) freshwater columns.

  12. Impact of El Niño events on pelagic fisheries in Peruvian waters

    Science.gov (United States)

    Ñiquen, Miguel; Bouchon, Marilú

    2004-03-01

    Using data from stock assesment surveys on pelagic resources during El Niño events of 1972/73, 1982/83, 1997/98, we analyze biological changes on pelagic ecosystems and pelagic fisheries during different stages of development of El Niño phenomenon: emergence, full, final and post-Niño. Results indicate changes in spatial distribution of resources, their concentration and size structure. In anchovy (Engraulis ringens) a decrease in biomass was observed, which was estimated at 1.2 million tons in September 1998, the lowest throughout the 1990s. This resource showed an asymmetric distribution towards the south of Peru. Other pelagic resources increased their biomass during or after Niño events, primarily sardine (Sardinops sagax), jack mackerel (Trachurus murphyi), pacific mackerel (Scomber japonicus), and longnose anchovy (Anchoa nasus). At the end of the El Niño phenomenon we found less productivity but more diversity in the pelagic ecosystem. During the 1997/98 El Niño, the diversity index (Manual de Ecologia, 1a Edition, Editorial Trillas, Mexico, 267pp) increased from 0.87 to 1.23-1.70. In both the emergence stage and fully developed stages of El Niño we found large numbers of sardine and longnose anchovy present simultaneously. Size structure of sardine, jack mackerel, and pacific mackerel showed an increase in juveniles. Anchovy during El Niño showed a single modal group composed of adults, but the post-Niño phase indicated an increase in juveniles with an average length of 6-7 cm. In El Niño conditions spawning among anchovy was low, but among sardine and pacific mackerel it was high. We observed, for the first time during full spawning, juvenile sardines with a total length of 18-20 cm. The anchovy spawning season during the post-Niño phase was considerably lengthened, from April to December 1998. Drastic change occurred in fisheries when monospecific fisheries, based on anchovy before El Niño, became multispecific fisheries based on sardine, jack

  13. Fishing in Easter Island, a recent history (1950-2010

    Directory of Open Access Journals (Sweden)

    Kyrstn Zylich

    2014-10-01

    Full Text Available Easter Island (Rapa Nui is well studied in terms of its archaeology; however, information regarding the history of fishing is extremely limited. Marine resources have likely been exploited from the time the first Polynesians arrived on this remote island. While large pelagics are part of the traditional Rapa Nui diet, inshore fish and invertebrates have also made their way into the diet. Official records of fisheries catches in what is now the Easter Island Province of Chile, which also includes the uninhabited island of Salas y Gómez, are very limited and were available for only some years. Using anecdotal information, historical descriptions and the limited quantitative information available, we reconstructed fisheries catches in the Exclusive Economic Zone (EEZ of the Easter Island Province over the 1950-2010 time period. Totaling almost 6,000 ton, legal catches have been increasing rapidly since the late 1970s, but are now stagnating at around 150-200 ton yr-1. The main species targeted were Pacific chub or 'nanue' (Kyphosus sandwicensis and yellowfin tuna or 'kahi ave ave' (Thunnus albacares, with spiny lobster or 'ura' (Panulirus pascuensis being the most important invertebrate species. There are indications of a substantial illegal fishery for large pelagics in the EEZ of the province, estimated at 200-2,000 ton yr-1, which may have operated for two decades and may be the cause for the declining artisanal catch of tuna by Rapa Nui fishers. Continued pressure on these geographically remote oceanic and inshore marine species, especially those popular amongst tourists, makes accounting for fisheries catches an even greater priority.

  14. Environmental conditions influencing the larval fish assemblage during summer in the Gulf of Gabes (Tunisia: South central Mediterranean

    Directory of Open Access Journals (Sweden)

    W. K. KOCHED

    2015-11-01

    Full Text Available An oceanographic survey was carried out during the summer of 2009, from June 25 to July 3 in the Gulf of Gabes. The study area is characterized by a wide continental shelf.A plankton sampling scheme was carried out to study the structure of the larval fish assemblages that characterizes the surface mixed layer, and to assess the influence of the environmental parameters on their spatial distribution.A total of 36 taxa were identified, 3 classified to the level of genus, 5 to family and 28 to species. The majority of identified fish larvae belonged to demersal species, mainly picarel Spicara smaris (23.76% of the total larval fish abundance, followed by red mullet Mullus barbatus (14.92% and several species of the Sparidae family (9.15%. Small pelagic species as Sardinella Sardinella aurita and European anchovy Engraulis encrasicolus were also abundant (27.75 % and dominated the fish larvae community in offshore stations. Five large pelagic species were found among the larvae, including bullet tuna Auxis rochei, Atlantic black skipjack Euthynnus alletteratus, albacore Thunnus alalunga, swordfish Xiphias gladius and the highly migratory Atlantic bluefin tuna Thunnus thynnus. All these apex predator species appear in 38.5% of the sampling stations and contribute about 7.9% of the total larval catches. The larval fish assemblage of the Gulf of Gabes is predominantly composed of neritic species in correspondence with the shallow depths of the study area. Canonical Correspondence Analysis (CCA showed that larval distributions were mainly conditioned by depth. However, other factors, like hydrographic processes, play also a very important role in shaping the spatial pattern of larval fish distribution.

  15. Multibiomarker approach in fish to assess the impact of pollution in a large Brazilian river, Paraiba do Sul

    Energy Technology Data Exchange (ETDEWEB)

    Linde-Arias, Ana Rosa [Laboratorio de Toxicologia, Centro de Estudos da Saude do Trabalhador e Ecologia Humana, Escola Nacional de Saude Publica Sergio Arouca, Fundacao Oswaldo Cruz, Leopoldo Bulhoes, 1480, Rio de Janeiro (Brazil)], E-mail: arlinde@ensp.fiocruz.br; Inacio, Alan F.; Novo, Leonardo A.; Alburquerque, Carla de; Moreira, Josino C. [Laboratorio de Toxicologia, Centro de Estudos da Saude do Trabalhador e Ecologia Humana, Escola Nacional de Saude Publica Sergio Arouca, Fundacao Oswaldo Cruz, Leopoldo Bulhoes, 1480, Rio de Janeiro (Brazil)

    2008-12-15

    This article examines the advantages of the use of biomarkers as environmental indicators by applying it to Paraiba do Sul watershed, one of the most important Brazilian water bodies, which is in a critical environmental situation. We use a multibiomarker approach in fish as an integrated strategy to assess the impact of pollution. It comprehends a general biomarker of fish health, the condition factor (CF), and specific biomarkers of contaminant exposure such as metallothionein (MT), acetylcholinesterase (AChE) activity and biliary polycyclic aromatic hydrocarbons (PAH) metabolites. Our results revealed different effects in the fish from diverse locations with varying degrees of pollution. Furthermore, fish located just upstream of the water-treatment plant of the metropolitan area of Rio de Janeiro has shown to be affected by metals. This study indicates the usefulness of integrating a set of biomarkers to define the effects of anthropogenic inputs in aquatic bodies under complex polluted situations. - Integrated approach using biomarkers proofs suitable for environmental assessment of a diversely polluted river.

  16. Fish and land use influence Gammarus lacustris and Hyalella azteca (Amphipoda) densities in large wetlands across the upper Midwest

    Science.gov (United States)

    Anteau, Michael J.; Afton, Alan D.; Anteau, Andrea C.E.; Moser, E. Barry

    2011-01-01

    Gammarus lacustrisK/i> and Ki>Hyalella azteca (hereafter G. lacustris and H. azteca, respectively) are important components of secondary production in wetlands and shallow lakes of the upper Midwest, USA. Within the past 50 years, amphipod densities have decreased while occurrences of fish and intensity of agricultural land use have increased markedly across this landscape. We investigated influences of fish, sedimentation, and submerged aquatic vegetation (SAV) on densities of G. lacustris and H. azteca in semipermanent and permanent wetlands and shallow lakes (n = 283) throughout seven eco-physiographic regions of Iowa, Minnesota, and North Dakota during 2004–2005. G. lacustris and H. azteca densities were positively correlated with densities of SAV (P P P = 0.01 and P = 0.013, respectively) and with high densities of fathead minnows (Pimephales promelas; P P = 0.033, respectively). H. azteca densities also were negatively correlated with densities of small fish (e.g., other minnows [Cyprinidae] and sticklebacks [Gasterosteidae]; P = 0.048) and common carp (Cyprinus spp.; P = 0.022). G. lacustris densities were negatively correlated with high levels of suspended solids (an index for sedimentation; P H. azteca densities were positively correlated with the width of upland-vegetation buffers (P = 0.004). Our results indicate that sedimentation and fish reduce amphipod densities and may contribute to the current low densities of amphipods in the upper Midwest. Thus, removing/excluding fish, and providing a thick buffer of upland vegetation around wetlands may help restore amphipod densities and wetland and water quality within this landscape.

  17. Large-scale, multidirectional larval connectivity among coral reef fish populations in the Great Barrier Reef Marine Park

    KAUST Repository

    Williamson, David H.

    2016-11-15

    Larval dispersal is the key process by which populations of most marine fishes and invertebrates are connected and replenished. Advances in larval tagging and genetics have enhanced our capacity to track larval dispersal, assess scales of population connectivity, and quantify larval exchange among no-take marine reserves and fished areas. Recent studies have found that reserves can be a significant source of recruits for populations up to 40 km away, but the scale and direction of larval connectivity across larger seascapes remain unknown. Here, we apply genetic parentage analysis to investigate larval dispersal patterns for two exploited coral reef groupers (Plectropomus maculatus and Plectropomus leopardus) within and among three clusters of reefs separated by 60–220 km within the Great Barrier Reef Marine Park, Australia. A total of 69 juvenile P. maculatus and 17 juvenile P. leopardus (representing 6% and 9% of the total juveniles sampled, respectively) were genetically assigned to parent individuals on reefs within the study area. We identified both short-distance larval dispersal within regions (200 m to 50 km) and long-distance, multidirectional dispersal of up to ~250 km among regions. Dispersal strength declined significantly with distance, with best-fit dispersal kernels estimating median dispersal distances of ~110 km for P. maculatus and ~190 km for P. leopardus. Larval exchange among reefs demonstrates that established reserves form a highly connected network and contribute larvae for the replenishment of fished reefs at multiple spatial scales. Our findings highlight the potential for long-distance dispersal in an important group of reef fishes, and provide further evidence that effectively protected reserves can yield recruitment and sustainability benefits for exploited fish populations.

  18. Digenea trematodes in fish of the North Adriatic Sea

    Directory of Open Access Journals (Sweden)

    Vesna PARADIŽNIK

    2007-12-01

    Full Text Available The paper gives an overview of trematodes that have been isolated from the north Adriatic Sea , during a 10-year research program. A total of 63 marine fish species of pelagic and benthic of the classes Chondrichthyes and Osteichthyes were analyzed. We found that 21 fish species ted digenean trematodes (33.33% prevalence, and 12 fish species are reported as hosts for the t time. During our research, 63 species of fish (total of 2659 fish were examined and 25.16 % e found invaded by endohelminths, belonging to 22 digeneans species.

  19. Pelagic effects of offshore wind farm foundations in the stratified North Sea

    Science.gov (United States)

    Floeter, Jens; van Beusekom, Justus E. E.; Auch, Dominik; Callies, Ulrich; Carpenter, Jeffrey; Dudeck, Tim; Eberle, Sabine; Eckhardt, André; Gloe, Dominik; Hänselmann, Kristin; Hufnagl, Marc; Janßen, Silke; Lenhart, Hermann; Möller, Klas Ove; North, Ryan P.; Pohlmann, Thomas; Riethmüller, Rolf; Schulz, Sabrina; Spreizenbarth, Stefan; Temming, Axel; Walter, Bettina; Zielinski, Oliver; Möllmann, Christian

    2017-08-01

    A recent increase in the construction of Offshore Wind Farms (OWFs) has initiated numerous environmental impact assessments and monitoring programs. These focus on sea mammals, seabirds, benthos or demersal fish, but generally ignore any potential effects OWFs may have on the pelagic ecosystem. The only work on the latter has been through modelling analyses, which predict localised impacts like enhanced vertical mixing leading to a decrease in seasonal stratification, as well as shelf-wide changes of tidal amplitudes. Here we provide for the first-time empirical bio-physical data from an OWF. The data were obtained by towing a remotely operated vehicle (TRIAXUS ROTV) through two non-operating OWFs in the summer stratified North Sea. The undulating TRIAXUS transects provided high-resolution CTD data accompanied by oxygen and chlorophyll-a measurements. We provide empirical indication that vertical mixing is increased within the OWFs, leading to a doming of the thermocline and a subsequent transport of nutrients into the surface mixed layer (SML). Nutrients were taken up rapidly because underwater photosynthetically active radiation (PAR) enabled net primary production in the entire water column, especially within submesoscale chlorophyll-a pillars that were observed at regular intervals within the OWF regions. Video Plankton Recorder (VPR) images revealed distinct meroplankton distribution patterns in a copepod-dominated plankton community. Hydroacoustic records did not show any OWF effects on the distribution of pelagic fish. The results of a pre-OWF survey show however, that it is difficult to fully separate the anthropogenic impacts from the natural variability.

  20. NEFSC Small Pelagics Acoustic/Midwater Trawl Survey (DE0002, EK500)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The small pelagics cruise will map the distribution of small pelagic species such as Atlantic mackerel, Atlantic herring, silver hake, butterfish, and squid, in the...

  1. NEFSC Small Pelagics Acoustic/Midwater Trawl Survey (DE9903, EK500)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The small pelagics cruise will map the distribution of small pelagic species such as Atlantic mackerel, Atlantic herring, silver hake, butterfish, and squid, in the...

  2. NEFSC Small Pelagics Acoustic/Midwater Trawl Survey (DE0201, EK500)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The small pelagics cruise will map the distribution of small pelagic species such as Atlantic mackerel, Atlantic herring, silver hake, butterfish, and squid, in the...

  3. NEFSC Small Pelagics Acoustic/Midwater Trawl Survey (DE0101, EK500)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The small pelagics cruise will map the distribution of small pelagic species such as Atlantic mackerel, Atlantic herring, silver hake, butterfish, and squid, in the...

  4. NEFSC Small Pelagics Acoustic/Midwater Trawl Survey (DE0302, EK500)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The small pelagics cruise will map the distribution of small pelagic species such as Atlantic mackerel, Atlantic herring, silver hake, butterfish, and squid, in the...

  5. Larval fish assemblages across an upwelling front: Indication for active and passive retention

    Science.gov (United States)

    Tiedemann, Maik; Brehmer, Patrice

    2017-03-01

    In upwelling areas, enrichment, concentration and retention are physical processes that have major consequences for larval fish survival. While these processes generally increase larval survival, strong upwelling can also increase mortality due to an offshore transport of larvae towards unfavorable habitats. In 2013 a survey was conducted along the Senegalese coast to investigate the upwelling effect with regard to larval fish assemblages and possible larval fish retention. According to water column characteristics two distinct habitats during an upwelling event were discriminated, i.e. the inshore upwelled water and the transition area over the deepest part of the Senegalese shelf. Along the two areas 42,162 fish larvae were collected representing 133 species within 40 families. Highest larval fish abundances were observed in the inshore area and decreasing abundances towards the transition, indicating that certain fish species make use of the retentive function of the inner shelf area as spawning grounds. Two larval fish assemblages overlap both habitats, which are sharply delimited by a strong upwelling front. One assemblage inhabited the inshore/upwelling area characterized by majorly neritic and pelagic species (Sparidae spp., Sardinella aurita), that seem to take the advantage of a passive retention on the shelf. The second assemblage consisted of a mix of pelagic and mesopelagic species (Engraulis encrasicolus, Carangidae spp. and Myctophidae spp.). Some species of the second assemblage, e.g. horse mackerels (Trachurus trachurus and Trachurus trecae), large finned-lantern fish (Hygophum macrochir) and foureyed sole (Microchirus ocellatus), revealed larval peak occurrences at intermediate and deep water layers, where the near-ground upwelling layer is able to transport larvae back to the shelf. This indicates active larval retention for species that are dominant in the transition area. Diel vertical migration patterns of S. aurita, E. encrasicolus and M

  6. Phylogeny-function analysis of (meta)genomic libraries: screening for expression of ribosomal RNA genes by large-insert library fluorescent in situ hybridization (LIL-FISH).

    Science.gov (United States)

    Leveau, Johan H J; Gerards, Saskia; de Boer, Wietse; van Veen, Johannes A

    2004-09-01

    We assessed the utility of fluorescent in situ hybridization (FISH) in the screening of clone libraries of (meta)genomic or environmental DNA for the presence and expression of bacterial ribosomal RNA (rRNA) genes. To establish proof-of-principle, we constructed a fosmid-based library in Escherichia coli of large-sized genomic DNA fragments of the mycophagous soil bacterium Collimonas fungivorans, and hybridized 768 library clones with the Collimonas-specific fluorescent probe CTE998-1015. Critical to the success of this approach (which we refer to as large-insert library FISH or LIL-FISH) was the ability to induce fosmid copy number, the exponential growth status of library clones in the FISH assay and the use of a simple pooling strategy to reduce the number of hybridizations. Twelve out of 768 E. coli clones were suspected to harbour and express Collimonas 16S rRNA genes based on their hybridization to CTE998-1015. This was confirmed by the finding that all 12 clones were also identified in an independent polymerase chain reaction-based screening of the same 768 clones using a primer set for the specific detection of Collimonas 16S ribosomal DNA (rDNA). Fosmids isolated from these clones were grouped by restriction analysis into two distinct contigs, confirming that C. fungivorans harbours at least two 16S rRNA genes. For one contig, representing 1-2% of the genome, the nucleotide sequence was determined, providing us with a narrow but informative view of Collimonas genome structure and content.

  7. Fishing amplifies forage fish population collapses.

    Science.gov (United States)

    Essington, Timothy E; Moriarty, Pamela E; Froehlich, Halley E; Hodgson, Emma E; Koehn, Laura E; Oken, Kiva L; Siple, Margaret C; Stawitz, Christine C

    2015-05-26

    Forage fish support the largest fisheries in the world but also play key roles in marine food webs by transferring energy from plankton to upper trophic-level predators, such as large fish, seabirds, and marine mammals. Fishing can, thereby, have far reaching consequences on marine food webs unless safeguards are in place to avoid depleting forage fish to dangerously low levels, where dependent predators are most vulnerable. However, disentangling the contributions of fishing vs. natural processes on population dynamics has been difficult because of the sensitivity of these stocks to environmental conditions. Here, we overcome this difficulty by collating population time series for forage fish populations that account for nearly two-thirds of global catch of forage fish to identify the fingerprint of fisheries on their population dynamics. Forage fish population collapses shared a set of common and unique characteristics: high fishing pressure for several years before collapse, a sharp drop in natural population productivity, and a lagged response to reduce fishing pressure. Lagged response to natural productivity declines can sharply amplify the magnitude of naturally occurring population fluctuations. Finally, we show that the magnitude and frequency of collapses are greater than expected from natural productivity characteristics and therefore, likely attributed to fishing. The durations of collapses, however, were not different from those expected based on natural productivity shifts. A risk-based management scheme that reduces fishing when populations become scarce would protect forage fish and their predators from collapse with little effect on long-term average catches.

  8. Pinging down the food web: multi-frequency acoustic discrimination of jellyfish and fish

    OpenAIRE

    Christopher P Lynam; Brierley, Andrew S.; Axelsen, Bjørn Erik

    2004-01-01

    Jellyfish are gaining increasing prominence in many pelagic marine ecosystems worldwide. It has been argued that jellyfish-dominated communities will be the end-point in ecosystems perturbed by high fishing effort, and that increases in jellyfish abundance could be indicative of, and consequences of, climate-induced changes and/or regime shifts in pelagic ecosystems. Jellyfish are difficult to sample using conventional netting techniques, and data on changes in distribution and abundance are ...

  9. Novel Acoustic Techniques for Assessing Fish Schooling in the Context of an Operational Ocean Observatory

    Science.gov (United States)

    2008-09-30

    and onshore waters. A unique acoustic scattering source was identified during the experiment as dense, monotypic aggregations of a pelagic gastropod ...can often reveal hidden coherent structure. IMPACT/ APPLICATIONS The distribution of fish and the variability in their distribution has...direct and waveguide scattering for application to fish. REFERENCES Pitcher, T. J., and J. K. Parrish. 1993. Function of shoaling behavior in teleosts

  10. Marine foraging and annual fish consumption of a south polar Skua population in the maritime Antarctic

    NARCIS (Netherlands)

    Hahn, S.M.; Ritz, M.S.; Reinhardt, K.

    2008-01-01

    Pelagic fish are an important component of Antarctic food webs but few quantitative data exist on energy transfer from fish to seabirds for the Seasonal Pack-ice Zone. We studied a local population of south polar, skuas Catharacta maccormicki during a whole breeding cycle and estimated its entire

  11. Structure and seasonal variability of fish food webs in an estuarine tropical marine protected area (Senegal): Evidence from stable isotope analysis

    Science.gov (United States)

    Faye, Djibril; Tito de Morais, Luis; Raffray, Jean; Sadio, Oumar; Thiaw, Omar Thiom; Le Loc'h, François

    2011-05-01

    West African tropical estuaries play an important role in the growth and survival of many commercially exploited fish species and enable the sustainability of considerable artisanal fishery yields. However, their trophic functioning remains poorly understood. In the Sine Saloum estuary (Senegal), a marine protected area (MPAs) was designated in 2003 to manage fisheries resources. The present study aimed to determine the structure, trophic functioning and seasonal patterns of the fish assemblages in this MPA. Throughout the study, 28 fish species were collected, with higher values of biomass (3826 kg km -2) recorded during the wet season and lower values during the dry season (1228 kg km -2). Fish assemblages in both seasons were dominated by species with marine affinity, which accounted for 87% of the total biomass in the wet season and 70% in the dry season, with their abundance varying from 83% to 57%, respectively. Based on stable isotopic composition (δ 13C and δ 15N), species were combined into trophic groups. Primary consumers were partitioned into suspensivores (pelagic copepods, oysters and mussels), which fed mainly on particulate organic matter, and intermediate consumers, feeding on freshly deposited organic matter and benthic microalgae ( Sarotherodon melanotheron and Arca senilis). Secondary consumers were divided into three groups. The first group included mullet, which fed by grazing on benthic microalgae (benthic affinity feeders). The second group, pelagic affinity feeders, was the most heterogeneous and fed mainly on pelagic components. The last secondary consumer group termed the intermediate group, included piscivores and benthic and pelagic invertebrate feeders, which dominated the top of the food web. The food chain in October was lengthened due to the occurrence of tertiary consumers. Food webs were dominated by secondary consumers, which constituted 89% of total biomass in the dry season and 71% in the wet season. The fish food web varied

  12. Hierarchical stochastic modeling of large river ecosystems and fish growth across spatio-temporal scales and climate models: the Missouri River endangered pallid sturgeon example

    Science.gov (United States)

    Wildhaber, Mark L.; Wikle, Christopher K.; Moran, Edward H.; Anderson, Christopher J.; Franz, Kristie J.; Dey, Rima

    2017-01-01

    We present a hierarchical series of spatially decreasing and temporally increasing models to evaluate the uncertainty in the atmosphere – ocean global climate model (AOGCM) and the regional climate model (RCM) relative to the uncertainty in the somatic growth of the endangered pallid sturgeon (Scaphirhynchus albus). For effects on fish populations of riverine ecosystems, cli- mate output simulated by coarse-resolution AOGCMs and RCMs must be downscaled to basins to river hydrology to population response. One needs to transfer the information from these climate simulations down to the individual scale in a way that minimizes extrapolation and can account for spatio-temporal variability in the intervening stages. The goal is a framework to determine whether, given uncertainties in the climate models and the biological response, meaningful inference can still be made. The non-linear downscaling of climate information to the river scale requires that one realistically account for spatial and temporal variability across scale. Our down- scaling procedure includes the use of fixed/calibrated hydrological flow and temperature models coupled with a stochastically parameterized sturgeon bioenergetics model. We show that, although there is a large amount of uncertainty associated with both the climate model output and the fish growth process, one can establish significant differences in fish growth distributions between models, and between future and current climates for a given model.

  13. Characterizing driver-response relationships in marine pelagic ecosystems for improved ocean management.

    Science.gov (United States)

    Hunsicker, Mary E; Kappel, Carrie V; Selkoe, Kimberly A; Halpern, Benjamin S; Scarborough, Courtney; Mease, Lindley; Amrhein, Alisan

    2016-04-01

    Scientists and resource managers often use methods and tools that assume ecosystem components respond linearly to environmental drivers and human stressors. However, a growing body of literature demonstrates that many relationships are-non-linear, where small changes in a driver prompt a disproportionately large ecological response. We aim to provide a comprehensive assessment of the relationships between drivers and ecosystem components to identify where and when non-linearities are likely to occur. We focused our analyses on one of the best-studied marine systems, pelagic ecosystems, which allowed us to apply robust statistical techniques on a large pool of previously published studies. In this synthesis, we (1) conduct a wide literature review on single driver-response relationships in pelagic systems, (2) use statistical models to identify the degree of non-linearity in these relationships, and (3) assess whether general patterns exist in the strengths and shapes of non-linear relationships across drivers. Overall we found that non-linearities are common in pelagic ecosystems, comprising at least 52% of all driver-response relation- ships. This is likely an underestimate, as papers with higher quality data and analytical approaches reported non-linear relationships at a higher frequency (on average 11% more). Consequently, in the absence of evidence for a linear relationship, it is safer to assume a relationship is non-linear. Strong non-linearities can lead to greater ecological and socioeconomic consequences if they are unknown (and/or unanticipated), but if known they may provide clear thresholds to inform management targets. In pelagic systems, strongly non-linear relationships are often driven by climate and trophodynamic variables but are also associated with local stressors, such as overfishing and pollution, that can be more easily controlled by managers. Even when marine resource managers cannot influence ecosystem change, they can use information

  14. The comparative feeding ecology of temperate and tropical deep-sea fishes from the western North Atlantic

    Science.gov (United States)

    Crabtree, R. E.; Carter, J.; Musick, J. A.

    1991-10-01

    A study of the feeding habits of 32 species of fishes from the continental slope, rise, and abyss of temperate and tropical regions of the western North Atlantic was conducted to ascertain if regional faunal differences were related to differences in trophic structure. Fishes consumed a wide variety of benthic and pelagic prey and appear to have diets comparable to their counterparts on the continental shelf. Commonly occurring small to moderate sized species fed predominately on small crustaceans and polychaetes, while less common large-bodied species igested decapods and teleosts and displayed ontogenetic shifts in diets. In some cases, presence or absence of a particular taxon from the respective areas appears related to food availability, although no single causal factor adequately explains all of the observed faunal differences.

  15. Anguilliform fish reveal large scale contamination by mine trace elements in the coral reefs of New Caledonia.

    Science.gov (United States)

    Bonnet, Xavier; Briand, Marine J; Brischoux, François; Letourneur, Yves; Fauvel, Thomas; Bustamante, Paco

    2014-02-01

    Due to intensive mining activity, increasing urbanization and industrialization, vast amounts of contaminants are discharged into the lagoon of New Caledonia, one of the largest continuous coral reef systems and a major biodiversity hotspot. The levels of 11 trace element concentrations were examined in the muscles of predator fish in the south-western lagoon (moray eels and congers). These species are sedentary, widespread, abundant, and they are easily collected using a sea snake sampling technique. We found the highest mean and maximal concentrations of different trace elements ever found in coral fish, notably regarding trace elements typical from mining activity (e.g., mean values for Cr and Ni, respectively: 5.53 ± 6.99 μg g(-1) [max, 35.7 μg g(-1)] and 2.84 ± 3.38 μg g(-1) [max, 18.0 μg g(-1)]). Results show that important trace element contamination extends throughout the lagoon to the barrier reef, following a concentration gradient from the oldest nickel factory (Nouméa).

  16. Seasonal Variations in the Use of Profundal Habitat among Freshwater Fishes in Lake Norsjø, Southern Norway, and Subsequent Effects on Fish Mercury Concentrations

    Directory of Open Access Journals (Sweden)

    Tom Robin Olk

    2016-11-01

    Full Text Available This study is based on monthly sampling of fish from grates mounted at an industrial water intake, located at a depth of 50 m in Lake Norsjø (Southern Norway during the year 2014, to investigate seasonal variations in the use of the profundal habitat and subsequent variations in total Hg-concentrations in profundal fish. Data on various fish present in a cold and dark hypolimnion of a large, deep, dimictic lake within the upper temperate zone of the Northern Hemisphere are rare. While predominant species such as A. charr (Salvelinus alpinus and E. smelt (Osmerus eperlanus were continuously present in this habitat, whitefish (Coregonus lavaretus occupied this habitat primarily during wintertime, while other common species like brown trout (Salmo trutta, perch (Perca fluviatilis and northern pike (Esox lucius were almost absent. Besides stomach analyses (diet and biometry, stable isotope analyses (δ15N and δ13C and total mercury (Tot-Hg analyses were carried out on the caught fish. The δ13C signature and stomach analyses revealed a combined profundal-pelagic diet for all three species, A. charr with the most profundal-based diet. Length was the strongest predictor for Hg in whitefish and A. charr, while age was the strongest explanatory variable for Hg in E. smelt. A. charr was the only species exhibiting seasonal variation in Hg, highest during winter and spring.

  17. FISH mapping of a human chromosome 16 constitutional pericentric inversion inv(16)(p13q22) found in a large kindred

    Energy Technology Data Exchange (ETDEWEB)

    Stallings, R.L. [Univ. of Pittsburgh, PA (United States); Bianchi, D.W. [Tufts Univ. School of Medicine, Boston, MA (United States)

    1994-09-01

    Fluorescence in situ hybridization analysis (FISH) was used to map the constitutional chromosome 16 pericentric inversion breakpoints inv(16)(p13q22) detected in one individual (II-2) from a large kindred. The breakpoints found in individual II-2 mapped to distinctly different locations than the chromosome 16 pericentric inversion breakpoints commonly acquired in acute nonlymphocytic leukemia. The constitutional pericentric inversion breakpoints also do not map to regions where low abundance repetitive DNA sequences found in bands 16p13 and q22 are located. The results indicate that low abundance, chromosome 16-specific repetitive DNA sequences in bands p13 and q22 are probably not causally related to the inversion that is found in many members of a large kindred. 9 refs., 1 fig.

  18. [Evaluation of Antilles fish ciguatoxicity by mouse and chick bioassays].

    Science.gov (United States)

    Pottier, I; Vernoux, J P

    2003-03-01

    Ciguatera is a common seafood poisoning in Western Atlantic and French West Indies. Ciguatera fish poisoning in the Caribbean is a public health problem. A toxicological study was carried out on 178 Caribbean fish specimens (26 species) captured off Guadeloupe and Saint Barthelemy between 1993 and 1999. The mouse bioassay and the chick feeding test were used to control fish edibility. Ciguatoxins presence was assumed when symptomatology was typical of ciguatera in mouse and chick. Fishes were classified in three groups: non toxic fish (edible), low toxic fish (not edible) and toxic fish (not edible). 75% of fishes were non toxic. Toxic fish specimens belonged to four families of high trophic level carnivores: Carangidae, Lutjanidae, Serranidae et Sphyraenidae. Percentages of toxic fishes to humans reached 55% for Caranx latus and 33% for Caranx bartholomaei and Caranx lugubris. Only a significant correlation between weight and toxicity was only found for C. latus and snappers. Small carnivorous groupers (Serranidae) were also toxic. Atoxic fish species were (a) pelagic fish (Coryphaena hippurus, Auxis thazard and Euthynnus pelamis), (b) invertebrates feeders (Malacanthus plumieri, Balistes vetula), (c) small high-risk fish or (d) fish of edible benthic fish families. Liver of four fishes (Mycteroperca venenosa, Caranx bartholomaei, Seriola rivoliana, Gymnothorax funebris) contained ciguatoxins at a significant level although their flesh was safe. This study confirms the usefulness of mouse and chick bioassays for sanitary control of fish.

  19. Stable isotope analysis of vertebrae reveals ontogenetic changes in habitat in an endothermic pelagic shark.

    Science.gov (United States)

    Carlisle, Aaron B; Goldman, Kenneth J; Litvin, Steven Y; Madigan, Daniel J; Bigman, Jennifer S; Swithenbank, Alan M; Kline, Thomas C; Block, Barbara A

    2015-01-22

    Ontogenetic changes in habitat are driven by shifting life-history requirements and play an important role in population dynamics. However, large portions of the life history of many pelagic species are still poorly understood or unknown. We used a novel combination of stable isotope analysis of vertebral annuli, Bayesian mixing models, isoscapes and electronic tag data to reconstruct ontogenetic patterns of habitat and resource use in a pelagic apex predator, the salmon shark (Lamna ditropis). Results identified the North Pacific Transition Zone as the major nursery area for salmon sharks and revealed an ontogenetic shift around the age of maturity from oceanic to increased use of neritic habitats. The nursery habitat may reflect trade-offs between prey availability, predation pressure and thermal constraints on juvenile endothermic sharks. The ontogenetic shift in habitat coincided with a reduction of isotopic niche, possibly reflecting specialization upon particular prey or habitats. Using tagging data to inform Bayesian isotopic mixing models revealed that adult sharks primarily use neritic habitats of Alaska yet receive a trophic subsidy from oceanic habitats. Integrating the multiple methods used here provides a powerful approach to retrospectively study the ecology and life history of migratory species throughout their ontogeny.

  20. Chasing after Non-cyanobacterial Nitrogen Fixation in Marine Pelagic Environments

    Directory of Open Access Journals (Sweden)

    Pia H. Moisander

    2017-09-01

    Full Text Available Traditionally, cyanobacterial activity in oceanic photic layers was considered responsible for the marine pelagic dinitrogen (N2 fixation. Other potentially N2-fixing bacteria and archaea have also been detected in the pelagic water column, however, the activity and importance of these non-cyanobacterial diazotrophs (NCDs remain poorly constrained. In this perspective we summarize the N2 fixation rates from recently published studies on photic and aphotic layers that have been attributed to NCD activity via parallel molecular measurements, and discuss the status, challenges, and data gaps in estimating non-cyanobacterial N2 fixation NCNF in the ocean. Rates attributed to NCNF have generally been near the detection limit thus far (<1 nmol N L−1 d−1. Yet, if considering the large volume of the dark ocean, even low rates of NCNF could make a significant contribution to the new nitrogen input to the ocean. The synthesis here shows that nifH transcription data for NCDs have been reported in only a few studies where N2 fixation rates were detected in the absence of diazotrophic cyanobacteria. In addition, high apparent diversity and regional variability in the NCDs complicate investigations of these communities. Future studies should focus on further investigating impacts of environmental drivers including oxygen, dissolved organic matter, and dissolved inorganic nitrogen on NCNF. Describing the ecology of NCDs and accurately measuring NCNF rates, are critical for a future evaluation of the contribution of NCNF to the marine nitrogen budget.

  1. Variation in brain organization of coral reef fish larvae according to life history traits.

    Science.gov (United States)

    Lecchini, David; Lecellier, Gael; Lanyon, Rynae Greta; Holles, Sophie; Poucet, Bruno; Duran, Emilio

    2014-01-01

    In coral reefs, one of the great mysteries of teleost fish ecology is how larvae locate the relatively rare patches of habitat to which they recruit. The recruitment of fish larvae to a reef, after a pelagic phase lasting between 10 and 120 days, depends strongly on larval ability to swim and detect predators, prey and suitable habitat via sensory cues. However, no information is available about the relationship between brain organization in fish larvae and their sensory and swimming abilities at recruitment. For the first time, we explore the structural diversity of brain organization (comparative sizes of brain subdivisions: telencephalon, mesencephalon, cerebellum, vagal lobe and inferior lobe) among larvae of 25 coral reef fish species. We then investigate links between variation in brain organization and life history traits (swimming ability, pelagic larval duration, social behavior, diel activity and cue use relying on sensory perception). After accounting for phylogeny with independent contrasts, we found that brain organization covaried with some life history traits: (1) fish larvae with good swimming ability (>20 cm/s), a long pelagic duration (>30 days), diurnal activity and strong use of cues relying on sensory perception for detection of recruitment habitat had a larger cerebellum than other species. (2) Fish larvae with a short pelagic duration (fish larvae exhibiting solitary behavior during their oceanic phase had larger inferior and vagal lobes. Overall, we hypothesize that a well-developed cerebellum may allow fish larvae to improve their chances of successful recruitment after a long pelagic phase in the ocean. Our study is the first one to bring together quantitative information on brain organization and the relative development of major brain subdivisions across coral reef fish larvae, and more specifically to address the way in which this variation correlates with the recruitment process.

  2. Molecular cytogenetic identification and characterization of Robertsonian chromosomes in the large Japanese field mouse (Apodemus speciosus) using FISH.

    Science.gov (United States)

    Yamagishi, Manabu; Matsubara, Kazumi; Sakaizumi, Mitsuru

    2012-10-01

    Robertsonian (Rb) karyotypic polymorphism in Apodemus speciosus has interested many researchers with particular referece to the genetic divergence between Rb and non-Rb populations. Failure to find morphologic, biochemical, or genetic differences in previous studies reveals the necessity of focusing on loci on Rb chromosomes, which can be characterized by FISH mapping with DNA probes. In an Rb heterozygote, DNA probes from laboratory mouse chromosomes (MMUs) 1 and 10 were simultaneously hybridized to the long arm of a metacentric and a medium-sized acrocentric chromosome and to the short arm of the metacentric and a small acrocentric chromosome, respectively. Four additional probes derived from each of MMUs 1 and 10 were mapped to the long and short arms, respectively, of the Rb chromosome identified by the above markers. Homologies between the long arm of the Rb chromosome and MMU 1 and between the short arm and MMU 10 were supported by all ten markers, which were dispersed along nearly the entire lengths of the Rb chromosomes. These results indicate that the long and short arms of the Rb chromosomes are homologous to Apodemus speciosus chromosomes 12 and 19 (defined in a previous study), respectively. This ten-marker series can be useful for detecting chromosome-specific divergence between the two karyotypic populations at the gene level.

  3. Composition and interrelationships of a large Neotropical freshwater fish group, the subfamily Cheirodontinae (Characiformes: Characidae): a case study based on mitochondrial and nuclear DNA sequences.

    Science.gov (United States)

    Mariguela, T C; Ortí, G; Avelino, G S; Abe, K T; Oliveira, C

    2013-07-01

    Characidae is the most species-rich family of freshwater fishes in the order Characiformes, with more than 1000 valid species that correspond to approximately 55% of the order. Few hypotheses about the composition and internal relationships within this family are available and most fail to reach an agreement. Among Characidae, Cheirodontinae is an emblematic group that includes 18 genera (1 fossil) and approximately 60 described species distributed throughout the Neotropical region. The taxonomic and systematic history of Cheirodontinae is complex, and only two hypotheses about the internal relationships in this subfamily have been reported to date. In the present study, we test the composition and relationships of fishes assigned to Cheirodontinae based on a broad taxonomic sample that also includes some characid incertae sedis taxa that were previously considered to be part of Cheirodontinae. We present phylogenetic analyses of a large molecular dataset of mitochondrial and nuclear DNA sequences. Our results reject the monophyly of Cheirodontinae as previously conceived, as well as the tribes Cheirodontini and Compsurini, and the genera Cheirodon, Compsura, Leptagoniates, Macropsobrycon, Odontostilbe, and Serrapinnus. On the basis of these results we propose: (1) the exclusion of Amazonspinther and Spintherobolus from the subfamily Cheirodontinae since they are the sister-group of all remaining Characidae; (2) the removal of Macropsobrycon xinguensis of the genus Macropsobrycon; (3) the removal of Leptagoniates pi of the genus Leptagoniates; (4) the inclusion of Leptagoniates pi in the subfamily Cheirodontinae; (5) the removal of Cheirodon stenodon of the genus Cheirodon and its inclusion in the subfamily Cheirodontinae under a new genus name; (6) the need to revise the polyphyletic genera Compsura, Odontostilbe, and Serrapinnus; and (7) the division of Cheirodontinae in three newly defined monophyletic tribes: Cheirodontini, Compsurini, and Pseudocheirodontini

  4. Fish Allergy

    Science.gov (United States)

    ... Old Feeding Your 1- to 2-Year-Old Fish Allergy KidsHealth > For Parents > Fish Allergy Print A ... From Home en español Alergia al pescado About Fish Allergy A fish allergy is not exactly the ...

  5. Flat and complex temperate reefs provide similar support for fish: Evidence for a unimodal species-habitat relationship.

    Science.gov (United States)

    Paxton, Avery B; Pickering, Emily A; Adler, Alyssa M; Taylor, J Christopher; Peterson, Charles H

    2017-01-01

    Structural complexity, a form of habitat heterogeneity, influences the structure and function of ecological communities, generally supporting increased species density, richness, and diversity. Recent research, however, suggests the most complex habitats may not harbor the highest density of individuals and number of species, especially in areas with elevated human influence. Understanding nuances in relationships between habitat heterogeneity and ecological communities is warranted to guide habitat-focused conservation and management efforts. We conducted fish and structural habitat surveys of thirty warm-temperate reefs on the southeastern US continental shelf to quantify how structural complexity influences fish communities. We found that intermediate complexity maximizes fish abundance on natural and artificial reefs, as well as species richness on natural reefs, challenging the current paradigm that abundance and other fish community metrics increase with increasing complexity. Naturally occurring rocky reefs of flat and complex morphologies supported equivalent abundance, biomass, species richness, and community composition of fishes. For flat and complex morphologies of rocky reefs to receive equal consideration as essential fish habitat (EFH), special attention should be given to detecting pavement type rocky reefs because their ephemeral nature makes them difficult to detect with typical seafloor mapping methods. Artificial reefs of intermediate complexity also maximized fish abundance, but human-made structures composed of low-lying concrete and metal ships differed in community types, with less complex, concrete structures supporting lower numbers of fishes classified largely as demersal species and metal ships protruding into the water column harboring higher numbers of fishes, including more pelagic species. Results of this study are essential to the process of evaluating habitat function provided by different types and shapes of reefs on the seafloor

  6. Pike ( Esox lucius L.) stocking as a biomanipulation tool .1. Effects on the fish population in Lake Lyng, Denmark

    DEFF Research Database (Denmark)

    Berg, Søren; Jeppesen, E.; Søndergaard, M.

    1997-01-01

    relationship between stocking density of pike in May or June and the abundance of juvenile planktivorous fish (r(2) = 0.85, p littoral zone in August. No relationship was found in the pelagic zone (r(2) = 0.21, p > 0.4). Pike survival was low in late August/early September. We suggest that growth...... of the piscivorous perch increased due to increased Secchi depth and a continuous high density of 0+ planktivores in the pelagic zone of the lake during the years of pike stocking, possibly caused by behaviourial changes and the forcing of the 0+ planktivores into the pelagic zone...

  7. The fishing and natural mortality of large, piscivorous Bull Trout and Rainbow Trout in Kootenay Lake, British Columbia (2008–2013

    Directory of Open Access Journals (Sweden)

    Joseph L. Thorley

    2017-01-01

    Full Text Available Background Estimates of fishing and natural mortality are important for understanding, and ultimately managing, commercial and recreational fisheries. High reward tags with fixed station acoustic telemetry provides a promising approach to monitoring mortality rates in large lake recreational fisheries. Kootenay Lake is a large lake which supports an important recreational fishery for large Bull Trout and Rainbow Trout. Methods Between 2008 and 2013, 88 large (≥500 mm Bull Trout and 149 large (≥500 mm Rainbow Trout were marked with an acoustic transmitter and/or high reward ($100 anchor tags in Kootenay Lake. The subsequent detections and angler recaptures were analysed using a Bayesian individual state-space Cormack–Jolly–Seber (CJS survival model with indicator variable selection. Results The final CJS survival model estimated that the annual interval probability of being recaptured by an angler was 0.17 (95% CRI [0.11–0.23] for Bull Trout and 0.14 (95% CRI [0.09–0.19] for Rainbow Trout. The annual interval survival probability for Bull Trout was estimated to have declined from 0.91 (95% CRI [0.76–0.97] in 2009 to just 0.46 (95% CRI [0.24–0.76] in 2013. Rainbow Trout survival was most strongly affected by spawning. The annual interval survival probability was 0.77 (95% CRI [0.68–0.85] for a non-spawning Rainbow Trout compared to 0.41 (95% CRI [0.30–0.53] for a spawner. The probability of spawning increased with the fork length for both species and decreased over the course of the study for Rainbow Trout. Discussion Fishing mortality was relatively low and constant while natural mortality was relatively high and variable. The results indicate that angler effort is not the primary driver of short-term population fluctations in the Rainbow Trout abundance. Variation in the probability of Rainbow Trout spawning suggests that the spring escapement at the outflow of Trout Lake may be a less reliable index of abundance than

  8. Drifting algae and fish: Implications of tropical Sargassum invasion due to ocean warming in western Japan

    Science.gov (United States)

    Yamasaki, Mami; Aono, Mikina; Ogawa, Naoto; Tanaka, Koichiro; Imoto, Zenji; Nakamura, Yohei

    2014-06-01

    Evidence is accumulating that the invasion and extinction of habitat-forming seaweed species alters coastal community structure and ecological services, but their effects on the pelagic environment have been largely ignored. Thus, we examined the seasonal occurrence patterns of indigenous temperate and invasive tropical drifting algae and associated fish species every month for 2 years (2009-2011) in western Japan (Tosa Bay), where a rapid shift from temperate to tropical Sargassum species has been occurring in the coastal area since the late 1980s due to rising seawater temperatures. Of the 19 Sargassum species (31.6%) in drifting algae, we found that six were tropical species, whereas a study in the early 1980s found only one tropical species among 12 species (8.3%), thereby suggesting an increase in the proportion of tropical Sargassum species in drifting algae during the last 30 years. Drifting temperate algae were abundantly present from late winter to summer, whereas tropical algal clumps occurred primarily during summer. In the warm season, fish assemblages did not differ significantly between drifting temperate and tropical algae, suggesting the low host-algal specificity of most fishes. We also found that yellowtail juveniles frequently aggregated with drifting temperate algae from late winter to spring when drifting tropical algae were unavailable. Local fishermen collect these juveniles for use as aquaculture seed stock; therefore, the occurrence of drifting temperate algae in early spring is important for local fisheries. These results suggest that the further extinction of temperate Sargassum spp. may have negative impacts on the pelagic ecosystem and associated regional fisheries.

  9. Age- and size-dependent mating performance and fertility in a pelagic copepod, Temora longicornis

    DEFF Research Database (Denmark)

    Sichlau, Mie Hylstofte; Kiørboe, Thomas

    2011-01-01

    Prepress abstract: In many species, size and age have been shown to be strong determinants of the reproductive success for both sexes. Here we examine age- and size dependent reproductive performance (egg- and sperm production, mating success) in a pelagic copepod. Compared to smaller males, larger...... males produce larger spermatophores containing more spermatozoa, and fertilize a larger fraction of available females. Females mating with large males produce more offspring than those mating with small males. Similarly, large females have higher egg production rates as well as a higher life-time egg...... production than small females. Ageing effects are evident in this species: Mortality rate increases and fertility decreases rapidly with age. The average adult longevity under optimal laboratory conditions was 30 days in both males and females, but females produce eggs for only 18 days, and males can...

  10. Responses of mesopelagic fish assemblages to environmental disturbance: ocean deoxygenation and oceanic fronts

    OpenAIRE

    Netburn, Amanda Nicole

    2016-01-01

    Throughout the global ocean, there is an abundant and diverse assemblage of fishes aggregated at mesopelagic (200-1000 m) depths. These fishes are critical to pelagic food webs and carbon transport. In the southern California Current Ecosystem, with naturally hypoxic mesopelagic waters, mesopelagic fishes may be vulnerable to predicted ocean deoxygenation. Additionally, water property discontinuities at oceanic fronts can disproportionately affect abundance, compositions, and reproduction o...

  11. Born small, die young: Intrinsic, size-selective mortality in marine larval fish

    KAUST Repository

    Garrido, S.

    2015-11-24

    Mortality during the early stages is a major cause of the natural variations in the size and recruitment strength of marine fish populations. In this study, the relation between the size-at-hatch and early survival was assessed using laboratory experiments and on field-caught larvae of the European sardine (Sardina pilchardus). Larval size-at-hatch was not related to the egg size but was significantly, positively related to the diameter of the otolith-at-hatch. Otolith diameter-at-hatch was also significantly correlated with survival-at-age in fed and unfed larvae in the laboratory. For sardine larvae collected in the Bay of Biscay during the spring of 2008, otolith radius-at-hatch was also significantly related to viability. Larval mortality has frequently been related to adverse environmental conditions and intrinsic factors affecting feeding ability and vulnerability to predators. Our study offers evidence indicating that a significant portion of fish mortality occurs during the endogenous (yolk) and mixed (yolk /prey) feeding period in the absence of predators, revealing that marine fish with high fecundity, such as small pelagics, can spawn a relatively large amount of eggs resulting in small larvae with no chances to survive. Our findings help to better understand the mass mortalities occurring at early stages of marine fish.

  12. A Study of the Pelagic Larval Duration of Acropora humilis, Coral Recruitment and Connectivity in the Saudi Arabian Red Sea

    KAUST Repository

    Khalil, Maha

    2011-12-12

    Combined knowledge of the pelagic larval duration of coral species and coral recruitment patterns can provide evidence of inter-reef connectivity and indicate a reef’s ability to recover. We attempted to determine the maximum pelagic larval duration of Acropora humilis. Larvae were reared in a controlled environment unfavorable for settlement. The larvae lived in a pelagic state for a maximum of 29 days, although this is probably an underestimate of actual longevity for this species. Given the information available from the literature with respect to larval dispersal rates, it is not expected that larvae with this longevity will disperse further than 10-20 km from their natal reef, if at all. A long-term recruitment monitoring project was also set up on Abu Shosha Reef, which suffered nearly complete coral loss due to a bleaching event in summer of 2010. In April 2011, 60 settlement plates were placed on the reef. In July, a total of 102 living scleractinian recruits were counted on the plates. While pocilloporids were the most dominant recruits on the reef (57.8%), about 20.6% of living recruits belonged to Acroporidae, a family whose live cover on the reef is extremely low (0.67%). However, the overall mean density of recruits was very low (1.7 living recruits/100cm2) compared to similar studies around the world despite the spawning season having just ended. Fish surveys showed herbivore biomass to be very low compared to other reef systems in the world, but densities were significantly higher than another reef in the Red Sea with about 10 times more live coral cover. Recovery from bleaching for Abu Shosha and similar reefs in the region may be very slow relative to rates observed in other parts of the world if recruitment rates and herbivore communities remain low.

  13. Effects of littoral habitat complexity and sunfish composition on fish production

    Science.gov (United States)

    Carey, M.P.; Maloney, K.O.; Chipps, S.R.; Wahl, David H.

    2010-01-01

    Habitat complexity is a key driver of food web dynamics because physical structure dictates resource availability to a community. Changes in fish diversity can also alter trophic interactions and energy pathways in food webs. Few studies have examined the direct, indirect, and interactive effects of biodiversity and habitat complexity on fish production. We explored the effects of habitat complexity (simulated vegetation), sunfish diversity (intra- vs. inter-specific sunfish), and their interaction using a mesocosm experiment. Total fish production was examined across two levels of habitat complexity (low: 161 strands m-2 and high: 714 strands m-2) and two sunfish diversity treatments: bluegill only (Lepomis macrochirus) and bluegill, redear sunfish (Lepomis microlophus), and green sunfish (Lepomis cyanellus) combination. We also measured changes in total phosphorus, phytoplankton, periphyton, and invertebrates to explain patterns in fish production. Bluegill and total fish production were unaffected by the sunfish treatments. Habitat complexity had a large influence on food web structure by shifting primary productivity from pelagic to a more littoral pathway in the high habitat treatments. Periphyton was higher with dense vegetation, leading to reductions in total phosphorus, phytoplankton, cladoceran abundance and fish biomass. In tanks with low vegetation, bluegill exhibited increased growth. Habitat complexity can alter energy flow through food webs ultimately influencing higher trophic levels. The lack of an effect of sunfish diversity on fish production does not imply that conserving biodiversity is unimportant; rather, we suggest that understanding the context in which biodiversity is important to food web dynamics is critical to conservation planning. ?? 2010 John Wiley & Sons A/S.

  14. Seabird bycatch in pelagic longline fisheries is grossly underestimated when using only haul data.

    Directory of Open Access Journals (Sweden)

    Nigel Brothers

    Full Text Available Hundreds of thousands of seabirds are killed each year as bycatch in longline fisheries. Seabirds are predominantly caught during line setting but bycatch is generally recorded during line hauling, many hours after birds are caught. Bird loss during this interval may lead to inaccurate bycatch information. In this 15 year study, seabird bycatch was recorded during both line setting and line hauling from four fishing regions: Indian Ocean, Southern Ocean, Coral Sea and central Pacific Ocean. Over 43,000 albatrosses, petrels and skuas representing over 25 species were counted during line setting of which almost 6,000 seabirds attempted to take the bait. Bait-taking interactions were placed into one of four categories. (i The majority (57% of bait-taking attempts were "unsuccessful" involving seabirds that did not take the bait nor get caught or hooked. (ii One-third of attempts were "successful" with seabirds removing the bait while not getting caught. (iii One-hundred and seventy-six seabirds (3% of attempts were observed being "caught" during line setting, with three albatross species - Laysan (Phoebastria immutabilis, black-footed (P. nigripes and black-browed (Thalassarche melanophrys- dominating this category. However, of these, only 85 (48% seabird carcasses were retrieved during line hauling. Most caught seabirds were hooked through the bill. (iv The remainder of seabird-bait interactions (7% was not clearly observed, but likely involved more "caught" seabirds. Bait taking attempts and percentage outcome (e.g. successful, caught varied between seabird species and was not always related to species abundance around fishing vessels. Using only haul data to calculate seabird bycatch grossly underestimates actual bycatch levels, with the level of seabird bycatch from pelagic longline fishing possibly double what was previously thought.

  15. Seabird bycatch in pelagic longline fisheries is grossly underestimated when using only haul data.

    Science.gov (United States)

    Brothers, Nigel; Duckworth, Alan R; Safina, Carl; Gilman, Eric L

    2010-08-31

    Hundreds of thousands of seabirds are killed each year as bycatch in longline fisheries. Seabirds are predominantly caught during line setting but bycatch is generally recorded during line hauling, many hours after birds are caught. Bird loss during this interval may lead to inaccurate bycatch information. In this 15 year study, seabird bycatch was recorded during both line setting and line hauling from four fishing regions: Indian Ocean, Southern Ocean, Coral Sea and central Pacific Ocean. Over 43,000 albatrosses, petrels and skuas representing over 25 species were counted during line setting of which almost 6,000 seabirds attempted to take the bait. Bait-taking interactions were placed into one of four categories. (i) The majority (57%) of bait-taking attempts were "unsuccessful" involving seabirds that did not take the bait nor get caught or hooked. (ii) One-third of attempts were "successful" with seabirds removing the bait while not getting caught. (iii) One-hundred and seventy-six seabirds (3% of attempts) were observed being "caught" during line setting, with three albatross species - Laysan (Phoebastria immutabilis), black-footed (P. nigripes) and black-browed (Thalassarche melanophrys)- dominating this category. However, of these, only 85 (48%) seabird carcasses were retrieved during line hauling. Most caught seabirds were hooked through the bill. (iv) The remainder of seabird-bait interactions (7%) was not clearly observed, but likely involved more "caught" seabirds. Bait taking attempts and percentage outcome (e.g. successful, caught) varied between seabird species and was not always related to species abundance around fishing vessels. Using only haul data to calculate seabird bycatch grossly underestimates actual bycatch levels, with the level of seabird bycatch from pelagic longline fishing possibly double what was previously thought.

  16. Coastal pollution limits pelagic larval dispersal.

    Science.gov (United States)

    Puritz, Jonathan B; Toonen, Robert J

    2011-01-01

    The ecological impact of large coastal human populations on marine ecosystems remains relatively unknown. Here, we examine the population structure of Patiria miniata, the bat star, and correlate genetic distances with a model based on flow rates and proximity to P. miniata populations for the four major stormwater runoff and wastewater effluent sources of the Southern California Bight. We show that overall genetic connectivity is high (F(ST)~0.005); however, multivariate analyses show that genetic structure is highly correlated with anthropogenic inputs. The best models included both stormwater and wastewater variables and explained between 26.55 and 93.69% of the observed structure. Additionally, regressions between allelic richness and distance to sources show that populations near anthropogenic pollution have reduced genetic diversity. Our results indicate that anthropogenic runoff and effluent are acting as barriers to larval dispersal, effectively isolating a high gene flow species that is virtually free of direct human impact.

  17. Fish Stock Endogeneity in a Harvest Function: ‘El Niño’ Effects on the Chilean Jack Mackerel Fishery

    Directory of Open Access Journals (Sweden)

    Sebastián Vergara

    2007-03-01

    Full Text Available There are several examples of pelagic fisheries that have experienced fishing collapse when facing downward abundance cycles. Improving understanding about pelagic catch’s stock dependence can help avoid new cases of fishing collapse. This paper analyses the possible endogeneity of the fish stock variable in a pelagic fishery harvest function. The harvest function is estimated using panel data and ‘El Niño’ episodes as instrumental variable for the Chilean jack mackerel biomass. This strategy produces consistent estimates of the fish biomass coefficient. The paper makes two contributions. First, it corrects for endogeneity of the fish stock variable, an issue often underestimated in empirical fishery economics. Secondly, it shows that ‘El Niño’ episodes have negative effects on the Chilean jack mackerel biomass.

  18. Analysis of the parasitic copepod species richness among Mediterranean fish

    Science.gov (United States)

    Raibaut, André; Combes, Claude; Benoit, Françoise

    1998-06-01

    as follows: (1) In many cases, parasite and host phylogeny seem to play an important role. There are fish families with copepods and families with few species of these parasites. The phyletic constraints could be due to the morphological characteristics of the habitat (e.g. structure of the gills) or biological/ecological characteristics that we were unable to identify. (2) It appears that the presence in a same environment of related fish species (e.g. several species of the same genus, or numerous genera of the same family) is correlated with high parasite richness. A likely explanation is that such situations favours alternated processes of lateral transfers and speciation. (3) Some eco-ethological criteria seem to favour the establishment of a large parasite species richness. It should be noted for instance that Mediterranean fishes the most often infected with copepods are generally nectonic or pelagic, migratory, and gregarious species.

  19. [Stoichiometry of cytochromes and oxygen tension in skeletal muscles of marine fish].

    Science.gov (United States)

    Soldatov, A A; Parfenova, I A

    2014-01-01

    The character of oxygen tension distribution and peculiarities of cytochromes stoichiometry in skeletal muscles of bottom and pelagic species of marine fish were compared. It is shown, that the limitation of muscle activity increases the number of hypoxic zones in the muscle tissue. The mitochondrial electron-transporting chain then obtain the uncompensated type of organization, expressed in the increase of the share of the terminal complex aa3 on the background of general reduction of cytochromes content in the muscles. The reaction is of an adaptive character and can be implemented by pelagic fish species in conditions of experimental hypokinesia.

  20. Positive Darwinian selection in the singularly large taste receptor gene family of an ‘ancient’ fish, Latimeria chalumnae

    OpenAIRE

    Adnan S. Syed; Korsching, Sigrun I.

    2014-01-01

    Background Chemical senses are one of the foremost means by which organisms make sense of their environment, among them the olfactory and gustatory sense of vertebrates and arthropods. Both senses use large repertoires of receptors to achieve perception of complex chemosensory stimuli. High evolutionary dynamics of some olfactory and gustatory receptor gene families result in considerable variance of chemosensory perception between species. Interestingly, both ora/v1r genes and the closely re...

  1. Japanese and Taiwanese pelagic longline fleet dynamics and the impacts of climate change in the southern Indian Ocean

    Science.gov (United States)

    Michael, P. E.; Wilcox, C.; Tuck, G. N.; Hobday, A. J.; Strutton, P. G.

    2017-06-01

    Climate change is projected to continue shifting the distribution of marine species, leading to changes in local assemblages and different interactions with human activities. With regard to fisheries, understanding the relationship between fishing fleets, target species catch per unit effort (CPUE), and the environment enhances our ability to anticipate fisher response and is an essential step towards proactive management. Here, we explore the potential impact of climate change in the southern Indian Ocean by modelling Japanese and Taiwanese pelagic longline fleet dynamics. We quantify the mean and variability of target species CPUE and the relative value and cost of fishing in different areas. Using linear mixed models, we identify fleet-specific effort allocation strategies most related to observed effort and predict the future distribution of effort and tuna catch under climate change for 2063-2068. The Japanese fleet's strategy targets high-value species and minimizes the variability in CPUE of the primary target species. Conversely, the Taiwanese strategy indicated flexible targeting of a broad range of species, fishing in areas of high and low variability in catch, and minimizing costs. The projected future mean and variability in CPUE across species suggest a slight increase in CPUE in currently high CPUE areas for most species. The corresponding effort projections suggest a slight increase in Japanese effort in the western and eastern study area, and Taiwanese effort increasing east of Madagascar. This approach provides a useful method for managers to explore the impacts of different fishing and fleet management strategies for the future.

  2. Life-history diversity and its importance to population stability and persistence of a migratory fish: steelhead in two large North American watersheds.

    Science.gov (United States)

    Moore, Jonathan W; Yeakel, Justin D; Peard, Dean; Lough, Jeff; Beere, Mark

    2014-09-01

    Life-history strategies can buffer individuals and populations from environmental variability. For instance, it is possible that asynchronous dynamics among different life histories can stabilize populations through portfolio effects. Here, we examine life-history diversity and its importance to stability for an iconic migratory fish species. In particular, we examined steelhead (Oncorhynchus mykiss), an anadromous and iteroparous salmonid, in two large, relatively pristine, watersheds, the Skeena and Nass, in north-western British Columbia, Canada. We synthesized life-history information derived from scales collected from adult steelhead (N = 7227) in these watersheds across a decade. These migratory fishes expressed 36 different manifestations of the anadromous life-history strategy, with 16 different combinations of freshwater and marine ages, 7·6% of fish performing multiple spawning migrations, and up to a maximum of four spawning migrations per lifetime. Furthermore, in the Nass watershed, various life histories were differently prevalent through time - three different life histories were the most prevalent in a given year, and no life history ever represented more than 45% of the population. These asynchronous dynamics among life histories decreased the variability of numerical abundance and biomass of the aggregated population so that it was > 20% more stable than the stability of the weighted average of specific life histories: evidence of a substantial portfolio effect. Year of ocean entry was a key driver of dynamics; the median correlation coefficient of abundance of life histories that entered the ocean the same year was 2·5 times higher than the median pairwise coefficient of life histories that entered the ocean at different times. Simulations illustrated how different elements of life-history diversity contribute to stability and persistence of populations. This study provides evidence that life-history diversity can dampen fluctuations in

  3. Economic aspects of fishing of dolphinfish in Sicily

    Directory of Open Access Journals (Sweden)

    L. Cannizaro

    1999-12-01

    Full Text Available Dolphinfish fishing with Fish Aggregating Devices (FADs and purseseine nets is normally practised everywhere in Sicily and the Pelagic Archipelago. The fishing season starts in July when the FADs are placed and finishes in December. In the 1996 fishing season, in 5 sample ports, catches and fishing effort were taken through interviews during landing, fishing running costs were taken by interviewing fishermen and prices per kilos paid to fishermen were taken through direct observation. Catches, costs and profits per sample port, per week and for the entire fishing season were then calculated or estimated. Though it is freshly marketed only in Sicily, the resource would appear to provide a lucrative activity.

  4. Diel variation in fish assemblages in tidal creeks in southern Brazil

    Directory of Open Access Journals (Sweden)

    JF. Oliveira-Neto

    Full Text Available Tidal creeks are strongly influenced by tides and are therefore exposed to large differences in salinity and depth daily. Here we compare fish assemblages in tidal creeks between day and night in two tidal creeks in southern Brazil. Monthly day and night, simultaneous collections were carried out in both creeks using fyke nets. Clupeiformes tended to be caught more during the day. Cathorops spixii, Genidens genidens and Rypticus randalli tended to be caught at night. Sciaenidae also tended to be caught more during the night. In general, pelagic species were diurnal, while deep water species were nocturnal. These trends are probably due to a variety of causes, such as phylogeny, predation and net avoidance.

  5. [Effects of large bio-manipulation fish pen on community structure of crustacean zooplankton in Meiliang Bay of Taihu Lake].

    Science.gov (United States)

    Ke, Zhi-Xin; Xie, Ping; Guo, Long-Gen; Xu, Jun; Zhou, Qiong

    2012-08-01

    In 2005, a large bio-manipulation pen with the stock of silver carp and bighead carp was built to control the cyanobacterial bloom in Meiliang Bay of Taihu Lake. This paper investigated the seasonal variation of the community structure of crustacean zooplankton and the water quality within and outside the pen. There were no significant differences in the environmental parameters and phytoplankton biomass within and outside the pen. The species composition and seasonal dynamics of crustacean zooplankton within and outside the pen were similar, but the biomass of crustacean zooplankton was greatly suppressed by silver carp and bighead carp. The total crustacean zooplankton biomass and cladocerans biomass were significantly lower in the pen (P crustacean zooplankton was observed in the Bay. Many crustacean species were only dominated in given seasons. Large-sized crustacean (mainly Daphnia sp. and Cyclops vicnus) dominated in winter and spring, while small-sized species (mainly Bosmina sp., Ceriodaphnia cornuta, and Limnoithona sinensis) dominated in summer and autumn. Canonical correspondence analysis showed that water transparency, temperature, and phytoplankton biomass were the most important factors affecting the seasonal succession of the crustacean.

  6. Fish cardiovascular physiology and disease.

    Science.gov (United States)

    Sherrill, Johanna; Weber, E Scott; Marty, Gary D; Hernandez-Divers, Stephen

    2009-01-01

    Fish patients with cardiovascular disorders present a challenge in terms of diagnostic evaluation and therapeutic options. Veterinarians can approach these cases in fish using methods similar to those employed for other companion animals. Clinicians who evaluate and treat fish in private, aquarium, zoologic, or aquaculture settings need to rely on sound clinical judgment after thorough historical and physical evaluation. Pharmacokinetic data and treatments specific to cardiovascular disease in fish are limited; thus, drug types and dosages used in fish are largely empiric. Fish cardiovascular anatomy, physiology, diagnostic evaluation, monitoring, common diseases, cardiac pathologic conditions, formulary options, and comprehensive references are presented with the goal of providing fish veterinarians with clinically relevant tools.

  7. Oceanic circulation models help to predict global biogeography of pelagic yellow-bellied sea snake.

    Science.gov (United States)

    Brischoux, François; Cotté, Cédric; Lillywhite, Harvey B; Bailleul, Frédéric; Lalire, Maxime; Gaspar, Philippe

    2016-08-01

    It is well recognized that most marine vertebrates, and especially tetrapods, precisely orient and actively move in apparently homogeneous oceanic environments. Here, we investigate the presumptive role of oceanic currents in biogeographic patterns observed in a secondarily marine tetrapod, the yellow-bellied sea snake (Hydrophis [Pelamis] platurus). State-of-the-art world ocean circulation models show how H. platurus, the only pelagic species of sea snake, can potentially exploit oceanic currents to disperse and maintain population mixing between localities that spread over two-thirds of the Earth's circumference. The very close association of these snakes with surface currents seems to provide a highly efficient dispersal mechanism that allowed this species to range extensively and relatively quickly well beyond the central Indo-Pacific area, the centre of origin, abundance and diversity of sea snakes. Our results further suggest that the pan-oceanic population of this species must be extraordinarily large. © 2016 The Author(s).

  8. Evidence of micro-debris ingestion by Sargassum-associated fishes in the northern Gulf of Mexico

    Science.gov (United States)

    Vick, P.; Hernandez, F., Jr.; Muffelman, S.; Lestrade, O.

    2016-02-01

    Sargassum natans and S. fluitans collectively form a pelagic macroalgae complex (Sargassum) which is commonly found in surface waters of the Western-Central Atlantic Ocean (including the Gulf of Mexico). Mats and windrows of Sargassum support large and diverse assemblages of marine fishes and invertebrates, including many early life stages which use Sargassum as nursery areas. Sargassum is a near-surface habitat, and therefore is subject to oceanographic processes (e.g., Langmuir cells, frontal zones) that aggregate floating objects, including marine debris. Relatively little is known about the impacts of marine debris (which often gets broken down into "micro-debris") within Sargassum communities, although micro-debris particles may serve as vectors for toxic compounds if consumed by organisms. Here we present preliminary results from a pilot study examining the frequency of micro-debris occurrence in the stomachs of Sargassum-associated fishes. Neuston and plankton purse seine nets were used to collect Sargassum and associated fauna during surveys in the northern Gulf of Mexico (May, June and July 2014). Marine debris was present in all Sargassum collections, and ranged from relatively large items (e.g., soda bottles) to smaller particles (e.g., microplastics, monofilament threads). The associated fish community was dominated by relatively few taxa, including pipefishes, filefishes and the Sargassumfish, which collectively comprised approximately 85% of the total catch. Stomach contents from juvenile fishes contained mostly natural prey items, including copepods, small decapods, hydroids, and fishes. Micro-debris particles were observed in the stomachs of eight fish species, including juvenile Mahi Mahi, Planehead Filefish and Bermuda chub, among others. Overall, our initial observations suggest that there is some ingestion of micro-debris by fishes associated with Sargassum, although the frequency of occurrence is relatively low.

  9. Physical forcing and the dynamics of the pelagic ecosystem in the eastern tropical Pacific: simulations with ENSO-scale and global-warming climate drivers

    Energy Technology Data Exchange (ETDEWEB)

    Watters, G. M.; Olson, R. J. [Inter-American Tropical Tuna Commission, La Jolla, CA (United States); Francis, C.; Aydin, K. Y. [Washington Univ., School of Aquatic and Fisheries Sciences, Seattle, WA (United States); Fiedler, P. C.; Reilley, S. B. [NOAA Fisheries, LaJolla, CA (United States); Polovnia, J. J.; Boggs, C. H.; Essington, T. E. [NOAA Fisheries, Honolulu, HI (United States); Walters, C. J. [British Columbia Univ., Fisheries Centre, Vancouver, BC (Canada); Kitchell, J. F. [Wisconsin Univ., Center for Limnology, Madison, WI (United States)

    2003-09-01

    The effects of climate variation on animals at the middle and upper trophic levels in the eastern tropical Pacific Ocean was investigated at El Nino-Southern Oscillation (ENSO) scales. Objectives of the work were: (1) to explore how a single, ENSO-scale climate pulse might affect middle and upper trophic levels of the pelagic ecosystem in the eastern tropical Pacific Ocean; (2) explore ecosystem response to changes in periodicity of warm and cold events during sustained ENSO-scale cycling; and (3) explore how the greenhouse effect might affect pelagic ecosystem in the eastern tropical Pacific Ocean. Two physical forcing scenarios were used: (1) physical effects on phytoplankton biomass, and (2) simultaneous physical effects on phytoplankton biomass and predator recruitment. The effects of climate anomaly pulses, climatic cycles and global warming were simulated. Pulses caused oscillations to propagate through the ecosystem; cycles affected the shapes of these oscillations; and warming caused trends to develop. These results gave rise to several conclusions: (1) it seems unlikely that biomass trajectories of single populations at middle and upper trophic levels could be used to detect bottom-up effects; (2) under constant fishing mortality, direct physical effects on predator recruitment are the dominant source of interannual variability in pelagic ecosystems; (3) top-down effects of fishing are less able to cascade through the food web if direct effects are the dominant source of physical variability in the system; and (4) predictions about the effects of long-term climate change on animals at middle and upper trophic levels may be misleading if future levels of fishing are not considered. 37 refs., 4 tabs., 7 figs.

  10. Subsurface phytoplankton blooms fuel pelagic production in the North Sea

    DEFF Research Database (Denmark)

    Richardson, Kathrine; Visser, Andre; Pedersen, Flemming

    2000-01-01

    convincingly that energy fixed during the spring bloom is fueling the pelagic production occurring during summer months. We argue here that periodic phytoplankton blooms are occurring during the summer in the North Sea at depths of >25 m and that the accumulated new production [sensu (Dugdale and Goering......, Limnol. Oceanogr., 12, 196-206, 1967)] occurring in these blooms may be greater than that occurring in the spring bloom in the same regions. Thus, such blooms may explain apparent discrepancies in production yields between different temperate marine systems...

  11. Seasonal and environmental influences on recruitment patterns and habitat usage among resident and transient fishes in a World Heritage Site subtropical estuary.

    Science.gov (United States)

    Pichler, H A; Gray, C A; Broadhurst, M K; Spach, H L; Nagelkerken, I

    2017-01-01

    This study investigated whether the fish communities inhabiting shallow non-vegetated habitats in two divergent bays in a subtropical World Heritage Site estuarine system differed according to wet (spring-summer) and dry (autumn-winter) seasons or polyhaline and mesohaline zones, within the broader objective of facilitating spatio-temporal management. Species richness (total of 74 taxa; total length, LT  = 11-552 mm) and abundance (51 109 individuals) were mostly greater in the wet than dry season and in polyhaline than mesohaline areas. There was a major effect of rainfall on recruitment, particularly among transient fishes, which could be the result of enhanced survival of young via greater productivity (food resources) and protection from predators (via turbidity reducing visual cues). Salinity had strong interactive effects with rainfall and temperature in one bay, with greater species richness and overall abundances as well as large abundances of four key species [Anchoa januaria and Atherinella brasiliensis (pelagic residents), Cetengraulis edentulus (pelagic transient) and Diapterus rhombeus (demersal transient)] during the wet season in polyhaline areas; possibly reflecting a biodiversity hotspot that might be affected by distance to the estuary mouth and convergence hydrology. Regionally, the results support enforcing spatio-temporal restrictions to minimize anthropogenic activities within statutory (but not always enforced) protected areas. Globally, the data reiterate the need to identify and understand biotic and abiotic effects on estuarine ichthyofaunal distributions and abundances as a precursor to their management.

  12. The pelagic ecosystem of the tropical Pacific Ocean: dynamic spatial modelling and biological consequences of ENSO

    Science.gov (United States)

    Lehodey, Patrick

    A feature of the central equatorial Pacific is a strong divergent equatorial upwelling called the cold tongue, which is favorable to the development of a large zonal band with high levels of primary production. Contiguous to the cold tongue, is the western Pacific warm pool, which is characterized by warmer water with lower levels of primary production. At the top of the food web, the tropical tunas are a major component of the pelagic ecosystem and have their maximum biomass in the warm pool. However, during ENSO (El Niño Southern Oscillation) events, variability is observed in both environmental factors and the spatial distribution of tuna. A Spatial Environmental Population Dynamics Model (SEPODYM) is used to assist in the analysis and interpretation of these fishery oceanographic observations. A modelling approach is described and applied to the population and fisheries of skipjack tuna, one of the top predator species with its greatest biomass in the tropical pelagic ecosystem. Environmental variables are used in the model for delineating the spawning area of skipjack, reproducing the transport of its larvae and juveniles, and simulating tuna forage. The forage production is deduced from a simple ecological transfer based on new primary production with biomass calculated as a single population. The model considers an interaction between predicted tuna density and forage density. A habitat index combining temperature preferences with forage distribution is used to constrain the movement of adult tuna. Results of the simulation allow realistic prediction of the large-scale distribution of the species. There is a remarkable out-of-phase pattern linked to ENSO between the western Pacific region and the cold tongue. This pattern is consistent with the observed movements of skipjack.

  13. Off the scale: a new species of fish-scale gecko (Squamata: Gekkonidae: Geckolepis) with exceptionally large scales.

    Science.gov (United States)

    Scherz, Mark D; Daza, Juan D; Köhler, Jörn; Vences, Miguel; Glaw, Frank

    2017-01-01

    The gecko genus Geckolepis, endemic to Madagascar and the Comoro archipelago, is taxonomically challenging. One reason is its members ability to autotomize a large portion of their scales when grasped or touched, most likely to escape predation. Based on an integrative taxonomic approach including external morphology, morphometrics, genetics, pholidosis, and osteology, we here describe the first new species from this genus in 75 years: Geckolepis megalepissp. nov. from the limestone karst of Ankarana in northern Madagascar. The new species has the largest known body scales of any gecko (both relatively and absolutely), which come off with exceptional ease. We provide a detailed description of the skeleton of the genus Geckolepis based on micro-Computed Tomography (micro-CT) analysis of the new species, the holotype of G. maculata, the recently resurrected G. humbloti, and a specimen belonging to an operational taxonomic unit (OTU) recently suggested to represent G. maculata. Geckolepis is characterized by highly mineralized, imbricated scales, paired frontals, and unfused subolfactory processes of the frontals, among other features. We identify diagnostic characters in the osteology of these geckos that help define our new species and show that the OTU assigned to G. maculata is probably not conspecific with it, leaving the taxonomic identity of this species unclear. We discuss possible reasons for the extremely enlarged scales of G. megalepis in the context of an anti-predator defence mechanism, and the future of Geckolepis taxonomy.

  14. High-levels of microplastic pollution in a large, remote, mountain lake.

    Science.gov (United States)

    Free, Christopher M; Jensen, Olaf P; Mason, Sherri A; Eriksen, Marcus; Williamson, Nicholas J; Boldgiv, Bazartseren

    2014-08-15

    Despite the large and growing literature on microplastics in the ocean, little information exists on microplastics in freshwater systems. This study is the first to evaluate the abundance, distribution, and composition of pelagic microplastic pollution in a large, remote, mountain lake. We quantified pelagic microplastics and shoreline anthropogenic debris in Lake Hovsgol, Mongolia. With an average microplastic density of 20,264 particles km(-2), Lake Hovsgol is more heavily polluted with microplastics than the more developed Lakes Huron and Superior in the Laurentian Great Lakes. Fragments and films were the most abundant microplastic types; no plastic microbeads and few pellets were observed. Household plastics dominated the shoreline debris and were comprised largely of plastic bottles, fishing gear, and bags. Microplastic density decreased with distance from the southwestern shore, the most populated and accessible section of the park, and was distributed by the prevailing winds. These results demonstrate that without proper waste management, low-density populations can heavily pollute freshwater systems with consumer plastics.

  15. Cytochemical features of olfactory receptor cells in benthic and pelagic Sculpins (Cottoidei from Lake Baikal

    Directory of Open Access Journals (Sweden)

    Klimenkov Igor V.

    2016-01-01

    Full Text Available Electron and laser confocal microscopy were used to analyze the adaptive cytochemical features of the olfactory epithelium in three genetically close deep-water Cottoidei species endemic to Lake Baikal − golomyanka (Baikal oilfish Comephorus baicalensis, longfin Baikal sculpin Cottocomephorus inermis and fat sculpin Batrachocottus nikolskii − whose foraging strategies are realized under different hydrostatic pressure regimes. Hypobaric hypoxia that developed in B. nikolskii (a deep-water benthic species upon delivery to the surface caused distinct destructive changes in cells of the olfactory epithelium. In C. baicalensis and C. inermis, whose foraging behavior involves daily vertical migrations between deep and shallow layers, these cells are characterized by a significantly higher structural and functional stability than in deep-water B. nikolskii. The results of morphological study and quantitative analysis of functionally active mitochondria in cells of the olfactory epithelium of closely related deep-water fish species with different modes of life provide evidence that tolerance of the olfactory apparatus to hypobaric hypoxia is different in pelagic and benthic species. These results help elucidate the mechanisms responsible for the consistent functioning of the olfactory system in animals evolutionarily adapted to extreme environmental factors, and provide theoretical and practical implications in different fields of biology, neurology and extreme medicine.

  16. Fish Hearing.

    Science.gov (United States)

    Blaxter, J. H. S.

    1980-01-01

    Provides related information about hearing in fish, including the sensory stimulus of sound in the underwater environment, mechanoreceptors in fish, pressure perception and the swimbladder, specializations in sound conduction peculiar to certain fish families. Includes numerous figures. (CS)

  17. Fish Allergy

    Science.gov (United States)

    ... in a clear and consistent manner, so that consumers with food allergies and their caregivers can be informed as ... the menu, cross-contact with fish is possible. Ethnic ... fish. Avoid foods like fish sticks and anchovies. Some individuals with ...

  18. Exxon Valdez to Deepwater Horizon: comparable toxicity of both crude oils to fish early life stages.

    Science.gov (United States)

    Incardona, John P; Swarts, Tanya L; Edmunds, Richard C; Linbo, Tiffany L; Aquilina-Beck, Allisan; Sloan, Catherine A; Gardner, Luke D; Block, Barbara A; Scholz, Nathaniel L

    2013-10-15

    The 2010 Deepwater Horizon disaster in the Gulf of Mexico was the largest oil spill in United States history. Crude oils are highly toxic to developing fish embryos, and many pelagic fish species were spawning in the northern Gulf in the months before containment of the damaged Mississippi Canyon 252 (MC252) wellhead (April-July). The largest prior U.S. spill was the 1989 grounding of the Exxon Valdez that released 11 million gallons of Alaska North Slope crude oil (ANSCO) into Prince William Sound. Numerous studies in the aftermath of the Exxon Valdez spill defined a conventional crude oil injury phenotype in fish early life stages, mediated primarily by toxicity to the developing heart. To determine whether this type of injury extends to fishes exposed to crude oil from the Deepwater Horizon - MC252 incident, we used zebrafish to compare the embryotoxicity of ANSCO alongside unweathered and weathered MC252 oil. We also developed a standardized protocol for generating dispersed oil water-accommodated fractions containing microdroplets of crude oil in the size range of those detected in subsurface plumes in the Gulf. We show here that MC252 oil and ANSCO cause similar cardiotoxicity and photo-induced toxicity in zebrafish embryos. Morphological defects and patterns of cytochrome P450 induction were largely indistinguishable and generally correlated with polycyclic aromatic compound (PAC) composition of each oil type. Analyses of embryos exposed during different developmental windows provided additional insight into mechanisms of crude oil cardiotoxicity. These findings indicate that the impacts of MC252 crude oil on fish embryos and larvae are consistent with the canonical ANSCO cardiac injury phenotype. For those marine fish species that spawned in the northern Gulf of Mexico during and after the Deepwater Horizon incident, the established literature can therefore inform the assessment of natural resource injury in the form of potential year-class losses.

  19. Scales of benthic–pelagic coupling and the intensity of species interactions: From recruitment limitation to top-down control

    Science.gov (United States)

    Navarrete, Sergio A.; Wieters, Evie A.; Broitman, Bernardo R.; Castilla, Juan Carlos

    2005-01-01

    Large and usually unpredictable variation in species interaction strength has been a major roadblock to applying local experimental results to large-scale management and conservation issues. Recent studies explicitly considering benthic-pelagic coupling are starting to shed light on, and find regularities in, the causes of such large-scale variation in coastal ecosystems. Here, we evaluate the effects of variation in wind-driven upwelling on community regulation along 900 km of coastline of the southeastern Pacific, between 29°S and 35°S during 72 months. Variability in the intensity of upwelling occurring over tens of km produced predictable variation in recruitment of intertidal mussels, but not barnacles, and did not affect patterns of community structure. In contrast, sharp discontinuities in upwelling regimes produced abrupt and persistent breaks in the dynamics of benthic and pelagic communities over hundreds of km (regional) scales. Rates of mussel and barnacle recruitment changed sharply at ≈32°-33°S, determining a geographic break in adult abundance of these competitively dominant species. Analysis of satellite images demonstrates that regional-scale discontinuities in oceanographic regimes can couple benthic and pelagic systems, as evidenced by coincident breaks in dynamics and concentration of offshore surface chlorophyll-a. Field experiments showed that the paradigm of top-down control of intertidal benthic communities holds only south of the discontinuity. To the north, populations seem recruitment-limited, and predators have negligible effects, despite attaining similarly high abundances and potential predation effects across the region. Thus, geographically discontinuous oceanographic regimes set bounds to the strength of species interactions and define distinct regions for the design and implementation of sustainable management and conservation policies. PMID:16332959

  20. Scales of benthic-pelagic coupling and the intensity of species interactions: from recruitment limitation to top-down control.

    Science.gov (United States)

    Navarrete, Sergio A; Wieters, Evie A; Broitman, Bernardo R; Castilla, Juan Carlos

    2005-12-13

    Large and usually unpredictable variation in species interaction strength has been a major roadblock to applying local experimental results to large-scale management and conservation issues. Recent studies explicitly considering benthic-pelagic coupling are starting to shed light on, and find regularities in, the causes of such large-scale variation in coastal ecosystems. Here, we evaluate the effects of variation in wind-driven upwelling on community regulation along 900 km of coastline of the southeastern Pacific, between 29 degrees S and 35 degrees S during 72 months. Variability in the intensity of upwelling occurring over tens of km produced predictable variation in recruitment of intertidal mussels, but not barnacles, and did not affect patterns of community structure. In contrast, sharp discontinuities in upwelling regimes produced abrupt and persistent breaks in the dynamics of benthic and pelagic communities over hundreds of km (regional) scales. Rates of mussel and barnacle recruitment changed sharply at approximately 32 degrees -33 degrees S, determining a geographic break in adult abundance of these competitively dominant species. Analysis of satellite images demonstrates that regional-scale discontinuities in oceanographic regimes can couple benthic and pelagic systems, as evidenced by coincident breaks in dynamics and concentration of offshore surface chlorophyll-a. Field experiments showed that the paradigm of top-down control of intertidal benthic communities holds only south of the discontinuity. To the north, populations seem recruitment-limited, and predators have negligible effects, despite attaining similarly high abundances and potential predation effects across the region. Thus, geographically discontinuous oceanographic regimes set bounds to the strength of species interactions and define distinct regions for the design and implementation of sustainable management and conservation policies.

  1. Ecological distribution of pelagic copepods and species relationship to acidification, liming and natural recovery in a boreal area

    Directory of Open Access Journals (Sweden)

    Svein Birger WÆRVÅGEN

    2003-02-01

    Full Text Available Distribution and ecology of pelagic copepods were studied in a boreal area strongly affected by acidification in southern Norway. Differential regional composition of bedrock geology and Quaternary deposits combined with liming have produced aquatic sites with contrasting acidification and recovery histories. The omnivorous species Eudiaptomus gracilis showed a striking ability to tolerate both acidification and chemical recovery. The predominantly carnivorous species Heterocope saliens increased numerically during acidification, both because it is tolerant to acidic environments and because fish predation diminished or disappeared altogether. After chemical recovery, H. saliens, having an endogenous egg-bank, most readily produced viable populations with numerical abundance depending upon fish predation pressure. Thermocyclops oithonoides and Cyclops scutifer were negatively affected by strongly acidic environments, whereas Mesocyclops leuckarti tolerated acidic conditions better. All three cyclopoid species increased in abundance after chemical recovery, most probably from small residual populations. The hypolimnetic C. scutifer faced dispersal problems in re-establishing following liming. Deep lakes (>20 m harboured considerable residual populations of C. scutifer which recovered rapidly to pre-acidic conditions. Cyclops abyssorum inhabited the pelagial during early recovery of formerly chronically acidified lakes as a fugitive species, probably due to rapid dispersal capacities. Littoral cyclopoids, such as Acanthocyclops vernalis and Diacyclops nanus, were commonly distributed in the free waters of the most acidic lakes (pH = 4.5-4.8, but disappeared from the pelagial shortly after chemical recovery. The total community of pelagic copepods forms a promising tool to identify historical acidification and trajectories of recovery in the freshwater environment.

  2. Dehydration and drinking responses in a pelagic sea snake.

    Science.gov (United States)

    Lillywhite, Harvey B; Brischoux, François; Sheehy, Coleman M; Pfaller, Joseph B

    2012-08-01

    Recent investigations of water balance in sea snakes demonstrated that amphibious sea kraits (Laticauda spp.) dehydrate in seawater and require fresh water to restore deficits in body water. Here, we report similar findings for Pelamis platurus, a viviparous, pelagic, entirely marine species of hydrophiine ("true") sea snake. We sampled snakes at Golfo de Papagayo, Guanacaste, Costa Rica and demonstrated they do not drink seawater but fresh water at variable deficits of body water incurred by dehydration. The threshold dehydration at which snakes first drink fresh water is -18.3 ± 1.1 % (mean ± SE) loss of body mass, which is roughly twice the magnitude of mass deficit at which sea kraits drink fresh water. Compared to sea kraits, Pelamis drink relatively larger volumes of water and make up a larger percentage of the dehydration deficit. Some dehydrated Pelamis also were shown to drink brackish water up to 50% seawater, but most drank at lower brackish values and 20% of the snakes tested did not drink at all. Like sea kraits, Pelamis dehydrate when kept in seawater in the laboratory. Moreover, some individuals drank fresh water immediately following capture, providing preliminary evidence that Pelamis dehydrate at sea. Thus, this widely distributed pelagic species remains subject to dehydration in marine environments where it retains a capacity to sense and to drink fresh water. In comparison with sea kraits, however, Pelamis represents a more advanced stage in the evolutionary transition to a fully marine life and appears to be less dependent on fresh water.

  3. Late Viséan pelagic chondrichthyans from northern Europe

    Directory of Open Access Journals (Sweden)

    Michał Ginter

    2015-12-01

    Full Text Available The relatively rich assemblages of shark teeth from pelagic limestone (Mississippian, late Viséan, late Asbian–middle Brigantian of three northern European regions: the Rhenish Mountains (Westenfeld Quarry, Germany, the Holy Cross Mountains (Todowa Grząba at the edge of Ostrówka Quarry, Poland, and Derbyshire (Cawdor Quarry, Matlock, England, UK display certain similarities, with the absolute predominance of the teeth of Falcatidae (small Symmoriiformes and the constant presence of Thrinacodus spp. The largest and most diverse assemblage from Todowa Grząba contains at least three species of a falcatid Denaea, a xenacanthimorph Bransonella nebraskensis, a newly described phoebodontid Thrinacodus dziki sp. nov., a few ctenacanthiform and euselachian teeth, and two abraded euchondrocephalan dental elements. Anachronistidae, common in the most of late Viséan pelagic faunas, are absent from Todowa Grząba and Westenfeld. The material under study differs from the shallow-water chondrichthyan fauna, hitherto described from the Mississippian carbonate platform facies, by its taxonomic content (particularly almost total absence of Euchondrocephali, generally lower diversity, and higher frequency of small teeth.

  4. Oceanography and the base of the pelagic food web in the southern Indian Ocean

    DEFF Research Database (Denmark)

    Visser, Andre; Nielsen, Torkel Gissel; Middelboe, Mathias

    2015-01-01

    Processes governing productivity at the base of the pelagic food web of the southern Indian Ocean are influenced primarily by physical–chemical conditions with implications for the structure and function of the entire pelagic food web. Here, we report observations along a great circle transect fr...

  5. Pelagic habitat visualization: the need for a third (and fourth) dimension: HabitatSpace

    Science.gov (United States)

    Beegle-Krause, C; Vance, Tiffany; Reusser, Debbie; Stuebe, David; Howlett, Eoin

    2009-01-01

    Habitat in open water is not simply a 2-D to 2.5-D surface such as the ocean bottom or the air-water interface. Rather, pelagic habitat is a 3-D volume of water that can change over time, leading us to the term habitat space. Visualization and analysis in 2-D is well supported with GIS tools, but a new tool was needed for visualization and analysis in four dimensions. Observational data (cruise profiles (xo, yo, z, to)), numerical circulation model fields (x,y,z,t), and trajectories (larval fish, 4-D line) need to be merged together in a meaningful way for visualization and analysis. As a first step toward this new framework, UNIDATA’s Integrated Data Viewer (IDV) has been used to create a set of tools for habitat analysis in 4-D. IDV was designed for 3-D+time geospatial data in the meteorological community. NetCDF JavaTM libraries allow the tool to read many file formats including remotely located data (e.g. data available via OPeNDAP ). With this project, IDV has been adapted for use in delineating habitat space for multiple fish species in the ocean. The ability to define and visualize boundaries of a water mass, which meets specific biologically relevant criteria (e.g., volume, connectedness, and inter-annual variability) based on model results and observational data, will allow managers to investigate the survival of individual year classes of commercially important fisheries. Better understanding of the survival of these year classes will lead to improved forecasting of fisheries recruitment.

  6. Isolation of novel pelagic bacteria from the German bight and their seasonal contributions to surface picoplankton.

    Science.gov (United States)

    Eilers, H; Pernthaler, J; Peplies, J; Glöckner, F O; Gerdts, G; Amann, R

    2001-11-01

    We tested new strategies for the isolation of abundant bacteria from coastal North Sea surface waters, which included reducing by several orders of magnitude the concentrations of inorganic N and P compounds in a synthetic seawater medium. Agar plates were resampled over 37 days, and slowly growing colonies were allowed to develop by repeatedly removing all newly formed colonies. A fivefold increase of colonies was observed on plates with reduced nutrient levels, and the phylogenetic composition of the culture collection changed over time, towards members of the Roseobacter lineage and other alpha-proteobacteria. Novel gamma-proteobacteria from a previously uncultured but cosmopolitan lineage (NOR5) formed colonies only after 12 days of plate incubation. A time series of German Bight surface waters (January to December 1998) was screened by fluorescence in situ hybridization (FISH) with isolate-specific and general probes. During spring and early summer, a prominent fraction of FISH-detectable bacteria (mean, 51%) were affiliated with the Cytophaga-Flavobacterium group (CF) of the Bacteroidetes. One Cytophaga sp. lineage with cultured representatives formed almost 20% of the CF group. Members of the Roseobacter cluster constituted approximately 50% of alpha-proteobacteria, but none of the Roseobacter-related isolates formed populations of >1% in the environment. Thus, the readily culturable members of this clade are probably not representative of Roseobacter species that are common in the water column. In contrast, members of NOR5 were found at high abundances (>10(5) cells ml(-1)) in the summer plankton. Some abundant pelagic bacteria are apparently able to form colonies on solid media, but appropriate isolation techniques for different species need to be developed.

  7. Complex movements, philopatry and expanded depth range of a severely threatened pelagic shark, the oceanic whitetip (Carcharhinus longimanus in the western North Atlantic.

    Directory of Open Access Journals (Sweden)

    Lucy A Howey-Jordan

    Full Text Available Oceanic whitetip sharks (Carcharhinus longimanus have recently been targeted for conservation in the western North Atlantic following severe declines in abundance. Pop-up satellite archival tags were applied to 11 mature oceanic whitetips (10 females, 1 male near Cat Island in the central Bahamas 1-8 May 2011 to provide information about the horizontal and vertical movements of this species. Another large female was opportunistically tagged in the U.S. Exclusive Economic Zone (EEZ. Data from 1,563 total tracking days and 1,142,598 combined depth and temperature readings were obtained. Sharks tagged at Cat Island stayed within 500 km of the tagging site for ~30 days before dispersing across 16,422 km(2 of the western North Atlantic. Maximum individual displacement from the tagging site ranged from 290-1940 km after times at liberty from 30-245 days, with individuals moving to several different destinations (the northern Lesser Antilles, the northern Bahamas, and north of the Windward Passage. Many sharks returned to The Bahamas after ~150 days. Estimated residency times within The Bahamas EEZ, where longlining and commercial trade of sharks is illegal, were generally high (mean = 68.2% of time. Sharks spent 99.7% of their time shallower than 200 m and did not exhibit differences in day and night mean depths. There was a positive correlation between daily sea surface temperature and mean depth occupied, suggesting possible behavioral thermoregulation. All individuals made short duration (mean = 13.06 minutes dives into the mesopelagic zone (down to 1082 m and 7.75°C, which occurred significantly more often at night. Ascent rates during these dives were significantly slower than descent rates, suggesting that these dives are for foraging. The sharks tracked appear to be most vulnerable to pelagic fishing gear deployed from 0-125 m depths, which they may encounter from June to October after leaving the protected waters of The Bahamas EEZ.

  8. Complex movements, philopatry and expanded depth range of a severely threatened pelagic shark, the oceanic whitetip (Carcharhinus longimanus) in the western North Atlantic.

    Science.gov (United States)

    Howey-Jordan, Lucy A; Brooks, Edward J; Abercrombie, Debra L; Jordan, Lance K B; Brooks, Annabelle; Williams, Sean; Gospodarczyk, Emily; Chapman, Demian D

    2013-01-01

    Oceanic whitetip sharks (Carcharhinus longimanus) have recently been targeted for conservation in the western North Atlantic following severe declines in abundance. Pop-up satellite archival tags were applied to 11 mature oceanic whitetips (10 females, 1 male) near Cat Island in the central Bahamas 1-8 May 2011 to provide information about the horizontal and vertical movements of this species. Another large female was opportunistically tagged in the U.S. Exclusive Economic Zone (EEZ). Data from 1,563 total tracking days and 1,142,598 combined depth and temperature readings were obtained. Sharks tagged at Cat Island stayed within 500 km of the tagging site for ~30 days before dispersing across 16,422 km(2) of the western North Atlantic. Maximum individual displacement from the tagging site ranged from 290-1940 km after times at liberty from 30-245 days, with individuals moving to several different destinations (the northern Lesser Antilles, the northern Bahamas, and north of the Windward Passage). Many sharks returned to The Bahamas after ~150 days. Estimated residency times within The Bahamas EEZ, where longlining and commercial trade of sharks is illegal, were generally high (mean = 68.2% of time). Sharks spent 99.7% of their time shallower than 200 m and did not exhibit differences in day and night mean depths. There was a positive correlation between daily sea surface temperature and mean depth occupied, suggesting possible behavioral thermoregulation. All individuals made short duration (mean = 13.06 minutes) dives into the mesopelagic zone (down to 1082 m and 7.75°C), which occurred significantly more often at night. Ascent rates during these dives were significantly slower than descent rates, suggesting that these dives are for foraging. The sharks tracked appear to be most vulnerable to pelagic fishing gear deployed from 0-125 m depths, which they may encounter from June to October after leaving the protected waters of The Bahamas EEZ.

  9. Description of the East Brazil Large Marine Ecosystem using a trophic model

    Directory of Open Access Journals (Sweden)

    Kátia M.F. Freire

    2008-09-01

    Full Text Available The objective of this study was to describe the marine ecosystem off northeastern Brazil. A trophic model was constructed for the 1970s using Ecopath with Ecosim. The impact of most of the forty-one functional groups was modest, probably due to the highly reticulated diet matrix. However, seagrass and macroalgae exerted a strong positive impact on manatee and herbivorous reef fishes, respectively. A high negative impact of omnivorous reef fishes on spiny lobsters and of sharks on swordfish was observed. Spiny lobsters and swordfish had the largest biomass changes for the simulation period (1978-2000; tunas, other large pelagics and sharks showed intermediate rates of biomass decline; and a slight increase in biomass was observed for toothed cetaceans, large carnivorous reef fishes, and dolphinfish. Recycling was an important feature of this ecosystem with low phytoplankton-originated primary production. The mean transfer efficiency between trophic levels was 11.4%. The gross efficiency of the fisheries was very low (0.00002, probably due to the low exploitation rate of most of the resources in the 1970s. Basic local information was missing for many groups. When information gaps are filled, this model may serve more credibly for the exploration of fishing policies for this area within an ecosystem approach.

  10. Does new technology inspire new directions? Examples drawn from pelagic visual ecology.

    Science.gov (United States)

    Johnsen, Sönke

    2007-12-01

    Oceanography has seen the recent development of many new tools and techniques. The subfield of pelagic visual ecology in particular has benefited from the development of more reliable, portable, and economic tools and techniques that can be taken to sea including spectrometers, microspectrophotometery, electroretinography, and ultraviolet and polarization imaging systems. These advances have led to a relative wealth of data on the visual physiology of pelagic species and on the optical properties of these species and their environment. These data, particularly in combination with computational methods, have tested long-standing hypotheses in pelagic ecology and led to new hypotheses and research directions. While the ability to study pelagic species still lags far behind what is possible in terrestrial and coastal environments, a renaissance may be developing in the study of the integrative biology of pelagic species.

  11. Oceanographic and behavioural assumptions in models of the fate of coral and coral reef fish larvae.

    Science.gov (United States)

    Wolanski, Eric; Kingsford, Michael J

    2014-09-06

    A predictive model of the fate of coral reef fish larvae in a reef system is proposed that combines the oceanographic processes of advection and turbulent diffusion with the biological process of horizontal swimming controlled by olfactory and auditory cues within the timescales of larval development. In the model, auditory cues resulted in swimming towards the reefs when within hearing distance of the reef, whereas olfactory cues resulted in the larvae swimming towards the natal reef in open waters by swimming against the concentration gradients in the smell plume emanating from the natal reef. The model suggested that the self-seeding rate may be quite large, at least 20% for the larvae of rapidly developing reef fish species, which contrasted with a self-seeding rate less than 2% for non-swimming coral larvae. The predicted self-recruitment rate of reefs was sensitive to a number of parameters, such as the time at which the fish larvae reach post-flexion, the pelagic larval duration of the larvae, the horizontal turbulent diffusion coefficient in reefal waters and the horizontal swimming behaviour of the fish larvae in response to auditory and olfactory cues, for which better field data are needed. Thus, the model suggested that high self-seeding rates for reef fish are possible, even in areas where the 'sticky water' effect is minimal and in the absence of long-term trapping in oceanic fronts and/or large-scale oceanic eddies or filaments that are often argued to facilitate the return of the larvae after long periods of drifting at sea. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

  12. Widespread N-acetyl-D-glucosamine uptake among pelagic marine bacteria and its ecological implications.

    Science.gov (United States)

    Riemann, Lasse; Azam, Farooq

    2002-11-01

    Dissolved free and combined N-acetyl-D-glucosamine (NAG) is among the largest pools of amino sugars in the ocean. NAG is a main structural component in chitin and a substantial constituent of bacterial peptidoglycan and lipopolysaccharides. We studied the distribution and kinetics of NAG uptake by the phosphoenolpyruvate:NAG phosphotransferase systems (PTS) in marine bacterial isolates and natural bacterial assemblages in near-shore waters. Of 78 bacterial isolates examined, 60 took up 3H-NAG, while 18 showed no uptake. No systematic pattern in NAG uptake capability relative to phylogenetic affiliation was found, except that all isolates within Vibrionaceae took up NAG. Among 12 isolates, some showed large differences in the relationship between polymer hydrolysis (measured as chitobiase activity) and uptake of the NAG, the hydrolysis product. Pool turnover time and estimated maximum ambient concentration of dissolved NAG in samples off Scripps Pier (La Jolla, Calif.) were 5.9 +/- 3.0 days (n = 10) and 5.2 +/- 0.9 nM (n = 3), respectively. Carbohydrate competition experiments indicated that glucose, glucosamine, mannose, and fructose were taken up by the same system as NAG. Sensitivity to the antibiotic and NAG structural analog streptozotocin (STZ) was developed into a culture-independent approach, which demonstrated that approximately one-third of bacteria in natural marine assemblages that were synthesizing DNA took up NAG. Isolates possessing a NAG PTS system were found to be predominantly facultative anaerobes. These results suggest the hypothesis that a substantial fraction of bacteria in natural pelagic assemblages are facultative anaerobes. The adaptive value of fermentative metabolism in the pelagic environment is potentially significant, e.g., to bacteria colonizing microenvironments such as marine snow that may experience periodic O2-limitation.

  13. Seasonal and latitudinal patterns of pelagic community metabolism in surface waters of the Atlantic Ocean

    Directory of Open Access Journals (Sweden)

    S. Agusti

    2012-01-01

    Full Text Available Temporal and spatial patterns in the variability of the pelagic metabolism at the surface of the Atlantic Ocean were analyzed in a series of four oceanographic cruises (LATITUDE 1, 2, 3 and 4. The cruises crossed the oligotrophic waters of North and South subtropical gyres and this explained the low values of both gross primary production (GPP and community respiration (R found. Net community production (NCP, the balance between production and consumption, was strongly related to the variability in R rates (R2=0.72, P<0.0001. NCP was net heterotrophic in 83 % of the data, but showed strong temporal and spatial patterns. At the inter-tropical zone, around 10°–12° N and 10°–12° S, a large variability was observed with values of NCP oscillating from net heterotrophic to net autotrophic seasonally. This variability implied NCP to be net autotrophic in boreal fall and austral spring, and net heterotrophic in boreal spring and austral fall, in the areas around the boundaries of the inter-tropical zone. The variability observed concur with the seasonal climatic and oceanographic regimes of the inter-tropical area, whith documented seasonal changes of the North and South Atlantic equatorial currents system, the Guinea Dome, and the Benguela current. When considering the season of the data obtained, significant differences between spring and fall were found for the surface Atlantic, with water temperature and respiration increasing in autumn, showing a net heterotrophic metabolism, and with temperature and respiration decreasing in spring, where NCP were closer to the metabolic balance. In contrast, no seasonal differences were found for GPP and chlorophyll-a concentration. The results showed new spatial and temporal patterns in the pelagic metabolic balance of the surface Atlantic Ocean with consequences for the carbon flux.

  14. Benthic Foraminifera, Food in the Deep Sea, and Limits to Bentho-Pelagic Coupling

    Science.gov (United States)

    Thomas, E.; Boscolo-Galazzo, F.; Arreguin-Rodrigu, G. J.; Ortiz, S.; Alegret, L.

    2015-12-01

    The deep-sea is the largest habitat on Earth, contains highly diverse biota, but is very little known. Many of its abundant benthic biota (e.g., nematodes) are not preserved in the fossil record. Calcareous and agglutinated benthic foraminifera (unicellular eukaryotes, Rhizaria; efficient dispersers) and ostracodes (Animalia, Crustacea; non-efficient dispersers) are the most common organisms providing a fossil record of deep-sea environments. Very little food is supplied to the deep-sea, because organic matter produced by photosynthesis is largely degraded before it arrives at the seafloor. Only a few % of organic matter is carried to the ocean bottom by 'marine snow', with its particle size and behavior in the water column controlled by surface ecosystem structure, including type of dominant primary producers (diatoms, cyanobacteria). Food supply and its seasonality are generally seen as the dominant control on benthic assemblages (combined with oxygenation), providing bentho-pelagic coupling between primary and benthic productivity. Benthic foraminiferal assemblages (composition and density) thus are used widely to estimate past productivity, especially during episodes of global climate change, ocean acidification, and mass extinction of primary producers. We show that some environmental circumstances may result in interrupting bentho-pelagic coupling, e.g. through lateral supply of organic matter along continental margins (adding more refractory organic matter), through trophic focusing and/or fine particle winnowing on seamounts (giving an advantage to suspension feeders), and through carbonate undersaturation (giving advantage to infaunal over epifaunal calcifyers). In addition, increased remineralization of organic matter combined with increased metabolic rates may cause assemblages to reflect more oligotrophic conditions at stable primary productivity during periods of global warming. As a result, benthic foraminiferal accumulation rates must be carefully

  15. Stable-isotope analysis of a deep-sea benthic-fish assemblage: evidence of an enriched benthic food web.

    Science.gov (United States)

    Boyle, M D; Ebert, D A; Cailliet, G M

    2012-04-01

    In this study, fishes and invertebrates collected from the continental slope (1000 m) of the eastern North Pacific Ocean were analysed using stable-isotope analysis (SIA). Resulting trophic positions (T(P) ) were compared to known diets and habitats from the literature. Dual isotope plots indicated that most species groups (invertebrates and fishes) sorted as expected along the carbon and nitrogen axes, with less intraspecific variability than interspecific variability. Results also indicated an isotopically distinct benthic and pelagic food web, as the benthic food web was more enriched in both nitrogen and carbon isotopes. Trophic positions from SIA supported this finding, resulting in the assignment of fishes to different trophic positions from those expected based on published dietary information. These differences can be explained largely by the habitat of the prey and the percentage of the diet that was scavenged. A mixing model estimated dietary contributions of prey similar to those of the known diet of Bathyraja trachura from stomach-content analysis (SCA). Linear regressions indicated that trophic positions calculated from SIA and SCA, when plotted against B. trachura total length for 32 individuals, exhibited similar variation and patterns. Only the T(P) from SCA yielded significant results (stomach content: P 0·05). © 2012 The Authors. Journal of Fish Biology © 2012 The Fisheries Society of the British Isles.

  16. Ingestion of microplastics by commercial fish off the Portuguese coast.

    Science.gov (United States)

    Neves, Diogo; Sobral, Paula; Ferreira, Joana Lia; Pereira, Tânia

    2015-12-15

    The digestive tract contents of 263 individuals from 26 species of commercial fish were examined for microplastics. These were found in 17 species, corresponding to 19.8% of the fish of which 32.7% had ingested more than one microplastic. Of all the fish that ingested microplastics, 63.5% was benthic and 36.5% pelagic species. A total of 73 microplastics were recorded, 48 (65.8%) being fibres and 25 (34.2%) being fragments. Polymers were polypropylene, polyethylene, alkyd resin, rayon, polyester, nylon and acrylic. The mean of ingested microplastics was 0.27 ± 0.63 per fish, (n=263). Pelagic fish ingested more particles and benthic fish ingested more fibres, but no significant differences were found. Fish with the highest number of microplastics were from the mouth of the Tagus river. Scomber japonicus registered the highest mean of ingested microplastics, suggesting its potential as indicator species to monitor and investigate trends in ingested litter, in the MSFD marine regions.

  17. Sustainability of capture of fish bycatch in the prawn trawling in northeastern Brazil

    Directory of Open Access Journals (Sweden)

    Carlos Antonio Beserra da Silva Junior

    Full Text Available The prawn fishery produces more discards than any other type of catch and captures a large quantity of immature individuals. This research aimed to assess the sustainability of capture of fish bycatch in prawn trawling. Each species was assessed according to two groups of criteria: (1 their relative vulnerability to capture by trawl and mortality due to this fishery (2 recovery capacity of the specie after a possible collapse of the population. Within each group, each species was ranked (1-3, being 1 the highest value, meaning the species is highly susceptible to capture or has a low resilience. A total of 8,894 individuals were caught, belonging to 28 families. The species with capture least sustainable were Stellifer rastrifer and Isopisthus parvipinnis. These latter species are highly susceptible since they are either benthic or demersal, and their diet may include benthic organism. Chirocentrodon bleekerianus and Anchoa tricolor were the most likely fishes to be sustainable since they are pelagic, they are least susceptible to capture by trawls, and also have a greater capacity to recover, as most individuals have bred before capture. Due to the fishery's multi-specific nature, it is difficult to implement mitigation measures for specific species. Thus, the creation of fishing exclusion zones should be considered as the most appropriate management measure.

  18. From crypsis to mimicry: changes in colour and the configuration of the visual system during ontogenetic habitat transitions in a coral reef fish.

    Science.gov (United States)

    Cortesi, Fabio; Musilová, Zuzana; Stieb, Sara M; Hart, Nathan S; Siebeck, Ulrike E; Cheney, Karen L; Salzburger, Walter; Marshall, N Justin

    2016-08-15

    Animals often change their habitat throughout ontogeny; yet, the triggers for habitat transitions and how these correlate with developmental changes - e.g. physiological, morphological and behavioural - remain largely unknown. Here, we investigated how ontogenetic changes in body coloration and of the visual system relate to habitat transitions in a coral reef fish. Adult dusky dottybacks, Pseudochromis fuscus, are aggressive mimics that change colour to imitate various fishes in their surroundings; however, little is known about the early life stages of this fish. Using a developmental time series in combination with the examination of wild-caught specimens, we revealed that dottybacks change colour twice during development: (i) nearly translucent cryptic pelagic larvae change to a grey camouflage coloration when settling on coral reefs; and (ii) juveniles change to mimic yellow- or brown-coloured fishes when reaching a size capable of consuming juvenile fish prey. Moreover, microspectrophotometric (MSP) and quantitative real-time PCR (qRT-PCR) experiments show developmental changes of the dottyback visual system, including the use of a novel adult-specific visual gene (RH2 opsin). This gene is likely to be co-expressed with other visual pigments to form broad spectral sensitivities that cover the medium-wavelength part of the visible spectrum. Surprisingly, the visual modifications precede changes in habitat and colour, possibly because dottybacks need to first acquire the appropriate visual performance before transitioning into novel life stages.

  19. Trace elements in Antarctic fish species and the influence of foraging habitats and dietary habits on mercury levels

    Energy Technology Data Exchange (ETDEWEB)

    Goutte, Aurélie, E-mail: aurelie.goutte@ephe.sorbonne.fr [École Pratique des Hautes Études (EPHE), SPL, UPMC Univ Paris 06, UMR 7619 METIS, F-75005, 4 place Jussieu, Paris (France); Cherel, Yves [Centre d' Etudes Biologiques de Chizé, UMR 7372, CNRS-Université de La Rochelle, 79360 Villiers-en-Bois (France); Churlaud, Carine [Littoral Environnement et Sociétés (LIENSs), UMR 7266, CNRS-Université de la Rochelle, 2 rue Olympe de Gouges, 17000 La Rochelle (France); Ponthus, Jean-Pierre [École Pratique des Hautes Études (EPHE), SPL, UPMC Univ Paris 06, UMR 7619 METIS, F-75005, 4 place Jussieu, Paris (France); Massé, Guillaume [Unité Mixte Internationale Takuvik, Pavillon Alexandre-Vachon, Université Laval, QC, Québec (Canada); Bustamante, Paco [Littoral Environnement et Sociétés (LIENSs), UMR 7266, CNRS-Université de la Rochelle, 2 rue Olympe de Gouges, 17000 La Rochelle (France)

    2015-12-15

    This study aims at describing and interpreting concentration profiles of trace elements in seven Antarctic fish species (N = 132 specimens) off Adélie Land. Ichthyofauna plays a key role in the Antarctic ecosystem, as they occupy various ecological niches, including cryopelagic (ice-associated), pelagic, and benthic habitats. Firstly, trace element levels in the studied specimens were similar to those previously observed in fish from the Southern Ocean. Apart from manganese and zinc, concentrations of arsenic, cadmium, copper, iron, mercury (Hg), nickel, selenium and silver differed among fish species. Muscle δ{sup 13}C and δ{sup 15}N values were determined to investigate whether the fish foraging habitats and dietary habits could explain Hg levels. Species and foraging habitat (δ{sup 13}C) were strong predictors for variations of Hg concentrations in muscle tissues. The highest Hg contamination was found in shallow benthic fish compared to cryopelagic and pelagic fish. This pattern was likely due to the methylation of Hg in the coastal sediment and the photodemethylation by ultraviolet radiation in surface waters. - Highlights: • Trace elements and stable isotopes were analyzed in seven Antarctic fish species. • Levels of trace elements in liver and in muscle differed among species. • Hg load was higher in benthic fish than in cryopelagic and pelagic fish. • These findings could be due to the high methylation rate of Hg in the sediment.

  20. Bottom fish assemblages at the shelf and continental slope off East Greenland

    DEFF Research Database (Denmark)

    Jørgensen, Ole A; Hvingel, Carsten; Møller, P.R.

    2015-01-01

    During 2006 and 2008 two bottom trawl surveys were conducted at East Greenland to 72°N covering depths down to 1500 m. In the 149 trawl hauls in total 113 fish species were recorded of which 37 were considered pelagic and excluded from the analyses. As a first step the abundance data for the 76 b...

  1. Bottom fish assemblages at the shelf and continental slope off East Greenland

    DEFF Research Database (Denmark)

    Jørgensen, Ole A; Hvingel, Carsten; Møller, P.R.

    2015-01-01

    During 2006 and 2008 two bottom trawl surveys were conducted at East Greenland to 72°N covering depths down to 1500 m. In the 149 trawl hauls in total 113 fish species were recorded of which 37 were considered pelagic and excluded from the analyses. As a first step the abundance data for the 76 b...

  2. Fish geographic distribution range shifts as recorded in the eastern Mediterranean during the last 5 Ma

    Science.gov (United States)

    Agiadi, Konstantina; Karakitsios, Vasileios

    2013-04-01

    Marine fish species geographic distribution is known to reflect the individuals' response to changes in oceanic circulation, temperature, salinity, local geography, other species presence and/or abundance, food availability and other biotic and abiotic factors1. New and published records on the eastern Mediterranean fish, from the end of the Messinian salinity crisis to the present, are here examined, in correlation with palaeoenvironmental data, in order to draw conclusions regarding the abiotic parameters most affecting the fish distribution during the last 5 Ma in this area. This investigation shows that the environmental variables do not affect the fish fauna in a uniform way. Rather, three faunal components may be separated, each occupying a different depth range in the water column. Pelagic fish dwell for the most part on the uppermost 200 m, and their distribution seems to be affected mainly by climatic variability. Mesopelagic fish occupy mostly intermediate depths and their distribution is regulated by the prevailing water circulation patterns. Benthic and benthopelagic fish, which live close or in contact with the sea bottom, are mostly affected by the nature and depth of the substratum. Furthermore, examples from the Ionian2,3 and the Aegean Sea indicate that, during the last 5 Ma, large-scale range shifts, similar to those occurring today, frequently took place in this area. This observation significantly alters previously views on the stability of fish assemblages and the processes occurring today. Acknowledgments. This research has been co-financed by the European Union (European Social Fund - ESF) and Greek national funds through the Operational Program "Education and Lifelong Learning" of the National Strategic Reference Framework (NSRF) - Research Funding Program: Heracleitus II. Investing in knowledge society through the European Social Fund. References 1 Wooton RJ. 1998. Ecology of teleost fishes,Fish and Fisheries Series,24.Kluwers.392p. 2

  3. Identifying marine pelagic ecosystem management objectives and indicators

    DEFF Research Database (Denmark)

    Trenkel, Verena M.; Hintzen, Niels T.; Farnsworth, Keith D.

    2015-01-01

    International policy frameworks such as the Common Fisheries Policy and the European Marine Strategy Framework Directive define high-level strategic goals for marine ecosystems. Strategic goals are addressed via general and operational management objectives. To add credibility and legitimacy...... to the development of objectives, for this study stakeholders explored intermediate level ecological, economic and social management objectives for Northeast Atlantic pelagic ecosystems. Stakeholder workshops were undertaken with participants being free to identify objectives based on their own insights and needs....... Overall 26 objectives were proposed, with 58% agreement in proposed objectives between two workshops. Based on published evidence for pressure-state links, examples of operational objectives and suitable indicators for each of the 26 objectives were then selected. It is argued that given the strong...

  4. Factors influencing movement of two migratory fishes within the tailrace of a large neotropical dam and their implications for hydropower impacts

    Science.gov (United States)

    Suzuki, F. M.; Dunham, Jason; Silva, L. G. M.; Alves, C. B. M.; Pompeu, P.S.

    2017-01-01

    Fish attempting to move upstream through hydroelectric dams can be trapped and killed in turbines. Understanding fish movement patterns can provide useful insights for how to manage dam operations to minimize fish kill in turbines. We evaluated the movements of two migratory fish (Curimba-Prochilodus argenteus and Mandi-Pimelodus maculatus) using acoustic telemetry in the tailrace of Três Marias Dam (São Francisco River, Brazil) from 31 October 2011 to 16 February 2012. The majority of tagged fish left the tailrace in less than one week; however, some individuals returned, performing several visits to the tailrace. Mandi remained longer in the tailrace than Curimba. The number of visits was influenced by diel period, turbine and spillway discharge. Although the diel period was the only important contributor to the visits performed by Curimba, the movements of Mandi were significantly influenced by three factors. We found that whereas Curimba was predominantly diurnal, Mandi showed nocturnal habits. Additionally, visits of Mandi were significantly greater during higher turbine and spillway discharge. We discuss the implications of these results for understanding fish movements in the Três Marias Dam tailrace and their potential implications for adapting hydroelectric operations to minimize fish kills.

  5. Many small pelagic fish species spawn in areas where their eggs ...

    African Journals Online (AJOL)

    spamer

    interaction of upwelling plumes and shelf waves ... 9: Size frequency distributions of (a–c) anchovy larvae and (d–f) sardine larvae in the inshore, midshore ... Crawford. (1981) reported that, before the collapse of the sardine resource in ...

  6. timating the abundance of pelagic fish in the Benguela system off ...

    African Journals Online (AJOL)

    spamer

    IN SITU MEASUREMENTS OF THE ACOUSTIC TARGET STRENGTH OF. CAPE HORSE MACKEREL .... Estimated speed of sound (m s-1). 1 500. Absorption ..... because horse mackerel react strongly to light (Koike et al. 1991, Barange and ...

  7. Assimilation of diazotrophic nitrogen into pelagic food webs.

    Directory of Open Access Journals (Sweden)

    Ryan J Woodland

    Full Text Available The fate of diazotrophic nitrogen (N(D fixed by planktonic cyanobacteria in pelagic food webs remains unresolved, particularly for toxic cyanophytes that are selectively avoided by most herbivorous zooplankton. Current theory suggests that N(D fixed during cyanobacterial blooms can enter planktonic food webs contemporaneously with peak bloom biomass via direct grazing of zooplankton on cyanobacteria or via the uptake of bioavailable N(D (exuded from viable cyanobacterial cells by palatable phytoplankton or microbial consortia. Alternatively, N(D can enter planktonic food webs post-bloom following the remineralization of bloom detritus. Although the relative contribution of these processes to planktonic nutrient cycles is unknown, we hypothesized that assimilation of bioavailable N(D (e.g., nitrate, ammonium by palatable phytoplankton and subsequent grazing by zooplankton (either during or after the cyanobacterial bloom would be the primary pathway by which N(D was incorporated into the planktonic food web. Instead, in situ stable isotope measurements and grazing experiments clearly documented that the assimilation of N(D by zooplankton outpaced assimilation by palatable phytoplankton during a bloom of toxic Nodularia spumigena Mertens. We identified two distinct temporal phases in the trophic transfer of N(D from N. spumigena to the plankton community. The first phase was a highly dynamic transfer of N(D to zooplankton with rates that covaried with bloom biomass while bypassing other phytoplankton taxa; a trophic transfer that we infer was routed through bloom-associated bacteria. The second phase was a slowly accelerating assimilation of the dissolved-N(D pool by phytoplankton that was decoupled from contemporaneous variability in N. spumigena concentrations. These findings provide empirical evidence that N(D can be assimilated and transferred rapidly throughout natural plankton communities and yield insights into the specific processes

  8. Fish allergy and fish allergens

    DEFF Research Database (Denmark)

    Kuehn, A; Hilger, Christiane; Ollert, Markus

    2016-01-01

    but patients with this phenotype constitute an important sub-group among fish-allergic individuals. 2. Newly identified fish allergens, enolases, aldolases, and fish gelatin, are of high relevance as the majority of the fish-allergic individuals seem to develop specific IgE against these proteins. The present...

  9. Changes in fish diets and food web mercury bioaccumulation induced by an invasive planktivorous fish

    Science.gov (United States)

    Eagles-Smith, Collin A.; Suchanek, Thomas H.; Colwell, Arthur E.; Anderson, Norman L.; Moyle, Peter B.

    2008-01-01

    The invasion, boom, collapse, and reestablishment of a population of the planktivorous threadfin shad in Clear Lake, California, USA, were documented over a 20-year period, as were the effects of changing shad populations on diet and mercury (Hg) bioaccumulation in nearshore fishes. Threadfin shad competitively displaced other planktivorous fish in the lake, such as inland silversides, young-of-year (YOY) largemouth bass, and YOY bluegill, by reducing zooplankton abundance. As a result, all three species shifted from a diet that was dominated by zooplankton to one that was almost entirely zoobenthos. Stable carbon isotopes corroborated this pattern with each species becoming enriched in δ13C, which is elevated in benthic vs. pelagic organisms. Concomitant with these changes, Hg concentrations increased by ∼50% in all three species. In contrast, obligate benthivores such as prickly sculpin showed no relationship between diet or δ13C and the presence of threadfin shad, suggesting that effects of the shad were not strongly linked to the benthic fish community. There were also no changes in Hg concentrations of prickly sculpin. The temporary extirpation of threadfin shad from the lake resulted in zooplankton densities, foraging patterns, isotope ratios, and Hg concentrations in pelagic fishes returning to pre-shad values. These results indicate that even transient perturbations of the structure of freshwater food webs can result in significant alterations in the bioaccumulation of Hg and that food webs in lakes can be highly resilient.

  10. Ontogenetic, spatial and temporal variation in trophic level and diet of Chukchi Sea fishes

    Science.gov (United States)

    Marsh, Jennifer M.; Mueter, Franz J.; Iken, Katrin; Danielson, Seth

    2017-01-01

    Climate warming and increasing development are expected to alter the ecosystem of the Chukchi Sea, including its fish communities. As a component of the Arctic Ecosystem Integrated Survey, we assessed the ontogenetic, spatial and temporal variability of the trophic level and diet of key fish species in the Chukchi Sea using N and C stable isotopes. During August and September of 2012 and 2013, 16 common fish species and two primary, invertebrate consumers were collected from surface, midwater and bottom trawls within the eastern Chukchi Sea. Linear mixed-effects models were used to detect possible variation in the relationship between body length and either δ13C or δ15N values among water masses and years for 13 fish species with an emphasis on Arctic cod (Boreogadus saida). We also examined the fish community isotopic niche space, trophic redundancy, and trophic separation within each water mass as measures of resiliency of the fish food web. Ontogenetic shifts in trophic level and diet were observed for most species and these changes tended to vary by water mass. As they increased in length, most fish species relied more on benthic prey with the exception of three forage fish species (walleye pollock, Gadus chalcogrammus, capelin, Mallotus villosus, and Pacific sandlance, Ammodytes hexapterus). Species that exhibited interannual differences in diet and trophic level were feeding at lower trophic levels and consumed a more pelagic diet in 2012 when zooplankton densities were higher. Fish communities occupied different isotopic niche spaces depending on water mass association. In more northerly Arctic waters, the fish community occupied the smallest isotopic niche space and relied heavily on a limited range of intermediate δ13C prey, whereas in warmer, nutrient-rich Bering Chukchi Summer Water, pelagic prey was important. In the warmest, Pacific-derived coastal water, fish consumed both benthic and pelagic prey. Examining how spatial gradients in trophic

  11. Spatial variability of benthic-pelagic coupling in an estuary ecosystem: consequences for microphytobenthos resuspension phenomenon.

    Directory of Open Access Journals (Sweden)

    Martin Ubertini

    Full Text Available The high degree of physical factors in intertidal estuarine ecosystem increases material processing between benthic and pelagic compartments. In these ecosystems, microphytobenthos resuspension is a major phenomenon since its contribution to higher trophic levels can be highly significant. Understanding the sediment and associated microphytobenthos resuspension and its fate in the water column is indispensable for measuring the food available to benthic and pelagic food webs. To identify and hierarchize the physical/biological factors potentially involved in MPB resuspension, the entire intertidal area and surrounding water column of an estuarine ecosystem, the Bay des Veys, was sampled during ebb tide. A wide range of physical parameters (hydrodynamic regime, grain size of the sediment, and suspended matter and biological parameters (flora and fauna assemblages, chlorophyll were analyzed to characterize benthic-pelagic coupling at the bay scale. Samples were collected in two contrasted periods, spring and late summer, to assess the impact of forcing variables on benthic-pelagic coupling. A mapping approach using kriging interpolation enabled us to overlay benthic and pelagic maps of physical and biological variables, for both hydrological conditions and trophic indicators. Pelagic Chl a concentration was the best predictor explaining the suspension-feeders spatial distribution. Our results also suggest a perennial spatio-temporal structure of both benthic and pelagic compartments in the ecosystem, at least when the system is not imposed to intense wind, with MPB distribution controlled by both grain size and bathymetry. The benthic component appeared to control the pelagic one via resuspension phenomena at the scale of the bay. Co-inertia analysis showed closer benthic-pelagic coupling between the variables in spring. The higher MPB biomass observed in summer suggests a higher contribution to filter-feeders diets, indicating a higher

  12. Not all sharks are "swimming noses": variation in olfactory bulb size in cartilaginous fishes.

    Science.gov (United States)

    Yopak, Kara E; Lisney, Thomas J; Collin, Shaun P

    2015-03-01

    Olfaction is a universal modality by which all animals sample chemical stimuli from their environment. In cartilaginous fishes, olfaction is critical for various survival tasks including localizing prey, avoiding predators, and chemosensory communication with conspecifics. Little is known, however, about interspecific variation in olfactory capability in these fishes, or whether the relative importance of olfaction in relation to other sensory systems varies with regard to ecological factors, such as habitat and lifestyle. In this study, we have addressed these questions by directly examining interspecific variation in the size of the olfactory bulbs (OB), the region of the brain that receives the primary sensory projections from the olfactory nerve, in 58 species of cartilaginous fishes. Relative OB size was compared among species occupying different ecological niches. Our results show that the OBs maintain a substantial level of allometric independence from the rest of the brain across cartilaginous fishes and that OB size is highly variable among species. These findings are supported by phylogenetic generalized least-squares models, which show that this variability is correlated with ecological niche, particularly habitat. The relatively largest OBs were found in pelagic-coastal/oceanic sharks, especially migratory species such as Carcharodon carcharias and Galeocerdo cuvier. Deep-sea species also possess large OBs, suggesting a greater reliance on olfaction in habitats where vision may be compromised. In contrast, the smallest OBs were found in the majority of reef-associated species, including sharks from the families Carcharhinidae and Hemiscyllidae and dasyatid batoids. These results suggest that there is great variability in the degree to which these fishes rely on olfactory cues. The OBs have been widely used as a neuroanatomical proxy for olfactory capability in vertebrates, and we speculate that differences in olfactory capabilities may be the result of

  13. Landscape-scale Habitat Templates and Life Histories of Endangered and Invasive Fish Species in Large Rivers of the Mid-Continent USA (Invited)

    Science.gov (United States)

    Jacobson, R. B.; Braaten, P. J.; Chapman, D.; DeLonay, A. J.

    2013-12-01

    Many fish species migrate through river systems to complete their life cycles, occupying specific habitats during specific life stages. Regional geomorphology sets a template for their habitat-use patterns and ontogenetic development. In large rivers of the Mid-continent USA, understanding of relations of fish life histories to landscape-scale habitat templates informs recovery of endangered species and prevention of spread of invasive species. The endangered pallid sturgeon has evolved in the Missouri-Mississippi river system over 150 Ma. Its present-day distribution probably results from extensive drainage re-arrangements during the Pleistocene, followed by contemporary fragmentation. The reproductive and early life-stage needs of pallid sturgeon encompass hundreds of km, as adults migrate upstream to spawn and free embryos and larvae disperse downstream. Spawning requires coarse, hard substrate for incubation of adhesive eggs but adult pallid sturgeon are found predominately over sand, indicating that coarse substrate is a critical but transient habitat need. Once hatched, free-embryos initiate 9-17 days of downstream dispersal that distributes them over several hundreds of km. Lotic conditions at the dispersal terminus are required for survival. Persistent recruitment failure has been attributed to dams and channelization, which have fragmented migration and dispersal corridors, altered flow regimes, and diminished rearing habitats. Key elements of the natural history of this species remain poorly understood because adults are rare and difficult to observe, while the earliest life stages are nearly undetectable. Recent understanding has been accelerated using telemetry and hydroacoustics, but such assessments occur in altered systems and may not be indicative of natural behaviors. Restoration activities attempt - within considerable uncertainty -- to restore elements of the habitat template where they are needed. In comparison, invasive Asian carps have been

  14. New Method for the Quantitative Analysis of Smear Slides in Pelagic and Hemi-Pelagic Sediments of the Bering Sea

    Science.gov (United States)

    Drake, M. K.; Aiello, I. W.; Ravelo, A. C.

    2014-12-01

    Petrographic microscopy of smear slides is the standard method to initially investigate marine sediments in core sediment studies (e.g. IODP expeditions). The technique is not commonly used in more complex analysis due to concerns over the subjectivity of the method and variability in operator training and experience. Two initiatives sponsored by Ocean Leadership, a sedimentology training workshop and a digital reference of smear slide components (Marsaglia et al., 2013) have been implemented to address the need for advanced training. While the influence of subjectivity on the quality of data has yet to be rigorously tested, the lack of standardization in the current method of smear slide analysis (SSA) remains a concern. The relative abundance of the three main components, (total diatoms, silt-to-sand sized siliciclastics, and clay minerals) of high and low density Bering Sea hemi-pelagic sediments from the ocean margin (Site U144; Site U1339) and pelagic sediments from the open-ocean (Site U1340) were analyzed. Our analyses show visual estimation is a reproducible method to quantify the relative abundance of the main sediment components. Furthermore, we present a modified method for SSA, with procedural changes objectively guided by statistical analyses, including constraints to increase randomness and precision in both the preparation and analysis of the smear slide. For example, repeated measure ANOVAs found a smear slide could be accurately quantified by counting three fields of view. Similarly, the use of replicate smear slides to quantify a sample was analyzed. Finally, the data produced from this modified SSA shows a strong correlation to continuously logged physical parameters of sediment such as gamma ray attenuation (Site U1339 r2= 0.41; Site U1340 r2= 0.36). Therefore, the modified SSA combined with other independent methods (e.g. laser particle size analysis, scanning electron microscopy, and physical properties) can be a very effective tool for the

  15. Large-Scale Examination of Spatio-Temporal Patterns of Drifting Fish Aggregating Devices (dFADs from Tropical Tuna Fisheries of the Indian and Atlantic Oceans.

    Directory of Open Access Journals (Sweden)

    Alexandra Maufroy

    Full Text Available Since the 1990s, massive use of drifting Fish Aggregating Devices (dFADs to aggregate tropical tunas has strongly modified global purse-seine fisheries. For the first time, a large data set of GPS positions from buoys deployed by French purse-seiners to monitor dFADs is analysed to provide information on spatio-temporal patterns of dFAD use in the Atlantic and Indian Oceans during 2007-2011. First, we select among four classification methods the model that best separates "at sea" from "on board" buoy positions. A random forest model had the best performance, both in terms of the rate of false "at sea" predictions and the amount of over-segmentation of "at sea" trajectories (i.e., artificial division of trajectories into multiple, shorter pieces due to misclassification. Performance is improved via post-processing removing unrealistically short "at sea" trajectories. Results derived from the selected model enable us to identify the main areas and seasons of dFAD deployment and the spatial extent of their drift. We find that dFADs drift at sea on average for 39.5 days, with time at sea being shorter and distance travelled longer in the Indian than in the Atlantic Ocean. 9.9% of all trajectories end with a beaching event, suggesting that 1,500-2,000 may be lost onshore each year, potentially impacting sensitive habitat areas, such as the coral reefs of the Maldives, the Chagos Archipelago, and the Seychelles.

  16. Taxonomic and trait based recolonization dynamics of a riverine fish assemblage following a large scale human mediated disturbance: the red mud disaster in Hungary

    Directory of Open Access Journals (Sweden)

    Tibor Eros

    2015-12-01

    Full Text Available We examined the recovery of a fish assemblage following the catastrophic spill of highly alkaline (pH~13 red sludge into a lowland river (i to characterize taxonomic and trait based colonization of fishes in the river in the first three years of the recovery, and (ii to determine which structural and trait based variables best predicted colonization. Species richness showed comparable values to pre-disturbance state less than one year after the spill. We found only moderate changes in the dominance of the most abundant species between pre- and post-disturbance periods, and consistent changes in the relative abundance of some rare species during the post-disturbance period. Frequency of occurrence (% of the fishes in the watershed, and their relative abundance (% proved to be the most important predictor variables in colonization, whereas trait based variables had a less important role. Our study about one of the largest scale and most serious documented fish kill shows that both taxonomic and trait based structure of fish assemblages can regenerate remarkable fast in a modified river and also shows that unfortunate chemical spills provide insights into the assembly of stream fish assemblages.

  17. Fractal hypothesis of the pelagic microbial ecosystem - Can simple ecological principles lead to self-similar complexity in the pelagic microbial food web?

    Directory of Open Access Journals (Sweden)

    Selina eVåge

    2015-12-01

    Full Text Available Trophic interactions are highly complex and modern sequencing techniques reveal enormous biodiversity across multiple scales in marine microbial communities . Within the chemically and physically relatively homogeneous pelagic environment, this calls for an explanation beyond spatial and temporal heterogeneity. Based on observations of simple parasite-host and predator-prey interactions occurring at different trophic levels and levels of phylogenetic resolution, we present a theoretical perspective on this enormous biodiversity, discussing in particular self-similar aspects of pelagic microbial food web organization. Fractal methods have been used to describe a variety of natural phenomena, with studies of habitat structures being an application in ecology. In contrast to mathematical fractals where pattern generating rules are readily known, however, identifying mechanisms that lead to natural fractals is not straight-forward. Here we put forward the hypothesis that trophic interactions between pelagic microbes may be organized in a fractal-like manner, with the emergent network resembling the structure of the Sierpinski triangle. We discuss a mechanism that could be underlying the formation of repeated patterns at different trophic levels and discuss how this may help understand characteristic biomass size-spectra that hint at scale-invariant properties of the pelagic environment. If the idea of simple underlying principles leading to a fractal-like organization of the pelagic food web could be formalized, this would extend an ecologists mindset on how biological complexity could be accounted for. It may furthermore benefit ecosystem modeling by facilitating adequate model resolution across multiple scales.

  18. Marine fish diversity and habitat use along the western coast of the Black Sea

    Directory of Open Access Journals (Sweden)

    Viorel Dumitru Gavril

    2015-11-01

    I identified 34 species of fish in the Shabla-Tyulenovo area and 39 species in the Constanta area, of which 19 species preferred sandy bottoms, 21 rocky bottoms, 16 rocky habitats with Cystoseira sp., 19 man-made structures and 9 were pelagic. For 7 species habitat preferences could not be determined as a result of capture only by fishing. In conclusion, the scuba visual transects along with fishing methods provide a relevant image to the current state of the fish diversity along the western coast of the Black Sea.

  19. Quantifying the interplay between environmental and social effects on aggregated-fish dynamics

    CERN Document Server

    Capello, Manuela; Cotel, Pascal; Deneubourg, Jean-Louis; Dagorn, Laurent

    2011-01-01

    Demonstrating and quantifying the respective roles of social interactions and external stimuli governing fish dynamics is key to understanding fish spatial distribution. If seminal studies have contributed to our understanding of fish spatial organization in schools, little experimental information is available on fish in their natural environment, where aggregations often occur in the presence of spatial heterogeneities. Here, we applied novel modeling approaches coupled to accurate acoustic tracking for studying the dynamics of a group of gregarious fish in a heterogeneous environment. To this purpose, we acoustically tracked with submeter resolution the positions of twelve small pelagic fish (Selar crumenophthalmus) in the presence of an anchored floating object, constituting a point of attraction for several fish species. We constructed a field-based model for aggregated-fish dynamics, deriving effective interactions for both social and external stimuli from experiments. We tuned the model parameters that...

  20. Climate change is projected to reduce carrying capacity and redistribute species richness in North Pacific pelagic marine ecosystems.

    Science.gov (United States)

    Woodworth-Jefcoats, Phoebe A; Polovina, Jeffrey J; Drazen, Jeffrey C

    2017-03-01

    Climate change is expected to impact all aspects of marine ecosystems, including fisheries. Here, we use output from a suite of 11 earth system models to examine projected changes in two ecosystem-defining variables: temperature and food availability. In particular, we examine projected changes in epipelagic temperature and, as a proxy for food availability, zooplankton density. We find that under RCP8.5, a high business-as-usual greenhouse gas scenario, increasing temperatures may alter the spatial distribution of tuna and billfish species richness across the North Pacific basin. Furthermore, warmer waters and declining zooplankton densities may act together to lower carrying capacity for commercially valuable fish by 2-5% per decade over the 21st century. These changes have the potential to significantly impact the magnitude, composition, and distribution of commercial fish catch across the pelagic North Pacific. Such changes will in turn ultimately impact commercial fisheries' economic value. Fishery managers should anticipate these climate impacts to ensure sustainable fishery yields and livelihoods.

  1. The pelagic birds of Tuxedni wilderness, Alaska: Annual report

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report summarizes a study of seabird colonies on Chisik and Duck Islands comprising the Tuxedni Wilderness in lower Cook Inlet. A description of the study area,...

  2. Astaxanthin production in marine pelagic copepods grazing on two different phytoplankton diets

    Science.gov (United States)

    Van Nieuwerburgh, Lies; Wänstrand, Ingrid; Liu, Jianguo; Snoeijs, Pauli

    2005-02-01

    The red carotenoid astaxanthin is a powerful natural antioxidant of great importance in aquatic food webs where it is abundant in eggs and body tissues of fish and crustaceans. Little is known about the impact of the phytoplankton diet on astaxanthin production in copepods, its major pelagic producers. We followed the transfer of carotenoids from phytoplankton to copepods in a mesocosm experiment on the northern Atlantic coast (Norway) and recorded the astaxanthin production in copepods. Wild copepods grazed on nutrient-manipulated phytoplankton blooms, which differed in community composition and nutrient status (nitrogen or silicate limitation). The copepod pigments consisted mainly of free astaxanthin and mono- and diesters of astaxanthin. We found no significant difference in astaxanthin production per copepod individual or per unit C depending on the phytoplankton community. However, in the mesocosms astaxanthin per unit C decreased compared with natural levels, probably through a lower demand for photoprotection by the copepods in the dense phytoplankton blooms. The total astaxanthin production per litre was higher in the silicate-limited mesocosms through increased copepod density. Pigment ratio comparisons suggested that the copepod diet here consisted more of diatoms than in the nitrogen-limited mesocosms. Silicate-saturated diatoms were less grazed, possibly because they could invest more in defence mechanisms against their predators. Our study suggests that the production of astaxanthin in aquatic systems can be affected by changes in nutrient dynamics mediated by phytoplankton community composition and copepod population growth. This bottom-up force may have implications for antioxidant protection at higher trophic levels in the food web.

  3. Antarctic Fishes.

    Science.gov (United States)

    Eastman, Joseph T.; DeVries, Arthur L.

    1986-01-01

    Explains the adaptations to Antarctic waters that Notothenioidei, a group of advanced bony fishes, have exhibited. Discusses the fishes' mechanisms of production of antifreeze properties and their capacities for neutral buoyancy in water. (ML)

  4. Hide and seek in the open sea: pelagic camouflage and visual countermeasures.

    Science.gov (United States)

    Johnsen, Sönke

    2014-01-01

    Camouflage is exceptionally challenging in pelagic environments because of their featureless nature. Thus, it is perhaps no surprise that pelagic species have evolved highly sophisticated cryptic strategies, three of which-transparency, mirrors, and counter illumination-are rare or absent in other habitats. Pelagic visual systems are equally complex, and several visual capabilities, including UV and polarization sensitivity and intraocular filters, are thought to facilitate detection of camouflaged animals. This article reviews the optical nature of the pelagic realm and both the camouflage and camouflage-breaking strategies of its inhabitants, focusing primarily on underlying principles and what remains to be discovered. A theme throughout is that far more is known about the structures of the optical and visual systems involved than about their function, an imbalance that is due primarily to the rarity of observations of undisturbed behavior.

  5. 2013 Small Pelagics Acoustic/Trawl Survey (PC1306, EK60)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Objectives of the 2013 Small Pelagics Acoustic/Trawl Survey were to sample the northern Gulf of Mexico with a 90-ft high opening trawl to facilitate assessments of...

  6. 75 FR 33733 - Fisheries Off West Coast States; Coastal Pelagic Species Fisheries; Closure

    Science.gov (United States)

    2010-06-15

    ... Fisheries Off West Coast States; Coastal Pelagic Species Fisheries; Closure AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA), Commerce. ACTION... as part of the live bait fishery or incidental to other fisheries; the incidental harvest of...

  7. 2013 Small Pelagics Acoustic/Trawl Survey (PC1306, ME70)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Objectives of the 2013 Small Pelagics Acoustic/Trawl Survey were to sample the northern Gulf of Mexico with a 90-ft high opening trawl to facilitate assessments of...

  8. EPA2011 Microbial & nutrient database - Evaluating the ecological health of Puget Sound's pelagic foodweb

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — To evaluate effects of human influence on the health of Puget Sound's pelagic ecosystems, we propose a sampling program across multiple oceanographic basins...

  9. Townet database - Evaluating the ecological health of Puget Sound's pelagic foodweb

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — To evaluate effects of human influence on the health of Puget Sound's pelagic ecosystems, we propose a sampling program across multiple oceanographic basins...

  10. EPA Townetting CTD casts - Evaluating the ecological health of Puget Sound's pelagic foodweb

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — To evaluate effects of human influence on the health of Puget Sound's pelagic ecosystems, we propose a sampling program across multiple oceanographic basins...

  11. Fish Dishes.

    Science.gov (United States)

    Derby, Marie

    2003-01-01

    Describes an art project that was inspired by Greek pottery, specifically dishes shaped as fish. Explains that fourth-grade students drew a fish shape that was later used to create their clay version of the fish. Discusses how the students examined the pottery to make decisions about color and design. (CMK)

  12. Fish and long-chain n-3 polyunsaturated fatty acid intakes during pregnancy and risk of postpartum depression: a prospective study based on a large national birth cohort

    DEFF Research Database (Denmark)

    Strøm, Marin; Mortensen, Erik Lykke; Halldorsson, Thorhallur I

    2009-01-01

    that long-chain n-3 polyunsaturated fatty acids (PUFAs) might have a beneficial effect on depression. OBJECTIVE: The objective was to explore the association between intake of fish and n-3 PUFAs during pregnancy and PPD in the Danish National Birth Cohort (DNBC). DESIGN: Exposure information from the DNBC...... was linked to the Danish patient and prescription registries for data on clinically identified cases of depression up to 1 y postpartum. Intake of fish and n-3 PUFAs was assessed in midpregnancy with a food-frequency questionnaire. Admission to the hospital for PPD (PPD-admission) and prescription...... of antidepressants (PPD-prescription) were treated as separate outcomes. A total of 54,202 women were included in the present study sample. RESULTS: Rates of depression were 0.3% (PPD-admission) and 1.6% (PPD-prescription). No association was observed between fish intake and risk of PPD-admission [crude odds ratio...

  13. Comagmatic granophyric granite in the Fish Canyon Tuff, Colorado: Implications for magma-chamber processes during a large ash-flow eruption

    Science.gov (United States)

    Lipman, P.; Dungan, M.; Bachmann, Olivier

    1997-01-01

    The 27.8 Ma Fish Canyon Tuff, a vast ash-flow sheet (??5000 km3) of uniform phenocryst-rich dacite, is representative of "monotonous intermediate" eruptions from a magma chamber that lacked compositional gradients. Sparse small fragments of comagmatic granophyre in late-erupted tuff and postcaldera lava, having mineral compositions indistinguishable from phenocrysts in the tuff and precaldera lava-like rocks, record complex events in the Fish Canyon chamber just prior to eruption. Sanidine phenocrysts in the granophyre preserve zoning evidence of mingling with andesitic magma, then shattering by decompression and volatile loss accompanying early Fish Canyon eruptions before overgrowth by granophyre. The textural and chemical disequilibria indicate that the eruption resulted from batholith-scale remobilization of a shallow subvolcanic chamber, contrary to previous interpretations of magma storage and phenocryst growth in the lower crust.

  14. Investigation of XoxF methanol dehydrogenases reveals new methylotrophic bacteria in pelagic marine and freshwater ecosystems.

    Science.gov (United States)

    Ramachandran, Arthi; Walsh, David A

    2015-10-01

    The diversity and distribution of methylotrophic bacteria have been investigated in the oceans and lakes using the methanol dehydrogenase mxaF gene as a functional marker. However, pelagic marine (OM43) and freshwater (LD28 and PRD01a001B) methylotrophs within the Betaproteobacteria lack mxaF, instead possessing a related xoxF4-encoded methanol dehydrogenase. Here, we developed and employed xoxF4 as a complementary functional gene marker to mxaF for studying methylotrophs in aquatic environment. Using xoxF4, we detected OM43-related and LD28-related methylotrophs in the ocean and freshwaters of North America, respectively, and showed the coexistence of these two lineages in a large estuarine system (St Lawrence Estuary). Gene expression patterns of xoxF4 supported a positive relationship between xoxF4-containing methylotroph activity and spring time productivity, suggesting phytoplankton blooms are a source of methylotrophic substrates. Further investigation of methanol dehydrogenase diversity in pelagic ecosystems using comparative metagenomics provided strong support for a widespread distribution of xoxF4 (as well as several distinct xoxF5) containing methylotrophs in marine and freshwater surface waters. In total, these results demonstrate a geographical distribution of OM43/LD28-related methylotrophs that includes marine and freshwaters and suggest that methylotrophy occurring in the water column is an important component of lake and estuary carbon cycling and biogeochemistry.

  15. Potential retention effect at fish farms boosts zooplankton abundance

    Science.gov (United States)

    Fernandez-Jover, D.; Toledo-Guedes, K.; Valero-Rodríguez, J. M.; Fernandez-Gonzalez, V.; Sanchez-Jerez, P.

    2016-11-01

    Coastal aquaculture activities influence wild macrofauna in natural environments due to the introduction of artificial structures, such as floating cages, that provide structural complexity in the pelagic system. This alters the abundance and distribution of the affected species and also their feeding behaviour and diet. Despite this, the effects of coastal aquaculture on zooplankton assemblages and the potential changes in their abundance and distribution remain largely unstudied. Traditional plankton sampling hauls between the farm mooring systems entail some practical difficulties. As an alternative, light traps were deployed at 2 farms in the SW Mediterranean during a whole warm season. Total zooplankton capture by traps at farms was higher than at control locations on every sampling night. It ranged from 3 to 10 times higher for the taxonomic groups: bivalvia, cladocera, cumacea, fish early-life-stages, gastropoda, polychaeta and tanaidacea; 10-20 times higher for amphipoda, chaetognatha, isopoda, mysidacea and ostracoda, and 22 times higher for copepoda and the crustacean juvenile stages zoea and megalopa. Permutational analysis showed significant differences for the most abundant zooplankton groups (copepoda, crustacean larvae, chaetognatha, cladocera, mysidacea and polychaeta). This marked incremental increase in zooplankton taxa at farms was consistent, irrespective of the changing environmental variables registered every night. Reasons for the greater abundance of zooplankton at farms are discussed, although results suggest a retention effect caused by cage structures rather than active attraction through physical or chemical cues.

  16. United Fishing Agency Fish Auction Sampling Data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Contains information collected such as: lengths, weights, sex, quantity, species, etc. from various bottomfish and pelagic species during frequent visits to the...

  17. Viruses in subarctic lakes and their impact on benthic and pelagic bacteria.

    Science.gov (United States)

    Säwström, Christin; Ask, Jenny; Karlsson, Jan

    2009-12-01

    Virus-bacterium interactions were investigated in the pelagic and benthic habitats in a set of lakes along an altitudinal gradient in the subarctic northern Sweden. Viral and bacterial abundances showed a significant variation between the lakes, with the highest benthic microbial abundances recorded in a high-altitude lake [993 m above sea level (a.s.l.)], whereas the highest pelagic microbial abundances were found in a low-altitude lake (270 m a.s.l.). In the pelagic habitat, there was also a distinct difference in microbial abundances between the summer-autumn and the winter sampling occasion. A positive relationship was noted between viruses and bacteria in both the pelagic and the benthic habitats. Visibly virus-infected bacterial cells were uncommon in the pelagic habitat and undetectable in the benthos. Both lytic and lysogenic pelagic viral production rates were undetectable or low; thus, a possible explanation for the relative high viral abundances found in the water column could be an allochthonous input of viruses or release of sediment-derived viruses. Overall, our results provide novel information about the relevance of viruses in the subarctic region and indicate that viruses play only a minor role in the nutrient and carbon cycling in the microbial communities of subarctic lakes.

  18. Interspecies and spatial trends in polycyclic aromatic hydrocarbons (PAHs) in Atlantic and Mediterranean pelagic seabirds

    Energy Technology Data Exchange (ETDEWEB)

    Roscales, Jose L., E-mail: jlroscales@iqog.csic.es [Research Institute of Biodiversity (IRBio) and department of Animal Biology (Vertebrates), Barcelona University, Av Diagonal 645, 08028 Barcelona (Spain); Department of Instrumental Analysis and Environmental Chemistry, Institute of Organic Chemistry, CSIC, Juan de la Cierva 3, 28006 Madrid (Spain); Gonzalez-Solis, Jacob [Research Institute of Biodiversity (IRBio) and department of Animal Biology (Vertebrates), Barcelona University, Av Diagonal 645, 08028 Barcelona (Spain); Calabuig, Pascual [Wildlife Fauna Tafira Recuperation Center, Cabildo de Gran Canaria, Canary Islands (Spain); Jimenez, Begona [Department of Instrumental Analysis and Environmental Chemistry, Institute of Organic Chemistry, CSIC, Juan de la Cierva 3, 28006 Madrid (Spain)

    2011-10-15

    PAHs were analyzed in the liver of 5 species of pelagic seabirds (Procellariiformes) from the northeast Atlantic and the Mediterranean. The main objective was to assess the trophic and geographic trends of PAHs in seabirds to evaluate their suitability as bioindicators of chronic marine pollution by these compounds. Although higher levels of PAHs have been described in the Mediterranean compared to other oceanic regions, we did not find significant spatial patterns and observed only minor effects of the geographic origin on seabird PAHs. However, we found significant higher PAH levels in petrel compared to shearwater species, which could be related to differences in their exploitation of mesopelagic and epipelagic resources, respectively, and the vertical dynamic of PAHs in the water column. Overall, although this study enhances the need of multi-species approaches to show a more comprehensive evaluation of marine pollution, seabirds emerged as poor indicators of pelagic chronic PAH levels. - Highlights: > PAHs in pelagic seabirds show specific inter-species patterns related to trophic ecology. > Geographic origin shows a minor effect over PAH levels in pelagic seabirds. > Pelagic seabirds seem to be poor indicators of chronic PAH levels. - PAH levels in Atlantic and Mediterranean pelagic seabirds show specific inter-species patterns related to trophic ecology but a minor influence of their geographic origin.

  19. Analysis of summer phosphorus fluxes within the pelagic zone of Eau Galle Reservoir, Wisconsin

    Science.gov (United States)

    James, W.F.; Barko, J.W.

    1993-01-01

    Major phosphorus (P) fluxes to and from the pelagic zone (i.e., open water region including epilimnion, metalimnion, and hypolimnion) were estimated from data collected over a 6 year period during the summer in Eau Galle Reservoir, Wisconsin. P inputs to the pelagic zone included profundal sediments, the watershed, groundwater, and transport of P from the littoral zone. P outputs from the pelagic zone included discharge from the reservoir, deposition, and transport of P to the littoral zone. Nighttime convective circulation was assumed to be the dominant mechanism of P exchange between the littoral and pelagic zones. Littoral P inputs, often neglected from budgetary analyses, accounted for 15% of the total measured P input and 25% of the internal P input to the pelagic zone. External P inputs were greatest, accounting for 42% of the total measured P input to the pelagic zone. These results emphasize the need for control of various sources of P inputs in the development of lake and reservoir management strategies.

  20. Key Arctic pelagic mollusc (Limacina helicina) threatened by ocean acidification

    Science.gov (United States)

    Comeau, S.; Gorsky, G.; Jeffree, R.; Teyssié, J.-L.; Gattuso, J.-P.

    2009-02-01

    Thecosome pteropods (shelled pelagic molluscs) can play an important role in the food web of various ecosystems and play a key role in the cycling of carbon and carbonate. Since they harbor an aragonitic shell, they could be very sensitive to ocean acidification driven by the increase of anthropogenic CO2 emissions. The impact of changes in the carbonate chemistry was investigated on Limacina helicina, a key species of Arctic ecosystems. Pteropods were kept in culture under controlled pH conditions corresponding to pCO2 levels of 350 and 760 μatm. Calcification was estimated using a fluorochrome and the radioisotope 45Ca. It exhibits a 28% decrease at the pH value expected for 2100 compared to the present pH value. This result supports the concern for the future of pteropods in a high-CO2 world, as well as of those species dependent upon them as a food resource. A decline of their populations would likely cause dramatic changes to the structure, function and services of polar ecosystems.

  1. Recurrent uranium relocations in distal turbidites emplaced in pelagic conditions

    Science.gov (United States)

    Colley, S.; Thomson, J.

    1985-11-01

    The sediments of the Madeira Abyssal Plain, east of Great Meteor Seamount, are dominated by distal turbidite deposition. While the turbidites exhibit a wide compositional range (25-80% CaCO 3), individual examples can be correlated over a wide area and are relatively homogenous. Organic C oxidation, by bottom water oxygen, proceeds from the turbidite tops downwards after emplacement in pelagic conditions, and the progress of this oxidation front is marked by a sharp colour contrast in the sediments ( WILSONet al., 1985). In turbidites with C org ≫ 0.5%, redistribution of authigenic U occurs to form a concentration peak (4-9 ppm U), just below the oxidation front or colour change. Several tens μg U/cm 2 may be mobilised, and in all examples studied ≫60% of the remobilised U is relocated into the peak. Following burial by subsequent turbidites, such U concentration peaks are persistent as relict indicators of their extinct oxidation fronts for at least 2 × 10 5 years. In the case of thin turbidites where labile C org is almost exhausted, the U peaks may be located in underlying sedimentary units because of their relationship to the oxidation front. A redox mechanism for U peak formation is suggested from these data rather than a complexation with organic matter.

  2. Metal concentrations in pelagic seabirds from the North Pacific Ocean.

    Science.gov (United States)

    Honda, K; Marcovecchio, J E; Kan, S; Tatsukawa, R; Ogi, H

    1990-01-01

    Concentrations of four essential elements (Fe, Mn, Zn, and Cu) and two toxic metals (Cd and Hg) were measured in selected tissues of 19 pelagic seabird species collected in the North Pacific and neighboring waters. Essential metal concentrations were generally highest in the liver and less variable than toxic metals among species and also within each species. Fe concentrations in the muscle were higher in Alcidae than in the other families, whereas the opposite trend was found for Fe and Mn in the liver. Zn concentrations varied among species, depending on the Cd concentrations. On the other hand, toxic metal concentrations were highest in the liver or kidney and varied widely among species, greatly depending on differences in the diet among species. Extraordinarily high Hg concentrations were found in Black-footed Albatrosses,Diomedea nigripes, exceeding 300 μg/g wet weight in some, and seemed to be due to constraints on the elimination of Hg. Also, some geographical differences in Cd and Hg concentrations of the seabirds were observed. The concentrations of Cd and Hg reported here, however, seem to be natural rather than due to environmental pollution.

  3. Large-Scale Ichthyoplankton and Water Mass Distribution along the South Brazil Shelf

    Science.gov (United States)

    de Macedo-Soares, Luis Carlos Pinto; Garcia, Carlos Alberto Eiras; Freire, Andrea Santarosa; Muelbert, José Henrique

    2014-01-01

    Ichthyoplankton is an essential component of pelagic ecosystems, and environmental factors play an important role in determining its distribution. We have investigated simultaneous latitudinal and cross-shelf gradients in ichthyoplankton abundance to test the hypothesis that the large-scale distribution of fish larvae in the South Brazil Shelf is associated with water mass composition. Vertical plankton tows were collected between 21°27′ and 34°51′S at 107 stations, in austral late spring and early summer seasons. Samples were taken with a conical-cylindrical plankton net from the depth of chlorophyll maxima to the surface in deep stations, or from 10 m from the bottom to the surface in shallow waters. Salinity and temperature were obtained with a CTD/rosette system, which provided seawater for chlorophyll-a and nutrient concentrations. The influence of water mass on larval fish species was studied using Indicator Species Analysis, whereas environmental effects on the distribution of larval fish species were analyzed by Distance-based Redundancy Analysis. Larval fish species were associated with specific water masses: in the north, Sardinella brasiliensis was found in Shelf Water; whereas in the south, Engraulis anchoita inhabited the Plata Plume Water. At the slope, Tropical Water was characterized by the bristlemouth Cyclothone acclinidens. The concurrent analysis showed the importance of both cross-shelf and latitudinal gradients on the large-scale distribution of larval fish species. Our findings reveal that ichthyoplankton composition and large-scale spatial distribution are determined by water mass composition in both latitudinal and cross-shelf gradients. PMID:24614798

  4. Metazoan Parasites of Antarctic Fishes.

    Science.gov (United States)

    Oğuz, Mehmet Cemal; Tepe, Yahya; Belk, Mark C; Heckmann, Richard A; Aslan, Burçak; Gürgen, Meryem; Bray, Rodney A; Akgül, Ülker

    2015-06-01

    To date, there have been nearly 100 papers published on metazoan parasites of Antarctic fishes, but there has not yet been any compilation of a species list of fish parasites for this large geographic area. Herein, we provide a list of all documented occurrences of monogenean, cestode, digenean, acanthocephalan, nematode, and hirudinean parasites of Antarctic fishes. The list includes nearly 250 parasite species found in 142 species of host fishes. It is likely that there are more species of fish parasites, which are yet to be documented from Antarctic waters.

  5. Toward a phenological mismatch in estuarine pelagic food web?

    Science.gov (United States)

    Chevillot, Xavier; Drouineau, Hilaire; Lambert, Patrick; Carassou, Laure; Sautour, Benoit; Lobry, Jérémy

    2017-01-01

    Alterations of species phenology in response to climate change are now unquestionable. Until now, most studies have reported precocious occurrence of life cycle events as a major phenological response. Desynchronizations of biotic interactions, in particular predator-prey relationships, are however assumed to strongly impact ecosystems’ functioning, as formalized by the Match-Mismatch Hypothesis (MMH). Temporal synchronicity between juvenile fish and zooplankton in estuaries is therefore of essential interest since estuaries are major nursery grounds for many commercial fish species. The Gironde estuary (SW France) has suffered significant alterations over the last three decades, including two Abrupt Ecosystem Shifts (AES), and three contrasted intershift periods. The main objective of this study was to depict modifications in fish and zooplankton phenology among inter-shift periods and discuss the potential effects of the resulting mismatches at a community scale. A flexible Bayesian method was used to estimate and compare yearly patterns of species abundance in the estuary among the three pre-defined periods. Results highlighted (1) an earlier peak of zooplankton production and entrance of fish species in the estuary and (2) a decrease in residence time of both groups in the estuary. Such species-specific phenological changes led to changes in temporal overlap between juvenile fish and their zooplanktonic prey. This situation questions the efficiency and potentially the viability of nursery function of the Gironde estuary, with potential implications for coastal marine fisheries of the Bay of Biscay. PMID:28355281

  6. A stochastic bioenergetics model based approach to translating large river flow and temperature in to fish population responses: the pallid sturgeon example

    Science.gov (United States)

    Wildhaber, Mark L.; Dey, Rima; Wikle, Christopher K.; Moran, Edward H.; Anderson, Christopher J.; Franz, Kristie J.

    2015-01-01

    In managing fish populations, especially at-risk species, realistic mathematical models are needed to help predict population response to potential management actions in the context of environmental conditions and changing climate while effectively incorporating the stochastic nature of real world conditions. We provide a key component of such a model for the endangered pallid sturgeon (Scaphirhynchus albus) in the form of an individual-based bioenergetics model influenced not only by temperature but also by flow. This component is based on modification of a known individual-based bioenergetics model through incorporation of: the observed ontogenetic shift in pallid sturgeon diet from marcroinvertebrates to fish; the energetic costs of swimming under flowing-water conditions; and stochasticity. We provide an assessment of how differences in environmental conditions could potentially alter pallid sturgeon growth estimates, using observed temperature and velocity from channelized portions of the Lower Missouri River mainstem. We do this using separate relationships between the proportion of maximum consumption and fork length and swimming cost standard error estimates for fish captured above and below the Kansas River in the Lower Missouri River. Critical to our matching observed growth in the field with predicted growth based on observed environmental conditions was a two-step shift in diet from macroinvertebrates to fish.

  7. Phylogeny-function analysis of (meta)genomic libraries: screening for expression of ribosomal RNA genes by large-insert library fluorescent in situ hybridization (LIL-FISH)

    NARCIS (Netherlands)

    Leveau, J.H.J.; Gerards, S.; De Boer, W.; Van Veen, J.A.

    2004-01-01

    We assessed the utility of fluorescent in situ hybridization (FISH) in the screening of clone libraries of (meta)genomic or environmental DNA for the presence and expression of bacterial ribosomal RNA (rRNA) genes. To establish proof-of-principle, we constructed a fosmid-based library in Escherichia

  8. Short-term changes in energy allocation by Hemiodontidae fish after the construction of a large reservoir (Lajeado Dam, Tocantins River

    Directory of Open Access Journals (Sweden)

    Estevão Rodrigues Medeiros

    Full Text Available The present study investigated energy allocation patterns in three fish species from the family Hemiodontidae (Argonectes robertsi, Hemiodus microlepis, and Hemiodus unimaculatus, before and after the construction of Lajeado Dam, Tocantins River, Amazon basin. Changes in the use of energy (between somatic and reproductive processes were indirectly evaluated by means of temporal variations in fish body condition, feeding activity, visceral fat storage, and reproductive effort. Fish were collected from October 1999 to September 2004, in periods that preceded and followed the construction of the dam. We recorded significant changes in all ecological traits for the three analyzed species (for males and females. In general, there was an intense reduction in reproductive activity after river damming, whereas visceral fat and body condition increased consistently. In contrast, there was no clear trend in feeding activity (i.e., stomach weight, with little changes in species diet during the analyzed period. These results indicate that the impoundment changed the energy allocation process between somatic and reproductive activities, since fish started to allocate energy mainly to somatic processes. These changes may have a negative effect on the persistence of populations in Lajeado Reservoir, because improvements in somatic condition will not necessarily translate into increased fitness.

  9. Evaluation of Evidence for Altered Behavior and Auditory Deficits in Fishes Due to Human-Generated Noise Sources

    Science.gov (United States)

    2006-04-01

    Rutilus rutilus). Some of the roach were exposed to cobalt , which reversibly blocks the responsiveness of lateral line receptors (Karlsen and Sand...cartilaginous fishes, such as pelagic and benthic sharks, skates, and rays, since their auditory systems have potentially important variations in

  10. Complexity in benthic-pelagic marine ecosystems in the late Ordovician (central New York)

    Energy Technology Data Exchange (ETDEWEB)

    Byrne, S.M.

    1985-01-01

    Cisne and Chandlee (1982) outlined a paleogeographic model for marine invertebrates collected from Middle Ordovician strata in central New York. Subsequent interpretations of their stratigraphic and geographic distributions were based on control by levels of oxygen. Especially critical were the presumed distribution of the trilobite Triarthus and three graptolites, Orthograptus, Climacograptus, and Corynoides, which were supposed to have occupied vertically stratified habitats in the water column. In order to test this general thesis 42 stratigraphically discrete samples were collected from continuously exposed Late Ordovician mudstones in central New York, which contained taxa virtually identically to those employed by Cisne. The sampling interval spanned about 1.5 million years and over 1/4 of the samples contained relatively large numbers of graptolites. Over 3000 graptolite rhabdosomes were identified. The later Ordovician Orthograptus are preserved both with and without Climacograptus and with various benthic taxa. However neither Orthograptus nor Climacograptus display a consistent stratigraphic pattern, and Triarthus co-occurred with both graptolites, introducing a discordant note into any attempt at a simple modeling of early Paleozoic benthic/pelagic ecosystems.

  11. Arthropod visual predators in the early pelagic ecosystem: evidence from the Burgess Shale and Chengjiang biotas.

    Science.gov (United States)

    Vannier, J; García-Bellido, D C; Hu, S-X; Chen, A-L

    2009-07-22

    Exceptional fossil specimens with preserved soft parts from the Maotianshan Shale (ca 520 Myr ago) and the Burgess Shale (505 Myr ago) biotas indicate that the worldwide distributed bivalved arthropod Isoxys was probably a non-benthic visual predator. New lines of evidence come from the functional morphology of its powerful prehensile frontal appendages that, combined with large spherical eyes, are thought to have played a key role in the recognition and capture of swimming or epibenthic prey. The swimming and steering of this arthropod was achieved by the beating of multiple setose exopods and a flap-like telson. The appendage morphology of Isoxys indicates possible phylogenetical relationships with the megacheirans, a widespread group of assumed predator arthropods characterized by a pre-oral 'great appendage'. Evidence from functional morphology and taphonomy suggests that Isoxys was able to migrate through the water column and was possibly exploiting hyperbenthic niches for food. Although certainly not unique, the case of Isoxys supports the idea that off-bottom animal interactions such as predation, associated with complex feeding strategies and behaviours (e.g. vertical migration and hunting) were established by the Early Cambrian. It also suggests that a prototype of a pelagic food chain had already started to build-up at least in the lower levels of the water column.

  12. Towards an integrated forecasting system for pelagic fisheries

    DEFF Research Database (Denmark)

    Christensen, Asbjørn; Butenschön, Momme; Gürkan, Zeren;

    2012-01-01

    for a successful and extendable coupled model framework. The integrated approach, simulating ecosystem dynamics from physics to fish, allows analysis of the pathways in the ecosystem to investigate the propagation of changes in the ocean climate and lower trophic levels to quantify the impacts on the higher...... trophic level, in this case the sandeel population, demonstrated here on the basis of hindcast data. The coupled forecasting system has been tested for some typical scientific questions appearing in spatial fish stock management and marine spatial planning, including determination of local‐and basin...

  13. Vertical distribution, diversity and assemblages of mesopelagic fishes in the western Mediterranean

    Science.gov (United States)

    Olivar, M. P.; Bernal, A.; Molí, B.; Peña, M.; Balbín, R.; Castellón, A.; Miquel, J.; Massutí, E.

    2012-04-01

    The mesopelagic fish community of the western Mediterranean was studied during two cruises carried out in December 2009 and July 2010 in the shelf and slope zones around the Balearic Islands. Much of what was previously known about this deep water group of fishes in the Mediterranean Sea came from studies performed using planktonic and small midwater nets. This study was the first attempt to use large pelagic trawls and small nets combined with information about the main sound scattering layers to analyse mesopelagic fish composition, diversity and species assemblages. This community is characterised by a relatively low diversity compared to other oceanic regions of the world, with Myctophiformes and Stomiiformes being the main contributors. Bathymetry and the level of the water column were the most important factors structuring the investigated fish assemblages, and similar vertical patterns were observed for the different species collected during the two study periods. A shelf assemblage composed of a few species of myctophids, with Notoscopelus elongatus being the main contributor, was distinguished. The slope assemblage included both Myctophiformes and Stomiiformes that showed differences in their day-night main location along the water column. In terms of species behaviour, two important groups were detected. The first was non-migrant or weakly migrant species, with the paradigmatic example being the gonostomatid Cyclothone braueri, which occurred at a depth of 400-600 m; this species is partly responsible for the permanent acoustic (38 kHz) response at this depth. The second group, near-surface migrants at night, was represented by most of the juvenile and adult myctophids, exemplified by Ceratoscopelus maderensis, with the exception of just a few of the largest size classes of some species, such as Lampanyctus crocodilus and N. elongatus that remain near the bottom.

  14. BIOTECHNOLOGY OF THE FISH AQUACULTURE

    Directory of Open Access Journals (Sweden)

    L. P. Buchatsky

    2013-12-01

    Full Text Available The latest progress in biotechnology on fish aquaculture and different modern methods of investigations for increasing of fish productivity in aquaculture are analyzed. Except for the applied aspect, the use of modern biotechnological methods of investigations opens new possibilities for fundamental researches of sex-determining mechanisms, polyploidy, distant hybridization, and developmental biology of bony fishes. Review contains examples of utilizing modern biotechnology methods to obtain transgenic fishes with accelerated growth and for designing surrogate fishes. Methods for receiving unisexual shoals of salmon and sturgeon female fishes with the view of obtaining a large quantity of caviar, as well as receiving sterile (triploid fishes are analyzed. Great attention is given to androgenesis, particularly to disperm one, in connection with the problem of conserving rare and vanishing fish species using only sperm genetic material. Examples how distant hybrids may be obtained with the use of disperm androgenesis and alkylated DNA are given. Methods of obtaining fish primordium germ cells, recent developments in cultivation of fish stem cells and their use in biotechnology, as well as ones of transplantation of oogonium and spermatogonium to obtain surrogate fishes. The examples of successful experiments on spermatogonial xenotransplantation and characteristic of antifreezing fish proteins and also the prospect of their practical usage are given.

  15. Mitigating seabird bycatch during hauling by pelagic longline vessels.

    Directory of Open Access Journals (Sweden)

    Eric Gilman

    identify opportunities to nearly eliminate seabird bycatch. Globally, findings fill a gap in knowledge of methods to mitigate seabird bycatch during pelagic longline hauling.

  16. Mitigating seabird bycatch during hauling by pelagic longline vessels.

    Science.gov (United States)

    Gilman, Eric; Chaloupka, Milani; Wiedoff, Brett; Willson, Jeremy

    2014-01-01

    to nearly eliminate seabird bycatch. Globally, findings fill a gap in knowledge of methods to mitigate seabird bycatch during pelagic longline hauling.

  17. Global diversity and biogeography of deep-sea pelagic prokaryotes

    Science.gov (United States)

    Salazar, Guillem; Cornejo-Castillo, Francisco M; Benítez-Barrios, Verónica; Fraile-Nuez, Eugenio; Álvarez-Salgado, X Antón; Duarte, Carlos M; Gasol, Josep M; Acinas, Silvia G

    2016-01-01

    The deep-sea is the largest biome of the biosphere, and contains more than half of the whole ocean's microbes. Uncovering their general patterns of diversity and community structure at a global scale remains a great challenge, as only fragmentary information of deep-sea microbial diversity exists based on regional-scale studies. Here we report the first globally comprehensive survey of the prokaryotic communities inhabiting the bathypelagic ocean using high-throughput sequencing of the 16S rRNA gene. This work identifies the dominant prokaryotes in the pelagic deep ocean and reveals that 50% of the operational taxonomic units (OTUs) belong to previously unknown prokaryotic taxa, most of which are rare and appear in just a few samples. We show that whereas the local richness of communities is comparable to that observed in previous regional studies, the global pool of prokaryotic taxa detected is modest (~3600 OTUs), as a high proportion of OTUs are shared among samples. The water masses appear to act as clear drivers of the geographical distribution of both particle-attached and free-living prokaryotes. In addition, we show that the deep-oceanic basins in which the bathypelagic realm is divided contain different particle-attached (but not free-living) microbial communities. The combination of the aging of the water masses and a lack of complete dispersal are identified as the main drivers for this biogeographical pattern. All together, we identify the potential of the deep ocean as a reservoir of still unknown biological diversity with a higher degree of spatial complexity than hitherto considered. PMID:26251871

  18. Global diversity and biogeography of deep-sea pelagic prokaryotes

    KAUST Repository

    Salazar, Guillem

    2015-08-07

    The deep-sea is the largest biome of the biosphere, and contains more than half of the whole ocean\\'s microbes. Uncovering their general patterns of diversity and community structure at a global scale remains a great challenge, as only fragmentary information of deep-sea microbial diversity exists based on regional-scale studies. Here we report the first globally comprehensive survey of the prokaryotic communities inhabiting the bathypelagic ocean using high-throughput sequencing of the 16S rRNA gene. This work identifies the dominant prokaryotes in the pelagic deep ocean and reveals that 50% of the operational taxonomic units (OTUs) belong to previously unknown prokaryotic taxa, most of which are rare and appear in just a few samples. We show that whereas the local richness of communities is comparable to that observed in previous regional studies, the global pool of prokaryotic taxa detected is modest (∼3600 OTUs), as a high proportion of OTUs are shared among samples. The water masses appear to act as clear drivers of the geographical distribution of both particle-attached and free-living prokaryotes. In addition, we show that the deep-oceanic basins in which the bathypelagic realm is divided contain different particle-attached (but not free-living) microbial communities. The combination of the aging of the water masses and a lack of complete dispersal are identified as the main drivers for this biogeographical pattern. All together, we identify the potential of the deep ocean as a reservoir of still unknown biological diversity with a higher degree of spatial complexity than hitherto considered.

  19. Job Satisfaction in the Coastal Pelagic Fisheries of Senegal

    Science.gov (United States)

    Sall, Aliou

    2012-01-01

    The marine fishery in Senegal, West Africa, is a major source of employment and food security. It currently faces the consequences of ecological degradation. This paper examines job satisfaction among small-scale purse seine fishers, who constitute one of the dominant fishing metiers in Senegal. The research sample consists of 80 purse seine…

  20. Metabolic rates, enzyme activities and chemical compositions of some deep-sea pelagic worms, particularly Nectonemertes mirabilis (Nemertea; Hoplonemertinea) and Poeobius meseres (Annelida; Polychaeta)

    Science.gov (United States)

    Thuesen, Erik V.; Childress, James J.

    1993-05-01

    Investigations of metabolic rate, enzyme activity and chemical composition were undertaken on two abundant deep-sea pelagic worms: Nectonemertes mirabilis (Nemertea; Hoplonemertinea) and Poeobius meseres (Annelida; Polychaeta). Six other species of worms ( Pelagonemertes brinkmanni (Nemertea) and the following polychaetes: Pelagobia species A, Tomopteris nisseni, Tomopteris pacifica, Tomopteris species A, and Traviopsis lobifera) were captured in smaller numbers and used for comparison in the physiological and biochemical measurements. Polychaete worms had the highest oxygen consumption rates and, along with N. mirabilis, displayed significant size effects on metabolic rate. Poeobius meseres had the lowest rates of oxygen consumption and displayed no significant relationship of oxygen consumption rate to wet weight. No significant effect of size on the activities of citrate synthase, lactate dehydrogenase or pyruvate kinase was observed in P. meseres or N. mirabilis. Lipid content was higher than protein content for all the worms in this study. Carbohydrate was of little significance in these worms and was usually <0.01% of the total weight. Citrate synthase activities of pelagic worms showed excellent correlation with metabolic rates. It appears that polychaete worms as a group have higher metabolic rates than bathypelagic shrimps, copepods and fishes, and may be the animals with the highest metabolic rates in the bathypelagic regions of the world's oceans.

  1. Analysis of Propulsion Efficiency on Fishing Boat 30 GRT

    OpenAIRE

    Hasbullah, Mansyur; Muhammad, Andi Haris; Daud, Syarifuddin

    2016-01-01

    Fishing vessel is defined as a ship, boat or other floating component used to do fishing activities, to support fishing operations, fish cultivation, fish processing, fisheries training and research/exploration of fishery. The fishing boat consist of ship or a small boat be in the form of canoe boat (without engine) driven by paddle power or sail, outboard motor boats up to large fishing boat made of wood, fiber or steel with diesel engine propulsion. Shipbuilding material take effect on the ...

  2. The shallow-water fish assemblage of Isla del Coco National Park, Costa Rica: structure and patterns in an isolated, predator-dominated ecosystem

    Science.gov (United States)

    Friedlander, Alan M.; Zgliczynski, Brian J.; Ballesteros, Enric; Aburto-Oropeza, Octavio; Bolaños, Allan; Sala, Enric

    2012-01-01

    Fishes at Isla del Coco National Park, Costa Rica, were surveyed as part of a larger scientific expedition to the area in September 2009. The average total biomass of nearshore fishes was 7.8 tonnes per ha, among the largest observed in the tropics, with apex predators such as sharks, jacks, and groupers accounting for nearly 40% of the total biomass. The abundance of reef and pelagic sharks, particularly large aggregations of threatened species such as the scalloped hammerhead shark (up to 42 hammerheads ha-1) and large schools of jacks and snappers show the capacity for high biomass in unfished ecosystems in the Eastern Tropical Pacific. However, the abundance of hammerhead and reef whitetip sharks appears to have been declining since the late 1990s, and likely causes may include increasing fishing pressure on sharks in the region and illegal fishing inside the Park. One Galapagos shark tagged on September 20, 2009 in the Isla del Coco National Park moved 255km southeast towards Malpelo Island in Colombia, when it stopped transmitting. These results contribute to the evidence that sharks conduct large-scale movements between marine protected areas (Isla del Coco, Malpelo, Galápagos) in the Eastern tropical Pacific and emphasize the need for regional-scale management. More than half of the species and 90% of the individuals observed were endemic to the tropical eastern Pacific. These high biomass and endemicity values highlight the uniqueness of the fish assemblage at Isla del Coco and its importance as a global biodiversity hotspot.

  3. The shallow-water fish assemblage of Isla del Coco National Park, Costa Rica: structure and patterns in an isolated, predator-dominated ecosystem

    Directory of Open Access Journals (Sweden)

    Alan M. Friedlander

    2012-11-01

    Full Text Available Fishes at Isla del Coco National Park, Costa Rica, were surveyed as part of a larger scientific expedition to the area in September 2009. The average total biomass of nearshore fishes was 7.8 tonnes per ha, among the largest observed in the tropics, with apex predators such as sharks, jacks, and groupers accounting for nearly 40% of the total biomass. The abundance of reef and pelagic sharks, particularly large aggregations of threatened species such as the scalloped hammerhead shark (up to 42 hammerheads ha-1 and large schools of jacks and snappers show the capacity for high biomass in unfished ecosystems in the Eastern Tropical Pacific. However, the abundance of hammerhead and reef whitetip sharks appears to have been declining since the late 1990s, and likely causes may include increasing fishing pressure on sharks in the region and illegal fishing inside the Park. One Galapagos shark tagged on September 20, 2009 in the Isla del Coco National Park moved 255km southeast towards Malpelo Island in Colombia, when it stopped transmitting. These results contribute to the evidence that sharks conduct large-scale movements between marine protected areas (Isla del Coco, Malpelo, Galápagos in the Eastern tropical Pacific and emphasize the need for regional-scale management. More than half of the species and 90% of the individuals observed were endemic to the tropical eastern Pacific. These high biomass and endemicity values highlight the uniqueness of the fish assemblage at Isla del Coco and its importance as a global biodiversity hotspot.

  4. Determination of fish trophic levels in an estuarine system

    Science.gov (United States)

    Pasquaud, S.; Pillet, M.; David, V.; Sautour, B.; Elie, P.

    2010-01-01

    The concept of trophic level is particularly relevant in order to improve knowledge of the structure and the functioning of an ecosystem. A precise estimation of fish trophic levels based on nitrogen isotopic signatures in environments as complex and fluctuant as estuaries requires a good description of the pelagic and benthic trophic chains and a knowledge of organic matter sources at the bottom. In this study these points are considered in the case of the Gironde estuary (south west France, Europe). To obtain a good picture of the food web, fish stomach content analyses and a bibliographic synthesis of the prey feeding ecology were carried out. Fish trophic levels were calculated from these results and δ 15N data. The feeding link investigation enabled us to identify qualitatively and quantitatively the different preys consumed by each fish group studied, to distinguish the prey feeding on benthos from those feeding on pelagos and to characterize the different nutritive pools at the base of the system. Among the species studied, only Liza ramada and the flatfish ( Platichthys flesus and Solea solea) depend mainly on benthic trophic compartments. All the other fish groups depend on several trophic (benthic and/or pelagic) sources. These results enabled us to correct the calculation of fish trophic levels which are coherent with their feeding ecology data obtained from the nitrogen isotopic integrative period. The present work shows that trophic positions are linked with the feeding ecology of fish species and vary according to individual size. Ecological data also allow the correction of the isotopic data by eliminating absurd results and showing the complementarity of the two methods. This work is the first to consider source variability in the fish food web. This is an indispensable step for trophic studies in a dynamic environment. The investigation of matter fluxes and recycling processes at the food web base would provide a useful improvement in future

  5. A strategy for detecting derelict fishing gear at sea.

    Science.gov (United States)

    McElwee, Kris; Donohue, Mary J; Courtney, Catherine A; Morishige, Carey; Rivera-Vicente, Ariel

    2012-01-01

    Derelict fishing gear (DFG) is a highly persistent form of marine pollution known to cause environmental and economic damage. At-sea detection of DFG would support pelagic removal of this gear to prevent and minimize impacts on marine environments and speci