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Sample records for cod pelagic trawl

  1. Improving selectivity of the Baltic cod pelagic trawl fishery: Experiments to assess the next step

    DEFF Research Database (Denmark)

    Madsen, Niels; Tschernij, Vesa; Holst, René

    2010-01-01

    Due to declining cod (Gadus morhua) stocks, the Baltic Sea was one of the first areas regulated by the European Communities where selective escape windows were implemented to improve the exploitation pattern. Increasing discard rates and the potential for a significant increase of the spawning...... stock and the yield of the fishery are important reasons to further improve the selectivity of the fishery and to asses the potential next step in this process. In this study, we tested three relatively different design concepts, in the Baltic cod pelagic trawl fishery, that are relevant to past...... or present legislation and that were developed to meet requirements of increased selectivity performance. A standard nominal 135 mm diamond mesh codend, a codend with two nominal 125 mm bottom windows, and a codend with a nominal 125 mm nominal top window were tested using the covered codend method. A Danish...

  2. 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...

  3. Selective haddock (Melanogrammus aeglefinus) trawling: Avoiding cod (Gadus morhua) bycatch

    DEFF Research Database (Denmark)

    Krag, Ludvig Ahm; Holst, René; Madsen, Niels;

    2010-01-01

    The critical condition of the North Sea cod stocks has resulted in restrictions on not only cod, but also haddock and other species that are caught together with cod. Thus full exploitation of the haddock stock is unachievable unless cod can be excluded from the haddock catch. We designed a selec...... dependent: smaller cod escaped the trawl in greater numbers than did larger individuals. Whiting, saithe. lemon sole, and plaice were included in the analysis. (C) 2009 Elsevier B.V. All rights reserved....

  4. 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...

  5. 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...

  6. 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.

  7. 77 FR 11412 - Fisheries of the Exclusive Economic Zone Off Alaska; Pacific Cod by Catcher Vessels Using Trawl...

    Science.gov (United States)

    2012-02-27

    ... a timely fashion and would delay the directed fishing closure of Pacific cod for CVs using trawl... Director, Office of Sustainable Fisheries, National Marine Fisheries Service. BILLING CODE 3510-22-P...

  8. 78 FR 18528 - Fisheries of the Exclusive Economic Zone Off Alaska; Pacific Cod by Catcher Vessels Using Trawl...

    Science.gov (United States)

    2013-03-27

    ... a timely fashion and would delay the directed fishing closure of Pacific cod for CVs using trawl... Director, Office of Sustainable Fisheries, National Marine Fisheries Service. BILLING CODE 3510-22-P...

  9. 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.

  10. 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...

  11. 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...

  12. 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...

  13. 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...

  14. 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...

  15. AFSC/RACE/FBEP/Hurst: Contrasting coastal and shelf nursery habitats of Pacific cod in the southeastern Bering Sea

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset is from a study examining the use of demersal and pelagic habitats in the southeast Bering Sea by age-0 Pacific cod, based on 4 years of demersal trawl...

  16. Understanding the release efficiency of Atlantic cod (Gadus morhua) from trawls with a square mesh panel: effects of panel area, panel position, and stimulation of escape response

    DEFF Research Database (Denmark)

    Herrmann, Bent; Wienbeck, Harald; Karlsen, Junita Diana

    2015-01-01

    Based on size selectivity data for more than 25 000 cod (Gadus morhua) collected during experimental trawl fishing with six different codends, all of which included a square mesh panel,we investigated the effect on cod-release efficiency based on the size of the square mesh panel area, position...... of the square mesh panel, and stimulation of the escape response. Based on the results, we were able to explain why the BACOMAcodend, applied in the Baltic Sea cod directed trawl fishery, releases juvenile cod efficiently, whereas other designs, including a squaremesh panel with similar mesh size, are less...... efficient. Our main findings reveal that the release efficiency of the square mesh panel in the BACOMA codend depends largely on the overlap of the square mesh panel and the catch-accumulation zone in the codend, where cod do not have the option of just drifting further back in the trawl when proximate...

  17. The comparative statuses of the Far Eastern seas and the northwestern Pacific Ocean based on the range of integral characteristics of pelagic and bottom trawl macrofauna

    Directory of Open Access Journals (Sweden)

    Igor V. Volvenko

    2015-03-01

    Full Text Available Comparison of the pelagial and benthal of the Far Eastern seas (mainly within the borders of the Russian EEZ and the contiguous part of the Pacific Ocean according to the macrofauna population density, species richness, evenness and diversity, and average individual weight of animals, is provided on the basis of the results of multiannual broad-scale pelagic and bottom trawl surveys carried out in 1977–2010.

  18. 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.

  19. 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

    The southern North Sea, and the German Bight, has been systematically bottom-trawled at least since the late 19th century (Christiansen, 2009; Reiss et al., 2009; Kröncke 2011; Emeis et al., 2015, Neumann et al., 2016). As a result, benthic habitats and benthic biogenic structures created by bivalves, polychaetes and hydroids where destroyed or reduced. The parallel removal of hard substrate (gravel and boulders) avoids the resettlement of hard-substrate depended species. For example, the Oyster ground, a huge oyster bank a hundred years ago (Olsen, 1883), turned into a muddy depression today. In addition, shallow depth of max 40 m, strong tidal currents and frequent storms result in a high-energy environment with low sedimentation rates and recurrent sediment resuspension. The decrease in benthic filtering capacity by disturbance in epifauna and bottom roughness (Callaway et al., 2007) apparently influence pelagic-benthic coupling of biogeochemical fluxes. Heip et al. (1995) indicate that benthic respiration at depths prevailing in the German Bight accounts for 10-40% of total respiration, whereas pelagic respiration accounts for 60-90%. Previous estimates are in the middle of this range (Heip et al., 1995). To test these hypotheses and to assess the partitioning of benthic and pelagic processes, and the factors influencing organic matter mineralization, we measured pelagic production and respiration based on Winkler titration, in-situ benthic fluxes using chamber landers, we did ex-situ incubations of intact sediment cores and analysed still images from a towed benthic video sled. In addition, O2 fluxes in permeable sediments were estimated by integrating the volumetric rate measurements of the upper sediment layer over in-situ microsensor-measured O2 penetration depth. Our current results show significant seasonality in benthic respiration, with highest rates in summer and lowest rates in winter. No significant differences in total benthic respiration rates

  20. 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.

  1. Improving the size- and species selectivity of cod (Gadus morhua) in demersal mixed-species trawl fisheries

    DEFF Research Database (Denmark)

    Krag, Ludvig Ahm

    reduce the catch of cod without simultaneously reduce the catch of the target species. To optimise the trade-off between discard and loss of marketable catch, solutions have to be specific to particular fisheries or populations of fish. Papers 1 and 3 provide specific examples of how size- and species...

  2. Improving the size- and species selectivity of cod (Gadus morhua) in demersal mixed-species trawl fisheries

    DEFF Research Database (Denmark)

    Krag, Ludvig Ahm

    reduce the catch of cod without simultaneously reduce the catch of the target species. To optimise the trade-off between discard and loss of marketable catch, solutions have to be specific to particular fisheries or populations of fish. Papers 1 and 3 provide specific examples of how size- and species...

  3. Use of selective devices in trawls to support recovery of the Kattegat cod stock: a review of experiments and experience

    DEFF Research Database (Denmark)

    Madsen, Niels; Valentinsson, Daniel

    2010-01-01

    this provides a valuable management tool for reducing the bycatch of cod and reducing mortality, and thus helping to rebuild the depleted stock. Gear research in the area has been focused on devices that allow for continued exploitation of the Norway lobster (Nephrops norvegicus) and flatfish, but minimizing...

  4. A robust method for compiling trawl survey data used in the assessment of central Baltic cod ( Gadus morhua L.)

    DEFF Research Database (Denmark)

    Sparholt, H.; Tomkiewicz, Jonna

    2000-01-01

    of adult cod of all ages aggregated to minimise the effects of age determination discrepancies. The established index of spawning stock biomass did not correlate significantly better with VPA estimates than simpler indices ignoring depth stratification and fishing power. However, the method is preferable...

  5. 50 CFR 660.130 - Trawl fishery-management measures.

    Science.gov (United States)

    2010-10-01

    ... Figure 1 of part 660, subpart D. (ii) (6) Midwater (or pelagic) trawl gear. Midwater trawl gear must have... Luis, East San Lucia Bank, Point Conception, Hidden Reef/Kidney Bank (within Cowcod Conservation...

  6. Improving the selectivity of beam trawls in The Netherlands: the effect of large mesh top panels on the catch rates of sole, plaice, cod and whiting

    NARCIS (Netherlands)

    Marlen, van B.

    2003-01-01

    This paper presents the results of experiments aimed to improve the selectivity of beam trawls in the North Sea for roundfish whilst minimizing losses on target flatfish. Large-meshed top panels were designed for the tickler chain type of beam trawls used in this fishery. The design process involved

  7. Bell-shaped size selection in a bottom trawl: A case study for Nephrops directed fishery with reduced catches of cod

    DEFF Research Database (Denmark)

    Lövgren, Johan; Herrmann, Bent; Feekings, Jordan P.

    2016-01-01

    and size selectivity have motivated the development of selective systems in trawl fisheries that utilize more than one selective device simultaneously. An example can be found in the Swedish demersal trawl fishery targeting Norway lobster (Nephrops norvegicus), which simultaneously aims at avoiding catches...

  8. Improving the selectivity of beam trawls in The Netherlands: the effect of large mesh top panels on the catch rates of sole, plaice, cod and whiting

    NARCIS (Netherlands)

    Marlen, van B.

    2003-01-01

    This paper presents the results of experiments aimed to improve the selectivity of beam trawls in the North Sea for roundfish whilst minimizing losses on target flatfish. Large-meshed top panels were designed for the tickler chain type of beam trawls used in this fishery. The design process involved

  9. CPS Trawl Life History Length Frequency Data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Length distribution of a subset of individuals from a species (mainly non-target) caught during SWFSC-FRD fishery independent trawl surveys of coastal pelagic...

  10. 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...

  11. 50 CFR 660.381 - Limited entry trawl fishery management measures.

    Science.gov (United States)

    2010-10-01

    ... Figure 1 of part 660, subpart G. (ii) (6) Midwater (or pelagic) trawl gear. Midwater trawl gear must have..., Point Sur Deep, Big Sur Coast/Port San Luis, East San Lucia Bank, Point Conception, Hidden...

  12. 2013-2014 California Current Ecosystem (CCE14): Acoustic-Trawl Survey of Coastal Pelagic Fishes (Legs I and II); and Investigations of hake survey methods, life history, and associated ecosystem (Legs III and IV) (SH1405, EK60)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The 2014 acoustic-trawl method (ATM) project aboard Bell M. Shimada represents a joint effort between the SWFSC and the NWFSC in investigating elements of the...

  13. 2013-2014 California Current Ecosystem (CCE14): Acoustic-Trawl Survey of Coastal Pelagic Fishes (Legs I and II); and Investigations of hake survey methods, life history, and associated ecosystem (Legs III and IV) (SH1405, ME70)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The 2014 acoustic-trawl method (ATM) project aboard Bell M. Shimada represents a joint effort between the SWFSC and the NWFSC in investigating elements of the...

  14. Cod reproductive ecology

    DEFF Research Database (Denmark)

    Røjbek, Maria

    In recent decades, Baltic cod has experienced a period of low recruitment. In the same period the pelagic Baltic Sea ecosystem experienced a regime shift, due to hydrographic changes, affecting all trophic levels. The rationale for the thesis is built on the hypothesis that the regime shift has r...

  15. 75 FR 52478 - Fisheries of the Exclusive Economic Zone Off Alaska; Reallocation of Pacific Cod in the Bering...

    Science.gov (United States)

    2010-08-26

    ... fisheries data in a timely fashion and would delay the reallocation of Pacific cod specified from trawl.... Carrie Selberg, Acting Director, Office of Sustainable Fisheries, National Marine Fisheries...

  16. AFSC/RACE/MACE: Results of 2012 Chukchi Sea Acoustic/Trawl Survey

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — We conducted acoustic-trawl (AT) surveys of the Alaska northern Bering and Chukchi Seas during ice-free periods with a focus on Arctic cod (Boreogadus saida), a key...

  17. Species and size selectivity of two midwater trawls used in an acoustic survey of the Alaska Arctic

    Science.gov (United States)

    De Robertis, Alex; Taylor, Kevin; Williams, Kresimir; Wilson, Christopher D.

    2017-01-01

    Acoustic-trawl (AT) survey methods are widely used to estimate the abundance and distribution of pelagic organisms. This technique relies on estimates of size and species composition from trawl catches along with estimates of the acoustic properties of these animals to convert measurements of acoustic backscatter into animal abundance. However, trawls are selective samplers, and if the catch does not represent the size and species composition of the animals in the acoustic beam the resulting abundance estimates will be biased. We conducted an experiment to quantify trawl selectivity for species encountered during an AT survey of the Alaska Arctic. The pelagic assemblage in this environment was dominated by small young-of-the-year (age-0) fishes and jellyfish, which may be poorly retained in trawls. A large midwater trawl (Cantrawl) and a smaller midwater trawl (modified Marinovich) were used during the survey. The Marinovich was equipped with 8 small-mesh recapture nets which were used to estimate the probability that an individual that enters the trawl is retained. In addition, paired hauls were made with the Cantrawl and Marinovich to estimate the difference in selectivity between the two trawls. A statistical model was developed to combine the catches of the recapture nets and the paired hauls to estimate the length-dependent selectivity of the trawls for the most abundant species (e.g., age-0 fishes and jellyfish). The analysis indicated that there was substantial size and species selectivity: although the modified Marinovich generally had a higher catch per unit effort, many of the animals encountered in this environment were poorly retained by both trawls. The observed size and species selectivity of the trawls can be used to select appropriate nets for sampling pelagic fishes, and correct survey estimates for the biases introduced in the trawl capture process.

  18. Improving the effectiveness of escape windows in directed Norway lobster Nephrops norvegicus trawl fisheries

    DEFF Research Database (Denmark)

    Madsen, Niels; Holst, René; Frandsen, Rikke

    2012-01-01

    A substantial improvement in the bycatch selectivity of Norway lobster Nephrops norvegicus trawls is required, particularly with respect to cod Gadus morhua , whose stocks are at low levels in several areas. Conventional escape windows are not adequate to properly release cod and other bycatch sp...

  19. Winter Bottom Trawl Survey

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The standardized NEFSC Winter Bottom Trawl Survey was initiated in 1992 and covered offshore areas from the Mid-Atlantic to Georges Bank. Inshore strata were covered...

  20. Spring Bottom Trawl Survey

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The standardized NEFSC Spring Bottom Trawl Survey was initiated in 1968 and covered an area from Cape Hatteras, NC, to Nova Scotia, Canada, at depths >27m....

  1. Fall Bottom Trawl Survey

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The standardized NEFSC Fall Bottom Trawl Survey was initiated in 1963 and covered an area from Hudson Canyon, NY to Nova Scotia, Canada. Throughout the years,...

  2. Atlantic Cod Show a Highly Variable Sensitivity to Electric-Induced Spinal Injuries

    NARCIS (Netherlands)

    Soetaert, M.; Haan, de D.; Verschueren, B.; Decostere, A.; Puvanendran, V.; Saunders, J.; Polet, H.; Chiers, K.

    2016-01-01

    Pulse trawling is the most promising alternative to conventional beam trawls targeting Sole Solea solea (also known as Solea vulgaris), but due to the electric fields created by electrotrawls spinal injuries are reported in gadoid round fishes such as Atlantic Cod Gadus morhua. This study aimed t

  3. The 'W' prawn-trawl with emphasised drag-force transfer to its centre line to reduce overall system drag.

    Directory of Open Access Journals (Sweden)

    Cheslav Balash

    Full Text Available For prawn trawling systems, drag reduction is a high priority as the trawling process is energy intensive. Large benefits have occurred through the use of multiple-net rigs and thin twine in the netting. An additional positive effect of these successful twine-area reduction strategies is the reduced amount of otter board area required to spread the trawl systems, which leads to further drag reduction. The present work investigated the potential of redirecting the drag-strain within a prawn trawl away from the wings and the otter boards to the centre line of the trawl, where top and bottom tongues have been installed, with an aim to minimise the loading/size of the otter boards required to spread the trawl. In the system containing the new 'W' trawl, the drag redirected to the centre-line tongues is transferred forward through a connected sled and towing wires to the trawler. To establish the extent of drag redirection to the centre-line tongues and the relative drag benefits of the new trawl system, conventional and 'W' trawls of 3.65 m headline length were tested firstly over a range of spread ratios in the flume tank, and subsequently at optimum spread ratio in the field. The developed 'W' trawl effectively directed 64% of netting-drag off the wings and onto the centre tongues, which resulted in drag savings in the field of ∼20% for the associated 'W' trawl/otter-board/sled system compared to the traditional trawl/otter-board arrangement in a single trawl or twin rig configuration. Furthermore, based on previously published data, the new trawl when used in a twin rig system is expected to provide approximately 12% drag reduction compared to quad rig. The twin 'W' trawl system also has benefits over quad rig in that a reduced number of cod-end/By-catch Reduction Device units need to be installed and attended each tow.

  4. 78 FR 55228 - Fisheries of the Exclusive Economic Zone Off Alaska; Reallocation of Pacific Cod in the Western...

    Science.gov (United States)

    2013-09-10

    ... fisheries data in a timely fashion and would delay the reallocation of Pacific cod specified from trawl C/Ps...: September 5, 2013. James P. Burgess, Acting Deputy Director, Office of Sustainable Fisheries,...

  5. Modelling axisymmetric cod-ends made of different mesh types

    DEFF Research Database (Denmark)

    Priour, D.; Herrmann, Bent; O'Neill, F.G.

    2009-01-01

    Cod-ends are the rearmost part of trawl fishing gears. They collect the catch, and for many important species it is where fish selection takes place. Generally speaking they are axisymmetric, and their shape is influenced by the catch volume, the mesh shape, and the material characteristics. The ...

  6. 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...

  7. 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.

  8. The vertical separation of fish in the aft end of a demersal trawl

    DEFF Research Database (Denmark)

    Krag, Ludvig Ahm; Holst, René; Madsen, Niels

    2009-01-01

    and to compare the performance of the two frames. The vertical distribution of cod in the aft end of the trawl was close to uniform, whereas haddock (Melanogrammus aeglefinus), whiting (Merlangius merlangus), plaice (Pleuronectes platessa), and lemon sole (Microstomus kitt) showed more uneven distributions....... The use of guiding bars in the separator frame significantly (p lemon sole in the upper compartment. The vertical separation of cod was density-dependent; high densities of fish resulted in a more uniform distribution of cod. The species separations found...

  9. Development of energy efficient mid-water trawls to Murmansk trawl fleets

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-12-01

    Two experimental trawls were designed as a joint task between the Danish partners and the Russian trawler fleets which were going to test them. The new design incorporate use of modern Western high strength material. The engineering performance of the trawls was analysed using computer based simulation programs and flume tank tests. The new designs were compared with two conventional trawls used by the Russian partners with respect to overall geometry and towing resistance. The new trawls have better performance than the conventional trawls. The vertical opening in the trawl mouth is greater and the towing resistance is less. The trawls fishing capacity was tested and compared with the conventional trawls on commercial fishing trips in August and September 1996. One trawl of a typical Danish two bridle design was far better than the corresponding Russian trawl. In some fisheries the catch per haul was more than four times the catch of the Russian trawl. The other trawl, a four bridle design, which was a compromise between Danish and Russian design philosophies had a catch efficiency comparable to the Russian trawl. The experimental trawls were both easier to tow than to conventional trawls. A reduction in the towing power of 20% for the trawl designed to MurmanRyprom and 30% for the Turbo trawl designed to Murmansk Trawl Fleet when towed at the same speed is foreseen. The reduction in the overall fuel consumption is estimated to 5% and 7% only due to the operation profile and the layout of the vessels. (LN)

  10. Localisation of nursery areas based on comparative analyses of the horizontal and vertical distribution patterns of juvenile Baltic cod (Gadus morhua)

    DEFF Research Database (Denmark)

    Nielsen, J. Rasmus; Lundgren, Bo; Kristensen, Kasper

    2013-01-01

    Baltic cod are determined, and their nursery areas are localised according to the environmental factors affecting them. Comparative statistical analyses of biological, hydrographic and hydroacoustic data are carried out based on standard ICES demersal trawl surveys and special integrated trawl...... patterns related to the seabed topography, water layer depth, and the presence of hydrographic frontal zones (pycnoclines) as well as intraspecific patterns in relation to the presence of adult cod. The extent of the nursery areas also depends on the cod year class strength. Juvenile cod (≥3 cm...

  11. Cooperative Research Twin Trawl Sweep Comparison Study

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The "Twin-Trawl Sweep Efficiency Study" was intended to compare the sweep efficiency and selectivity of the NEFSC standardized bottom trawl to that of a standardized...

  12. Cooperative Research Paired Trawl Sweep Comparison Study

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — In the spring of 2009, Northeast Fisheries Science Center (NEFSC) replaced the previous standard bottom trawl gear (Yankee 36) with a new standard survey trawl...

  13. Influence of twin and multi-rig trawl systems on CPUE in the Danish Norway lobster (Nephrops norvegicus) fishery

    DEFF Research Database (Denmark)

    Feekings, Jordan P.; Berg, Casper Willestofte; Krag, Ludvig Ahm;

    2016-01-01

    analyse catchrates of four target species, Norway lobster (Nephrops norvegicus), cod (Gadus morhua), plaice (Pleuronectesplatessa) and haddock (Melanogrammus aeglefinus), to try and understand how the use of multi-rig trawlshave altered catch rates within the Danish demersal trawl fishery over the last 16...

  14. Integer-valued trawl processes

    DEFF Research Database (Denmark)

    Barndorff-Nielsen, Ole E.; Lunde, Asger; Shephard, Neil;

    2014-01-01

    This paper introduces a new continuous-time framework for modelling serially correlated count and integer-valued data. The key component in our new model is the class of integer-valued trawl processes, which are serially correlated, stationary, infinitely divisible processes. We analyse the proba......This paper introduces a new continuous-time framework for modelling serially correlated count and integer-valued data. The key component in our new model is the class of integer-valued trawl processes, which are serially correlated, stationary, infinitely divisible processes. We analyse...

  15. 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...

  16. 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...

  17. 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.

  18. 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.

  19. The impact of gear regulation changes on discard rates: the case of the Baltic Sea cod fishery

    DEFF Research Database (Denmark)

    Feekings, Jordan P.; Madsen, Niels; Lewy, Peter

    2012-01-01

    stocks have decline considerably over the past 30 years which has subsequently led to numerous legislations and policies being introduced to improving the state of the stocks. We evaluate whether the developments made to trawls used in the Baltic Sea cod fishery to improve selectivity and the increase...... in minimum landing size (MLS) have had any marked effect on the discard rates of the target species, cod. Results show that the gear regulation changes enforced in the Baltic demersal trawl fishery have had diverse effects on discard rates and are largely dependent on the gear, recruitment, and compliance...

  20. 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.

  1. 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

  2. Density dependent catchability in bottom trawl surveys

    OpenAIRE

    Aglen, Asgeir; Engås, Arill; Godø, Olav Rune; McCallum, Barry R.; Stansbury, Don; Walsh, Stephen J.

    1997-01-01

    Fish form schools, layer or patches in which the individual fish's behaviour is not independent of its neighbours movements. On the other hand, at low densities fish may have the freedom to act as single individuals independently of what other fish are doing. Potentially, if these contrasts occur in nature, they may give rise to behavioural differences of fish in front of the trawl at high and low densities with successive effects on catchability and bottom trawl indices of stock ...

  3. 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.

  4. Relationship between mid-water trawling effort and catch composition uncertainty in two large lakes (Huron and Michigan) dominated by alosines, osmerids, and coregonines

    Science.gov (United States)

    Warner, David M.; Claramunt, Randall M.; Schaeffer, Jeffrey S.; Yule, Daniel L.; Hrabik, Tom R.; Peintka, Bernie; Rudstam, Lars G.; Holuszko, Jeffrey D.; O'Brien, Timothy P.

    2012-01-01

    Because it is not possible to identify species with echosounders alone, trawling is widely used as a method for collecting species and size composition data for allocating acoustic fish density estimates to species or size groups. In the Laurentian Great Lakes, data from midwater trawls are commonly used for such allocations. However, there are no rules for how much midwater trawling effort is required to adequately describe species and size composition of the pelagic fish communities in these lakes, so the balance between acoustic sampling effort and trawling effort has been unguided. We used midwater trawl data collected between 1986 and 2008 in lakes Michigan and Huron and a variety of analytical techniques to develop guidance for appropriate levels of trawl effort. We used multivariate regression trees and re-sampling techniques to i. identify factors that influence species and size composition of the pelagic fish communities in these lakes, ii. identify stratification schemes for the two lakes, iii. determine if there was a relationship between uncertainty in catch composition and the number of tows made, and iv. predict the number of tows required to reach desired uncertainty targets. We found that depth occupied by fish below the surface was the most influential explanatory variable. Catch composition varied between lakes at depths RSE [relative standard error = 100 × (SE/mean)] and the number of tows made for the proportions of the different size and species groups. We found for the fifth (Lake Huron) and sixth (Lake Michigan) largest lakes in the world, 15–35 tows were adequate to achieve target RSEs (15% and 30%) for ubiquitous species, but rarer species required much higher, and at times, impractical effort levels to reach these targets.

  5. Food resource utilization by juvenile Baltic cod Gadus morhua : a mechanism potentially influencing recruitment success at the demersal juvenile stage?

    DEFF Research Database (Denmark)

    Hüssy, Karin; St. John, Michael; Böttcher, U.

    1997-01-01

    those reported to be consumed by juveniles in other areas. The apparent overlap in food resource utilization among the different size groups of demersal juveniles observed in this study suggests that in years with low prey abundance, or high abundance of pelagic juveniles, strong intra......Pelagic and demersal juvenile Baltic cod Gadus morhua L. were collected during surveys in the Bornholm Basin (Baltic Sea) in autumn 1994. Stomach contents were examined for prey composition in order to evaluate the potential importance of the pelagic and demersal habitats for recruitment success....... Juvenile cod less than 40 mm fed exclusively on pelagic prey such as copepods and cladocerans. Between 40 and 50 mm the juveniles began to consume benthic prey such as mysids and amphipods; however, copepods were still the dominant food organisms. Between 50 and 70 mm the dominant prey items consumed were...

  6. Relationships between water mass characteristics and estimates of fish population abundance from trawl surveys.

    Science.gov (United States)

    Smith, S J; Perry, R I; Fanning, L P

    1991-01-01

    The Canadian Department of Fisheries and Oceans conducts annual bottom trawl surveys to monitor changes in the abundance of the major commercially important groundfish populations. Some of these surveys have been in operation for almost 20 yr. The estimates from these surveys often indicate rapid changes in abundance over time beyond that expected from the population dynamics of the fish. Much of this interannual change has been interpreted as variation, the magnitude of which has often made it difficult to measure anything but the most severe effects of fishing, pollution or any other intervention on the population. Recent studies have shown that some of this variation may be attributed to changes in catchability of fish due to the effects of environmental variables on fish distribution. Annual changes in abundance as estimated from such field surveys may be confounded by changes in catchability due to annual changes in environmental conditions. In this study, trawl catches of age 4 Atlantic cod (Gadus morhua) from surveys conducted during March 1979-1988 were compared with concurrent measurements of bottom salinity, temperature and depth. Large catches of age 4 cod are more likely to occur in water characterized as the intermediate cold layer defined by salinities of 32-33.5 and temperatures<5°C. This relationship also appears to be modified by depth. We further show that internnual changes in the estimated abundance from the surveys were, in a number of cases, coincident with changes in the proportion of the bottom water composed of the intermediate cold water layer. The implications that these patterns may have on interpreting trends in the estimates of abundance from trawl surveys are discussed.

  7. 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.

  8. Net escapement of Antartic krill in trawls

    DEFF Research Database (Denmark)

    Krafft, B.A.; Krag, Ludvig Ahm; Herrmann, Bent;

    This document describes the aims and methodology of a three year project (commenced in 2012) entitled Net Escapement of Antarctic krill in Trawls (NEAT). The study will include a morphology based mathematical modeling (FISHSELECT) of different sex and maturity groups of Antarctic krill (Euphausia...

  9. 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...

  10. Characteristics of juvenile survivors reveal spatio-temporal differences in early life stage survival of Baltic cod

    DEFF Research Database (Denmark)

    Huwer, Bastian; Hinrichsen, H.H.; Böttcher, U.

    2014-01-01

    The spatio-temporal origin of surviving juvenile Baltic cod Gadus morhua was investigated by coupling age information from otolith microstructure analysis and hydrodynamic modeling, which allowed backtracking of drift routes in time and space. The suitability of hydrodynamic modeling for drift...... simulations of early life stages of Baltic cod up to the pelagic juvenile stage was validated by comparing model simulations with the catch distribution from a survey targeting pelagic juveniles, and mortality rates and hatch date distributions of pelagic and demersal juveniles were estimated. Hatch dates...... and hatch locations of juvenile survivors showed distinct patterns which did not agree well with the abundance and spatial distribution of eggs, suggesting marked spatio-temporal differences in larval survival. The good agreement of the spatio-temporal origin of survivors from this field investigation...

  11. Bottom-trawling along submarine canyons impacts deep sedimentary regimes

    Science.gov (United States)

    Paradis, Sarah; Puig, Pere; Masqué, Pere; Juan-Díaz, Xènia; Martín, Jacobo; Palanques, Albert

    2017-01-01

    Many studies highlight that fish trawling activities cause seafloor erosion, but the assessment of the remobilization of surface sediments and its relocation is still not well documented. These impacts were examined along the flanks and axes of three headless submarine canyons incised on the Barcelona continental margin, where trawling fleets have been operating for decades. Trawled grounds along canyon flanks presented eroded and highly reworked surface sediments resulting from the passage of heavy trawling gear. Sedimentation rates on the upper canyon axes tripled and quadrupled its natural (i.e. pre-industrialization) values after a substantial increase in total horsepower of the operating trawling fleets between 1960 s and 1970 s. These impacts affected the upper canyon reaches next to fishing grounds, where sediment resuspended by trawling can be transported towards the canyon axes. This study highlights that bottom trawling has the capacity to alter natural sedimentary environments by promoting sediment-starved canyon flanks, and by enhancing sedimentation rates along the contiguous axes, independently of canyons’ morphology. Considering the global mechanisation and offshore expansion of bottom trawling fisheries since the mid-20th century, these sedimentary alterations may occur in many trawled canyons worldwide, with further ecological impacts on the trophic status of these non-resilient benthic communities. PMID:28233856

  12. Using small meshed collecting bags on trawls to quantify trawls seabed disturbance of aquatic organisms

    DEFF Research Database (Denmark)

    Krag, Ludvig Ahm

    activities has been documented by collecting samples before and after the fishing process or by comparing areas of different fishing intensity. These investigations are expensive and labor demanding and are inappropriate for documenting effects of smaller technological changes aimed at reducing trawling...... impact on commercial fishing grounds. In this study we develop and test small-meshed collecting bags designed to retain juvenile fish and benthic megafauna. The collecting bags are mounted in the wings and body of the trawl. The catches in the collection bags provide information of the species and size...

  13. 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.

  14. Factors determining variations in otolith microincrement width of demersal juvenile Baltic cod Gadus morhua

    DEFF Research Database (Denmark)

    Hüssy, Karin; Mosegaard, Henrik; Hinrichsen, H.H.;

    2003-01-01

    Pelagic and demersal juvenile Baltic cod Gadus morhua L. were collected on the slope and the top of Rønne bank in the Baltic Sea during 2 cruises in November and December 1998. The objective of this study was to evaluate distinct changes in otolith increment width observed in demersal juveniles b......, performed vertical migrations during the second interval, and stayed in association with the seafloor in the subsequent interval, corresponding to the time after the breakdown of the thermocline....

  15. Using otolith microstructure to analyse growth of juvenile Baltic cod Gadus morhua

    DEFF Research Database (Denmark)

    Hüssy, Karin; Mosegaard, Henrik; Hinrichsen, H.H.

    2003-01-01

    Pelagic and demersal juvenile Baltic cod Gadus morhua L. were collected on the slope and the top of Rønne bank in the Baltic Sea during 2 cruises in November and December 1998. The growth, age at settling and vertical migration pattern were studied by otolith microstructure analysis....... The relationship between fish and otolith size were found to change at settling, with an increase of fish size in relation to otolith size after settling. This change was more pronounced on the slope compared to the top of the bank. The timing of first settling at the 2 localities did not differ with respect...... to fish age. At both localities, fish that hatched early in the season spent a shorter time in the pelagic stage than late-hatched fish. However, significant differences in growth rate during the pelagic stage were observed, where fish captured on the slope grew faster. On the bank, individuals with fast...

  16. Mapping the spawning grounds of North Sea cod (Gadus morhua) by direct and indirect means.

    Science.gov (United States)

    Fox, Clive J; Taylor, Martin; Dickey-Collas, Mark; Fossum, Petter; Kraus, Gerd; Rohlf, Norbert; Munk, Peter; van Damme, Cindy J G; Bolle, Loes J; Maxwell, David L; Wright, Peter J

    2008-07-07

    Despite recent evidence for sub-stock structuring, North Sea cod are assessed as a single unit. As a consequence, knowledge of sub-stock trends is poor. In particular, there are no recent evaluations of which spawning grounds are active. Here we report results from the first ichthyoplankton survey to cover the whole North Sea. Also, this survey, conducted in 2004, was the first to make extensive use of DNA-based molecular methods to unambiguously identify early developmental stage cod eggs. We compare the findings from the plankton survey with estimated egg production inferred from the distribution of mature cod in contemporaneous trawl surveys. Results from both approaches were in general agreement and showed hot spots of egg production around the southern and eastern edges of the Dogger Bank, in the German Bight, the Moray Firth and to the east of the Shetlands. These areas broadly coincide with known spawning locations from the period 1940 to 1970. We were, however, unable to directly detect significant numbers of cod eggs at the historic spawning ground off Flamborough (northeast coast of England). The results demonstrate that most of the major spawning grounds of cod in the North Sea are still active but that some localized populations may have been reduced to the point where it is now difficult to detect the presence of eggs in the plankton.

  17. 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

  18. Industry Based Survey (IBS) Cod

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The "Gulf of Maine Atlantic Cod Industry-Based Survey" was a collaboration of the Massachusetts Division of Marine Fisheries and the fishing industry, with support...

  19. Northeast Regional Cod Tagging Program

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Scientific justification: Canadian and US stock assessments for Atlantic cod indicate considerable fluctuation in stock abundance and recruitment over the last 20...

  20. Size selectivity and trawling efficiency of two sampling trawls used in resource surveys of yellowtail flounder on Grand Bank, NAFO Div. 3LNO

    National Research Council Canada - National Science Library

    Walsh, S.J; McCallum, B.R

    1998-01-01

    .... Size selectivity and trawl efficiency of two shrimp trawls used in the surveys of the Grand Bank yellowtail flounder, Pleuronectes ferruginea, were analyzed from a series of comparative fishing tows...

  1. Feeding ecology of age-0 walleye pollock (Gadus chalcogrammus) and Pacific cod (Gadus macrocephalus) in the southeastern Bering Sea

    Science.gov (United States)

    Strasburger, Wesley W.; Hillgruber, Nicola; Pinchuk, Alexei I.; Mueter, Franz J.

    2014-11-01

    Walleye pollock (Gadus chalcogrammus) and Pacific cod (Gadus macrocephalus) are of particular economic and ecological importance in the southeastern Bering Sea. The spatial and temporal overlap of early life stages of both species may explain their strongly correlated recruitment trends. Pelagic larvae and juveniles were collected during four research cruises in May, July and September of 2008, an exceptionally cold year, and their stomach contents were examined. Feeding success and diet composition of walleye pollock and Pacific cod were consistently different in spring, summer, and fall. Pacific cod larvae and juveniles always consumed larger and progressively fewer prey items per stomach than walleye pollock; this difference was particularly pronounced in the fall. Our data suggest that co-occurring early life stages of walleye pollock and Pacific cod were dividing prey resources rather than competing for them, at least during the exceptionally cold conditions in 2008 in the southeastern Bering Sea.

  2. 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.

  3. Gear Selectivity of a Longfin Squid Bottom Trawl

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Loligo pealeii (longfin inshore squid) co-occurs with Atlantic butterfish (Peprilus triacanthus) throughout the year and discarding in the L. pealeii bottom trawl...

  4. Corpus Christi EFH Trawling Effects 2001-2002

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — We compared sediments and benthos of two adjacent zones of the middle Texas coast, one of which was closed to shrimp trawling for 7 months. Findings indicated that...

  5. NEFSC 2012 Spring Bottom Trawl Survey (HB1201, EK60)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC bottom trawl survey is a fisheries independent, multi-species survey that provides the primary scientific data for fisheries assessments in the U.S....

  6. NEFSC 2014 Fall Bottom Trawl Survey (HB1405, EK60)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC bottom trawl survey is a fisheries independent, multi-species survey that provides the primary scientific data for fisheries assessments in the U.S....

  7. NEFSC 2008 Fall Bottom Trawl Survey (HB0807, EK60)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC bottom trawl survey is a fisheries independent, multi-species survey that provides the primary scientific data for fisheries assessments in the U.S....

  8. NEFSC 2009 Fall Bottom Trawl Survey (HB0905, EK60)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC bottom trawl survey is a fisheries independent, multi-species survey that provides the primary scientific data for fisheries assessments in the U.S....

  9. NEFSC 2013 Fall Bottom Trawl Survey (HB1304, EK60)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC bottom trawl survey is a fisheries independent, multi-species survey that provides the primary scientific data for fisheries assessments in the U.S....

  10. NEFSC 2002 Fall Bottom Trawl Survey (AL0210, EK500)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC bottom trawl survey is a fisheries independent, multi-species survey that provides the primary scientific data for fisheries assessments in the U.S....

  11. SWFSC FED Mid Water Trawl Juvenile Rockfish Survey, Surface Data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — SWFSC FED Mid Water Trawl Juvenile Rockfish Survey: Station Information and Surface Data. Surveys have been conducted along the central California coast in May/June...

  12. SWFSC FED Mid Water Trawl Juvenile Rockfish Survey, CTD Data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — SWFSC FED Mid Water Trawl Juvenile Rockfish Survey: CTD Data. Surveys have been conducted along the central California coast in May/June every year since 1983. In...

  13. NEFSC 2003 Fall Bottom Trawl Survey (AL0305, EK500)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC bottom trawl survey is a fisheries independent, multi-species survey that provides the primary scientific data for fisheries assessments in the U.S....

  14. NEFSC 2005 Spring Bottom Trawl Survey (AL0504, EK500)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC bottom trawl survey is a fisheries independent, multi-species survey that provides the primary scientific data for fisheries assessments in the U.S....

  15. NEFSC 2004 Winter Bottom Trawl Survey (AL0401, EK500)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC bottom trawl survey is a fisheries independent, multi-species survey that provides the primary scientific data for fisheries assessments in the U.S....

  16. NEFSC 2004 Spring Bottom Trawl Survey (AL0403, EK500)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC bottom trawl survey is a fisheries independent, multi-species survey that provides the primary scientific data for fisheries assessments in the U.S....

  17. NEFSC 1999 Fall Bottom Trawl Survey (AL9911, EK500)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC bottom trawl survey is a fisheries independent, multi-species survey that provides the primary scientific data for fisheries assessments in the U.S....

  18. NEFSC 2005 Fall Bottom Trawl Survey (AL0509, EK500)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC bottom trawl survey is a fisheries independent, multi-species survey that provides the primary scientific data for fisheries assessments in the U.S....

  19. NEFSC 2004 Fall Bottom Trawl Survey (AL0409, EK500)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC bottom trawl survey is a fisheries independent, multi-species survey that provides the primary scientific data for fisheries assessments in the U.S....

  20. NEFSC 2015 Spring Bottom Trawl Survey (HB1501, EK60)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC bottom trawl survey is a fisheries independent, multi-species survey that provides the primary scientific data for fisheries assessments in the U.S....

  1. NEFSC 2001 Fall Bottom Trawl Survey (AL0110, EK500)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC bottom trawl survey is a fisheries independent, multi-species survey that provides the primary scientific data for fisheries assessments in the U.S....

  2. NEFSC 2012 Fall Bottom Trawl Survey (HB1206, EK60)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC bottom trawl survey is a fisheries independent, multi-species survey that provides the primary scientific data for fisheries assessments in the U.S....

  3. NEFSC 2002 Winter Bottom Trawl Survey (AL0203, EK500)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC bottom trawl survey is a fisheries independent, multi-species survey that provides the primary scientific data for fisheries assessments in the U.S....

  4. NEFSC 2008 Spring Bottom Trawl Survey (HB0802, EK60)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC bottom trawl survey is a fisheries independent, multi-species survey that provides the primary scientific data for fisheries assessments in the U.S....

  5. NEFSC 2014 Spring Bottom Trawl Survey (HB1401, EK60)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC bottom trawl survey is a fisheries independent, multi-species survey that provides the primary scientific data for fisheries assessments in the U.S....

  6. NEFSC 2008 Spring Bottom Trawl Survey (AL0801, EK500)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC bottom trawl survey is a fisheries independent, multi-species survey that provides the primary scientific data for fisheries assessments in the U.S....

  7. NEFSC 2009 Spring Bottom Trawl Survey (HB0901, EK60)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC bottom trawl survey is a fisheries independent, multi-species survey that provides the primary scientific data for fisheries assessments in the U.S....

  8. NEFSC 2005 Fall Bottom Trawl Survey (AL0508, EK500)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC bottom trawl survey is a fisheries independent, multi-species survey that provides the primary scientific data for fisheries assessments in the U.S....

  9. NEFSC 1998 Fall Bottom Trawl Survey (AL9811, EK500)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC bottom trawl survey is a fisheries independent, multi-species survey that provides the primary scientific data for fisheries assessments in the U.S....

  10. NEFSC 2007 Bottom Trawl Survey Calibration (HB0710, EK60)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC bottom trawl survey is a fisheries independent, multi-species survey that provides the primary scientific data for fisheries assessments in the U.S....

  11. 77 FR 29586 - Sea Turtle Conservation; Shrimp Trawling Requirements; Correction

    Science.gov (United States)

    2012-05-18

    ... Part 223 RIN 0648-BC10 Sea Turtle Conservation; Shrimp Trawling Requirements; Correction AGENCY... turtle excluder devices (TEDs) in their nets, and announced five public hearings to be held in...

  12. NEFSC 2000 Fall Bottom Trawl Survey (AL0007, EK500)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC bottom trawl survey is a fisheries independent, multi-species survey that provides the primary scientific data for fisheries assessments in the U.S....

  13. NEFSC 2002 Spring Bottom Trawl Survey (AL0204, EK500)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC bottom trawl survey is a fisheries independent, multi-species survey that provides the primary scientific data for fisheries assessments in the U.S....

  14. NEFSC 2011 Spring Bottom Trawl Survey (HB1102, EK60)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC bottom trawl survey is a fisheries independent, multi-species survey that provides the primary scientific data for fisheries assessments in the U.S....

  15. NEFSC 2011 Fall Bottom Trawl Survey (HB1105, EK60)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC bottom trawl survey is a fisheries independent, multi-species survey that provides the primary scientific data for fisheries assessments in the U.S....

  16. NEFSC 2008 Fall Bottom Trawl Survey (AL0803, EK500)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC bottom trawl survey is a fisheries independent, multi-species survey that provides the primary scientific data for fisheries assessments in the U.S....

  17. NEFSC 2005 Winter Bottom Trawl Survey (AL0502, EK500)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC bottom trawl survey is a fisheries independent, multi-species survey that provides the primary scientific data for fisheries assessments in the U.S....

  18. Bottom Trawl Survey Protocol Development (HB0706, EK60)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Cruise objectives include: 1) Investigate performance characteristics of new research bottom trawl; 2) Develop standard operating procedures for the NEFSC Bottom...

  19. NEFSC 2013 Spring Bottom Trawl Survey (HB1301, EK60)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC bottom trawl survey is a fisheries independent, multi-species survey that provides the primary scientific data for fisheries assessments in the U.S....

  20. NEFSC 2015 Fall Bottom Trawl Survey (HB1506, EK60)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC bottom trawl survey is a fisheries independent, multi-species survey that provides the primary scientific data for fisheries assessments in the U.S....

  1. NEFSC 2007 Bottom Trawl Survey Calibration (HB0711, EK60)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC bottom trawl survey is a fisheries independent, multi-species survey that provides the primary scientific data for fisheries assessments in the U.S....

  2. NEFSC 2000 Fall Bottom Trawl Survey (Al0006, EK500)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC bottom trawl survey is a fisheries independent, multi-species survey that provides the primary scientific data for fisheries assessments in the U.S....

  3. NEFSC 2010 Spring Bottom Trawl Survey (HB1002, EK60)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC bottom trawl survey is a fisheries independent, multi-species survey that provides the primary scientific data for fisheries assessments in the U.S....

  4. NEFSC 2003 Spring Bottom Trawl Survey (DE0303, EK500)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC bottom trawl survey is a fisheries independent, multi-species survey that provides the primary scientific data for fisheries assessments in the U.S....

  5. West Coast Groundfish Bottom Trawl Survey Data - Annual West Coast time series groundfish trawl data collection survey

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Members of the Fishery Resource Analysis and Monitoring Division Survey Team conduct an annual West Coast Groundfish Bottom Trawl Survey from May - October each...

  6. Improving fishing effort descriptors: Modelling engine power and gear-size relations of five European trawl fleets

    DEFF Research Database (Denmark)

    Eigaard, Ole Ritzau; Rihan, Dominic; Graham, Norman

    2011-01-01

    Based on information from an international inventory of gears currently deployed by trawlers in five European countries, the relationship between vessel engine power and trawl size is quantified for different trawl types, trawling techniques and target species. Using multiplicative modelling...

  7. Spatio-temporal variability of the North Sea cod recruitment in relation to temperature and zooplankton.

    Directory of Open Access Journals (Sweden)

    Delphine Nicolas

    Full Text Available The North Sea cod (Gadus morhua, L. stock has continuously declined over the past four decades linked with overfishing and climate change. Changes in stock structure due to overfishing have made the stock largely dependent on its recruitment success, which greatly relies on environmental conditions. Here we focus on the spatio-temporal variability of cod recruitment in an effort to detect changes during the critical early life stages. Using International Bottom Trawl Survey (IBTS data from 1974 to 2011, a major spatio-temporal change in the distribution of cod recruits was identified in the late 1990s, characterized by a pronounced decrease in the central and southeastern North Sea stock. Other minor spatial changes were also recorded in the mid-1980s and early 1990s. We tested whether the observed changes in recruits distribution could be related with direct (i.e. temperature and/or indirect (i.e. changes in the quantity and quality of zooplankton prey effects of climate variability. The analyses were based on spatially-resolved time series, i.e. sea surface temperature (SST from the Hadley Center and zooplankton records from the Continuous Plankton Recorder Survey. We showed that spring SST increase was the main driver for the most recent decrease in cod recruitment. The late 1990s were also characterized by relatively low total zooplankton biomass, particularly of energy-rich zooplankton such as the copepod Calanus finmarchicus, which have further contributed to the decline of North Sea cod recruitment. Long-term spatially-resolved observations were used to produce regional distribution models that could further be used to predict the abundance of North Sea cod recruits based on temperature and zooplankton food availability.

  8. 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....

  9. 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....

  10. Growth pattern and growth dependent mortality of larval and pelagic juvenile North Sea cod Gadus morhua

    DEFF Research Database (Denmark)

    Nielsen, Rune; Munk, Peter

    2004-01-01

    and May 2001), and larval/juvenile growth history from each of the sampling sequences was outlined. Growth rate was estimated by fitting a Laird-Gompertz equation to lengths-at-age, and we found the mean specific growth rate in length at age 20 d was 3.2% d(-1), declining to 1.9% d(-1) at an age of 90 d...

  11. Effects of trawl selectivity and genetic parameters on fish body length under long-term trawling

    Science.gov (United States)

    Yu, Yang; Sun, Peng; Cui, He; Sheng, Huaxiang; Zhao, Fenfang; Tang, Yanli; Chen, Zelin

    2015-10-01

    Long-term fishing pressure affects the biological characteristics of exploited fish stocks. The biological characteristics of hairtail ( Trichiurus lepturus) in the East China Sea are unable to recover because of long-term trawling. Fishing induces evolutionary effects on the fish's biological characteristics. Evidence of these changes includes small size at age, a shift to earlier age structure, and early maturation. Natural and artificial selection usually affect the fish's life history. Selection can induce different chances of reproduction, and individual fish can give a different genetic contribution to the next generation. In this study, analysis of time-dependent probability of significance and test of sensitivity were used to explore the effects of fish exploitation rate, mesh size, and heritability with long-term trawling. Results showed that fishing parameters were important drivers to exploited fish population. However, genetic traits altered by fishing were slow, and the changes in biological characteristics were weaker than those caused by fishing selection. Exploitation rate and mesh size exhibited similar evolutionary trend tendency under long-term fishing. The time-dependent probability of significance trend showed a gradual growth and tended to be stable. Therefore, the direction of fishing-induced evolution and successful management of fish species require considerable attention to contribute to sustainable fisheries in China.

  12. AFSC/ABL: Frederick Sound Echo-integrated Trawl Survey, 2001 to 2004

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The acoustic trawl database for Frederick Sounds echo-trawl survey was conducted from 2001 to 2004. The surveys were conducted throughout most of the southern part...

  13. Modified Herring Trawl Fish Catch Data, Gulf of Alaska Fjords, 2004-2011

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This dataset contains catch data from trawls at the sampling stations. We deployed a modified herring trawl in coastal waters within glacier fjords of Alaska....

  14. AFSC/ABL: Lynn Canal Echo-Integrated Trawl Surveys, 2001-2004

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The acoustic trawl database for Lynn Canals echo-trawl survey was conducted from 2001 to 2004 throughout southern Lynn Canal in southeast Alaska. Acoustic surveys...

  15. Fish assemblages in southern California using trawl data from the National Marine Fisheries Service

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Fish benthic trawls were completed by the National Marine Fisheries Service Groundfish Survey Program (NMFS GSP). Data from 477 fishery independent trawls ranging...

  16. Size selection of Antarctic krill (Euphausia superba) in trawls.

    Science.gov (United States)

    Krag, Ludvig A; Herrmann, Bent; Iversen, Svein A; Engås, Arill; Nordrum, Sigve; Krafft, Bjørn A

    2014-01-01

    Trawlers involved in the Antarctic krill (Euphausia superba) fishery use different trawl designs, and very little is known about the size selectivity of the various gears. Size selectivity quantifies a given trawl's ability to catch different sizes of a harvested entity, and this information is crucial for the management of a sustainable fishery. We established a morphological description of krill and used it in a mathematical model (FISHSELECT) to predict the selective potential of diamond meshes measuring 5-40 mm with mesh opening angles (oa) ranging from 10 to 90°. We expected the majority of krill to encounter the trawl netting in random orientations due to high towing speeds and the assumed swimming capabilities of krill. However, our results indicated that size selectivity of krill is a well-defined process in which individuals encounter meshes at an optimal orientation for escapement. The simulation-based results were supported by data from experimental trawl hauls and underwater video images of the mesh geometry during fishing. Herein we present predictions for the size selectivity of a range of netting configurations relevant to the krill fishery. The methods developed and results described are important tools for selecting optimal trawl designs for krill fishing.

  17. Impact of bottom trawling on sediment characteristics - A study along inshore waters off Veraval coast, India

    Digital Repository Service at National Institute of Oceanography (India)

    Bhagirathan, U.; Meenakumari, B.; Jayalakshmy, K.V.; Panda, S.K.; Madhu, V.R.; Vaghela, D

    of water depths 15-20 m, 21-25 m, 26-30 m, 31-35 m and 36-40 m in commercial trawling grounds. Trawling was conducted for 12 months in a span of 15 months (September 2005-November 2006) excluding the trawl ban period (June to August). The sediment texture...

  18. Assessing the Impact of Policy Changes in the Icelandic Cod Fishery Using a Hybrid Simulation Model

    Directory of Open Access Journals (Sweden)

    Sigríður Sigurðardóttir

    2014-01-01

    Full Text Available Most of the Icelandic cod is caught in bottom trawlers or longliners. These two fishing methods are fundamentally different and have different economic, environmental, and even social effects. In this paper we present a hybrid-simulation framework to assess the impact of changing the ratio between cod quota allocated to vessels with longlines and vessels with bottom trawls. It makes use of conventional bioeconomic models and discrete event modelling and provides a framework for simulating life cycle assessment (LCA for a cod fishery. The model consists of two submodels, a system dynamics model describing the biological aspect of the fishery and a discrete event model for fishing activities. The model was run multiple times for different quota allocation scenarios and results are presented where different scenarios are presented in the three dimensions of sustainability: environmental, social, and economic. The optimal allocation strategy depends on weighing the three different factors. The results were encouraging first-steps towards a useful modelling method but the study would benefit greatly from better data on fishing activities.

  19. Assessing the impact of policy changes in the Icelandic cod fishery using a hybrid simulation model.

    Science.gov (United States)

    Sigurðardóttir, Sigríður; Johansson, Björn; Margeirsson, Sveinn; Viðarsson, Jónas R

    2014-01-01

    Most of the Icelandic cod is caught in bottom trawlers or longliners. These two fishing methods are fundamentally different and have different economic, environmental, and even social effects. In this paper we present a hybrid-simulation framework to assess the impact of changing the ratio between cod quota allocated to vessels with longlines and vessels with bottom trawls. It makes use of conventional bioeconomic models and discrete event modelling and provides a framework for simulating life cycle assessment (LCA) for a cod fishery. The model consists of two submodels, a system dynamics model describing the biological aspect of the fishery and a discrete event model for fishing activities. The model was run multiple times for different quota allocation scenarios and results are presented where different scenarios are presented in the three dimensions of sustainability: environmental, social, and economic. The optimal allocation strategy depends on weighing the three different factors. The results were encouraging first-steps towards a useful modelling method but the study would benefit greatly from better data on fishing activities.

  20. Impact and distribution of bottom trawl fishing on mud-bottom communities in the Kattegat

    DEFF Research Database (Denmark)

    Pommer, Christina Dahl; Olesen, Michael; Hansen, Jorgen L. S.

    2016-01-01

    of trawled area demonstrated that the habitats are nearly 100% impacted, and frequencies of trawling beneath 100 m depth can reach 20 events per year. Multivariate analysis of community composition could not discriminate between lightly trawled and heavily trawled areas. However, a strong habitat selectivity...... to areas with higher activity. Thus, the Kattegat has been impacted to an extent where areas with reference conditions for certain habitats below 22 m no longer exist. Consequently, it is unknown how the benthic communities would have appeared without trawl disturbance and, thus, difficult to determine...

  1. 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...

  2. 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...

  3. KEMAMPUAN TANGKAP JARING TRAWL TERHADAP IKAN DEMERSAL DI PERAIRAN TARAKAN DAN SEKITARNYA

    Directory of Open Access Journals (Sweden)

    Asep Priatna

    2016-03-01

    Fish stock estimation is very important information as basis for developing fisheries. Until now, estimation of demersal fish stock is usually used swept area method by using trawl net fishing. However, there was the problem related to accuracy of fish abundant estimation that is how much the demersal fish could be accurately caught by the trawl net. To solve this problem, an approach estimation of dmersal fish stock using acoustic survey conducted simultaneously with demersal trawl fishing. Research activities were conducted on May, August and November 2012 in Tarakan waters, North Kalimantan using echosounder Simrad EY60-120 kHz and bottom trawl net with 26 m headrope. The result show that the catchability coefficient of trawl net estimated  0,3, it means that the trawl net could be able to catch 30% of demersal fish during swept area trawl fishing.

  4. 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.

  5. Job Satisfaction in the Shrimp Trawl Fisheries of Vietnam

    Science.gov (United States)

    Sinh, Le Xuan

    2012-01-01

    This paper investigates the job satisfaction of small-scale shrimp trawl fishers in the vicinity of Camau National Park in southern Vietnam. The research sample consisted of 77 fishers who belong to a growing population of shrimp fishers in the region. The results suggest that 60% would change their fishing metier, 78% would leave fishing for…

  6. Job Satisfaction in the Shrimp Trawl Fisheries of Chennai, India

    Science.gov (United States)

    Bavinck, Maarten

    2012-01-01

    Shrimp trawling represents an important fishing metier in South India, generating high levels of employment and economic value. It is also a contested metier, ostensibly contributing to environmental degradation and social inequality. This paper investigates the job satisfaction of crew members (captains and workers) on board the shrimp trawlers…

  7. Epibenthic assemblages of the Tail of the Grand Bank and Flemish Cap (northwest Atlantic) in relation to environmental parameters and trawling intensity

    Science.gov (United States)

    Murillo, Francisco Javier; Serrano, Alberto; Kenchington, Ellen; Mora, José

    2016-03-01

    warmer and saltier water. Conditional tests under a step-wise model identified the percentage of mud as having the greatest explanatory power (40%) of the tested environmental variables. Trawling Intensity explained 11% of the variation in the full data set in marginal tests. Species richness in the deep water assemblages (Cluster III) was significantly and negatively correlated with fishing intensity. The species most directly associated with high trawling intensity in the DCA were the hard-shelled scavenging and predatory gastropods and a thick-shelled bivalve, consistent with expectations based on the trawling impact literature. Our study fills a critical knowledge gap in this important fishing area, and our novel regional-scale maps of the epibenthic assemblages will facilitate the development of ecosystem-based models linking benthic and pelagic systems and inform biodiversity conservation.

  8. 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...

  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...

  10. 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...

  11. 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.

  12. Job Satisfaction in the Shrimp Trawl Fisheries of Chennai, India.

    Science.gov (United States)

    Bavinck, Maarten

    2012-10-01

    Shrimp trawling represents an important fishing métier in South India, generating high levels of employment and economic value. It is also a contested métier, ostensibly contributing to environmental degradation and social inequality. This paper investigates the job satisfaction of crew members (captains and workers) on board the shrimp trawlers of Chennai (former Madras). Research took place in 2007 and 2008 (N = 137). Results suggest a general satisfaction with being in the fishery. However, a little over three-fifths of fishers said they would be willing to change fishing métier and about one-half said they would leave the occupation. About one-half also said they would not advise a young person to enter the occupation. The tendency to move away from the fishery is argued to reflect a growing pessimism about the future of the shrimp trawl fisheries, but also an increasing awareness of other economic opportunities.

  13. Modelling potential impacts of bottom trawl fisheries on soft sediment biogeochemistry in the North Sea†

    Directory of Open Access Journals (Sweden)

    Parker Ruth

    2001-12-01

    Full Text Available Bottom trawling causes physical disturbance to sediments particularly in shelf areas. The disturbance due to trawling is most significant in deeper areas with softer sediments where levels of natural disturbance due to wave and tidal action are low. In heavily fished areas, trawls may impact the same area of seabed more than four times per year. A single pass of a beam trawl, the heaviest gear routinely used in shelf sea fisheries, can kill 5–65% of the resident fauna and mix the top few cm of sediment. We expect that sediment community function, carbon mineralisation and biogeochemical fluxes will be strongly affected by trawling activity because the physical effects of trawling are equivalent to those of an extreme bioturbator, and yet, unlike bioturbating macrofauna, trawling does not directly contribute to community metabolism. We used an existing box-model of a generalised soft sediment system to examine the effects of trawling disturbance on carbon mineralisation and chemical concentrations. We contrasted the effects of a natural scenario, where bioturbation is a function of macrobenthos biomass, with an anthropogenic impact scenario where physical disturbance results from trawling rather than the action of bioturbating macrofauna. Simulation results suggest that the effects of low levels of trawling disturbance will be similar to those of natural bioturbators but that high levels of trawling disturbance prevent the modelled system from reaching equilibrium due to large carbon fluxes between oxic and anoxic carbon compartments. The presence of macrobenthos in the natural disturbance scenario allowed sediment chemical storage and fluxes to reach equilibrium. This is because the macrobenthos are important carbon consumers in the system whose presence reduces the magnitude of available carbon fluxes. In soft sediment systems, where the level physical disturbance due to waves and tides is low, model results suggest that intensive trawling

  14. Cod avoidance by area regulations in Kattegat

    DEFF Research Database (Denmark)

    Eliasen, Søren Qvist

    2014-01-01

    presents two initiatives for cod avoidance in Kattegat; a fisher initiative sharing information about cod bycatch which could lead to real time closures in areas with high bycatch of juveniles, for vessels with low cod quota to avoid catch of all cod, and a Danish Swedish Government initiative of permanent......The article examines the experiences of two initiatives of cod avoidance by area regulations in the Kattegat in the light of the upcoming discard ban in EU fisheries. The first section highlights elements of the discard ban in the reformed EU Common Fisheries Policy (CFP). The second section...... and temporary area closures in Kattegat. The third section discusses the lessons learned in the light of implementation of the discard ban. The fourth section sums up the lessons learned; Regional measures of implementation of the discard ban should include all vessels with quota in the region to be regarded...

  15. AFSC/REFM: Pacific cod Localized Depletion Study

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Localized Depletion study for Pacific cod 2001-2005. Study was conducted using cod pot gear to measure localized abundance of Pacific cod inside and...

  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. The impact of shrimp trawling and associated sediment resuspension in mud dominated, shallow estuaries

    Energy Technology Data Exchange (ETDEWEB)

    Dellapenna, Timothy M.; Allison, Mead A.; Gill, Gary A.; Lehman, Ronald D.; Warnken, Kent W.

    2006-07-18

    To address the relative importance of shrimp trawling on seabed resuspension and bottom characteristics in shallow estuaries, a series of disturbance and monitoring experiments were conducted at a bay bottom mud site (2.5 m depth) in Galveston Bay, Texas in July 1998 and May 1999. Based on pre- and post-trawl sediment profiles of 7Be; pore water dissolved oxygen and sulfide concentration; and bulk sediment properties, it was estimated that the trawl rig, including the net, trawl doors, and ‘‘tickler chain,’’ excavate the seabed to a maximum depth of approximately 1.5 cm, with most areas displaying considerably less disturbance. Water column profile data in the turbid plume left by the trawl in these underconsolidated muds (85e90% porosity; <0.25 kPa undrained shear strength) demonstrate that suspended sediment inventories of up to 85e90 mg/cm2 are produced immediately behind the trawl net; an order of magnitude higher than pre-trawl inventories and comparable to those observed during a 9e10 m/s wind event at the study site. Plume settling and dispersion caused suspended sediment inventories to return to pre-trawl values about 14 min after trawl passage in two separate experiments, indicating particles re-settle primarily as flocs before they can be widely dispersed by local currents. As a result of the passage of the trawl rig across the seabed, shear strength of the sediment surface showed no significant increase, suggesting that bed armoring is not taking place and the trawled areas will not show an increase in critical shear stress.

  18. The effects of trawling on the benthic fauna of the Gulf of Nicoya, Costa Rica.

    Science.gov (United States)

    Rostad, T; Hansen, K L

    2001-12-01

    Four van Veen grab replicates where collected to sample macrofauna (organism retained on a 500 micron mesh sieve) at four stations in the Gulf of Nicoya, during October 24, 1997, January 16 and April 30, 1998. This information was used to search for any effects of trawling on the benthic fauna. Two stations where located in a trawled area, and two stations where in a protected area. Diversity (H') varied from 2.01 to 3.52 in the trawled area and from 2.13 to 2.78 in the protected area. Diversity was generally higher in the trawled area, and this was in contradiction to what we would have expected from other studies where the trend has been that trawling reduces diversity. Brittlestars and lancelets seemed to be the groups mostly harmed by the trawling, while amphipods where more abundant in trawled areas. The multivariate analyses did not reveal the patterns of faunal change as well as we hoped. This is surely because of our lack of more replicate samples. The multivariate analyses are easily confounded when few sites are analyzed. We have found differences in the type of fauna found in trawled and protected areas and, considering the differences in environmental variables in our stations and our lack of replication, this indicates that there are differences and a larger investigation is in order to reveal its magnitude.

  19. Stable isotopes reveal the effect of trawl fisheries on the diet of commercially exploited species

    DEFF Research Database (Denmark)

    Hinz, Hilmar; Moranta, Joan; Balestrini, Stephen

    2017-01-01

    Bottom trawling can change food availability for benthivorous demersal species by (i) changing benthic prey composition through physical seabed impacts and (ii) by removing overall benthic consumer biomass increasing the net availability of benthic prey for remaining individuals. Thus trawling ma...

  20. Distribution of Bottom Trawling Effort in the Yellow Sea and East China Sea

    Science.gov (United States)

    Zhang, Shengmao; Jin, Shaofei; Zhang, Heng; Fan, Wei; Tang, Fenghua; Yang, Shenglong

    2016-01-01

    Bottom trawling is one of the most efficient fishing activities, but serious and persistent ecological issues have been observed by fishers, scientists and fishery managers. Although China has applied the Beidou fishing vessel position monitoring system (VMS) to manage trawlers since 2006, little is known regarding the impacts of trawling on the sea bottom environments. In this study, continuous VMS data of the 1403 single-rig otter trawlers registered in the Xiangshan Port, 3.9% of the total trawlers in China, were used to map the trawling effort in 2013. We used the accumulated distance (AD), accumulated power distance (APD), and trawling intensity as indexes to express the trawling efforts in the Yellow Sea (YS) and East China Sea (ECS). Our results show that all three indexes had similar patterns in the YS and ECS, and indicated a higher fishing effort of fishing grounds that were near the port. On average, the seabed was trawled 0.73 times in 2013 over the entire fishing region, and 51.38% of the total fishing grounds were with no fishing activities. Because of VMS data from only a small proportion of Chinese trawlers was calculated fishing intensity, more VMS data is required to illustrate the overall trawling effort in China seas. Our results enable fishery managers to identify the distribution of bottom trawling activities in the YS and ECS, and hence to make effective fishery policy. PMID:27855215

  1. Trophic look at soft-bottom communities - Short-term effects of trawling cessation on benthos

    Science.gov (United States)

    Dannheim, Jennifer; Brey, Thomas; Schröder, Alexander; Mintenbeck, Katja; Knust, Rainer; Arntz, Wolf E.

    2014-01-01

    The trophic structure of the German Bight soft-bottom benthic community was evaluated for potential changes after cessation of bottom trawling. Species were collected with van-Veen grabs and beam trawls. Trophic position (i.e. nitrogen stable isotope ratios, δ15N) and energy flow (i.e. species metabolism approximated by body mass scaled abundance) of dominant species were compared in trawled areas and an area protected from fisheries for 14 months in order to detect trawling cessation effects by trophic characteristics. At the community level, energy flow was lower in the protected area, but we were unable to detect significant changes in trophic position. At the species level energy flow in the protected area was lower for predating/scavenging species but higher for interface feeders. Species trophic positions of small predators/scavengers were lower and of deposit feeders higher in the protected area. Major reasons for trophic changes after trawling cessation may be the absence of artificial and additional food sources from trawling likely to attract predators and scavengers, and the absence of physical sediment disturbance impacting settlement/survival of less mobile species and causing a gradual shift in food availability and quality. Our results provide evidence that species or community energy flow is a good indicator to detect trawling induced energy-flow alterations in the benthic system, and that in particular species trophic properties are suitable to capture subtle and short-term changes in the benthos following trawling cessation.

  2. 50 CFR 660.333 - Open access non-groundfish trawl fishery-management measures.

    Science.gov (United States)

    2010-10-01

    ... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Open access non-groundfish trawl fishery... COAST STATES West Coast Groundfish-Open Access Fisheries § 660.333 Open access non-groundfish trawl... the open access trip limit table, Table 3 (South) of this subpart. Trip limits for groundfish...

  3. EAARL Topography-Cape Cod National Seashore

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Elevation maps (also known as Digital Elevation Models or DEMs) of Cape Cod National Seashore were produced from remotely-sensed, geographically-referenced elevation...

  4. EAARL Topography-Cape Cod National Seashore

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Elevation maps (also known as Digital Elevation Models or DEMs) of Cape Cod National Seashore were produced from remotely-sensed, geographically-referenced elevation...

  5. EAARL Topography-Cape Cod National Seashore

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Elevation maps (also known as Digital Elevation Models or DEMs) of Cape Cod National Seashore were produced from remotely-sensed, geographically-referenced...

  6. Who's your mama? Riverine hybridisation of threatened freshwater Trout Cod and Murray Cod.

    Science.gov (United States)

    Couch, Alan J; Unmack, Peter J; Dyer, Fiona J; Lintermans, Mark

    2016-01-01

    Rates of hybridization and introgression are increasing dramatically worldwide because of translocations, restocking of organisms and habitat modifications; thus, determining whether hybridization is occuring after reintroducing extirpated congeneric species is commensurately important for conservation. Restocking programs are sometimes criticized because of the genetic consequences of hatchery-bred fish breeding with wild populations. These concerns are important to conservation restocking programs, including those from the Australian freshwater fish family, Percichthyidae. Two of the better known Australian Percichthyidae are the Murray Cod, Maccullochella peelii and Trout Cod, Maccullochella macquariensis which were formerly widespread over the Murray Darling Basin. In much of the Murrumbidgee River, Trout Cod and Murray Cod were sympatric until the late 1970s when Trout Cod were extirpated. Here we use genetic single nucleotide polymorphism (SNP) data together with mitochondrial sequences to examine hybridization and introgression between Murray Cod and Trout Cod in the upper Murrumbidgee River and consider implications for restocking programs. We have confirmed restocked riverine Trout Cod reproducing, but only as inter-specific matings, in the wild. We detected hybrid Trout Cod-Murray Cod in the Upper Murrumbidgee, recording the first hybrid larvae in the wild. Although hybrid larvae, juveniles and adults have been recorded in hatcheries and impoundments, and hybrid adults have been recorded in rivers previously, this is the first time fertile F1 have been recorded in a wild riverine population. The F1 backcrosses with Murray cod have also been found to be fertile. All backcrosses noted were with pure Murray Cod. Such introgression has not been recorded previously in these two species, and the imbalance in hybridization direction may have important implications for restocking programs.

  7. 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...

  8. Who’s your mama? Riverine hybridisation of threatened freshwater Trout Cod and Murray Cod

    Science.gov (United States)

    Unmack, Peter J.; Dyer, Fiona J.; Lintermans, Mark

    2016-01-01

    Rates of hybridization and introgression are increasing dramatically worldwide because of translocations, restocking of organisms and habitat modifications; thus, determining whether hybridization is occuring after reintroducing extirpated congeneric species is commensurately important for conservation. Restocking programs are sometimes criticized because of the genetic consequences of hatchery-bred fish breeding with wild populations. These concerns are important to conservation restocking programs, including those from the Australian freshwater fish family, Percichthyidae. Two of the better known Australian Percichthyidae are the Murray Cod, Maccullochella peelii and Trout Cod, Maccullochella macquariensis which were formerly widespread over the Murray Darling Basin. In much of the Murrumbidgee River, Trout Cod and Murray Cod were sympatric until the late 1970s when Trout Cod were extirpated. Here we use genetic single nucleotide polymorphism (SNP) data together with mitochondrial sequences to examine hybridization and introgression between Murray Cod and Trout Cod in the upper Murrumbidgee River and consider implications for restocking programs. We have confirmed restocked riverine Trout Cod reproducing, but only as inter-specific matings, in the wild. We detected hybrid Trout Cod–Murray Cod in the Upper Murrumbidgee, recording the first hybrid larvae in the wild. Although hybrid larvae, juveniles and adults have been recorded in hatcheries and impoundments, and hybrid adults have been recorded in rivers previously, this is the first time fertile F1 have been recorded in a wild riverine population. The F1 backcrosses with Murray cod have also been found to be fertile. All backcrosses noted were with pure Murray Cod. Such introgression has not been recorded previously in these two species, and the imbalance in hybridization direction may have important implications for restocking programs.

  9. A dataset from bottom trawl survey around Taiwan.

    Science.gov (United States)

    Shao, Kwang-Tsao; Lin, Jack; Wu, Chung-Han; Yeh, Hsin-Ming; Cheng, Tun-Yuan

    2012-01-01

    Bottom trawl fishery is one of the most important coastal fisheries in Taiwan both in production and economic values. However, its annual production started to decline due to overfishing since the 1980s. Its bycatch problem also damages the fishery resource seriously. Thus, the government banned the bottom fishery within 3 nautical miles along the shoreline in 1989. To evaluate the effectiveness of this policy, a four year survey was conducted from 2000-2003, in the waters around Taiwan and Penghu (Pescadore) Islands, one region each year respectively. All fish specimens collected from trawling were brought back to lab for identification, individual number count and body weight measurement. These raw data have been integrated and established in Taiwan Fish Database (http://fishdb.sinica.edu.tw). They have also been published through TaiBIF (http://taibif.tw), FishBase and GBIF (website see below). This dataset contains 631 fish species and 3,529 records, making it the most complete demersal fish fauna and their temporal and spatial distributional data on the soft marine habitat in Taiwan.

  10. A dataset from bottom trawl survey around Taiwan

    Directory of Open Access Journals (Sweden)

    Kwang-tsao Shao

    2012-05-01

    Full Text Available Bottom trawl fishery is one of the most important coastal fisheries in Taiwan both in production and economic values. However, its annual production started to decline due to overfishing since the 1980s. Its bycatch problem also damages the fishery resource seriously. Thus, the government banned the bottom fishery within 3 nautical miles along the shoreline in 1989. To evaluate the effectiveness of this policy, a four year survey was conducted from 2000–2003, in the waters around Taiwan and Penghu (Pescadore Islands, one region each year respectively. All fish specimens collected from trawling were brought back to lab for identification, individual number count and body weight measurement. These raw data have been integrated and established in Taiwan Fish Database (http://fishdb.sinica.edu.tw. They have also been published through TaiBIF (http://taibif.tw, FishBase and GBIF (website see below. This dataset contains 631 fish species and 3,529 records, making it the most complete demersal fish fauna and their temporal and spatial distributional data on the soft marine habitat in Taiwan.

  11. Walking the cod: an investigation into the relative robustness of cod, Gadus morhua, skeletal elements

    Directory of Open Access Journals (Sweden)

    Andrew K.G. Jones

    1999-12-01

    Full Text Available A simple experiment is described which details what happens to the bones of cod when they are walked on by a man. The pattern of fragmentation for various elements is illustrated and an index of robustness proposed for those elements in a cod skeleton most frequently recovered from archaeological sites.

  12. What a drag: Quantifying the global impact of chronic bottom trawling on continental shelf sediment

    Science.gov (United States)

    Oberle, Ferdinand K. J.; Storlazzi, Curt D.; Hanebuth, Till J. J.

    2016-07-01

    Continental shelves worldwide are subject to intense bottom trawling that causes sediment to be resuspended. The widely used traditional concepts of modern sedimentary transport systems on the shelf rely only on estimates for naturally driven sediment resuspension such as through storm waves, bottom currents, and gravity-driven flows but they overlook a critical anthropogenic factor. The strong influence of bottom trawling on a source-to-sink sediment budget is explored on the NW Iberian shelf. Use of Automated Information System vessel tracking data provides for a high-resolution vessel track reconstruction and the accurate calculation of the spatial distribution of bottom trawling intensity and associated resuspended sediment load. The mean bottom trawling-induced resuspended sediment mass for the NW Iberian shelf is 13.50 Mt yr- 1, which leads to a six-fold increase in off-shelf sediment transport when compared to natural resuspension mechanisms. The source-to-sink budget analysis provides evidence that bottom trawling causes a rapid erosion of the fine sediment on human time scales. Combining global soft sediment distribution data of the shelves with worldwide bottom trawling intensity estimates we show that the bottom trawling-induced resuspended sediment mass amounts to approximately the same mass of all sediment entering the shelves through rivers. Spatial delineations between natural and anthropogenic sediment resuspension areas are presented to aid in marine management questions.

  13. What a drag: Quantifying the global impact of chronic bottom trawling on continental shelf sediment

    Science.gov (United States)

    Oberle, Ferdinand K.J.; Storlazzi, Curt; Hanebuth, Till J.J.

    2016-01-01

    Continental shelves worldwide are subject to intense bottom trawling that causes sediment to be resuspended. The widely used traditional concepts of modern sedimentary transport systems on the shelf rely only on estimates for naturally driven sediment resuspension such as through storm waves, bottom currents, and gravity-driven flows but they overlook a critical anthropogenic factor. The strong influence of bottom trawling on a source-to-sink sediment budget is explored on the NW Iberian shelf. Use of Automated Information System vessel tracking data provides for a high-resolution vessel track reconstruction and the accurate calculation of the spatial distribution of bottom trawling intensity and associated resuspended sediment load. The mean bottom trawling-induced resuspended sediment mass for the NW Iberian shelf is 13.50 Mt yr− 1, which leads to a six-fold increase in off-shelf sediment transport when compared to natural resuspension mechanisms. The source-to-sink budget analysis provides evidence that bottom trawling causes a rapid erosion of the fine sediment on human time scales. Combining global soft sediment distribution data of the shelves with worldwide bottom trawling intensity estimates we show that the bottom trawling-induced resuspended sediment mass amounts to approximately the same mass of all sediment entering the shelves through rivers. Spatial delineations between natural and anthropogenic sediment resuspension areas are presented to aid in marine management questions.

  14. Benthic microbial abundance and activities in an intensively trawled ecosystem (Thermaikos Gulf, Aegean Sea)

    Science.gov (United States)

    Polymenakou, Paraskevi N.; Pusceddu, Antonio; Tselepides, Anastasios; Polychronaki, Thalia; Giannakourou, Antonia; Fiordelmondo, Carla; Hatziyanni, Eleni; Danovaro, Roberto

    2005-12-01

    Abundance of benthic bacteria, heterotrophic nanoflagellates and ciliates, extracellular enzymatic activities, bacterial C production, C mineralisation and sediment community oxygen consumption rates were measured in the Thermaikos Gulf (Northeastern Mediterranean), before (September 2001), and during intense trawling activities (October 2001 and February 2002). The biochemical composition of sedimentary organic matter has revealed that bottom trawling had an effect on the trophic state of Thermaikos Gulf. Changes on the benthic microbial food web were also recorded, during the three sampling seasons. Even though trawling-induced sediment resuspension did not alter significantly the abundance of the microbial components, with the exception of the most impacted station, it determined changes regarding their relative importance. Thus, the ratios of bacterium to nanoflagellates and ciliate to nanoflagellates abundance increased in the trawled stations, causing a sudden increase in bacterial C production, in comparison to the non-trawled station. Four months later, the effects of trawling on the microbial food web were less evident, masked possibly by the drastic decrease in the water temperature. The results of the present work suggest that bottom trawling induces alteration of the sedimentological variables and can be considered as a factor affecting the function of the microbial food web in marine coastal ecosystems. These alterations cause faster mobilisation of organic C buried in the sediment and increase nutrient concentrations and availability in the system, thus inducing an effect that could lead to coastal eutrophication.

  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. 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.

  17. 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.

  18. Restricted fish feeding reduces cod otolith opacity

    DEFF Research Database (Denmark)

    Høie, H.; Folkvord, A.; Mosegaard, Henrik

    2008-01-01

    The purpose of this work was to examine the effect of reduced feeding and constant temperature on cod otolith opacity. Three groups of juvenile cod were given restricted food rations at different times for 4 months, resulting in depressed somatic growth. Otolith opacity was measured on pictures...... in otolith opacity were found between individual fish both within groups and between groups. In two of the three groups significantly more translucent otolith material was deposited in response to reduced feeding. Our results show that variations in feeding and hence fish growth resulted in variation...

  19. A modified method for COD determination of solid waste, using a commercial COD kit and an adapted disposable weighing support.

    Science.gov (United States)

    André, L; Pauss, A; Ribeiro, T

    2017-03-01

    The chemical oxygen demand (COD) is an essential parameter in waste management, particularly when monitoring wet anaerobic digestion processes. An adapted method to determine COD was developed for solid waste (total solids >15%). This method used commercial COD tubes and did not require sample dilution. A homemade plastic weighing support was used to transfer the solid sample into COD tubes. Potassium hydrogen phthalate and glucose used as standards showed an excellent repeatability. A small underestimation of the theoretical COD value (standard values around 5% lower than theoretical values) was also observed, mainly due to the intrinsic COD of the weighing support and to measurement uncertainties. The adapted COD method was tested using various solid wastes in the range of 1-8 mgCOD, determining the COD of dried and ground cellulose, cattle manure, straw and a mixed-substrate sample. This new adapted method could be used to monitor and design dry anaerobic digestion processes.

  20. AFSC/REFM: Digitized 2005 GOA Trawl Logbooks merged with Fish Ticket and Observer data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The data include a full year of logbook forms for vessels 60-124 feet in length (the partial coverage fleet) that had participated in the trawl flatfish fishery of...

  1. SEAMAP Groundfish/Shrimp Trawl Red Snapper Analytical Dataset Provided to NRDA

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Southeast Fisheries Science Center Mississippi Laboratories has conducted standardized groundfish trawl surveys in the Gulf of Mexico since 1987. Prior to 1987,...

  2. Shelikof Strait Acoustic-Trawl Survey of Walleye Pollock (DY1203, ME70)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Midwater Assessment and Conservation Engineering (MACE) program of the Alaska Fisheries Science Center (AFSC) conducted an acoustic-trawl (AT) stock assessment...

  3. Oceanographic data - Integrated acoustic and trawl survey of Pacific hake off the Pacific Coast

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Integrated acoustic and trawl surveys are used to assess the distribution, biomass, and biology of Pacific hake along the Pacific coasts of the United States and...

  4. Trawling disturbance effects on the trophic ecology of two co-generic Astropectinid species

    Directory of Open Access Journals (Sweden)

    M. C. MANGANO

    2015-11-01

    Full Text Available Physical disturbance by trawling can have both negative and positive effects on populations of scavenging benthic organisms. In the present study the impact of fishing activity on feeding behaviour of the two Astropectinids, Astropecten bispinosus and A. irregularis, was assessed based on stomach contents analysis. The study was carried out along trawled seabed highlighting the positive response of the two facultative scavengers to carrion generated by trawl disturbance. Furthermore, there was greater food specialization in areas that were more heavily exploited by trawling. This specialisation could be linked to the availability of certain prey that results from the passage of fishing gears across the seabed. Interestingly, differences between the two species analysed have been highlighted in term of population dynamic, feeding rate, diet composition and diet diversity, testifying their capacity to coexist in the same fishing grounds. Normal 0 false false false EL X-NONE X-NONE  

  5. 76 FR 74725 - Fisheries Off West Coast States; Pacific Coast Groundfish Fishery Management Plan; Trawl...

    Science.gov (United States)

    2011-12-01

    ... seasonally to slow bycatch in the whiting fishery. In addition to closed areas to protect habitat from trawl... it will strive to the best of its ability to conduct site inspections in a timely fashion, not...

  6. Acoustic data - Integrated acoustic and trawl survey of Pacific hake off the Pacific Coast

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Integrated acoustic and trawl surveys are used to assess the distribution, biomass, and biology of Pacific hake along the Pacific coasts of the United States and...

  7. AFSC/RACE/MACE: Results of 2015 acoustic trawl survey Gulf of Alaska M1501

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Three trawl-resistant bottom- mounted moorings (TRBM) instrumented with newly developed autonomous battery powered 70 kHz split-beam echosounders were deployed in...

  8. AFSC/RACE/MACE: Results of 2014 acoustic trawl survey Bogoslof DY1402

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Scientists from the Midwater Assessment and Conservation Engineering (MACE) Program of the Alaska Fisheries Science Center (AFSC) regularly conduct acoustic-trawl...

  9. Veel haring, maar vrijwel geen jonge kabeljauw: International Bottom Trawl Survey 2003

    NARCIS (Netherlands)

    Heessen, H.J.L.

    2003-01-01

    Onderzoeksvaartuigen hebben de jaarlijkse International Bottom Trawl Survey (IBTS) uitgevoerd om een indruk te krijgen van de jongste jaarklassen van jonge haring, sprot en rondvis. Overzicht van de bestanden van kabeljauw, schelvis, wijting en haring 1978-2002

  10. NWFSC Observer Trawl Data, off West Coast of US, 2002-2006

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Observer Trawl Data collected during 2002-2006 off West Coast of US. This data product originates from data collected by fishery observers in the West Coast...

  11. NEFSC 2008 Spring Bottom Trawl Survey - Site Specific Calibration (HB0803, EK60)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC bottom trawl survey is a fisheries independent, multi-species survey that provides the primary scientific data for fisheries assessments in the U.S....

  12. Fish diversity in southern California using trawl data from the National Marine Fisheries Service

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Shannon Index of diversity was calculated from National Marine Fisheries Service Groundfish Survey Program (NMFS GSP) fish trawl data. Data from 477 fishery...

  13. Biological data - Integrated acoustic and trawl survey of Pacific hake off the Pacific Coast

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Integrated acoustic and trawl surveys are used to assess the distribution, biomass, and biology of Pacific hake along the Pacific coasts of the United States and...

  14. Measurements of gear and environmental parameters during surveys with the GOV trawl

    National Research Council Canada - National Science Library

    Stewart, P.A.M; Rivoirard, J

    1997-01-01

    .... To investigate the catching performance of the GOV trawl, data were collected on 11 surveys. It was thought that catch would depend mainly on fishing ground, depth, year, swept volume, towing speed, water temperature and light intensity...

  15. Shumagin Islands Acoustic-Trawl Survey of Walleye Pollock (DY1201, ME70)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Midwater Assessment and Conservation Engineering (MACE) program of the Alaska Fisheries Science Center (AFSC) conducted an acoustic-trawl (AT) stock assessment...

  16. AFSC/RACE/MACE: Results of 2015 acoustic trawl survey Shumagin/Sanak/PWS DY1502

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The surveys primary objective was to collect acoustic data and trawl information to estimate midwater abundance and distribution of walleye pollock (Gadus...

  17. Vulnerability of individual fish to capture by trawling is influenced by capacity for anaerobic metabolism.

    Science.gov (United States)

    Killen, Shaun S; Nati, Julie J H; Suski, Cory D

    2015-08-22

    The harvest of animals by humans may constitute one of the strongest evolutionary forces affecting wild populations. Vulnerability to harvest varies among individuals within species according to behavioural phenotypes, but we lack fundamental information regarding the physiological mechanisms underlying harvest-induced selection. It is unknown, for example, what physiological traits make some individual fish more susceptible to capture by commercial fisheries. Active fishing methods such as trawling pursue fish during harvest attempts, causing fish to use both aerobic steady-state swimming and anaerobic burst-type swimming to evade capture. Using simulated trawling procedures with schools of wild minnows Phoxinus phoxinus, we investigate two key questions to the study of fisheries-induced evolution that have been impossible to address using large-scale trawls: (i) are some individuals within a fish shoal consistently more susceptible to capture by trawling than others?; and (ii) if so, is this related to individual differences in swimming performance and metabolism? Results provide the first evidence of repeatable variation in susceptibility to trawling that is strongly related to anaerobic capacity and swimming ability. Maximum aerobic swim speed was also negatively correlated with vulnerability to trawling. Standard metabolic rate was highest among fish that were least vulnerable to trawling, but this relationship probably arose through correlations with anaerobic capacity. These results indicate that vulnerability to trawling is linked to anaerobic swimming performance and metabolic demand, drawing parallels with factors influencing susceptibility to natural predators. Selection on these traits by fisheries could induce shifts in the fundamental physiological makeup and function of descendent populations.

  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. 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.

  20. 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...

  1. 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.

  2. 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...

  3. 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.

  4. 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...

  5. 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...

  6. Sediments of Cape Cod Bay, Massachusetts (HOUGH42 shapefile)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Cape Cod Bay, lying on the Massachusetts coast partly enclosed by Cape Cod, is in a glaciated region of low relief. Coarse sediments generally occur in areas exposed...

  7. Occurrence of anisakid nematodes in Atlantic cod (Gadus morhua) and Greenland cod (Gadus ogac), West Greenland

    DEFF Research Database (Denmark)

    Mouritsen, Kim N.; Hedeholm, Rasmus; Schack, Henriette B.;

    2010-01-01

    Anisakid nematodes commonly infect gadids, and are of economic and aesthetic importance to the commercial fishing industry in Greenland as some species are pathogenic to humans. However, very little is known about the occurrence of these parasites and their impact on the hosts in Greenland waters....... During a survey in 2005, stomach sample of 227 Atlantic cod (Gadus morhua) and 64 Greenland cod (Gadus ogac) was collected in Godthaab and Sisimiut fiord systems in West Greenland waters. All cod were dissected for stomach contents and anisakid nematodes were removed from the visceral cavity. Third stage...... nematode species regarding prevalence of infection and mean infection intensity was evident, and there was no relationship between fish condition and the intensity of nematode infections. Standardised for size, capelin-eating cod were in better condition and more heavily infected than fish subsisting...

  8. Integrating the provision of ecosystem services and trawl fisheries for the management of the marine environment.

    Science.gov (United States)

    Muntadas, Alba; de Juan, Silvia; Demestre, Montserrat

    2015-02-15

    The species interaction and their biological traits (BT) determine the function of benthic communities and, hence, the delivery of ecosystem services. Therefore, disturbance of benthic communities by trawling may compromise ecosystem service delivery, including fisheries' catches. In this work, we explore 1) the impact of trawling activities on benthic functional components (after the BTA approach) and 2) how trawling impact may affect the ecosystem services delivered by benthic communities. To this aim, we assessed the provision of ecosystem services by adopting the concept of Ecosystem Service Providers (ESP), i.e. ecological units that perform ecosystem functions that will ultimately deliver ecosystem services. We studied thirteen sites subjected to different levels of fishing effort in the Mediterranean. From a range of environmental variables included in the study, we found ESPs to be mainly affected by fishing effort and grain size. Our results suggested that habitat type has significant effects on the distribution of ESPs and this natural variability influences ESP response to trawling at a specific site. In order to summarize the complex relationships between human uses, ecosystem components and the demand for ecosystem services in trawling grounds, we adapted a DPSIR (Drivers-Pressures-State Change-Impact-Response) framework to the study area, emphasizing the role of society as Drivers of change and actors demanding management Responses. This integrative framework aims to inform managers about the interactions between all the elements involved in the management of trawling grounds, highlighting the need for an integrated approach in order to ensure ecosystem service provision.

  9. 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

  10. 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.

  11. 78 FR 32612 - Collect on Delivery (COD)-Service Features

    Science.gov (United States)

    2013-05-31

    ... 111 Collect on Delivery (COD)--Service Features AGENCY: Postal Service\\TM\\. ACTION: Proposed rule... * * * * * 503 Extra Services * * * * * 13.0 Collect on Delivery (COD) * * * * * 13.2 Basic Information 13.2.1... collect on delivery (COD) service to mail an article for which the mailer has not been paid and have...

  12. 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

  13. Intensity of pelagic-benthic coupling in different regions along the Antarctic Polar Front - Clues from abyssal megafauna

    Science.gov (United States)

    Würzberg, Laura; Zinkann, Ann-Christine; Brandt, Angelika; Janussen, Dorte; Bohn, Jens M.; Schwabe, Enrico

    2014-10-01

    The zone surrounding the Antarctic Polar Front is a region characterized by elevated seasonal primary production. Studies on the implications for the fauna inhabiting the underlying deep-sea floor, however, are rare. The present study focuses on the abundance of megafaunal organisms caught by means of an Agassiz Trawl during the SYSTem COupling in the Southern Ocean II (SYSTCO II) expedition (RV Polarstern cruise ANT XXVIII/3). Biomass estimates in terms of volume as well as species richness of echinoderms were additionally taken into account. Abyssal stations (ca. 4000 m depth) located in three different regions along the Antarctic Polar Front characterized by different primary production regimes and oceanographic features were sampled. One shallower station (337 m depth) was used as reference station. Highest megafaunal abundances were found at the shallow station (147 individuals per 1000 m2). Megafaunal abundances were low to moderate at the abyssal stations (7.2-23.5 individuals per 1000 m2) with the exception of the region northwest of South Georgia, where distinctly higher abundances were found (up to 119.7 individuals per 1000 m2). The same pattern was observed for biomass estimates. At the other regions, magnitude of megafaunal abundances and echinoderm biomasses were found not to be linked to the surface levels of primary production. This indicates that strong pelagic-benthic coupling likely occurs only downstream of South Georgia. Echinoderm species richness does not appear to be directly related to the environmental conditions as it does not differ statistically between the considered areas.

  14. Patterns of dolphin bycatch in a north-western Australian trawl fishery.

    Science.gov (United States)

    Allen, Simon J; Tyne, Julian A; Kobryn, Halina T; Bejder, Lars; Pollock, Kenneth H; Loneragan, Neil R

    2014-01-01

    The bycatch of small cetaceans in commercial fisheries is a global wildlife management problem. We used data from skippers' logbooks and independent observers to assess common bottlenose dolphin (Tursiops truncatus) bycatch patterns between 2003 and 2009 in the Pilbara Trawl Fishery, Western Australia. Both datasets indicated that dolphins were caught in all fishery areas, across all depths and throughout the year. Over the entire datasets, observer reported bycatch rates (n = 52 dolphins in 4,124 trawls, or 12.6 dolphins/1,000 trawls) were ca. double those reported by skippers (n = 180 dolphins in 27,904 trawls, or 6.5 dolphins/1,000 trawls). Generalised Linear Models based on observer data, which better explained the variation in dolphin bycatch, indicated that the most significant predictors of dolphin catch were: (1) vessel--one trawl vessel caught significantly more dolphins than three others assessed; (2) time of day--the lowest dolphin bycatch rates were between 00:00 and 05:59; and (3) whether nets included bycatch reduction devices (BRDs)--the rate was reduced by ca. 45%, from 18.8 to 10.3 dolphins/1,000 trawls, after their introduction. These results indicated that differences among vessels (or skippers' trawling techniques) and dolphin behavior (a diurnal pattern) influenced the rates of dolphin capture; and that spatial or seasonal adjustments to trawling effort would be unlikely to significantly reduce dolphin bycatch. Recent skipper's logbook data show that dolphin bycatch rates have not declined since those reported in 2006, when BRDs were introduced across the fishery. Modified BRDs, with top-opening escape hatches from which dolphins might escape to the surface, may be a more effective means of further reducing dolphin bycatch. The vulnerability of this dolphin population to trawling-related mortality cannot be assessed in the absence of an ongoing observer program and without information on trawler-associated dolphin community size

  15. Population dynamics ofPhilocheras trispinosus (Crangonidae) with abundance of other caridean shrimps (Crustacea:Decapoda) caught by beam trawl in the Southern Black Sea, Turkey

    Institute of Scientific and Technical Information of China (English)

    Sabri Bilgin; Necla Ylmaz

    2016-01-01

    Objective:To determine growth and reproduction biology ofPhilocheras trispinosus (P. trispinosus) with abundance of other caridean shrimps caught by beam trawl in the Southern Black Sea. Methods: Samplings were carried out monthly with a beam trawl of 2 m length and 15 mm cod-end mesh size between December 2012 and November 2013. All individuals were sampled between 1 and 40+ m water depth from 146 hauls. Results:A total of 550P. trispinosus, 618Palaemon adspersus, 12Palaemon serratus, 11Philocheras fasciatus and 10Crangon crangon were sampled during the study period. The crangonid shrimps started appearing during the winter and spring and the number of individuals increased to reach their highest value in mid-winter and mid-spring. The seasonal von Bertalanffy growth parameters forP. trispinosus were estimated asL∞ = 29.3 mm total length,K = 0.860/year,t0 = –0.900 year,C = 0.180, andts= 0.010. The start of the slow growth period was at the beginning of July (WP = 0.510). Ovigerous females appeared in the sampling area between January and April. Size at sexual maturity was estimated as 25.69 mm total length. Conclusions: The results supported the distribution and abundance of caridean shrimp species from the study area and the population dynamics of the most abundant shrimp species,P. trispinosus. The current study can be answered as baseline data prior to management strategies to ensure sustainable conservation of the shrimp species.

  16. Influence of fleet renewal and trawl development on landings per unit effort of the Danish northern shrimp (Pandalus borealis) fishery

    DEFF Research Database (Denmark)

    Eigaard, Ole Ritzau; Munch-Petersen, Sten

    2011-01-01

    , the relationship between nominal effort data as recorded in logbooks (days fishing) and effective effort is likely to have changed, so to standardize the nominal lpue time-series, trawl-size development has been taken into account using generalized linear modelling. As logbooks do not provide trawl......-size information, this standardization was made possible by retrieving technical trawl and vessel data from industry order books. These data demonstrated an approximately linear relationship between vessel engine power and Pandalus trawl size, so validated the use of vessel horsepower from the logbooks as a proxy...

  17. Cycles and trends in cod populations.

    Science.gov (United States)

    Bjørnstad, O N; Fromentin, J M; Stenseth, N C; Gjøsaeter, J

    1999-04-27

    Year-to-year fluctuations in fish stocks are usually attributed to variability in recruitment, competition, predation, and changes in catchability. Trends in abundance, in contrast, are usually ascribed to human exploitation and large-scale environmental changes. In this study, we demonstrate, through statistical modeling of survey data (1921-1994) of cod from the Norwegian Skagerrak coast, that both short- and long-term variability may arise from the same set of age-structured interactions. Asymmetric competition and cannibalism between cohorts generate alternating years of high and low abundance. Intercohort interactions also resonate the recruitment variability so that long-term trends are induced. The coupling of age-structure and variable recruitment should, therefore, be considered when explaining both the short- and long-term fluctuations displayed by the coastal cod populations. Resonant effects may occur in many marine populations that exhibit this combination of traits.

  18. Commercial bottom trawling: a driver of deep seascape evolution in the Anthropocene?

    Science.gov (United States)

    Martín, Jacobo; Puig, Pere; Canals, Miquel; Company, Joan B.; Amblas, David; Lastras, Galderic; Palanques, Albert; Calafat, Antoni M.

    2013-04-01

    The offshore displacement of bottom trawling fleets has raised concerns over the impact of this human activity on deep-sea ecosystems and associated living resources, which are characterized by a lower resilience than shallow water correlatives. However, the effects of bottom trawling on sediment remobilization across continental margins and on the alteration of seafloor morphology still remain largely unaddressed. We present a compilation of results from studies conducted during the last decade in the La Fonera (Palamós) submarine canyon (NW Mediterranean Sea), where a bottom trawling fishing fleet is active on a daily basis at depths from 400 to 800 m. Deployments of mooring lines equipped with punctual and profiling current-meters, turbidimeters and sediment traps have documented that trawling gears passing along the canyon flanks generate daily sediment gravity flows, implying a periodic sediment removal from fishing grounds. These sediment-laden flows are able to reach the main canyon axis and progress to a minimum depth of 1200 m. Also, sediment accumulation rates in the lower canyon have increased since the industrialization of the local trawling fleet (1970s), suggesting a human-induced enhancement of along-canyon transfer of sediments from the fishing grounds to greater depths. Sedimentological and Pb-210 analysis of interface sediment cores collected from the canyon flanks confirm that widespread erosion and stirring of surface sediments is notable on trawled areas when compared to control (untrawled) sites at similar depths. This chronic reworking and removal of surface sediments from trawling grounds has ultimately led to modifications of the seafloor morphology over large spatial scales, as revealed by high-resolution multibeam bathymetry and Vessel Monitoring Systems (VMS) data sets. Untrawled canyon flank segments are dominated by a dense network of tributary valleys that progress upslope from the main canyon axis, reaching up to five orders of

  19. Deep Sea Coral voucher sequence dataset - Identification of deep-sea corals collected during the 2009 - 2014 West Coast Groundfish Bottom Trawl Survey

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data for this project resides in the West Coast Groundfish Bottom Trawl Survey Database. Deep-sea corals are often components of trawling bycatch, though their...

  20. AFSC/RACE/GAP/Palsson: Gulf of Alaska and Aleutian Islands Biennial Bottom Trawl Survey estimates of catch per unit effort, biomass, population at length, and associated tables

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The GOA/AI Bottom Trawl Estimate database contains abundance estimates for the Alaska Biennial Bottom Trawl Surveys conducted in the Gulf of Alaska and the Aleutian...

  1. Deciphering the lithological consequences of bottom trawling to sedimentary habitats on the shelf

    Science.gov (United States)

    Oberle, Ferdinand K. J.; Swarzenski, Peter W.; Reddy, Christopher M.; Nelson, Robert K.; Baasch, Benjamin; Hanebuth, Till J. J.

    2016-07-01

    Widespread bottom trawling on the NW Iberian shelf causes chronic sediment and habitat disturbance. The few studies that have investigated vessel-modified sedimentary-structure and texture of the seabed have typically classified their results as being either impacted by trawling or not. This study indicates that bottom trawling can result in a sequence of vastly different effects to the lithology of seabed sediment, which have in turn different ecological consequences. Here, we combined very high-resolution spatial bottom-trawling data with sedimentological (grain size, porosity) and geochemical datasets (excess 210Pb, 3D petroleum fingerprinting) to study sediment disturbance, including sorting and mixing. Our results were used to develop five conceptual disturbance scenarios: minimal seabed effects, sediment overturning, complete sediment mixing, sediment grading and layering, and loss of sediment. Considering that bottom trawling is a widespread and growing global fishing technique, such impacts need to be considered in the management of habitat conservation as well as in the reconstruction of late Holocene climate history from shallow-water deposits, not just on the NW Iberian shelf, but also globally.

  2. Effects of trawling on the diets of common demersal fish by-catch of a tropical prawn trawl fishery.

    Science.gov (United States)

    Dell, Q; Griffiths, S P; Tonks, M L; Rochester, W A; Miller, M J; Duggan, M A; van der Velde, T D; Pillans, R D; Coman, G J; Bustamante, R H; Milton, D A

    2013-03-01

    The ecological effect of prawn trawling on the benthos of the Gulf of Carpentaria, northern Australia, was investigated by examining stomach contents of common demersal fishes incidentally caught as by-catch in the fishery. Fishes were collected from high and low fishing intensity sites in three regions based on vessel monitoring system data. The diets of eight species of benthic fish predators were compared between regions and fishing intensities. A regional effect on diet was evident for seven species. Only one generalist species had no significant difference in diet among the three regions. For the comparisons within each region, five predator species had significantly different diet between high and low fishing intensities in at least one region. Across the three regions, high fishing intensity sites had predators that consumed a greater biomass of crustaceans, molluscs and echinoderms. At low fishing intensity sites, predators had diets comprising a greater biomass of cnidarians and teleosts, and a different assemblage of molluscs, crustaceans and fishes. These changes in diet suggest that there may have been a shift in the structure of the benthic community following intensive fishing. Analysis of predator diets is a useful tool to help identify changes in the benthic community composition after exposure to fishing. This study also provided valuable diet information on a range of abundant generalist benthic predators to improve the ecosystem modelling tools needed to support ecosystem-based fisheries management.

  3. Particulate COD balance of particulate cod in eletrocuagulation/flotation reactor treating tannery effluent

    Directory of Open Access Journals (Sweden)

    Rodrigo Babora Borri

    2012-04-01

    Full Text Available Mass balance or particulate organic matter was studied in terms of COD, by means of electrocoagulation/flotation (ECF reactor treating tannery effluent. Reactor was operated in fill and draw (batch mode. Operating in hydraulic residence time of 65 minutes, ECF reactor reached 55 % COD removal. Although volatile solids were also removed from liquid phase (removal of 40%, fixed solids concentration, and hence total solids concentration, showed to be higher in withdrawn effluent than in ECF’s influent. This was assigned to NaCl added in order to enhance conductivity in wastewater.

  4. Bottom trawling affects fish condition through changes in the ratio of prey availability to density of competitors

    DEFF Research Database (Denmark)

    Hiddink, Jan Geert; Moranta, Joan; Balestrini, Stephen

    2016-01-01

    and applications. Our study indicates that fish production may be maximized by keeping bottom-trawling intensities relatively low, although this may negatively ffect the economically more important Nephrops fishery. The effects of bottom trawls may be mitigated by switching to gears, which affect prey availability...

  5. Trawling bats exploit an echo-acoustic ground effect

    Directory of Open Access Journals (Sweden)

    Sandor eZsebok

    2013-04-01

    Full Text Available A water surface acts not only as an optic mirror but also as an acoustic mirror. Echolocation calls emitted by bats at low heights above water are reflected away from the bat, and hence the background clutter is reduced. Moreover, targets on the surface create an enhanced echo. Here, we formally quantified the effect of the substrate and target height on both target detection and –discrimination in a combined laboratory and field approach with Myotis daubentonii. In a two-alternative, forced-choice paradigm, the bats had to detect a mealworm and discriminate it from an inedible dummy (20 mm PVC disc. Psychophysical performance was measured as a function of height above either smooth substrates (water or PVC or above a clutter substrate (artificial grass. At low heights above the clutter substrate (10, 20 or 35 cm, the bats’ detection performance was worse than above a smooth substrate. At a height of 50 cm, the substrate structure had no influence on target detection. Above the clutter surface, also target discrimination was significantly impaired with decreasing target height. A detailed analysis of the bats’ echolocation calls during target approach shows that above the clutter substrate, the bats produce calls with significantly higher peak frequency. Flight-path reconstruction revealed that the bats attacked an object from below over water but from above over a clutter substrate.These results are consistent with the hypothesis that trawling bats exploit an echo-acoustic ground effect, in terms of a spatio-temporal integration of direct reflections with indirect reflections from the water surface, to optimize prey detection and –discrimination not only for prey on the water but also for some range above.

  6. Trawling bats exploit an echo-acoustic ground effect.

    Science.gov (United States)

    Zsebok, Sandor; Kroll, Ferdinand; Heinrich, Melina; Genzel, Daria; Siemers, Björn M; Wiegrebe, Lutz

    2013-01-01

    A water surface acts not only as an optic mirror but also as an acoustic mirror. Echolocation calls emitted by bats at low heights above water are reflected away from the bat, and hence the background clutter is reduced. Moreover, targets on the surface create an enhanced echo. Here, we formally quantified the effect of the surface and target height on both target detection and -discrimination in a combined laboratory and field approach with Myotis daubentonii. In a two-alternative, forced-choice paradigm, the bats had to detect a mealworm and discriminate it from an inedible dummy (20 mm PVC disc). Psychophysical performance was measured as a function of height above either smooth surfaces (water or PVC) or above a clutter surface (artificial grass). At low heights above the clutter surface (10, 20, or 35 cm), the bats' detection performance was worse than above a smooth surface. At a height of 50 cm, the surface structure had no influence on target detection. Above the clutter surface, also target discrimination was significantly impaired with decreasing target height. A detailed analysis of the bats' echolocation calls during target approach shows that above the clutter surface, the bats produce calls with significantly higher peak frequency. Flight-path reconstruction revealed that the bats attacked an target from below over water but from above over a clutter surface. These results are consistent with the hypothesis that trawling bats exploit an echo-acoustic ground effect, in terms of a spatio-temporal integration of direct reflections with indirect reflections from the water surface, to optimize prey detection and -discrimination not only for prey on the water but also for some range above.

  7. Estimation of seafloor impact from demersal trawls, seines and dredges based on gear design and dimensions

    DEFF Research Database (Denmark)

    Eigaard, Ole Ritzau; Bastardie, Francois; Breen, Michael

    a different approach using the gear itself (design and dimensions) for understanding and estimation of the physical interactions with the seafloor at the individual fishing operation level. With reference to the métier groupings of EU logbooks, we defined 17 distinct towed gear groups in European waters (11...... otter trawl groups, 3 beam trawl groups, 2 demersal seine groups, and 1 dredge group), for which we established seafloor “footprints”. The footprint of a gear was defined as the relative contribution from individual larger gear components, such as the trawl doors, sweeps and ground gear, to the total...... types based on a review of the scientific literature. For each defined gear group a vessel-size (kW or total length) – gear size (total gear width or circumference) relationship was estimated to enable the prediction of gear footprint area and sediment penetration from vessel size. The implications...

  8. Towards a framework for the quantitative assessment of trawling impact on the seabed and benthic ecosystem

    DEFF Research Database (Denmark)

    Rijnsdorp, A. D.; Bastardie, Francois; Bolam, S.G.

    2016-01-01

    and considers the physical effects of trawl gears on the seabed, on marine taxa, and on the functioning of the benthic ecosystem. Within the frame- work, a reductionist approach is applied that breaks down a fishing gear into its components, and a number of biological traits are chosen to de- termine either...... the vulnerability of the benthos to the impact of that gear component, or to provide a proxy for their ecological role. The approach considers gear elements, such as otter boards, twin trawl clump, and groundrope, and sweeps that herd the fish. The physical impact of these ele- ments on the seabed, comprising...... scraping of the seabed, sediment mobilization, and penetration, is a function of the mass, size, and speed of the individual component. The impact of the elements on the benthic community is quantified using a biological-trait approach that considers the vulnerability of the benthic community to trawl...

  9. Environmental DNA from seawater samples correlate with trawl catches of Subarctic, deepwater fishes

    DEFF Research Database (Denmark)

    Thomsen, Philip Francis; Møller, Peter Rask; Sigsgaard, Eva Egelyng

    2016-01-01

    Remote polar and deepwater fish faunas are under pressure from ongoing climate change and increasing fishing effort. However, these fish communities are difficult to monitor for logistic and financial reasons. Currently, monitoring of marine fishes largely relies on invasive techniques...... such as bottom trawling, and on official reporting of global catches, which can be unreliable. Thus, there is need for alternative and non-invasive techniques for qualitative and quantitative oceanic fish surveys. Here we report environmental DNA (eDNA) metabarcoding of seawater samples from continental slope...... depths in Southwest Greenland. We collected seawater samples at depths of 188-918 m and compared seawater eDNA to catch data from trawling. We used Illumina sequencing of PCR products to demonstrate that eDNA reads show equivalence to fishing catch data obtained from trawling. Twenty-six families were...

  10. An Improved Backstepping-Based Controller for Three-Dimensional Trajectory Tracking of a Midwater Trawl System

    Directory of Open Access Journals (Sweden)

    Zhao Yan

    2016-01-01

    Full Text Available An improved backstepping control method for three-dimensional trajectory tracking of a midwater trawl system is investigated. A new mathematical model of the trawl system while considering the horizontal expansion effect of two otter boards is presented based on the Newton Euler method. Subsequently, an active path tracking strategy of the trawl system based on the backstepping method is proposed. The nonstrict feedback characteristic of the proposed model employs a control allocation method and several parallel nonlinear PID (Proportion Integration Differentiation controllers to eliminate the high-order state variables. Then, the stability analysis by the Lyapunov Stability Theory shows that the proposed controller can maintain the stability of the trawl system even with the presence of external disturbances. To validate the proposed controller, a simulation comparison with a linear PID controller was conducted. The simulation results illustrate that the improved backstepping controller is effective for three-dimensional trajectory tracking of the midwater trawl system.

  11. Indirect effects of otter trawling on the condition and trophic level of Nephrops and flatfish in the Kattegat

    DEFF Research Database (Denmark)

    Hiddink, Jan Geert; Balestrin, Stephen; Moranta, Joan

    in the Kattegat (Sweden and Denmark). The results show that the abundance and body size of Nephrops was much higher in the fully closed areas, whereas that of the flatfish was less affected. The condition and trophic level for Nephrops were highest on intensively trawled areas suggesting that trawling reduces......The fishing gear used in bottom trawl fisheries cause mortality of benthic invertebrates and this can decrease the long-term availability of prey to exploited fish species by reducing the abundance of benthic invertebrates. Alternatively, low trawling levels could increase food production...... the condition (as weight-atlength) and trophic level of the fish Pleuronectes platessa, Limanda limanda, Hippoglossoides platessoides and the crustacean Nephrops norvegicus in an area with strong variation in commercial otter-trawling effort owing to the presence of MPAs with different levels of protection...

  12. The effect of electric pulse stimulation to juvenile cod and cod of commercial landing size

    NARCIS (Netherlands)

    Haan, de D.; Fosseidengen, J.E.; Fjelldal, P.G.; Burggraaf, D.

    2011-01-01

    The first pilot study on the effects of electric pulse stimulation on larger cod carried out in 2008 was based on a single nominal setting of the Verburg-Holland UK153 pulse system with the intention to determine the range of pulse characteristics with which injuries to the fish occurred. This study

  13. Effect of White Charcoal on COD Reduction in Wastewater Treatment

    Science.gov (United States)

    Pijarn, Nuchanaporn; Butsee, Manipa; Buakul, Kanokwan; Seng, Hasan; Sribuarai, Tinnphat; Phonprasert, Pongtep; Taneeto, Kla; Atthameth, Prasertsil

    2017-06-01

    The objective of this study is to compare the COD reduction in wastewater between using coconut shell and coconut spathe white charcoal from Khlong Wat NongPra-Ong, Krathumbaen, SamutSakhon province, Thailand. The waste water samples were collected using composite sampling method. The experimental section can be divided into 2 parts. The first part was study the optimum of COD adsorption time using both white charcoals. The second part was study the optimum amount of white charcoal for chemical oxygen demand (COD) reduction. The pre-treatment of wastewater was examined in parameters include temperature, alkalinity (pH), conductivity, turbidity, suspended solid (SS), total dissolved solid (TDS), and COD. The results show that both white charcoals can reduce COD of wastewater. The pH of pre-treatment wastewater had pH 9 but post-treatment wastewaters using both white charcoals have pH 8. The COD of pre-treatment wastewater had COD as 258 mg/L but post-treatment wastewater using coconut shell white charcoal had COD steady at 40 mg/L in 30 min and the amount of white charcoals 4 g. The COD of post-treatment wastewater using coconut spathe white charcoal had COD steady at 71 mg/L in 30 min and the amount of white charcoals 4 g. Therefore comparison of COD reduction between coconut shell white charcoal versus coconut spathe white charcoal found that the coconut shell white charcoal had efficiency for COD reduction better than coconut spathe white charcoal.

  14. Cod farming at the intersection of fisheries and aquaculture

    OpenAIRE

    Aarset, Bernt; Standal, Dag; Asche, Frank

    2000-01-01

    Over the past three decades, the powerful combination of capital, research, and promising prospects has propelled salmon aquaculture to a mature, billion dollar, worldwide industry. Aquaculture entrepreneurs now search for new opportunities, but so far these attempts do not generate profit. Cod is targeted as a promising species, and here we explore the opportunities for the farming of cod. Two questions arise: (1) What characterizes cod as a farmed species? (2) How do these characteristics a...

  15. Bio-economic evaluation of implementing trawl fishing gear with different selectivity

    DEFF Research Database (Denmark)

    Kronbak, Lone Grønbæk; Nielsen, J. Rasmus; Jørgensen, Ole A.

    2009-01-01

    for the fish stocks, fishermen and society. The bio-economic evaluation is applied to the case of the Danish trawl fishery in Kattegat and Skagerrak, which experiences a high level of discards and bycatches of several species. Four different kinds of selectivity scenarios are evaluated in comparison...... with a baseline. The results from the evaluation are indicators for the consequences on ecological and economic levels. The results show that implementation of different selective fishing gear in the Kattegat and Skagerrak mixed trawl fisheries generally implies a trade off over time between rebuilding the stocks...

  16. Antarctic krill; assessment of mesh size selectivity and escape mortality from trawls

    DEFF Research Database (Denmark)

    Krafft, Bjørn A.; Krag, Ludvig Ahm; Herrmann, Bent;

    2015-01-01

    This working paper presents the aims and methodology for a three-year-project (commenced in 2015) assessing size selectivity and escape mortality of Antarctic krill from trawl nets. The project is widely based on acquired experiences from a completed study Net Escapement of Antarctic krill...... in Trawls (NEAT), presented in WG-EMM 2012/24, WGEMM 2013/34, WG-EMM 2014/14 and WG-EMM 2014/16. Funding is provided by the Norwegian Research Council and ship-time for executing the field-experiments is offered free-of-charge by two Norwegian commercial fishing companies; Olympic Seafood AS and Aker Bio...

  17. Harvesting Atlantic Cod under Climate Variability

    Science.gov (United States)

    Oremus, K. L.

    2016-12-01

    Previous literature links the growth of a fishery to climate variability. This study uses an age-structured bioeconomic model to compare optimal harvest in the Gulf of Maine Atlantic cod fishery under a variable climate versus a static climate. The optimal harvest path depends on the relationship between fishery growth and the interest rate, with higher interest rates dictating greater harvests now at the cost of long-term stock sustainability. Given the time horizon of a single generation of fishermen under assumptions of a static climate, the model finds that the economically optimal management strategy is to harvest the entire stock in the short term and allow the fishery to collapse. However, if the biological growth of the fishery is assumed to vary with climate conditions, such as the North Atlantic Oscillation, there will always be pulses of high growth in the stock. During some of these high-growth years, the growth of the stock and its economic yield can exceed the growth rate of the economy even under high interest rates. This implies that it is not economically optimal to exhaust the New England cod fishery if NAO is included in the biological growth function. This finding may have theoretical implications for the management of other renewable yet exhaustible resources whose growth rates are subject to climate variability.

  18. 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.

  19. 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.

  20. Hydrogeologic framework of western Cape Cod, Massachusetts

    Science.gov (United States)

    Masterson, John P.; Stone, Byron D.; Walter, Donald A.; Savoie, Jennifer G.

    1997-01-01

    The aquifer of western Cape Cod consists of several hydrogeologic units composed of sand, gravel, silt, and clay (fig. 1) that were deposited during the late Wisconsinan glaciation of New England. The aquifer is a shallow, unconfined hydrologic system in which ground-water flows radially outward from the apex of the ground-water mound near the center of the peninsula toward the coast (fig.2). The aquifer is the sole source of water supply for the towns of Bourne, Sandwich, Falmouth, and Mashpee, and the Massachusetts Military Reservation (MMR).Previous geologic studies summarized the characteristics and relative ages of the glacial moraines and meltwater deposits and the relation of these sediments to the extent of the ice-sheet lobes during the last glaciation of southern New England (Oldale and Barlow, 1986; Hartshorn and others, 1991). Hydrogeologic studies in western Cape Cod characterized the shallow regional ground-water-flow system (LeBlanc and others, 1986) and analyzed simulated responses of the aquifer to changes in hydrologic stresses (Guswa and LeBlanc, 1985; Barlow and Hess, 1993; Masterson and Barlow, 1994; and Masterson and others, 1996). Recent concerns about widespread ground-water contamination, especially from sources on the MMR, have resulted in extensive investigations to characterize the local hydrogeology of the aquifer near the MMR (ABB Environmental Services, 1992). Masterson and others (1996) illustrated the strong influence of geology on ground-water flow and the importance of characterizing the hydrogeology to predict the migration of the contaminant plumes beneath the MMR.This report, a product of a cooperative study between the National Guard Bureau and the U.S. Geological Survey (USGS), characterizes the regional hydrogeology of the western Cape Cod aquifer on the basis of surficial glacial geology previously described by Mather and others (1940) and Oldale and Barlow (1986), and presents a new analysis of the subsurface hydrogeology

  1. Use of a fishery-independent trawl survey to evaluate distribution patterns of subadult sharks in Georgia

    Science.gov (United States)

    Belcher, C.N.; Jennings, Cecil A.

    2009-01-01

    We investigated the utility of a fishery-independent trawl survey for assessing a potential multispecies shark nursery in Georgia's nearshore and inshore waters. A total of 234 subadult sharks from six species were captured during 85 of 216 trawls. Catch rates and size distributions for subadult sharks and the ratio of neonates to juveniles were consistent among areas. The highest concentrations of subadult sharks occurred in creeks and sounds. Species composition varied among areas. The Atlantic sharpnose shark Rhizoprionodon terraenovae was the most abundant species in sound and nearshore stations, whereas the bonnethead Sphyrna tiburo was the most abundant species in creeks. The aggregate of other species occurred with higher frequency in the sounds and nearshore. Sampling characteristics of the trawl survey were compared with those from a fishery-independent longline survey of subadult sharks to assess the similarity of the two gears. A total of 193 subadult sharks from seven species were captured during 57 of 96 longline sets, whereas 52 subadults from four species were captured during 20 of 48 trawls. Selectivity and efficiency differed between the two gears. The trawl had lower catch rates, caught smaller sharks, and encountered a different suite of species than the longline. General seasonal trends in relative abundance also differed between the two gears; the longline showed an increasing trend in abundance, whereas the trawl showed a stable trend. Although trawls were not found to be efficient for sampling subadult sharks from most species, they can be a useful source of supplemental data.

  2. Modelling marine ecosystem response to climate change and trawling in the North Sea

    NARCIS (Netherlands)

    van der Molen, J.; Aldridge, J.N.; Coughlan, C.; Parker, E.R.; Stephens, D; Ruardij, P.

    2013-01-01

    The marine ecosystem response to climate change and demersal trawling was investigated using the coupled hydrodynamic-biogeochemical water column model GOTM-ERSEM-BFM for three contrasting sites in the North Sea. Climate change forcing was derived from the HadRM3-PPE-UK regional climate model for

  3. 76 FR 54887 - Fisheries Off West Coast States; Pacific Coast Groundfish Fishery Management Plan; Trawl...

    Science.gov (United States)

    2011-09-02

    ... hardware and software requirements for e- tickets to reflect more current computer operating systems and... procedures for the initial issuance of permits, endorsements, quota share, and catch history assignments... history assignment from one limited entry trawl endorsed permit to another. These trailing actions are...

  4. New approaches to the reduction of non-target mortality in beam trawling

    NARCIS (Netherlands)

    Marlen, van B.; Bergman, M.J.N.; Groenewold, S.; Fonds, M.

    2005-01-01

    This paper presents experiments with modified beam trawls aimed at reducing discard rates and direct mortality of benthic in-fauna and epi-fauna without affecting the level of landings. Drop-out panels made of large meshes in the belly of the net were effective in reducing by-catch, but the penalty

  5. Species selectivity in different sized topless trawl designs: Does size matter?

    DEFF Research Database (Denmark)

    Krag, Ludvig Ahm; Herrmann, Bent; Karlsen, Junita Diana;

    2015-01-01

    Most demersal trawl fisheries are conducted in a multispecies setting, and the catch consists of severaldifferent species. An inherent challenge in such fisheries is to provide both biologically and economicallysustainable exploitation of individually fluctuating stocks and vessel- or fleet-speci...

  6. A 'simple anterior fish excluder' (SAFE for mitigating penaeid-trawl bycatch.

    Directory of Open Access Journals (Sweden)

    Matthew J McHugh

    Full Text Available Various plastic strips and sheets (termed 'simple anterior fish excluders'-SAFEs were positioned across the openings of penaeid trawls in attempts at reducing the unwanted bycatches of small teleosts. Initially, three SAFEs (a single wire without, and with small and large plastic panels were compared against a control (no SAFE on paired beam trawls. All SAFEs maintained targeted Metapenaeus macleayi catches, while the largest plastic SAFE significantly reduced total bycatch by 51% and the numbers of Pomatomus saltatrix, Mugil cephalus and Herklotsichthys castelnaui by up to 58%. A redesigned SAFE ('continuous plastic' was subsequently tested (against a control on paired otter trawls, significantly reducing total bycatch by 28% and P. saltatrix and H. castelnaui by up to 42%. The continuous-plastic SAFE also significantly reduced M. macleayi catches by ~7%, but this was explained by ~5% less wing-end spread, and could be simply negated through otter-board refinement. Further work is required to refine the tested SAFEs, and to quantify species-specific escape mechanisms. Nevertheless, the SAFE concept might represent an effective approach for improving penaeid-trawl selectivity.

  7. Twin-truss system design for antarctic krill trawl processing ship

    Directory of Open Access Journals (Sweden)

    ZHOU Chungkai

    2017-05-01

    Full Text Available Aiming to improve the fishing efficiency of antarctic krill processing ships by averting the potential crushing of krill in the trawl to meet quality requirements, a twin-truss system design is proposed which has higher efficiency compared with the traditional system installed in ships. To simulate this design, an analysis of forces acting on the twin-truss structure is conducted under tethered and operating conditions using the structure model method, and an appropriate distance between trawl winch and truss structure, as well as the range for limiting the distance of the horizontal locating cable and truss structure, are obtained. It can also prevent the truss structure from breaking down, enabling the efficiency of trawling and horizontal locating cables during fishing operations. The simulation shows that the new twin-truss system design can improve the efficiency of trawl processing ships, whilst maintain the safety of the truss structure. This design can provide an optimal solution for the truss systems of national antarctic krill processing ships.

  8. 78 FR 41305 - Collect on Delivery (COD)-Service Features

    Science.gov (United States)

    2013-07-10

    ... From the Federal Register Online via the Government Publishing Office POSTAL SERVICE 39 CFR Part 111 Collect on Delivery (COD)--Service Features AGENCY: Postal Service TM . ACTION: Final rule... proposed rule were received, the Postal Service will adopt the proposed changes to Collect on Delivery (COD...

  9. Rationale for restocking the Eastern Baltic cod stock

    DEFF Research Database (Denmark)

    Støttrup, Josianne; Overton, Julia Lynne; Paulsen, Helge

    2008-01-01

    The Danish Institute for Fisheries Research and Bornholm's Salmon Hatchery examined the potential for restocking Baltic cod (Gadus morhua callarias L.) in the eastern Baltic Sea. This cod population has adapted to the unique brackish water conditions where successful spawning depends on regular i...

  10. 33 CFR 117.589 - Cape Cod Canal.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Cape Cod Canal. 117.589 Section 117.589 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES DRAWBRIDGE OPERATION REGULATIONS Specific Requirements Massachusetts § 117.589 Cape Cod Canal. The draw of the Conrail railroad bridge, mile 0.7 at...

  11. Could seals prevent cod recovery in the Baltic Sea?

    Directory of Open Access Journals (Sweden)

    Brian R MacKenzie

    Full Text Available Fish populations are increasingly affected by multiple human and natural impacts including exploitation, eutrophication, habitat alteration and climate change. As a result many collapsed populations may have to recover in ecosystems whose structure and functioning differ from those in which they were formerly productive and supported sustainable fisheries. Here we investigate how a cod (Gadus morhua population in the Baltic Sea whose biomass was reduced due to a combination of high exploitation and deteriorating environmental conditions might recover and develop in the 21st century in an ecosystem that likely will change due to both the already started recovery of a cod predator, the grey seal Halichoerus grypus, and projected climate impacts. Simulation modelling, assuming increased seal predation, fishing levels consistent with management plan targets and stable salinity, shows that the cod population could reach high levels well above the long-term average. Scenarios with similar seal and fishing levels but with 15% lower salinity suggest that the Baltic will still be able to support a cod population which can sustain a fishery, but biomass and yields will be lower. At present knowledge of cod and seal interactions, seal predation was found to have much lower impact on cod recovery, compared to the effects of exploitation and salinity. These results suggest that dual management objectives (recovery of both seal and cod populations are realistic but success in achieving these goals will also depend on how climate change affects cod recruitment.

  12. STUDY ON THE RELATIONSHIP BETWEEN J-INTEGRAL AND COD

    Institute of Scientific and Technical Information of China (English)

    Y. G. Cao; X. Y. Sun; K. Tanaka

    2007-01-01

    J-integral and crack opening displacement δ (COD) were important parameters for characterizationof fractures in engineering materials. The relationship between J-integral and COD has beeninvestigated for a long time and was generally represented as J = mσyδ, where σy is the yield strengthand m is a function of specimen geometry and material properties. To determine the value of m,extensive studies and experiments have been performed. The method that used the fracture-surfacetopography analysis (FRASTA) for determining J-integral from fracture surfaces of materials wasintroduced. On the basis of the relationship between COD and fracture surface average profile,the relationship between J-integral and COD was deduced and compared with the generally usedequation. The method was experimentally confirmed to be able to provide a new way to determinethe relationship between J-integral and COD.

  13. Impacts of trawling on benthic macro-fauna and -flora of the Spencer Gulf prawn fishing grounds

    Science.gov (United States)

    Svane, Ib; Hammett, Zoe; Lauer, Peter

    2009-05-01

    The overall effects of trawling on benthic habitats and their assemblages are dependent on the distribution and intensity of trawl effort. The benthic habitats of the Spencer Gulf prawn trawling grounds are subjected to known variable levels of trawling disturbance recorded from fisher's logbooks. These habitats have not been quantitatively investigated. The aim of the study was firstly to characterise the macro-faunal and -floral assemblages and secondly, to comparatively assess trawl impact by testing the null hypothesis of no differences between five sites exposed to different intensity of trawl effort. The distribution and abundance of benthic macro-fauna and -flora were studied at two sampling resolutions by using beam trawl sampling (˜10,000 m 2) and underwater stereophotography (˜4.5 m 2) at five sites with different levels of trawl disturbance (effort). The results showed that the Spencer Gulf prawn trawling grounds are characterised by sandy sediments with a low content of silt and clay, with the exception of one site with very fine gravel. Biomass, abundance and cover of macro-fauna and -flora were generally low throughout, but with large differences among sites. Biomass, abundance and cover were found to be negatively correlated to both trawl hours from 1994-1998 and during the period of study. ANOSIM and SIMPER analyses using biomass, abundance and percentage cover as variables showed significant differences between sites with eight species or taxonomic groups contributing more than 10% to the observed similarity within sites. The two northern sites were dominated by sponges and the bearded mussel, Trichomya hirsutus, and the southern hammer oyster, Malleus meridianus. Other species that contributed to the similarity within sites were the ascidian, Polycarpa viridis, mobile epifauna (the blue swimmer crab, Portunus pelagicus, and the western king prawn, Penaeus (Melicertus) latisulcatus) and demersal fish species (Degens leatherjacket, Thamnaconus

  14. 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

  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. 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.

  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. PMID:26492091

  18. 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.

  19. Potential Use of Atlantic Cod Trypsin in Biomedicine

    Directory of Open Access Journals (Sweden)

    Ágústa Gudmundsdóttir

    2013-01-01

    Full Text Available Surface proteins of viruses and bacteria used for cell attachment and invasion are candidates for degradation by proteases. Trypsin from Atlantic cod (Gadus morhua was previously demonstrated to have efficacy against influenza viruses in vitro and on skin. In this paper, cod trypsin is shown to be 3–12 times more effective in degrading large native proteins than its mesophilic analogue, bovine trypsin. This is in agreement with previous findings where cod trypsin was found to be the most active among twelve different proteases in cleaving various cytokines and pathological proteins. Furthermore, our results show that cod trypsin has high efficacy against herpes simplex virus type 1 (HSV-1 and the respiratory syncytial virus (RSV in vitro. The results on the antipathogenic properties of cod trypsin are important because rhinovirus, RSV, and influenza are the most predominant pathogenic viruses in upper respiratory tract infections. Results from a clinical study presented in this paper show that a specific formulation containing cod trypsin was preferred for wound healing over other methods used in the study. Apparently, the high digestive ability of the cold-adapted cod trypsin towards large native proteins plays a role in its efficacy against pathogens and its positive effects on wounds.

  20. Behavioral responses of Atlantic cod to sea temperature changes.

    Science.gov (United States)

    Freitas, Carla; Olsen, Esben Moland; Moland, Even; Ciannelli, Lorenzo; Knutsen, Halvor

    2015-05-01

    Understanding responses of marine species to temperature variability is essential to predict impacts of future climate change in the oceans. Most ectotherms are expected to adjust their behavior to avoid extreme temperatures and minimize acute changes in body temperature. However, measuring such behavioral plasticity in the wild is challenging. Combining 4 years of telemetry-derived behavioral data on juvenile and adult (30-80 cm) Atlantic cod (Gadus morhua), and in situ ocean temperature measurements, we found a significant effect of sea temperature on cod depth use and activity level in coastal Skagerrak. During summer, cod were found in deeper waters when sea surface temperature increased. Further, this effect of temperature was stronger on larger cod. Diel vertical migration, which consists in a nighttime rise to shallow feeding habitats, was stronger among smaller cod. As surface temperature increased beyond ∼15°C, their vertical migration was limited to deeper waters. In addition to larger diel vertical migrations, smaller cod were more active and travelled larger distances compared to larger specimens. Cold temperatures during winter tended, however, to reduce the magnitude of diel vertical migrations, as well as the activity level and distance moved by those smaller individuals. Our findings suggest that future and ongoing rises in sea surface temperature may increasingly deprive cod in this region from shallow feeding areas during summer, which may be detrimental for local populations of the species.

  1. Mothership Cost Earnings Data - Economic Data Collection for Monitoring the Economic Effects of the West Coast Groundfish Trawl Rationalization Program

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This project was initiated in response to regulation 50 CFR 660.114, which mandates that economic data be collected from every participant in the trawl...

  2. Acoustic-Trawl Survey of Walleye Pollock on the Eastern Bering Sea Shelf (DY1407, EK60)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — National Marine Fisheries Service (NMFS), Alaska Fisheries Science Center (AFSC) conducted an acoustic-trawl (AT) stock assessment survey on the eastern Bering Sea...

  3. NPRB711 Quantification of unobserved injury and mortality of Bering Sea crabs due to encounters with trawls on the seafloor

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The potential for unobserved mortality of crabs encountering bottom trawls, but not captured, has long been a concern in the management of Bering Sea fisheries. We...

  4. AFSC/RACE/MACE: Results of 2014 Acoustic-trawl survey of the Shumagin Islands and Sanak Trough dy1401

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The survey’s primary objective was to collect acoustic data and trawl information to estimate midwater abundance and distribution of walleye pollock (Gadus...

  5. AFSC/RACE/SAP: Detailed Crab Data From NOAA Fisheries Service 2012 Chukchi Sea Bottom Trawl Surveys

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset contains detailed crab data collected from the 2012 NOAA/NMFS/AFSC/RACE crab-groundfish bottom trawl survey of the Chukchi Sea. 71 survey stations were...

  6. The COD Model: Simulating Workgroup Performance

    Science.gov (United States)

    Biggiero, Lucio; Sevi, Enrico

    Though the question of the determinants of workgroup performance is one of the most central in organization science, precise theoretical frameworks and formal demonstrations are still missing. In order to fill in this gap the COD agent-based simulation model is here presented and used to study the effects of task interdependence and bounded rationality on workgroup performance. The first relevant finding is an algorithmic demonstration of the ordering of interdependencies in terms of complexity, showing that the parallel mode is the most simplex, followed by the sequential and then by the reciprocal. This result is far from being new in organization science, but what is remarkable is that now it has the strength of an algorithmic demonstration instead of being based on the authoritativeness of some scholar or on some episodic empirical finding. The second important result is that the progressive introduction of realistic limits to agents' rationality dramatically reduces workgroup performance and addresses to a rather interesting result: when agents' rationality is severely bounded simple norms work better than complex norms. The third main finding is that when the complexity of interdependence is high, then the appropriate coordination mechanism is agents' direct and active collaboration, which means teamwork.

  7. Farmed cod escapees and net-pen spawning left no clear genetic footprint in the local wild cod population

    Directory of Open Access Journals (Sweden)

    Rebekka Varne

    2015-11-01

    Full Text Available This study investigated a potential genetic introgression from farmed to wild cod Gadus morhua L. in the Trondheimsfjord, Norway. During the first 2 yr of operation of a cod farm in the inner part of the fjord, 2 large escape events and extensive pen spawning were reported. Analyses of 4 allozyme markers revealed no significant changes in allele frequencies between samples of wild cod before and after cod farming, although prominent allele frequency differences were demonstrated between wild and farmed samples. Analyses of 10 DNA markers showed a significant change between pre- and post-farming samples, due to contradictory allele frequency differences at Tch11, Pan I and Gmo132. Excluding those 3 markers due to null alleles (Tch11 and selection (Gmo132 and Pan I, the DNA markers paralleled the non-changed allele frequency signal from the allozymes. The topographies of the allozyme- and DNA-based dendrogram of the samples were congruent. Recaptures of tagged and released farmed cod indicated a seemingly random diffusion throughout the fjord and ended after approx. 6 mo. During an ongoing pen spawning, plankton net surveys sampling for cod eggs in the surroundings of the cod farm suggested the eggs originated from the farm. No larvae were present in the plankton samples. The apparent absence of introgression is explained relative to fitness and survival of pen-spawned larvae and adult escapees, and to a purging effect of the estuarine circulation of the Trondheimsfjord.

  8. Robust Optimal Output Tracking Control of A Midwater Trawl System Based on T-S Fuzzy Nonlinear Model

    Institute of Scientific and Technical Information of China (English)

    ZHOU Hua; CHEN Ying-long; YANG Hua-yong

    2013-01-01

    A robust optimal output tracking control method for a midwater trawl system is investigated based on T-S fuzzy nonlinear model.A simplified nonlinear mathematical model is first employed to represent a midwater trawl system,and then a T-S fuzzy model is adopted to approximate the nonlinear system.Since the strong nonlinearities and the external disturbance of the trawling system,a mixed H2/H∞ fuzzy output tracking control strategy via T-S fuzzy system is proposed to regulate the trawl depth to follow a desired trajectory.The trawl depth can be regulated by adjusting the winch velocity automatically and the tracking error can be minimized according to the robust optimal criterion.In order to validate the proposed control method,a computer simulation is conducted.The simulation results indicate that the proposed fuzzy robust optimal controller make the trawl net rapidly follow the desired trajectory under the model uncertainties and the external disturbance caused by wave and current.

  9. Estimating seabed pressure from demersal trawls, seines, and dredges based on gear design and dimensions

    DEFF Research Database (Denmark)

    Eigaard, Ole Ritzau; Bastardie, Francois; Breen, Mike

    2016-01-01

    This study assesses the seabed pressure of towed fishing gears and models the physical impact (area and depth of seabed penetration) from trip-based information of vessel size, gear type, and catch. Traditionally fishing pressures are calculated top-down by making use of large-scale statistics...... trawl groups, two demersal seine groups, and one dredge group), for which we established gear “footprints”. The footprint of a gear is defined as the relative contribution from individual larger gear components, such as trawl doors, sweeps, and groundgear, to the total area and severity of the gear......'s impact. An industry-based survey covering 13 countries provided the basis for estimating the relative impact-area contributions from individual gear components, whereas sediment penetration was estimated based on a literature review. For each gear group, a vessel size–gear size relationship was estimated...

  10. Lost in translation? Multi-metric macrobenthos indicators and bottom trawling

    DEFF Research Database (Denmark)

    Gislason, Henrik; Bastardie, Francois; Dinesen, Grete E.

    2017-01-01

    The member states of the European Union use multi-metric macrobenthos indicators to monitor the ecological status of their marine waters in relation to the Water Framework and Marine Strategy Framework Directives. The indicators translate the general descriptors of ecological quality...... trawling. We use linear mixed effects models to analyze how bottom trawling intensity affects the indicators used in the Danish (Danish Quality Index, DKI) and Swedish (Benthic Quality Index, BQI) environmental monitoring programs in the Kattegat, the sea area between Sweden and Denmark. Using year...... in the directives into a single value of ecological status by combining indices of species diversity, species sensitivity and density. Studies and inter-calibration exercises have shown that the indicators respond to chemical pollution and organic enrichment, but little is known about their response to bottom...

  11. Cod Fractions In Mechanical-Biological Wastewater Treatment Plant

    Directory of Open Access Journals (Sweden)

    Płuciennik-Koropczuk Ewelina

    2017-03-01

    Full Text Available The paper presents results of studies concerning the designation of COD fraction in the raw, mechanically treated and biologically treated wastewater. The test object was a wastewater treatment plant with the output of over 20,000 PE. The results were compared with data received in the ASM models. During investigation following fractions of COD were determined: dissolved non-biodegradable SI, dissolved easily biodegradable SS, in organic suspension slowly degradable XS and in organic suspension non-biodegradable XI. Methodology for determining the COD fraction was based on the guidelines ATV-A 131. The real percentage of each fraction in total COD in raw wastewater are different from data received in ASM models.

  12. Tendu leaves refuse as a Biosorbent for COD removal from ...

    African Journals Online (AJOL)

    Bioline

    industry, is effective biosorbent for the removal of COD; offering a cheap option for primary treatment of the effluent. ... Among these are both chemical and biological treatments such as ..... of water and waste water, 17th edition, (APHA.

  13. Removal of hard COD, nitrogenous compounds and phenols from a ...

    African Journals Online (AJOL)

    2015-07-04

    Jul 4, 2015 ... of phenols, COD and nitrogenous compounds in the wastewater. Keywords: ammonia ... Biological treatment has been widely used only to treat the ..... MOLVA M (2004) Removal of phenol from industrial wastewa- ters using ...

  14. Bio-economic evaluation of implementing trawl fishing gear with different selectivity

    DEFF Research Database (Denmark)

    Grønbæk Kronbak, Lone; Nielsen, J. Rasmus; Jørgensen, Ole A.

    2009-01-01

    with a baseline. The results from the evaluation are indicators for the consequences on ecological and economic levels. The results show that implementation of different selective fishing gear in the Kattegat and Skagerrak mixed trawl fisheries generally implies a trade off over time between rebuilding the stocks...... and economic loss. Moreover, the analysis shows that implementation of more selective gear is not always beneficial. (C) 2009 Elsevier Ltd. All rights reserved....

  15. Monitoring the desalting process of cod using dielectric spectroscopy.

    Science.gov (United States)

    De los Reyes, Ruth; Balbastre, Juan V; Andrés, Ana; Fito, Pedro; De los Reyes, Elias

    2009-01-01

    The desalted cod industry needs a suitable and reliable control system to check the desalting point of cod in order to provide a safe and high-quality product. The growth of the industries that are interested in a non-contacting, real-time control, encourages the development of new methods based on low-power radiation, such as dielectric spectroscopy. These techniques use the modification of wave parameters at some specific frequencies to provide information of the compositional characteristics of foods. In this work, cod parallelepipeds were desalted at 5 degrees C by immersing them in distilled water for different desalting times (15 and 30 minutes and 1, 2, 4, 6, 8, 12, 24 and 48 hours). Dielectric Spectroscopy studies have been performed on cod samples in the frequency range 200 MHz-20 GHz. The dielectric properties were measured using a coaxial probe (Agilent 85070E) connected to a Network Analyzer (Agilent E8362B) immediately after removing the cod samples from their desalting solutions. After desalting, the cod samples were separated from their desalting solutions and kept in repose for 24 h at 5 degrees C after which some of their physical properties were measured. This experimental procedure ensures that those properties have already reached their final values. Good correlations were found between the quality properties of the cod samples (a(w), Xw, Z(NaCl) and xNaCl) after 24 h and their loss factor (epsilon") measured at 10 GHz just before leaving them in repose, showing the feasibility of an in-line control system for cod desalting process at that frequency.

  16. Salted and dried Cod preserved by vacuum and modified atmosphere

    Directory of Open Access Journals (Sweden)

    Maria José Rodrigues

    2014-06-01

    Full Text Available Temperatures higher than 20ºC can boost the growth, on the salted and dried cod surface, of bacteria that present a red pigment (Rodrigues et al., 2003; Rodrigues et al., 2005. These organisms, besides the change of the food product appearance, also cause an unpleasant flavor and the product is rejected by the consumers, although does not cause any health concern. Currently, the export of salted and dried cod, to Africa, has increased and a great amount of product is rejected due to the high environmental temperature and the lack of a proper cold chain storage infrastructure. Vacuum packaging, and modified atmosphere packaging have been used for fresh and cooked seafood preservation, but, as far as the authors know, were never used to preserve salted and dried fish. In the present study it was observed the effect of vacuum packaging, packaging with 80%N2:20%CO2 and finally the addition of sodium metabisulfite on the salted and dried cod stored under temperature abuse (15ºC, 25ºC and 35ºC. Accordingly, packaging under vacum and, specially, packaging with 80%N2:20%CO2 successfuly increased the shellife of salted and dried cod . The addition of sodium metabisulfite has increased the shelflife of salted and dried cod preserved at 15ºC, but not of salted and dried cod preserved at 25ºC and 35ºC.

  17. Identification and evaluation of shark bycatch in Georgia's commercial shrimp trawl fishery with implications for management

    Science.gov (United States)

    Belcher, C.N.; Jennings, C.A.

    2011-01-01

    Many US states have recreational and commercial fisheries that occur in nursery areas occupied by subadult sharks and can potentially affect their survival. Georgia is one of few US states without a directed commercial shark fishery, but the state has a large, nearshore penaeid shrimp trawl fishery in which small sharks occur as bycatch. During our 1995–1998 investigation of bycatch in fishery-dependent sampling events, 34% of 127 trawls contained sharks. This bycatch totalled 217 individuals from six species, with Atlantic sharpnose shark, Rhizoprionodon terraenovae (Richardson), the most common and finetooth shark, Carcharhinus isodon (Müller & Henle) and spinner shark, Carcharhinus brevipinna (Müller & Henle), the least common. The highest catch rates for sharks occurred during June and July and coincided with the peak months of the pupping season for many species. Trawl tow speed and tow time did not significantly influence catch rates for shark species. Gear configurations [net type, turtle excluder device (TED), bycatch reduction device] affected catch rates for shark species. Results of this study indicate gear restrictions, a delayed season opening, or reduced bar spacing on TEDs may reduce shark bycatch in this fishery.

  18. The footprint of bottom trawling in European waters: distribution, intensity, and seabed integrity

    DEFF Research Database (Denmark)

    Eigaard, Ole Ritzau; Bastardie, Francois; Hinzen, N.T.

    2017-01-01

    for 2010-2012 at a grid cell resolution of 1 x 1 min longitude and latitude. Trawling intensity profiles with seabed impact at the surface and subsurface level are presented for 14 management areas in the North-east Atlantic, Baltic Sea and Mediterranean Sea. The footprint of the management areas ranged...... between 53-99% and 6-94% for the depth zone from 0 to 200 m (Shallow) and from 201 to 1000 m (Deep), respectively. The footprint was estimated as the total area of all grid cells that were trawled fully or partially. Excluding the untrawled proportions reduced the footprint estimates to 28-85% and 2......-77%. Largest footprints per unit landings were observed off Portugal and in the Mediterranean Sea. Mean trawling intensity ranged between 0.5 and 8.5 times per year, but was less in the Deep zone with a maximum intensity of 6.4. Highest intensities were recorded in the Skagerrak-Kattegat, Iberian Portuguese...

  19. Behavioral flexibility of the trawling long-footed bat, Macrophyllum macrophyllum (Phyllostomidae

    Directory of Open Access Journals (Sweden)

    Moritz eWeinbeer

    2013-11-01

    Full Text Available We assessed the behavioral flexibility of the trawling long-legged bat, Macrophyllum macrophyllum (Phyllostomidae in flight cage experiments by exposing it to prey suspended from nylon threads in the air and to food placed onto the water surface at varying distances to clutter-producing background (water plants. The bat revealed flexibility in foraging mode and caught prey in the air (aerial hawking and from the water surface (trawling. M. macrophyllum was constrained in finding food very near to and within clutter. As echolocation was the prime sensory mode used by M. macrophyllum for detection and localization of food, the bat might have been unable to perceive sufficient information from prey near clutter as background echoes from the water plant increasingly overlapped with echoes from food. The importance of echolocation for foraging is reflected in a stereotypic call pattern of M. macrophyllum that resembles other aerial insectivorous and trawling bats with a pronounced terminal phase (buzz prior to capture attempts. Our findings contrast studies of other phyllostomid bats that glean prey very near or from vegetation, often using additional sensory cues, such as prey-produced noise, to find food and that lack a terminal phase in echolocation behavior. In M. macrophyllum, acoustic characteristics of its foraging habitat have shaped its sonar system more than phylogeny.

  20. Quantifying the Escape Mortality of Trawl Caught Antarctic Krill (Euphausia superba)

    Science.gov (United States)

    Krafft, Bjørn A.; Krag, Ludvig A.; Engås, Arill; Nordrum, Sigve; Bruheim, Inge; Herrmann, Bent

    2016-01-01

    Antarctic krill (Euphausia superba) is an abundant fishery resource, the harvest levels of which are expected to increase. However, many of the length classes of krill can escape through commonly used commercial trawl mesh sizes. A vital component of the overall management of a fishery is to estimate the total fishing mortality and quantify the mortality rate of individuals that escape from fishing gear. The methods for determining fishing mortality in krill are still poorly developed. We used a covered codend sampling technique followed by onboard observations made in holding tanks to monitor mortality rates of escaped krill. Haul duration, hydrological conditions, maximum fishing depth and catch composition all had no significant effect on mortality of krill escaping 16 mm mesh size nets, nor was any further mortality associated with the holding tank conditions. A non- parametric Kaplan-Meier analysis was used to model the relationship between mortality rates of escapees and time. There was a weak tendency, though not significant, for smaller individuals to suffer higher mortality than larger individuals. The mortality of krill escaping the trawl nets in our study was 4.4 ± 4.4%, suggesting that krill are fairly tolerant of the capture-and-escape process in trawls. PMID:27622510

  1. Thermal niche of Atlantic cod Gadus morhua: limits, tolerance and optima

    DEFF Research Database (Denmark)

    Righton, David A.; Andersen, Ken Haste; Neat, Francis

    2010-01-01

    in those cod with a mean thermal history of between 8 and 10°C. Our direct observations of habitat occupation suggest that adult cod will be able to tolerate warming seas, but that climate change will affect cod populations at earlier life-history stages as well as exerting effects on cod prey species....

  2. 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.

  3. 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.

  4. 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...

  5. Shell plans big COD/sub 2/U miscible drive

    Energy Technology Data Exchange (ETDEWEB)

    1966-04-18

    Shell Oil Co. is seeking approval from the Texas Railroad Commission for the first field test using COD2U as a miscible slug. The test would take place in the Crossett Field, Crane and Upton Counties, 5 miles West of McCamey. Plan calls for injecting a large slug of COD2U in the Devonian reservoir, and following this with water to maintain reservoir pressure and serve as a sweeping medium. If the method works as anticipated, Shell says it will recover 32.8 million bbl of 44$-gravity crude--or 63.8% of the oil originally in place. Residue gas in now being injected in the field's North Cross unit. Widespread application of the process, if it works as hoped, seems unlikely because of the difficulty and cost of transporting COD2U where it is needed. However, ample supplies of COD2U are available in West Texas. There are at least 3 sources of COD2U in the vicinity. Norhtern Natural Gas Co. is venting some 20 MMcfd at is gas processing plant at Puckett field in Pecos County. Not far away is Hunt Oil Co.'s 57 Elsinore Ranch well, a dry hole that tested COD2U at the rate of 19 MMcfd. The most likely source of COD2U for Shell's proposed test is El Paso Natural Gas Co.'s processing plant at Brown-Basset Field in Terrell County, where gas is now being vented to the atmosphere at the rate of 40 MMscfd.

  6. 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].

  7. 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.

  8. 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.

  9. Bottom trawling and oxygen minimum zone influences on continental slope benthic community structure off Vancouver Island (NE Pacific)

    Science.gov (United States)

    De Leo, Fabio C.; Gauthier, Maéva; Nephin, Jessica; Mihály, Steven; Juniper, S. Kim

    2017-03-01

    Understanding responses of benthic ecosystems to cumulative impacts of natural stressors, long-term ocean change and increasing resource exploitation is an emerging area of interest for marine ecologists and environmental managers. Few, if any, studies have quantitatively addressed cumulative effects in the deep sea. We report here on a study from the continental slope off Vancouver Island (Canada) in the northeast Pacific Ocean, where the Oxygen Minimum Zone impinges on seabed habitats that are subjected to widespread bottom trawling, primarily by the fishery for thornyhead (Sebastolobus ssp.). We examined how the benthic megafauna in this area was influenced by varying levels of dissolved oxygen and trawling activity, along a depth gradient that was also likely to shape community composition. Continuous video and sonar records from two ROV surveys (50 linear km total; depth range 300-1400 m) respectively provided data on faunal attributes (composition, abundance and diversity) and the frequency of trawl door marks on the seabed. Faunal and trawl data were compiled in a geo-referenced database along with corresponding dissolved oxygen data, and pooled into 500 m segments for statistical analysis. Trawl mark occurrence peaked between 500 and 1100 m, corresponding to areas of slope subjected to hypoxia (<1.4 ml l-1) and severe hypoxia (<0.5 ml l-1). A combined total of 266,251 megafauna organisms from 87 taxa were enumerated in the two transects. Significant megafaunal assemblages according to depth, trawling intensity and bottom water dissolved oxygen concentration were identified by PERMANOVA analyses, with characterizing taxa identified for all three factors. Depth, dissolved oxygen and trawl mark density accounted for 21% to 52% of the variability in benthic community structure according to multiple regression (DISTLM) models. Species richness was highest at intermediate depths and in areas subject to intermediate levels of trawling, and higher under hypoxia

  10. 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

  11. 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...

  12. AFSC/RACE/EcoFOCI - Trawl catch data collected in support of FOCI assessment surveys and ecosystem observations in the Bering Sea and the Gulf of Alaska 1993 to Present

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The trawl database contains multiple tables of data. The ‘haul’ table contains the location, date, time and depth of the trawl haul. The ‘catch’ table contains the...

  13. When does fishing lead to more fish? Community consequences of bottom trawl fisheries in demersal food webs.

    Science.gov (United States)

    van Denderen, P Daniel; van Kooten, Tobias; Rijnsdorp, Adriaan D

    2013-10-22

    Bottom trawls are a globally used fishing gear that physically disturb the seabed and kill non-target organisms, including those that are food for the targeted fish species. There are indications that ensuing changes to the benthic invertebrate community may increase the availability of food and promote growth and even fisheries yield of target fish species. If and how this occurs is the subject of ongoing debate, with evidence both in favour and against. We model the effects of trawling on a simple ecosystem of benthivorous fish and two food populations (benthos), susceptible and resistant to trawling. We show that the ecosystem response to trawling depends on whether the abundance of benthos is top-down or bottom-up controlled. Fishing may result in higher fish abundance, higher (maximum sustainable) yield and increased persistence of fish when the benthos which is the best-quality fish food is also more resistant to trawling. These positive effects occur in bottom-up controlled systems and systems with limited impact of fish feeding on benthos, resembling bottom-up control. Fishing leads to lower yields and fish persistence in all configurations where susceptible benthos are more profitable prey. Our results highlight the importance of mechanistic ecosystem knowledge as a requirement for successful management.

  14. Prenatal stress from trawl capture affects mothers and neonates: a case study using the southern fiddler ray (Trygonorrhina dumerilii)

    Science.gov (United States)

    Guida, L.; Awruch, C.; Walker, T. I.; Reina, R. D.

    2017-04-01

    Assessing fishing effects on chondrichthyan populations has predominantly focused on quantifying mortality rates. Consequently, sub-lethal effects of capture stress on the reproductive capacity of chondrichthyans are largely unknown. We investigated the reproductive consequences of capture on pregnant southern fiddler rays (Trygonorrhina dumerilii) collected from Swan Bay, Australia, in response to laboratory-simulated trawl capture (8 h) followed immediately by air exposure (30 min). Immediately prior to, and for up to 28 days post trawling, all females were measured for body mass (BM), sex steroid concentrations (17-β estradiol, progesterone, testosterone) and granulocyte to lymphocyte (G:L) ratio. At parturition, neonates were measured for total length (TL), BM and G:L ratio. Trawling reduced maternal BM and elevated the G:L ratio for up to 28 days. Trawling did not significantly affect any sex steroid concentrations relative to controls. Neonates from trawled mothers were significantly lower in BM and TL than control animals, and had an elevated G:L ratio. Our results show that capture of pregnant T. dumerilii can influence their reproductive potential and affect the fitness of neonates. We suggest other viviparous species are likely to be similarly affected. Sub-lethal effects of capture, particularly on reproduction, require further study to improve fisheries management and conservation of chondrichthyans.

  15. A New Spectrophotometric Method for Measuring COD of Seawater

    Institute of Scientific and Technical Information of China (English)

    LIU Ying; JI Hongwei; XIN Huizhen; LIU Li

    2006-01-01

    This research studied a new spectrophotometric method for measuring the chemical oxygen demand (COD) of seawater. In this method, the COD was measured using a spectrophotometer instead of titrating with sodium thiosulphate.The measuring wavelength was selected to be 470 nm, and the COD of three standard glucose solutions (COD = 0.5, 1.5 and2.5 mgL-1, respectively) and two seawater samples (from the South Yellow Sea and Jiaozhou Bay) were measured using the spectrophotometric method and titrimetric method respectively. The results showed that the spectrophotometric method was somewhat better than the titrimetric method. The relative standard deviation (RSD) of the spectrophotometric method was less than 2.7%, and the recovery of seawater samples ranged from 96.3% to 103.8%. In addition, the spectrophotometric method has other advantages such as expeditiousness, operation simplicity, analysis automatization, etc. Therefore the spectrophotometric method can be used to measure the COD of seawater with satisfactory results.

  16. 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.

  17. 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.

  18. Implications of stock recovery for a neighbouring management unit: experience from the Baltic cod

    DEFF Research Database (Denmark)

    Eero, Margit; Hansen, Jakob Hemmer; Hüssy, Karin

    2014-01-01

    Cod in the Baltic Sea is assessed and managed as two separate stocks, i.e. eastern and western Baltic cod. The eastern Baltic cod has recently started to recover after several decades of severe depletion. In the present study, we suggest that the recovery of the eastern Baltic cod population has...... also substantially increased cod abundance in a specific area of the adjacent western Baltic management unit. This is investigated through long time-series of spatially resolved stock assessment data supplemented by genetic analyses of origin of the cod currently found in the transition area between...... the two populations. Due to immigrating cod from the east, there are currently large spatial differences in cod abundance and mean weight in the western Baltic management unit that raise new management concerns. First, the high abundance of cod of eastern origin found in the western Baltic management unit...

  19. COD removal characteristics in air-cathode microbial fuel cells

    KAUST Repository

    Zhang, Xiaoyuan

    2015-01-01

    © 2014 Elsevier Ltd. Exoelectrogenic microorganisms in microbial fuel cells (MFCs) compete with other microorganisms for substrate. In order to understand how this affects removal rates, current generation, and coulombic efficiencies (CEs), substrate removal rates were compared in MFCs fed a single, readily biodegradable compound (acetate) or domestic wastewater (WW). Removal rates based on initial test conditions fit first-order kinetics, but rate constants varied with circuit resistance. With filtered WW (100Ω), the rate constant was 0.18h- 1, which was higher than acetate or filtered WW with an open circuit (0.10h- 1), but CEs were much lower (15-24%) than acetate. With raw WW (100Ω), COD removal proceeded in two stages: a fast removal stage with high current production, followed by a slower removal with little current. While using MFCs increased COD removal rate due to current generation, secondary processes will be needed to reduce COD to levels suitable for discharge.

  20. Mapping spatial variation in demersal fish species diversity and composition in the North Sea: accounting for species- and size-related catchability in survey trawls

    NARCIS (Netherlands)

    Fraser, H.M.; Greenstreet, S.P.R.; Fryer, R.J.; Piet, G.J.

    2008-01-01

    The paper maps spatial patterns of groundfish species diversity. It considers how the catchability of different fish species in two different types of bottom trawls, the IBTS GOV and the 8-m beam trawl, influences the estimates of species diversity. Maps of groundfish species diversity derived from

  1. A comparison between benthic gillnet and bottom trawl for assessing fish assemblages in a shallow eutrophic lake near the Changjiang River estuary

    Science.gov (United States)

    Li, Yalei; Liu, Qigen; Chen, Liping; Zhao, Liangjie; Wu, Hao; Chen, Liqiao; Hu, Zhongjun

    2017-06-01

    Two fishing methods including gillnetting and trawling to estimate attributes of fish assemblage were compared in Dianshan Lake from August 2009 to July 2010. Species composition differed significantly between the gears, with four significant contributors in gillnet catches and one in trawl catches. Trawling collected more proportions of benthic species by number and biomass than gillnetting. Size distribution was significantly influenced by fishing technique; gillnetting captured relatively less small-sized fishes and trawling captured less large-sized individuals. Trawling produced species richness closer to the one expected than gillnetting. On the whole, trawl catch was a quadratic polynomial function of gillnet catch and a significantly negative correlation was found between them, both of which varied as different polynomial functions of temperature. However, trawl and gillnet catches were significantly correlated only in one of five month groups. It is concluded that single-gear-based surveys can be misleading in assessments of attributes of fish assemblages, bottom trawling is a more effective gear for assessing fish diversity than benthic gillnetting, and using gillnet catches as an indicator of fish density depends on fishing season in the lake.

  2. Iodine nutrition and toxicity in Atlantic cod (Gadus morhua larvae

    Directory of Open Access Journals (Sweden)

    S Penglase

    2013-02-01

    Full Text Available Copepods as feed promote better growth and development in marine fish larvae than rotifers. However, unlike rotifers, copepods contain several minerals such as iodine (I, at potentially toxic levels. Iodine is an essential trace element and both under and over supply of I can inhibit the production of the I containing thyroid hormones. It is unknown whether marine fish larvae require copepod levels of I or if mechanisms are present that prevent I toxicity. In this study, larval Atlantic cod (Gadus morhua were fed rotifers enriched to intermediate (26 mg I kg-1 dry weight; MI group or copepod (129 mg I kg-1 DW; HI group I levels and compared to cod larvae fed control rotifers (0.6 mg I kg-1 DW. Larval I concentrations were increased by 3 (MI and 7 (HI fold compared to controls during the rotifer feeding period. No differences in growth were observed, but the HI diet increased thyroid follicle colloid to epithelium ratios, and affected the essential element concentrations of larvae compared to the other groups. The thyroid follicle morphology in the HI larvae is typical of colloid goitre, a condition resulting from excessive I intake, even though whole body I levels were below those found previously in copepod fed cod larvae. This is the first observation of dietary induced I toxicity in fish, and suggests I toxicity may be determined to a greater extent by bioavailability and nutrient interactions than by total body I concentrations in fish larvae. Rotifers with 0.6 mg I kg-1 DW appeared sufficient to prevent gross signs of I deficiency in cod larvae reared with continuous water exchange, while modelling of cod larvae versus rotifer I levels suggests that optimum I levels in rotifers for cod larvae is 3.5 mg I kg-1 DW.

  3. Influence of dreissenid mussels on catchability of benthic fishes in bottom trawls

    Science.gov (United States)

    Kocovsky, Patrick M.; Stapanian, Martin A.

    2011-01-01

    Inferring trends in true abundance of fish populations from catch per unit effort data requires either the knowledge of capture probability or the assumption that it is constant, both of which are unlikely contingencies. We developed and validated an index of catchability (a proxy measure for capture probability) from a long-term data set describing nearshore waters of western Lake Erie, and we used the index to test the hypothesis that catchability of four abundant benthic species captured in bottom trawls changed after the invasion of dreissenid mussels. We estimated daytime and nighttime catchability for 1972–1990 (predreissenid period) and 1991–2009 (dreissenid period); we then tested for differences between nighttime and daytime catchability in the predreissenid and dreissenid periods and the nighttime–daytime differential in catchability during the dreissenid period. We also tested relationships between Secchi depth and the catchability index via linear regression. Catchability indices for white perch Morone americana, yellow perch Perca flavescens, and trout-perch Percopsis omiscomaycus did not differ between daytime and nighttime during the predreissenid period. After establishment of dreissenids, all three of these species had lower daytime catchability than nighttime catchability and had positive nighttime–daytime differentials, indicating a shift toward higher nighttime catchability relative to daytime catchability. Changes in catchability indices for freshwater drum Aplodinotus grunniens were opposite the changes observed for the other three species, possibly because the freshwater drum is the only species that actively feeds on dreissenids. Catchability indices were negatively related to water clarity (Secchi depth) for three of the species. Our results are consistent with the hypothesis that catchability of the four most common benthic fish species captured in bottom trawls within nearshore waters of western Lake Erie changed after the

  4. Challenges in licensing the industrial double-rig trawl fisheries in Brazil

    Directory of Open Access Journals (Sweden)

    Paulo Ricardo-Pezzuto

    2015-07-01

    Full Text Available Bottom trawling is important in Brazilian fisheries and is currently highly multi-specific due to the overexploitation of the original targets; unselective fishing method; very large permitted fishing area and the country's high marine biodiversity. Fishing licensing in Brazil was modified in 2012 and is now based in five criteria: target species; "expected by-catch"; "incidental catches"; fishing method and area of operation. Licenses of trawling fleets exhibit, therefore, dozens of species catchable under the first three criteria. In this paper, we analyze industrial double-rig trawling fleets targeting shrimps and demersal fishes, in order to verify in what extent the new system adhere to the current fishing reality, giving new information to improve the current management regime. A total of 4,194 trips from 191 vessels were studied between 2008 and 2010 in southern Brazil. In spite of depending economically on their targets, the fleets are formally authorized to catch a high percentage of species in common (41 to 71%, and the actual landings revealed an even greater overlapping among them (71 to 82%. Vessels licensed to catch demersal fishes obtained nearly 50% of their revenue from items not included in their licenses. It was concluded that the current system encourages excessive effort concentrations over fishing resources, as they can be legally caught by most vessels irrespective of their licenses. It is suggested that licensing should move from a species-based to a spatial-based approach, by defining smaller management areas according to the respective species assemblages. Landing composition would be, therefore, mostly a biological and technological consequence, making management more reasonable and workable under a multi-specific and mega-diverse scenario.

  5. Interaction between submicron COD crystals and renal epithelial cells

    Directory of Open Access Journals (Sweden)

    Peng H

    2012-08-01

    Full Text Available Hua Peng1,2 Jian-Ming Ouyang1,2 Xiu-Qiong Yao1, Ru-E Yang11Department of Chemistry, Jinan University, 2Institute of Biomineralization and Lithiasis Research, Jinan University, Guangzhou, ChinaObjectives: This study aims to investigate the adhesion characteristics between submicron calcium oxalate dihydrate (COD with a size of 150 ± 50 nm and African green monkey kidney epithelial cells (Vero cells before and after damage, and to discuss the mechanism of kidney stone formation.Methods: Vero cells were oxidatively injured by hydrogen peroxide to establish a model of injured cells. Scanning electron microscopy was used to observe Vero–COD adhesion. Inductively coupled plasma emission spectrometry was used to quantitatively measure the amount of adhered COD microcrystals. Nanoparticle size analyzer and laser scanning confocal microscopy were performed to measure the change in the zeta potential on the Vero cell surface and the change in osteopontin expression during the adhesion process, respectively. The level of cell injury was evaluated by measuring the changes in malonaldehyde content, and cell viability during the adhesion process.Results: The adhesion capacity of Vero cells in the injury group to COD microcrystals was obviously stronger than that of Vero cells in the control group. After adhesion to COD, cell viability dropped, both malonaldehyde content and cell surface zeta potential increased, and the fluorescence intensity of osteopontin decreased because the osteopontin molecules were successfully covered by COD. Submicron COD further damaged the cells during the adhesion process, especially for Vero cells in the control group, leading to an elevated amount of attached microcrystals.Conclusion: Submicron COD can further damage injured Vero cells during the adhesion process. The amount of attached microcrystals is proportional to the degree of cell damage. The increased amount of microcrystals that adhered to the injured epithelial

  6. Structure of chymotrypsin variant B from Atlantic cod, Gadus morhua

    DEFF Research Database (Denmark)

    Leth-Larsen, Rikke; Asgeirsson, B; Thórólfsson, M

    1996-01-01

    The amino-acid sequence of chymotrypsin variant B isolated from the pyloric caeca of Atlantic cod has been elucidated. The characterization of the primary structure is based on N-terminal Edman degradation and mass spectrometry of the native protein and enzymatically derived peptides. Chymotrypsin...... side-chains may contribute to the maintenance of flexibility at low temperatures. Several amino-acid sequence differences adjacent to the catalytic site are observed in the two cod chymotrypsin variants which also differ in kinetic properties. Unlike the mammalian chymotrypsins, which contain several...

  7. Penurunan COD air limbah industri penyamakan kulit menggunakan reagen fenton

    Directory of Open Access Journals (Sweden)

    Muhammad Sholeh

    2013-06-01

    Full Text Available The aim of the experiment was to obtain optimum condition for COD reduction in tannery wastewater using fenton's reagent. The effects of different reaction parameters included ferrous concentration, hydrogen peroxide concentration, and the pH walue of solution were investigated. The optimum values were achieved at 0.2%, 120 ppm, and 4 for FeSO H O , and pH, 4, 2 2 respectively. The optimum condition still unable to fulfill the quality standard for COD of wastewater.

  8. Could seals prevent cod recovery in the Baltic Sea?

    DEFF Research Database (Denmark)

    MacKenzie, Brian; Eero, Margit; Ojaveer, Henn

    2011-01-01

    Fish populations are increasingly affected by multiple human and natural impacts including exploitation, eutrophication, habitat alteration and climate change. As a result many collapsed populations may have to recover in ecosystems whose structure and functioning differ from those in which...... in an ecosystem that likely will change due to both the already started recovery of a cod predator, the grey seal Halichoerus grypus, and projected climate impacts. Simulation modelling, assuming increased seal predation, fishing levels consistent with management plan targets and stable salinity, shows...... these goals will also depend on how climate change affects cod recruitment....

  9. A wasted resource: cod discards in the North Sea

    DEFF Research Database (Denmark)

    Feekings, Jordan P.; Poos, Jan Jaap; Aarts, Geert

    2012-01-01

    The public, political, and stakeholder perception of fisheries discards is that they are a waste of a valuable resource. In the North Sea, fisheries discards are some of the highest in the world. Cod (Gadus morhua) has contributed considerably to the amount discarded. The declining cod stock with......, spatially and temporally, in discarding over the past decade while pinpointing the major reasons to why it occurs. We discuss how such information can be used to improve future fishing activities and their subsequent catch compositions under a discard...

  10. Recovery in eastern Baltic cod: is increased recruitment caused by decreased predation on early life stages?

    DEFF Research Database (Denmark)

    Neumann, Viola; Köster, Fritz; Schaber, M.

    2014-01-01

    Cod (Gadus morhua) recruitment in the eastern Baltic Sea is influenced by predation on early life stages by sprat (Sprattus sprattus) and herring (Clupea harengus), which is considered as one of the mechanisms preventing cod recovery in the 1990s. In the light of improved cod recruitment in the s......Cod (Gadus morhua) recruitment in the eastern Baltic Sea is influenced by predation on early life stages by sprat (Sprattus sprattus) and herring (Clupea harengus), which is considered as one of the mechanisms preventing cod recovery in the 1990s. In the light of improved cod recruitment...

  11. Growth, temperature and density relationships of North Sea cod ( Gadus morhua )

    DEFF Research Database (Denmark)

    Rindorf, Anna; Jensen, Henrik; Schrum, Corinna

    2008-01-01

    This study presents an analysis of the relationship between ambient temperature, cod density, fishing mortality, prey fish biomass, and growth of North Sea cod (Gadus morhua) as estimated from survey catches during the period from 1983 to 2006. Growth of young cod was positively related to temper......This study presents an analysis of the relationship between ambient temperature, cod density, fishing mortality, prey fish biomass, and growth of North Sea cod (Gadus morhua) as estimated from survey catches during the period from 1983 to 2006. Growth of young cod was positively related...

  12. Impact of bottom trawling on deep-sea sediment properties along the flanks of a submarine canyon.

    Directory of Open Access Journals (Sweden)

    Jacobo Martín

    Full Text Available The offshore displacement of commercial bottom trawling has raised concerns about the impact of this destructive fishing practice on the deep seafloor, which is in general characterized by lower resilience than shallow water regions. This study focuses on the flanks of La Fonera (or Palamós submarine canyon in the Northwestern Mediterranean, where an intensive bottom trawl fishery has been active during several decades in the 400-800 m depth range. To explore the degree of alteration of surface sediments (0-50 cm depth caused by this industrial activity, fishing grounds and control (untrawled sites were sampled along the canyon flanks with an interface multicorer. Sediment cores were analyzed to obtain vertical profiles of sediment grain-size, dry bulk density, organic carbon content and concentration of the radionuclide 210Pb. At control sites, surface sediments presented sedimentological characteristics typical of slope depositional systems, including a topmost unit of unconsolidated and bioturbated material overlying sediments progressively compacted with depth, with consistently high 210Pb inventories and exponential decaying profiles of 210Pb concentrations. Sediment accumulation rates at these untrawled sites ranged from 0.3 to 1.0 cm y-1. Sediment properties at most trawled sites departed from control sites and the sampled cores were characterized by denser sediments with lower 210Pb surface concentrations and inventories that indicate widespread erosion of recent sediments caused by trawling gears. Other alterations of the physical sediment properties, including thorough mixing or grain-size sorting, as well as organic carbon impoverishment, were also visible at trawled sites. This work contributes to the growing realization of the capacity of bottom trawling to alter the physical properties of surface sediments and affect the seafloor integrity over large spatial scales of the deep-sea.

  13. 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...

  14. 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...

  15. 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...

  16. Growth dynamics of saffron cod (Eleginus gracilis) and Arctic cod (Boreogadus saida) in the Northern Bering and Chukchi Seas

    Science.gov (United States)

    Helser, Thomas E.; Colman, Jamie R.; Anderl, Delsa M.; Kastelle, Craig R.

    2017-01-01

    Saffron cod (Eleginus gracilis) and Arctic cod (Boreogadus saida) are two circumpolar gadids that serve as critically important species responsible for energy transfer in Arctic food webs of the northern Bering and Chukchi Seas. To understand the potential effects of sea ice loss and warming temperatures on these species' basic life history, information such as growth is needed. Yet to date, limited effort has been dedicated to the study of their growth dynamics. Based on a large sample of otoliths collected in the first comprehensive ecosystem integrated survey in the northern Bering and Chukchi Seas, procedures were developed to reliably estimate age from otolith growth zones and were used to study the growth dynamics of saffron and Arctic cod. Annual growth zone assignment was validated using oxygen isotope signatures in otoliths and otolith morphology analyzed and compared between species. Saffron cod attained larger asymptotic sizes (L∞=363 mm) and achieved their maximum size at a faster rate (K=0.378) than Arctic cod (L∞=209 mm; K=0.312). For both species, regional differences in growth were found (pArctic cod grew to smaller asymptotic size but at faster rates in the more northerly central (L∞=197 mm;K=0.324) and southern Chukchi Sea (L∞=221 mm;K=0.297) when compared to the northern Bering Sea (L∞=266 mm;K=0.171), suggesting a possible cline in growth rates with more northerly latitudes. Comparison of growth to two periods separated by 30 years indicate that both species exhibited a decline in maximum size accompanied by higher instantaneous growth rates in more recent years.

  17. 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

  18. 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

  19. 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

  20. Fluorescence of muscle and connective tissue from cod and salmon

    DEFF Research Database (Denmark)

    Andersen, Charlotte Møller; Wold, J.P.

    2003-01-01

    Autofluorescence of salmon and cod muscle was measured and compared with autofluorescence of collagen type I and type V. Similarities between fluorescence of fish muscle and collagen were found in that the same peaks were obtained around 390, 430, and 480 nm, These similarities are supported by p...

  1. EAARL Coastal Topography–Cape Cod National Seashore, Massachusetts, 2002

    Science.gov (United States)

    Kranenburg, Christine; Hardy, Matthew; Nagle, David B.

    2017-01-01

    These datasets, prepared by the U.S. Geological Survey St. Petersburg Coastal and Marine Science Center in collaboration with the National Park Service, provide lidar-derived first-surface and bare-earth topography for Cape Cod National Seashore, Massachusetts. Elevation measurements were acquired by the Experimental Advanced Airborne Research Lidar (EAARL) during October 2002.

  2. Exophiala angulospora causes systemic inflammation in atlantic cod Gadus morhua.

    Science.gov (United States)

    Gjessing, Mona Cecilie; Davey, Marie; Kvellestad, Agnar; Vrålstad, Trude

    2011-10-06

    Species of Exophiala are opportunistic fungal pathogens that may infect a broad range of warm- and cold-blooded animals, including salmonids and Atlantic cod. In the present study, we observed abnormal swimming behaviour and skin pigmentation and increased mortality in cod kept in an indoor tank. Necropsy revealed foci of different sizes with a greyish to brownish colour in internal organs of diseased fish. The foci consisted of ramifying darkly pigmented fungal hyphae surrounded by distinct layers of inflammatory cells, including macrophage-like cells. In the inner layer with many hyphae, the macrophage-like cells were dead. We observed no apparent restriction of fungal growth by the inflammatory response. A darkly pigmented fungus was repeatedly isolated in pure culture from foci of diseased fish and identified as Exophiala angulospora using morphological and molecular characters. This species has not been previously reported to cause disease in cod, but has been reported as an opportunistic pathogen of both marine and freshwater fish. Based on the morphology and sequence analysis presented here, we conclude that E. angulospora caused the observed chronic multifocal inflammation in internal organs of cod, leading to severe disease and mortality.

  3. Arctic Climate Change: A Tale of Two Cod Species

    Science.gov (United States)

    Arctic cod play an important role in the Arctic trophic hierarchy as the consumer of primary productivity and a food source for many marine fish and mammals. Shifts in their distribution and abundance could have cascading affects in the marine environment. This paper investigates...

  4. A staging system for larval cod (Gadus morhua L.)

    OpenAIRE

    1986-01-01

    A staging system of larval cod is described. The system is based on the resorption of the yolk mass and the cell layers surrounding it combined with eye, mouth and gut development. A determination key is given. Each stage is described in detail.

  5. Regime shifts, resilience and recovery of a cod stock

    DEFF Research Database (Denmark)

    Lindegren, Martin; Diekmann, Rabea; Möllmann, Christian

    2010-01-01

    In the North and Baltic seas Atlantic cod Gadus morhua stocks collapsed as part or one of the major factors inducing large-scale ecosystem regime shifts. Determining the relative contribution of overfishing and climate variability in causing these shifts has proven difficult. While facing similar...

  6. 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

  7. Otter trawls in Greece: Landing profiles and potential mιtiers

    Directory of Open Access Journals (Sweden)

    S. KATSANEVAKIS

    2012-12-01

    Full Text Available A fleet of 326 bottom trawlers operate in Greek Seas and their landings represent approximately 30% of the total fish production in Greece. In this study, otter trawl landings data were analyzed in order to identify potential métiers. Landings data between 2002 and 2006 were used, collected from 42 ports in the Aegean and East Ionian Sea. A three-step procedure was applied to identify potential métiers: the first step involved a factorial analysis of the log-transformed landings profiles, the second step a classification of the factorial coordinates, and the third step a further aggregation of clusters based on expert knowledge. In all, six potential métiers were identified in the Aegean Sea, and five in the Ionian Sea. The most important target species were European hake (Merluccius merluccius, deepwater pink shrimp (Parapenaeus longirostris, red mullet (Mullus barbatus, caramote prawn (Melicertus kerathurus, picarel (Spicara smaris, cephalopods, bogue (Boops boops, anglers (Lophiusspp., and Norway lobster (Nephrops norvegicus. Otter trawls in Greece use more or less the same gear with minor modification, and métier selection is basically reflected as a choice of geographical sub-area and hauling depth. The limitations of using landings profiles to identify métiers and the need for further verification are discussed.

  8. 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.

  9. 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

  10. 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

  11. 75 FR 61642 - Fisheries of the Exclusive Economic Zone Off Alaska; Modified Nonpelagic Trawl Gear and Habitat...

    Science.gov (United States)

    2010-10-06

    ... Economic Zone Off Alaska; Modified Nonpelagic Trawl Gear and Habitat Conservation in the Bering Sea Subarea.... Matthew Island, and to allow for efficient flatfish harvest as the distribution of flatfish in the Bering... economic impact on the flatfish vessel fleet, the industry's participation in the modified gear...

  12. When does fishing lead to more fish? Community consequences of bottom trawl fisheries in demersal food webs

    NARCIS (Netherlands)

    Denderen, van P.D.; Kooten, van T.; Rijnsdorp, A.D.

    2013-01-01

    Bottom trawls are a globally used fishing gear that physically disturb the seabed and kill non-target organisms, including those that are food for the targeted fish species. There are indications that ensuing changes to the benthic invertebrate community may increase the availability of food and pro

  13. A simulation-based attempt to quantify the morphological component of size selection of Nephrops norvegicus in trawl codends

    DEFF Research Database (Denmark)

    Frandsen, Rikke; Herrmann, Bent; Madsen, Niels

    2010-01-01

    The selectivity for Nephrops (Nephrops norvegicus) in trawl codends generally is poor and the lack of steepness of the selection curve results in high discard rates and/or loss of legal-sized catch. This poor codend selectivity often is attributed to the irregular shape of Nephrops, which to some...

  14. Similar effects of bottom trawling and natural disturbance on composition and function of benthic communities across habitats

    DEFF Research Database (Denmark)

    van Denderen, Pieter Daniël; Bolam, S.G.; Hiddink, J.G.

    2015-01-01

    communities in similar ways. Both sources of disturbance caused declines in long-living, hard-bodied (exoskeleton) and suspension-feeding organisms. Given these similar impacts, there was no detectable trawling effect on communities exposed to high natural disturbance. Conversely, in 3 out of 5 areas with low...

  15. Benthic habitat characterisation of soft-bottom continental shelves: Integration of acoustic surveys, benthic samples and trawling disturbance intensity

    Science.gov (United States)

    de Juan, S.; Lo Iacono, C.; Demestre, M.

    2013-01-01

    Eleven sites were located on Mediterranean continental shelves to explore the link between the physical characteristics and epibenthic fauna from soft-sediment habitats. These sites, at 32-82 m in depth, were associated with fishing grounds and the trawling intensity was estimated at the site scale to assess the effects of trawling on benthic communities. Each site was surveyed with Multi-Beam (bathymetry and backscatter), side-scan sonar, benthic grabs and a surface dredge. The sites were clustered in three habitat types. Habitat 1, with moderate trawling disturbance, was characterised by homogeneous mud and associated epifauna that was also highly homogeneous across sites. Habitat 2, with sandy mud and scattered gravel and rocks, had a high abundance of sessile suspension feeders that probably attach to the coarser substratum and benefit from the low fishing disturbance in these sites. Habitat 3 included sites with heterogeneous sediments with maërl as the prevailing biocenosis and having the highest species richness, despite being subjected to variable trawling intensity. Statistical models were used to relate environmental parameters and the species abundance. More than 3 physical variables were necessary to explain the epifaunal patterns across sites, including the percentage of mud, sediment heterogeneity and fishing effort. These analyses are an essential step for extrapolating information from benthic samples to the larger scale of habitats, mapped through acoustic surveys. Despite this, a good integration is required between the mapping of physical habitat distribution and the ecological knowledge of communities.

  16. Similar effects of bottom trawling and natural disturbance on composition and function of benthic communities across habitats

    DEFF Research Database (Denmark)

    van Denderen, Pieter Daniël; Bolam, S.G.; Hiddink, J.G.

    2015-01-01

    communities in similar ways. Both sources of disturbance caused declines in long-living, hard-bodied (exoskeleton) and suspension-feeding organisms. Given these similar impacts, there was no detectable trawling effect on communities exposed to high natural disturbance. Conversely, in 3 out of 5 areas with low...

  17. Similar effects of bottom trawling and natural disturbance on composition and function of benthic communities across habitats

    DEFF Research Database (Denmark)

    van Denderen, Pieter Daniël; Bolam, S.G.; Hiddink, J.G.;

    2015-01-01

    bed shear stress, responses to trawling were detected and resulted in community compositions comparable with those in areas subject to high natural disturbance, with communities being composed of either small-sized, deposit-feeding animals or mobile scavengers and predators. The findings highlight...

  18. ASSESSMENT OF STOCK AND SPATIAL DISTRIBUTION OF SOLE (SOLEA SOLEA, L. IN ALBANIAN COAST USING RAPIDO TRAWL

    Directory of Open Access Journals (Sweden)

    Enton Spaho

    2012-06-01

    Full Text Available Common sole (Solea solea Linnaeus, 1758 is still not a specific target of fishery in Albania, but it represents an important target of the mixed-species catches of bottom trawlers and set netters operating in the coastal areas in the upper part of Albanian Adriatic Sea. Sole landings are low, amounting very few tonnes, but the demand will likely increase in the next future, because of the high quality of the fish fillet and the increase of consumers demand for wild sea fish. In order to identify the spawning areas and assess the spatial distribution and biomass of this species a rapido trawl survey was performed in year 2007. The smallest specimens were mostly concentrated in the shallowest stratum and the largest ones between 30 and 100 m depth. Solea Stock Biomass (SSB was 354 t, corresponding to 64% of the overall population recorded at sea at that time. In the context of fisheries, the Albanian fishing fleet involve a number of different fishing gears, while rapido trawl is introduced recently. The special technical and operating characteristics of rapido trawl makes it very effective in sole fishery and less harmful for the sea benthos and the species inhabiting it. This study aimed the estimation of spatial distribution of common sole and its biomass in the Albanian coast using rapido trawl gear.

  19. Using marine reserves to manage impact of bottom trawl fisheries requires consideration of benthic food-web interactions

    DEFF Research Database (Denmark)

    van Denderen, Pieter Daniël; Rijnsdorp, Adriaan D.; van Kooten, Tobias

    2016-01-01

    Marine protected areas (MPAs) are widely used to protect exploited fish species as well as to conserve marine habitats and their biodiversity. They have become a popular management tool also for bottom trawl fisheries, a common fishing technique on continental shelves worldwide. The effects of bo...

  20. 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.

  1. 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...

  2. 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...

  3. 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...

  4. 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...

  5. 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.

  6. 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

  7. 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.

  8. 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

  9. 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.

  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. Fishery discards: Factors affecting their variability within a demersal trawl fishery

    DEFF Research Database (Denmark)

    Feekings, Jordan P.; Bartolino, Valerio; Madsen, Niels;

    2012-01-01

    the factors that influence discarding within the Danish Kattegat demersal fleet over the period 1997 to 2008. Generalised additive models were used to assess how discards of the 3 main target species, Norway lobster, cod and plaice, and their subcomponents (under and over minimum landings size) are influenced...

  12. Visual surveys can reveal rather different 'pictures' of fish densities: Comparison of trawl and video camera surveys in the Rockall Bank, NE Atlantic Ocean

    Science.gov (United States)

    McIntyre, F. D.; Neat, F.; Collie, N.; Stewart, M.; Fernandes, P. G.

    2015-01-01

    Visual surveys allow non-invasive sampling of organisms in the marine environment which is of particular importance in deep-sea habitats that are vulnerable to damage caused by destructive sampling devices such as bottom trawls. To enable visual surveying at depths greater than 200 m we used a deep towed video camera system, to survey large areas around the Rockall Bank in the North East Atlantic. The area of seabed sampled was similar to that sampled by a bottom trawl, enabling samples from the towed video camera system to be compared with trawl sampling to quantitatively assess the numerical density of deep-water fish populations. The two survey methods provided different results for certain fish taxa and comparable results for others. Fish that exhibited a detectable avoidance behaviour to the towed video camera system, such as the Chimaeridae, resulted in mean density estimates that were significantly lower (121 fish/km2) than those determined by trawl sampling (839 fish/km2). On the other hand, skates and rays showed no reaction to the lights in the towed body of the camera system, and mean density estimates of these were an order of magnitude higher (64 fish/km2) than the trawl (5 fish/km2). This is probably because these fish can pass under the footrope of the trawl due to their flat body shape lying close to the seabed but are easily detected by the benign towed video camera system. For other species, such as Molva sp, estimates of mean density were comparable between the two survey methods (towed camera, 62 fish/km2; trawl, 73 fish/km2). The towed video camera system presented here can be used as an alternative benign method for providing indices of abundance for species such as ling in areas closed to trawling, or for those fish that are poorly monitored by trawl surveying in any area, such as the skates and rays.

  13. 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

  14. 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...

  15. Feeding opportunities of larval and juvenile cod (Gadus morhua) in a Greenlandic fjord: temporal and spatial linkages between cod and their preferred prey

    DEFF Research Database (Denmark)

    Swalethorp, Rasmus; Kjellerup, Sanne; Malanski, Evandro;

    2014-01-01

    preferences of the early-life stages of Atlantic cod (Gadus morhua) to quantify the availability of prey during a spring-summer season in a West Greenlandic fjord. We hypothesized that abundances of larval and juvenile cod at size were synchronized to optimal availability of preferred prey in space and time....... The present analysis is based on nine cruises each covering 5 stations visited between 24 May and 5 August 2010 comparing zooplankton abundance, cod gut content and distribution patterns. Cod 4–25 mm in length preferred prey of about 5 % of their own length. During ontogeny, their preferences changed from...

  16. 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.

  17. 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.

  18. 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.

  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. Host size-dependent anisakid infection in Baltic cod Gadus morhua associated with differential food preferences

    DEFF Research Database (Denmark)

    Zuo, Shaozhi; Huwer, Bastian; Bahlool, Qusay

    2016-01-01

    for these parasites. Here, we report from an investigation of 368 cod (total length [TL] 6-49 cm; caught in ICES Subdivision 25) that the infection level of juvenile cod (TL 6-30 cm) with larvae of C. osculatum and P. decipiens is absent or very low, whereas it increases drastically in larger cod (TL 31-48 cm......). A third nematode Hysterothylacium aduncum was rarely found. The study indicates that the prey animals for large cod act as transport hosts for the parasite larvae. Analyses of stomach contents of cod caught in the same area (2007-2014) showed that small benthic organisms (including polychaetes Harmothoë...

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. Isolation of putative probionts from cod rearing environment

    DEFF Research Database (Denmark)

    Lauzon, H.L.; Gudmundsdottir, S.; Pedersen, M.H.;

    2008-01-01

    , metabolite production and adhesion to fish cell lines. Our study demonstrated that 14% of screened bacteria (n = 188) had antagonistic properties towards fish pathogens. The majority of these isolates were Gram-positive (81%), belonging to Firmicutes (69.2%) and Actinobacteria (11.5%) phyla based on 16S r...... was designed to search for new probiotics to target this critical period in cod rearing. Potential probionts were selected from the naturalmicrobiota of cod aquacultural environment. The selection was based on several criteria: pathogen inhibition potential, growth characteristics, strain identification......RNA gene sequencing. Only 6 (3.2%) of 188 isolates could inhibit all three pathogens tested: Vibrio anguillarum, Aeromonas salmonicida subsp. achromogenes and Vibrio salmonicida. Differences observed in activity intensity and spectrum among inhibitory isolates emphasise the need to develop probiotic...

  9. A sensometric approach to cod-quality measurement

    DEFF Research Database (Denmark)

    Jensen, H.S.; Jørgensen, Bo

    1997-01-01

    The quality index method was used for describing the sensory quality of thawed whole cod and raw fillet and the quality of boiled fillet was assessed by profiling analysis. These data were compared to the water holding capacity of the minced cod by principal component analysis (PCA) and partial...... least squares regression. The sensory data and the water holding capacity were correlated to an extent that made possible the prediction of high and low values of water holding capacity. Multivariate methods were also used for extracting some information about the assessor variability. This was done...... by determining the ability of the assessors to predict the water holding capacity through partial least squares regression and by examining the distances between PCA-models of profiling data from the single assessors. (C) 1997 Elsevier Science Ltd. All rights reserved....

  10. Excess post hypoxic oxygen consumption in Atlantic cod (Gadus morhua)

    DEFF Research Database (Denmark)

    Plambech, M.; Deurs, Mikael van; Steffensen, J.F.;

    2013-01-01

    Atlantic cod Gadus morhua experienced oxygen deficit (DO2 ) when exposed to oxygen levels below their critical level (c. 73% of pcrit) and subsequent excess post-hypoxic oxygen consumption (CEPHO) upon return to normoxic conditions, indicative of an oxygen debt. The mean±s.e. CEPHO:DO2 was 6·9±1·......·9±1·5, suggesting that resorting to anaerobic energy production in severe hypoxia is energetically expensive...

  11. Excess post hypoxic oxygen consumption in Atlantic cod (Gadus morhua)

    DEFF Research Database (Denmark)

    Plambech, M.; Deurs, Mikael van; Steffensen, J.F.

    2013-01-01

    Atlantic cod Gadus morhua experienced oxygen deficit (DO2 ) when exposed to oxygen levels below their critical level (c. 73% of pcrit) and subsequent excess post-hypoxic oxygen consumption (CEPHO) upon return to normoxic conditions, indicative of an oxygen debt. The mean±s.e. CEPHO:DO2 was 6......·9±1·5, suggesting that resorting to anaerobic energy production in severe hypoxia is energetically expensive...

  12. Avoidance from petroleum hydrocarbons by the cod (Gadus morhua)

    OpenAIRE

    Bøhle, Bjørn

    1982-01-01

    In laboratory experiments cod was presented a choice situation between different concentrations of petroleum hydrocarbons, appearing as "water soluble fraction" and emulsified droplets derived from Fuel Oil No. 2. In most experiments, the fishes seemed to avoid water containing hydrocarbons, though some fishes for periods was indifferent also to considerable contaminated water. The over all results indicates that a majority of the fishes avoided water containing total hyd...

  13. Cape Cod Easterly Shore Beach Erosion Study. Volume 2

    Science.gov (United States)

    1979-04-01

    bacterial slimes. In addition, these structures might provide roosting and nesting sites for certain bird species. Proposed structural and non-structural...Charles E. McClenne, Associate Professor, Colgate University, dated 3 August 1977 Notes from visit to Cape Cod Easterly Shores Beach Erosion Control...ments should be supported by factual information insofar as practicable. Oral statements will be heard but, for accuracy of record, all important facts

  14. Positive regulation of botulinum neurotoxin gene expression by CodY in Clostridium botulinum ATCC 3502.

    Science.gov (United States)

    Zhang, Zhen; Dahlsten, Elias; Korkeala, Hannu; Lindström, Miia

    2014-12-01

    Botulinum neurotoxin, produced mainly by the spore-forming bacterium Clostridium botulinum, is the most poisonous biological substance known. Here, we show that CodY, a global regulator conserved in low-G+C Gram-positive bacteria, positively regulates the botulinum neurotoxin gene expression. Inactivation of codY resulted in decreased expression of botA, encoding the neurotoxin, as well as in reduced neurotoxin synthesis. Complementation of the codY mutation in trans rescued neurotoxin synthesis, and overexpression of codY in trans caused elevated neurotoxin production. Recombinant CodY was found to bind to a 30-bp region containing the botA transcription start site, suggesting regulation of the neurotoxin gene transcription through direct interaction. GTP enhanced the binding affinity of CodY to the botA promoter, suggesting that CodY-dependent neurotoxin regulation is associated with nutritional status.

  15. Association between nematode Hysterothylacium aduncum invasion of cod larvae and growth

    DEFF Research Database (Denmark)

    Mehrdana, Foojan; Bahlool, Qusay Z. M.; Kuhn, Jesper;

    invertebrates and fish species and for some species also higher vertebrate hosts. We have recently demonstrated that fry of North Sea cod has a high prevalence of infection with regard to the nematode Hysterothylacium aduncum and it was indicated that these infections could affect survival of cod and thereby...... affect the cod stock in the North Sea. The objective of the present study was to elucidate if infections are associated with a decrease or an increase of fish size when examining fish of the same age. We investigated effects of H. aduncum infections on the growth rate of cod larvae by using the otolith...... reading method. In our study, the prevalence of infection with H. aduncum in North Sea cod Gadus morhua larvae was studied during the years 1992-2001. A subsample of 65 cod was selected based on the body length (range 20 to 45 mm) with 32 infected and 33 uninfected fishes. For ageing the cod larvae...

  16. COD::CIF::Parser: an error-correcting CIF parser for the Perl language.

    Science.gov (United States)

    Merkys, Andrius; Vaitkus, Antanas; Butkus, Justas; Okulič-Kazarinas, Mykolas; Kairys, Visvaldas; Gražulis, Saulius

    2016-02-01

    A syntax-correcting CIF parser, COD::CIF::Parser, is presented that can parse CIF 1.1 files and accurately report the position and the nature of the discovered syntactic problems. In addition, the parser is able to automatically fix the most common and the most obvious syntactic deficiencies of the input files. Bindings for Perl, C and Python programming environments are available. Based on COD::CIF::Parser, the cod-tools package for manipulating the CIFs in the Crystallography Open Database (COD) has been developed. The cod-tools package has been successfully used for continuous updates of the data in the automated COD data deposition pipeline, and to check the validity of COD data against the IUCr data validation guidelines. The performance, capabilities and applications of different parsers are compared.

  17. Effect of produced water on cod (Gadus morhua) immune responses

    Energy Technology Data Exchange (ETDEWEB)

    Hamoutene, D.; Mabrouk, G.; Samuelson, S.; Mansour, A.; Lee, K. [Fisheries and Oceans Canada, Dartmouth, NS (Canada). Maritimes Region, Ocean Sciences Division; Volkoff, H.; Parrish, C. [Memorial Univ. of Newfoundland, St. John' s, NL (Canada); Mathieu, A. [Oceans Ltd., St. John' s, NL (Canada)

    2007-07-01

    Studies have shown that produced water (PW) discharged from North Sea offshore platforms affects the biota at greater distances from operational platforms than originally presumed. According to PW dispersion simulations, dilution by at least 240 times occurs within 50-100 m, and up to 9000 times by 20 km from the discharge. In this study, the effect of PW on cod immunity was investigated by exposing fish to 0, 100 ppm (x 10,000 dilution) or 200 ppm (x 500) of PW for 76 days. Immune responses were evaluated at the end of the exposure. Fish from the 3 groups were injected with Aeromonas salmonicida lipopolysaccharides (LPS). Blood cell observation and flow cytometry were used to investigate the serum cortisol levels and gill histology along with ratios and respiratory burst (RB) responses of both circulating and head-kidney white blood cells (WBCs). The study revealed that baseline immunity and stress response were not affected by PW, other than an irritant-induced change in gill cells found in treated cod. In all groups, LPS injection resulted in a pronounced decrease in RB of head-kidney cells and an increase in serum cortisol and protein levels. However, the group exposed to 200 ppm of PW exhibited the most significant changes. LPS injection was also shown to influence WBC ratios, but further studies are needed to determine if this impact is stronger in fish exposed to PW. This study suggested an effect of PW on cod immunity after immune challenge with LPS.

  18. Removal of COD from laundry wastewater by electrocoagulation/electroflotation

    Energy Technology Data Exchange (ETDEWEB)

    Wang, C.-T. [Department of Safety Health and Environmental Engineering, Chung Hwa University of Medical Technology, Tainan County, Hsien 717, Taiwan (China)], E-mail: ctwwang@mail.hwai.edu.tw; Chou, W.-L. [Department of Safety Health and Environmental Engineering and Institute of Occupational Safety and Hazard Prevention, HungKuang University, Sha-Lu, Taichung 433, Taiwan (China); Kuo, Y.-M. [Department of Safety Health and Environmental Engineering, Chung Hwa University of Medical Technology, Tainan County, Hsien 717, Taiwan (China)

    2009-05-15

    The removal efficiency of COD in the treatment of simulated laundry wastewater using electrocoagulation/electroflotation technology is described. The experimental results showed that the removal efficiency was better, reaching to about 62%, when applying ultrasound to the electrocoagulation cell. The solution pH approached neutrality in all experimental runs. The optimal removal efficiency of COD was obtained by using the applied voltage of 5 V when considering the energy efficiency and the acceptable removal efficiency simultaneously. The Cl{sup -} concentration of less than 2500 ppm had a positive effect on the removal efficiency. The performance of the monopolar connection of electrodes was better than that of the bipolar connection in this work. In addition, the removal efficiency of using Al electrodes was higher in comparison with using Fe electrodes in the study. The highest COD removal amount per joule was found to be 999 mg dm{sup -3} kW h{sup -1} while using two Al electrodes, although the removal efficiency increased with the number of Al plates.

  19. Lake Ontario Deepwater Sculpin bottom trawl catch and biological data, 1996-2016

    Science.gov (United States)

    Weidel, Brian C.

    2016-01-01

    Deepwater Sculpin are important in oligotrophic lakes as one of the few fishes that use deep profundal habitats and link invertebrates in those habitats to piscivores. In Lake Ontario the species was once abundant, however drastic declines in the mid-1900s led some to suggest the species had been extirpated and ultimately led Canadian and U.S. agencies to elevate the species’ conservation status in the 1990s. Following multiple decades of annual surveys with no captures, Deepwater Sculpin were first caught in low numbers in 1996 and by the early 2000s there were indications of population recovery. These data sets were used to update the status of Lake Ontario Deepwater Sculpin through 2016 to inform resource management and conservation. The entire data set includes tables for bottom trawl catches, length frequency, individual fish length weight, as well as gonad weight.

  20. Environmental DNA from seawater samples correlate with trawl catches of Subarctic, deepwater fishes

    DEFF Research Database (Denmark)

    Thomsen, Philip Francis; Møller, Peter Rask; Sigsgaard, Eva Egelyng;

    2016-01-01

    in fisheries. Nevertheless, our study demonstrates that eDNA reads can be used as a qualitative and quantitative proxy for marine fish assemblages in deepwater oceanic habitats. This relates directly to applied fisheries as well as to monitoring effects of ongoing climate change on marine biodiversity......Remote polar and deepwater fish faunas are under pressure from ongoing climate change and increasing fishing effort. However, these fish communities are difficult to monitor for logistic and financial reasons. Currently, monitoring of marine fishes largely relies on invasive techniques...... such as bottom trawling, and on official reporting of global catches, which can be unreliable. Thus, there is need for alternative and non-invasive techniques for qualitative and quantitative oceanic fish surveys. Here we report environmental DNA (eDNA) metabarcoding of seawater samples from continental slope...

  1. The effects of 118 years of industrial fishing on UK bottom trawl fisheries.

    Science.gov (United States)

    Thurstan, Ruth H; Brockington, Simon; Roberts, Callum M

    2010-05-04

    In 2009, the European Commission estimated that 88% of monitored marine fish stocks were overfished, on the basis of data that go back 20 to 40 years and depending on the species investigated. However, commercial sea fishing goes back centuries, calling into question the validity of management conclusions drawn from recent data. We compiled statistics of annual demersal fish landings from bottom trawl catches landing in England and Wales dating back to 1889, using previously neglected UK Government data. We then corrected the figures for increases in fishing power over time and a recent shift in the proportion of fish landed abroad to estimate the change in landings per unit of fishing power (LPUP), a measure of the commercial productivity of fisheries. LPUP reduced by 94%-17-fold--over the past 118 years. This implies an extraordinary decline in the availability of bottom-living fish and a profound reorganization of seabed ecosystems since the nineteenth century industrialization of fishing.

  2. Effort allocation of the Dutch beam trawl fleet in response to a temporarily closed area in the North Sea

    NARCIS (Netherlands)

    Rijnsdorp, A.D.; Piet, G.J.; Poos, J.J.

    2001-01-01

    The spawning stock of North Sea cod is at a historic low level and immediate management measures are needed to improve this situation. As a first step, the European Commission in 2001 closed a large area in the North Sea between February 15 and April 30 to all cod related fishing fleets in order to

  3. Common dolphin (Delphinus delphis bycatch in New Zealand commercial trawl fisheries.

    Directory of Open Access Journals (Sweden)

    Finlay N Thompson

    Full Text Available Marine mammals are regularly reported as bycatch in commercial and artisanal fisheries, but data are often insufficient to allow assessment of these incidental mortalities. Observer coverage of the mackerel trawl fishery in New Zealand waters between 1995 and 2011 allowed evaluation of common dolphin Delphinus delphis bycatch on the North Island west coast, where this species is the most frequently caught cetacean. Observer data were used to develop a statistical model to estimate total captures and explore covariates related to captures. A two-stage Bayesian hurdle model was used, with a logistic generalised linear model predicting whether any common dolphin captures occurred on a given tow of the net, and a zero-truncated Poisson distribution to estimate the number of dolphin captures, given that there was a capture event. Over the 16-year study period, there were 119 common dolphin captures reported on 4299 observed tows. Capture events frequently involved more than one individual, with a maximum of nine common dolphin observed caught in a single tow. There was a peak of 141 estimated common dolphin captures (95% c.i.: 56 to 276; 6.27 captures per 100 tows in 2002-03, following the marked expansion in annual effort in this fishery to over 2000 tows. Subsequently, the number of captures fluctuated although fishing effort remained relatively high. Of the observed capture events, 60% were during trawls where the top of the net (headline was <40 m below the surface, and the model determined that this covariate best explained common dolphin captures. Increasing headline depth by 21 m would halve the probability of a dolphin capture event on a tow. While lack of abundance data prevents assessment of the impact of these mortalities on the local common dolphin population, a clear recommendation from this study is the increasing of headline depth to reduce common dolphin captures.

  4. Common dolphin (Delphinus delphis) bycatch in New Zealand commercial trawl fisheries.

    Science.gov (United States)

    Thompson, Finlay N; Abraham, Edward R; Berkenbusch, Katrin

    2013-01-01

    Marine mammals are regularly reported as bycatch in commercial and artisanal fisheries, but data are often insufficient to allow assessment of these incidental mortalities. Observer coverage of the mackerel trawl fishery in New Zealand waters between 1995 and 2011 allowed evaluation of common dolphin Delphinus delphis bycatch on the North Island west coast, where this species is the most frequently caught cetacean. Observer data were used to develop a statistical model to estimate total captures and explore covariates related to captures. A two-stage Bayesian hurdle model was used, with a logistic generalised linear model predicting whether any common dolphin captures occurred on a given tow of the net, and a zero-truncated Poisson distribution to estimate the number of dolphin captures, given that there was a capture event. Over the 16-year study period, there were 119 common dolphin captures reported on 4299 observed tows. Capture events frequently involved more than one individual, with a maximum of nine common dolphin observed caught in a single tow. There was a peak of 141 estimated common dolphin captures (95% c.i.: 56 to 276; 6.27 captures per 100 tows) in 2002-03, following the marked expansion in annual effort in this fishery to over 2000 tows. Subsequently, the number of captures fluctuated although fishing effort remained relatively high. Of the observed capture events, 60% were during trawls where the top of the net (headline) was dolphin captures. Increasing headline depth by 21 m would halve the probability of a dolphin capture event on a tow. While lack of abundance data prevents assessment of the impact of these mortalities on the local common dolphin population, a clear recommendation from this study is the increasing of headline depth to reduce common dolphin captures.

  5. 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

  6. First Receiver and Shorebased Processor Data - Economic Data Collection for Monitoring the Economic Effects of the West Coast Groundfish Trawl Rationalization Program

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This project was initiated in response to regulation 50 CFR 660.114, which mandates that economic data be collected from every participant in the trawl...

  7. Catcher Processor Cost Earnings Data - Economic Data Collection for Monitoring the Economic Effects of the West Coast Groundfish Trawl Rationalization Program

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This project was initiated in response to regulation 50 CFR 660.114, which mandates that economic data be collected from every participant in the trawl...

  8. Catcher Vessel Cost Earnings Data - Economic Data Collection for Monitoring the Economic Effects of the West Coast Groundfish Trawl Rationalization Program

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This project was initiated in response to regulation 50 CFR 660.114, which mandates that economic data be collected from every participant in the trawl...

  9. AFSC/RACE/SAP: Detailed Crab Data From NOAA Fisheries Service Annual Eastern Bering Sea Summer Bottom Trawl Surveys 1975 - 2015

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset contains detailed crab data collected from the annual NOAA/NMFS/AFSC/RACE crab-groundfish bottom trawl survey of the eastern Bering Sea continental...

  10. Groundfish/Shrimp and Red Snapper trawl surveys conducted in the Gulf of Mexico from 1990-01-01 to 2014-12-30 (NCEI Accession 0147703)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Southeast Fisheries Science Center Mississippi Laboratories has conducted standardized groundfish trawl surveys in the Gulf of Mexico since 1987. Prior to 1987,...

  11. Inhibition of haemoglobin-mediated lipid oxidation in washed cod muscle and cod protein isolates by Fucus vesiculosus extract and fraction

    DEFF Research Database (Denmark)

    Wang, Tao; Jonsdottir, Rosa; Kristinsson, Hordur

    2010-01-01

    The effects of Fucus vesiculosus extract and fractions towards haemoglobin- (Hb-) catalysed lipid oxidation in washed cod muscle system and cod protein isolates during ice storage were examined. The extract and fractions were characterised in terms of total phlorotannin content (TPC), 2,2-diphenyl...

  12. Inhibition of haemoglobin-mediated lipid oxidation in washed cod muscle and cod protein isolates by Fucus vesiculosus extract and fraction

    DEFF Research Database (Denmark)

    Wang, Tao; Jonsdottir, Rosa; Kristinsson, Hordur

    2010-01-01

    The effects of Fucus vesiculosus extract and fractions towards haemoglobin- (Hb-) catalysed lipid oxidation in washed cod muscle system and cod protein isolates during ice storage were examined. The extract and fractions were characterised in terms of total phlorotannin content (TPC), 2,2-diphenyl...

  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. 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.

  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. Standardization of BOD₅/COD ratio as a biological stability index for MSW.

    Science.gov (United States)

    Cossu, Raffaello; Lai, Tiziana; Sandon, Annalisa

    2012-08-01

    The control of biodegradable substances is the key issue in evaluating the short and long-term emission potential and environmental impact of a landfill. Aerobic and anaerobic indices, such as respirometric index (RI) and biomethane potential production (GB21), can be used in the estimation of the stability of solid waste samples. Previous studies showed different degrees of relationship between BOD₅/COD ratio compared with RI4. Aim of this study is to standardize the parameter BOD₅/COD ratio and to test the methodology under different operating conditions (dynamic or static leaching and leaching duration, 6 and 24-h) keeping constant temperature and liquid/solid ratio (L/S=10 l/kg(TS)), with the introduction of a COD fractioning method. The COD fractioning is based on the differentiation between the soluble fraction (COD(sol)) and the colloidal fraction (COD(coll)) using a flocculation method. The BOD₅/COD and the BOD₅/COD(sol) indices are both consistent and significant and can be used as stability indices. The BOD₅/COD ratio does not seem to be influenced, for the same test duration, by the type of test, static or dynamic. In the same way the longer test duration (24-h) does not influence significantly the values of BOD₅/COD ratio. As a consequence a leaching test duration of 6-h is preferable to avoid the beginning of the hydrolysis and oxidation processes.

  20. Pelage Variation and Distribution of the Black Lion Tamarin, Leontopithecus chrysopygus.

    Science.gov (United States)

    Garbino, Guilherme Siniciato Terra; Rezende, Gabriela Cabral; Valladares-Padua, Claudio

    2016-01-01

    The black lion tamarin, Leontopithecus chrysopygus, is endemic to the Atlantic Forest of the interior of the state of São Paulo in Brazil. Since the discovery of the species, authors have described variations in the pelage of L. chrysopygus, but the nature of this variation has remained unknown. We examined museum specimens and living animals to see if the pelage of L. chrysopygus varies individually, geographically or ontogenetically. We reviewed all known locality records of the species, and concluded that the pelage of L. chrysopygus varies individually and ontogenetically, but not geographically. The extent of the golden chromogenetic fields is larger in younger individuals, and the pelage becomes darker after successive moults. We examined 2 juveniles that presented a pelage similar to adult L. caissara. Geographically, there is a clear break in the phenotypes attributed to L. caissara and L. chrysopygus, precluding clinal variation and corroborating the specific status of the former. The separation between these 2 species is coincident with a tectonic fault known as the 'Guapiara lineament', and may have been caused by a recent activation of this geological formation. We also suggest a historical contact zone between L. chrysopygus and the marmoset Callithrix aurita in the upper Rio Tietê region. © 2016 S. Karger AG, Basel.

  1. Reflex impairment, physiological stress, and discard mortality of European plaice Pleuronectes platessa in an otter trawl fishery

    DEFF Research Database (Denmark)

    Methling, Caroline; Skov, Peter Vilhelm; Madsen, Niels

    2017-01-01

    trawl and air exposure of varying duration, and for 50 control fish scored for reflex impairment on board the vessel. Mortality was only observed in fish exposed to air for >60 min, and averaged 11.1% (95% CI = 7.1–16.3%). Reflex impairment was found to be a significant (P ... whether reflex impairment can predict short-term mortality in commercially trawled European plaice upon landing and after air exposure of up to 90 min. Sub-lethal stress was assessed by a suite of physiological variables. Over a 10-day period, mortality was monitored for a total of 199 plaice following...... of mortality in a generalized linear model, excluding other initially included variables by using a stepwise method. Plasma cortisol, haematocrit, and plasma osmolality all indicated a profound and increasing level of stress with air exposure, accompanied by a near depletion of muscle phosphocreatine...

  2. New type of canned cod gonads and liver pastes

    Directory of Open Access Journals (Sweden)

    Grokhovsky V. A.

    2016-09-01

    Full Text Available The urgency of rational way of processing the offal of the Gadidae family (liver and gonads for food purposes has been proved. The possibility of using the frozen gonads (milt and caviar and the liver of the cod in the human nutrition (especially for the people of elderly age has been researched. The frozen gonads with addition of fish liver are proven to be used for producing the canned foods with high quality level. The physical, chemical and microbiological characteristics of the product have been determined by the standardized methods. The quality level of canned foods has been obtained using the developed criteria of the objective evaluation of the quality. The specimens of the canned pastes produced from the frozen cod milt, caviar and liver using different compositions have been researched. Near-to-optimal composition of the new product has been defined. The quality level of canned food is 88.6 %. The commercial sterility of the canned food specimens prepared using the developed technology has been established. The chemical composition and the sensory characteristics of canned food have been researched. It has been established that protein content in the canned food is 12.9 %, fat content – 13.5 %, water content – 71.2 %, sodium chloride content – 1.3 %, carbohydrates content – 0.5 %. The product is the uniform, finely ground, evenly mixed mass with the presence of the separate caviar grains. The color of the paste is light-beige. The canned food has the tender consistency, pleasant taste and aroma. The energy value of the product is 678 kJ (162 kcal. Using the frozen cod caviar, milt and liver for producing the developed assortment of canned foods will make it possible to solve the problem of the complex processing of fish, and also to manufacture the canned food of high quality on the shore enterprises from the frozen fish offal (caviar, milt and liver all the year round.

  3. Interactions between a Trawl fishery and spatial closures for biodiversity conservation in the Great Barrier Reef World Heritage Area, Australia.

    Directory of Open Access Journals (Sweden)

    Alana Grech

    Full Text Available BACKGROUND: The Queensland East Coast Otter Trawl Fishery (ECOTF for penaeid shrimp fishes within Australia's Great Barrier Reef World Heritage Area (GBRWHA. The past decade has seen the implementation of conservation and fisheries management strategies to reduce the impact of the ECOTF on the seabed and improve biodiversity conservation. New information from electronic vessel location monitoring systems (VMS provides an opportunity to review the interactions between the ECOTF and spatial closures for biodiversity conservation. METHODOLOGY AND RESULTS: We used fishing metrics and spatial information on the distribution of closures and modelled VMS data in a geographical information system (GIS to assess change in effort of the trawl fishery from 2001-2009 and to quantify the exposure of 70 reef, non-reef and deep water bioregions to trawl fishing. The number of trawlers and the number of days fished almost halved between 2001 and 2009 and new spatial closures introduced in 2004 reduced the area zoned available for trawl fishing by 33%. However, we found that there was only a relatively minor change in the spatial footprint of the fishery as a result of new spatial closures. Non-reef bioregions benefited the most from new spatial closures followed by deep and reef bioregions. CONCLUSIONS/SIGNIFICANCE: Although the catch of non target species remains an issue of concern for fisheries management, the small spatial footprint of the ECOTF relative to the size of the GBRWHA means that the impact on benthic habitats is likely to be negligible. The decline in effort as a result of fishing industry structural adjustment, increasing variable costs and business decisions of fishers is likely to continue a trend to fish only in the most productive areas. This will provide protection for most benthic habitats without any further legislative or management intervention.

  4. Demersal trawling in the nearshore region between Cape Seal and Klippen Point, Republic of South Africa, 1977-1979.

    Directory of Open Access Journals (Sweden)

    R. J. M Crawford

    1982-11-01

    Full Text Available Annual landings of fishes trawled demersally in the vicinity of the Tsitsikamma Coastal National Park increased by almost 75 between 1977 and 1979. Catches of sole Austroglossus pectoralis showed a large decrease over the same period, but catch rates for other species remained relatively constant suggesting that they have not yet been overexploited. Hake Merluccius capensis and horse mackerel Trachurus trachurus dominated the landings in all three years.

  5. Eastern Baltic cod recruitment revisited—dynamics and impacting factors

    DEFF Research Database (Denmark)

    Köster, Fritz; Huwer, Bastian; Hinrichsen, Hans-Harald

    2016-01-01

    and casting doubts about the magnitude of the recent increase in recruitment. Earlier studies identified main factors impacting on cod reproductive success to be related to the loss of two out of three spawning areas in the 1980s caused by lack of major Baltic inflows with a concurrent reduction in salinity...... and oxygen. Other important factors include prey availability for first-feeding larvae, egg predation by sprat and herring and cannibalism on juveniles, all in one way or the other related to the prevailing hydrographic conditions. These factors cannot explain increased reproductive success in the last...

  6. Suitability of otolith microchemistry for stock separation of Baltic cod

    DEFF Research Database (Denmark)

    Heidemann, F; Marohn, L; Hinrichsen, HH

    2012-01-01

    differences between individuals from the eastern and the western Baltic Sea and between North Sea and Baltic Sea samples. Sr/Ca, Ba/Ca, Y/Ca, Mg/Ca, Zr/Ca and Mn/Ca ratios had the strongest discriminatory power. A further separation of individuals caught in 3 different spawning grounds of the eastern Baltic......, however, was not possible. Elemental compositions from the core regions of otoliths from young of the year cod caught in eastern and western Baltic Sea spawning grounds showed significant differences in Sr/Ca, Ba/Ca and Mg/Ca concentrations. Analyses of similarities again showed significant differences...

  7. Identification and evaluation of shark bycatch in Georgia’s commercial shrimp trawl fishery with implications for management

    Science.gov (United States)

    Belcher, C.N.; Jennings, Cecil A.

    2011-01-01

    Many US states have recreational and commercial fisheries that occur in nursery areas occupied by subadult sharks and can potentially affect their survival. Georgia is one of few US states without a directed commercial shark fishery, but the state has a large, nearshore penaeid shrimp trawl fishery in which small sharks occur as bycatch. During our 1995-1998 investigation of bycatch in fishery-dependent sampling events, 34% of 127 trawls contained sharks. This bycatch totalled 217 individuals from six species, with Atlantic sharpnose shark, Rhizoprionodon terraenovae (Richardson), the most common and finetooth shark, Carcharhinus isodon (Müller & Henle) and spinner shark, Carcharhinus brevipinna (Müller & Henle), the least common. The highest catch rates for sharks occurred during June and July and coincided with the peak months of the pupping season for many species. Trawl tow speed and tow time did not significantly influence catch rates for shark species. Gear configurations [net type, turtle excluder device (TED), bycatch reduction device] affected catch rates for shark species. Results of this study indicate gear restrictions, a delayed season opening, or reduced bar spacing on TEDs may reduce shark bycatch in this fishery.

  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. 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...

  10. 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.

  11. A comparison of pelagic, littoral, and riverine bacterial assemblages in Lake Bangongco, Tibetan Plateau.

    Science.gov (United States)

    Liu, Yongqin; Priscu, John C; Yao, Tandong; Vick-Majors, Trista J; Michaud, Alexander B; Jiao, Nianzhi; Hou, Juzhi; Tian, Lide; Hu, Anyi; Chen, Zhong-Qiang

    2014-08-01

    Lakes of the Tibetan Plateau lack direct anthropogenic influences, providing pristine high-altitude (> 4000 m) sites to study microbial community structure. We collected samples from the pelagic, littoral, and riverine zones of Lake Bangongco, located on the western side of the Plateau, to characterize bacterial community composition and geochemistry in three distinct, but hydrologically connected aquatic environments during summer. Bacterial community composition differed significantly among zones, with communities changing from riverine zones dominated by Bacteroidetes to littoral and pelagic zones dominated by Gammaproteobacteria. Community composition was strongly related to the geochemical environment, particularly concentrations of major ions and total nitrogen. The dominance of Gammaproteobacteria in the pelagic zone contrasts with typical freshwater bacterial communities as well as other lakes on the Tibetan Plateau. © 2014 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

  12. DEVELOPMENT OF TECHNOLOGY FOR FISH CANNED PATE'S COD-FISH SPECIES

    OpenAIRE

    A. A. Efremova; L. K. Kuranova; O. A. Nikolaenko

    2014-01-01

    Summary. Fish and seafood play an important role in a balanced diet. The most reliable method of preservation is the production of canned fish. Cod fishery considered traditional objects of the North Basin, which catches in recent years stored at a consistently high level. They are represented, mainly cod, haddock, pollack, whiting. Lately there has been a tendency to increase yield loaves (polar bib). The aim of this work - the development of technology - canned pate's cod fish species with ...

  13. COD::CIF::Parser: an error-correcting CIF parser for the Perl language

    OpenAIRE

    Merkys, Andrius; Vaitkus, Antanas; Butkus, Justas; Okulič-Kazarinas, Mykolas; Kairys, Visvaldas; Gražulis, Saulius

    2016-01-01

    A syntax-correcting CIF parser, COD::CIF::Parser, is presented that can parse CIF 1.1 files and accurately report the position and the nature of the discovered syntactic problems. In addition, the parser is able to automatically fix the most common and the most obvious syntactic deficiencies of the input files. Bindings for Perl, C and Python programming environments are available. Based on COD::CIF::Parser, the cod-tools package for manipulating the CIFs in the Crystallogra...

  14. 闽南-台湾浅滩渔场单船拖网作业调查与分析%Investigation and analysis of the otter board trawl fishery in Minnan- Taiwan shallow fishing ground

    Institute of Scientific and Technical Information of China (English)

    沈长春

    2012-01-01

    根据2009—2010年闽南-台湾浅滩渔场单船拖网作业监测调查资料和生产统计数据,阐明单船拖网作业的渔业地位、渔场分布、网具类型,着重分析该作业渔获种类组成及主要捕捞对象的资源动态。结果表明:单船拖网作业产量位居闽南-台湾浅滩渔场各种海洋捕捞作业的首位,大吨位、大功率渔船数量连续多年不断增长;渔具型式以有翼单囊网具为主;部分渔船使用的拖网网囊尺寸远远低于国家标准;带鱼、二长棘鲷幼鱼损害现象较为严重;秋季8—10月蓝圆鲹和鲐鱼群体绝大多数个体可达到最小可捕规格。调查研究结果还表明,2002年以来单船拖网渔业资源结构已发生较大变化,生命周期短、营养级较低的蟹类、枪乌贼类、乌贼类和虾类资源渔获比重显著增长;原优势种类绿布氏筋鱼资源已出现严重衰竭;二长棘鲷资源量逐年减少,渔获群体明显趋向小型化、低龄化。%Based on the monitoring survey data (production records of monitoring vessel and appraisal analysis of samples) and production statistics data of the otter board trawlers in related county/city operating in Minnan- Taiwan shallow fishing ground during 2009--2010, this paper expounded the fishery role, distribution of fishing ground and fishing gears type used in the otter board trawl fishery, meanwhile the species composition and the resource dynamics of main catch targets were mainly analyzed. The results showed that the yield of the otter board trawl fishery was the first in various marine fisheries, the number of large tonnage and high - power fishing boats had been increasing for years, winged solo cod - ends accounted for most in the type of fishing gears, and mesh size of fishing gears became smaller and smaller, which caused serious damage to commercial young fish. The results also showed that the otter board trawl had substantial change in fishery resource structure, the

  15. 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.

  16. 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.

  17. Warm, windy winters drive cod north and homing of spawners keeps them there

    DEFF Research Database (Denmark)

    Rindorf, Anna; Lewy, Peter

    2006-01-01

    and larval phases of cod led to a northward shift in the distribution of juvenile North Sea cod the following year. A concomitant northern shift of mature fish around the time of spawning was linked directly to a tendency for northerly distributed juveniles to remain northerly throughout their life...... of older age groups. Unless a series of cold and calm years combined with a reduced mortality in the southern areas allows a southern spawning population to rebuild, the cod stock is unlikely to return to its previous area of distribution. Furthermore, protecting adult cod mainly in northern areas...

  18. Cod Fractions - Methods of Measurement and Use in Wastewater Treatment Technology

    Science.gov (United States)

    Myszograj, Sylwia; Płuciennik-Koropczuk, Ewelina; Jakubaszek, Anita

    2017-03-01

    The paper presents the results of studies concerning the designation of COD fraction in raw wastewater. The research was conducted in four municipal mechanical-biological sewage treatment plants and one industrial sewage treatment plant. The following fractions of COD were determined: non-biodegradable (inert) soluble SI, biodegradable soluble fraction SS, particulate slowly degradable XS and particulate non-biodegradable XI. The methodology for determining the COD fraction was based on the ATV-A131 guidelines and Łomotowski-Szpindor methodology. The real concentration of fractions in raw wastewater and the percentage of each fraction in total COD are different from data reported in the literature.

  19. Cod Fractions - Methods of Measurement and Use in Wastewater Treatment Technology

    Directory of Open Access Journals (Sweden)

    Myszograj Sylwia

    2017-03-01

    Full Text Available The paper presents the results of studies concerning the designation of COD fraction in raw wastewater. The research was conducted in four municipal mechanical-biological sewage treatment plants and one industrial sewage treatment plant. The following fractions of COD were determined: non-biodegradable (inert soluble SI, biodegradable soluble fraction SS, particulate slowly degradable XS and particulate non-biodegradable XI. The methodology for determining the COD fraction was based on the ATV-A131 guidelines and Łomotowski-Szpindor methodology. The real concentration of fractions in raw wastewater and the percentage of each fraction in total COD are different from data reported in the literature.

  20. Food consumption and daily feeding periodicity : comparison between pelagic and demersal whiting in the North Sea

    DEFF Research Database (Denmark)

    Pedersen, Jens

    2000-01-01

    Pelagic North Sea whiting Merlagius merlangus fed at night, while demersal whiting fed by day. The estimated specific daily ration ranged from 4.38 to 7.84% in 1992 and from 3.99 to 10.31% in 1993 using the in situ rate of gastric evacuation. Using Anderson's evacuation model the specific daily r...... composition and energy density of the prey and spatial distribution of the whiting, demonstrates the need for a sampling design that includes both pelagic and demersal layers when quantifying the food consumption of whiting.(C) 2000 The Fisheries Society of the British Isles....

  1. Female-biased sex ratios in marine pelagic copepods: Comment on Gusmao et al. (2013)

    DEFF Research Database (Denmark)

    Hirst, Andrew G.; Bonnet, D; Conway, DVP

    2013-01-01

    Gusmao et al. (2013; Mar Ecol Prog Ser 482:279-298) review causes of sex ratio skew in pelagic copepods and in doing so repeatedly dispute the paper of Hirst et al. (2010) ‘Does predation control adult sex ratios and longevities in marine pelagic copepods?’ Here we respond to some important errors...... in their citation of our paper and briefly highlight where future work is needed in order to attribute the causes of strong sex ratio skew seen in some copepod families...

  2. Nutritional condition and vertical distribution of Baltic cod larvae

    DEFF Research Database (Denmark)

    Grønkjær, P.; Clemmesen, C.; St. John, Michael

    1997-01-01

    Newly hatched Baltic cod Gadus morhua larvae are typically found at depths >60 m. This is a region of low light and prey availability, hence generating the hypothesis that larvae have to migrate from hatching depth to the surface layer to avoid starvation and improve their nutritional condition....... To lest this hypothesis, Baltic cod larvae were sampled during the spawning seasons of 1994 and 1995 with depth-resolving multiple opening/closing nets. Each larva was aged by otolith readings and its RNA/DNA ratio was determined as a measure of nutritional condition. The RNA/DNA ratios of these larvae...... aged 2-25 days (median 10 days) ranged from 0.4 to 6.2, corresponding to levels exhibited by starving and fast growing larvae in laboratory calibration studies (starvation, protein growth rate, G(pi)=-12.2% day(-1); fast-growing larvae, G(pi)=14.1% day(-1)) respectively. Seventy per cent of the field...

  3. 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

  4. Developing Baltic cod recruitment models I : Resolving spatial and temporal dynamics of spawning stock and recruitment for cod, herring, and sprat

    DEFF Research Database (Denmark)

    Köster, Fritz; Möllmann, C.; Neuenfeldt, Stefan

    2001-01-01

    -disaggregated multispecies virtual population analyses (MSVPA) were performed for interacting species cod, herring (Clupea harengus), and sprat in the different subdivisions of the Central Baltic. The MSVPA runs revealed distinct spatial trends in population abundance, spawning biomass, recruitment, and predation......-induced mortality. Results, when evaluated with respect to trends in population sizes from research surveys, were similar for the cod and sprat stocks but different for herring. Horizontal distributions from MSVPA runs and research surveys indicate that cod and sprat undergo migrations between basins during...

  5. 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...

  6. Atlantic cod (Gadus morhua hemoglobin genes: multiplicity and polymorphism

    Directory of Open Access Journals (Sweden)

    Gamperl A Kurt

    2009-09-01

    Full Text Available Abstract Background Hemoglobin (Hb polymorphism, assessed by protein gel electrophoresis, has been used almost exclusively to characterize the genetic structure of Atlantic cod (Gadus morhua populations and to establish correlations with phenotypic traits such as Hb oxygen binding capacity, temperature tolerance and growth characteristics. The genetic system used to explain the results of gel electrophoresis entails the presence of one polymorphic locus with two major alleles (HbI-1; HbI-2. However, vertebrates have more than one gene encoding Hbs and recent studies have reported that more than one Hb gene is present in Atlantic cod. These observations prompted us to re-evaluate the number of Hb genes expressed in Atlantic cod, and to perform an in depth search for polymorphisms that might produce relevant phenotypes for breeding programs. Results Analysis of Expressed Sequence Tags (ESTs led to the identification of nine distinct Hb transcripts; four corresponding to the α Hb gene family and five to the β Hb gene family. To gain insights about the Hb genes encoding these transcripts, genomic sequence data was generated from heterozygous (HbI-1/2 parents and fifteen progeny; five of each HbI type, i.e., HbI-1/1, HbI-1/2 and HbI-2/2. β Hb genes displayed more polymorphism than α Hb genes. Two major allele types (β1A and β1B that differ by two linked non-synonymous substitutions (Met55Val and Lys62Ala were found in the β1 Hb gene, and the distribution of these β1A and β1B alleles among individuals was congruent with that of the HbI-1 and HbI-2 alleles determined by protein gel electrophoresis. RT-PCR and Q-PCR analysis of the nine Hb genes indicates that all genes are expressed in adult fish, but their level of expression varies greatly; higher expression of almost all Hb genes was found in individuals displaying the HbI-2/2 electrophoretic type. Conclusion This study indicates that more Hb genes are present and expressed in adult

  7. Discarding Discards: Identification of influential factors and possible mitigation tools in demersal trawl fisheries

    DEFF Research Database (Denmark)

    Feekings, Jordan P.

    across seven European Union (EU) Member States for the North Sea over the period 2003-2010. Knowledge about the spatio-temporal nature of discards is imperative to researchers and regulators but is often lacking. Here we analysed the spatial and temporal distribution of cod discards throughout the entire...... in the Kattegat. Previous studies that have investigated the factors that influence discarding have typically focused on the discarded portion as a whole, without considering that discards above and below minimum landing size (MLS) occur for different reasons. The study documented that the factors influential...

  8. Life Cycle Inventory Analysis for a Small-Scale Trawl Fishery in Sendai Bay, Japan

    Directory of Open Access Journals (Sweden)

    Kazuhito Watanabe

    2016-04-01

    Full Text Available A reduced environmental burden, while maintaining high quality and low cost, has become an important factor for achieving sustainability in the fisheries sector. The authors performed life cycle inventory (LCI analysis targeting the fish production for a small-scale trawl fishery including small trawlers operating in Sendai Bay, Japan. The average annual cumulative CO2 emissions for the small trawlers were 4.7 ton-CO2/ton-product and 8.3 ton-CO2/million Japanese yen (JPN. Total fuel consumption contributed to 97% of the global warming potential. The range of variation in the basic unit of CO2 for each small trawler was also elucidated. Energy conservation through lower fuel consumption is shown to be an effective measure for reducing CO2 in a small trawler fishery. Moreover, the authors examined the system boundary, the determination of the functional unit, and the allocation method of applying LCI analysis to fisheries. Finally, the economy and environment of small trawler fisheries are discussed as important factors for sustainable fisheries, and the life cycle approach is applied to a new fishery type in Japan.

  9. Determination of effective effort on hake Merluccius merluccius in a Mediterranean trawl fishery

    Directory of Open Access Journals (Sweden)

    Francisco Alemany

    2003-12-01

    Full Text Available The direct control of fishing effort as a management tool is of special interest in the Mediterranean, where the lack of effective international management systems and the high diversity of the catches significantly increases the complexity of implementing TAC´s as an indirect control of fishing effort. However, its enforcement should be based on the precise knowledge of the relationship between the fishing effort and its corresponding fishing mortality. In this sense, the general aim of this study was to develop an approach for analysing this relationship. In order to estimate the annual effective fishing effort on hake, a relational data base including daily landings by vessel and species of trawl fleet based on the port of Palma, Mallorca island (western Mediterranean during the period 1983-1991 was built. Fishing mortalities were available from VPA. Fishing effort and fishing mortality were split by subfleets or métiers which were identified by cluster analysis. Significant linear relationships between the two parameters were obtained when fishing effort was considered as the number of days in which hake catch was higher than 10 kg multiplied by GRT of correspondent vessels. These CPUE values are mainly obtained when trawlers operate in the muddy bottoms of the shelf and on the upper slope, where hake populations are mostly distributed. On the other hand, no clear trends in catchability by métier were found during the period analysed.

  10. Fish bycatch of the laulao catfish Brachyplatystoma vaillantii (Valenciennes, 1840 trawl fishery in the Amazon Estuary

    Directory of Open Access Journals (Sweden)

    Erica Antunes Jimenez

    2013-06-01

    Full Text Available This study aimed to analyse the composition and seasonal variation in the fish bycatch of the Brachyplatystoma vaillantii trawl fishery in the Amazon Estuary in 2009 by monitoring the trips of 48 vessels. The bycatch represented 29% of the catches, totalling 22,228 specimens and 52 taxa, distributed in 22 families (the principal families were Ariidae, Pimelodidae, and Sciaenidae. Brachyplatystoma rousseauxii, Plagioscion squamosissimus, and Sciades herzbergii together contributed 69% of the bycatch and were considered consistent bycatch species. Although a higher proportion of bycatch was captured during the rainy season, the seasonal difference was not significant. A multidimensional scaling (MDS ordination analysis and an analysis of similarity (ANOSIM indicated that the species composition of the bycatch was similar across the seasons. However, larger numbers of B. rousseauxii and P. squamosissimus were captured during the rainy season, whereas S. herzbergii predominated during the dry season. The marine migrants and estuarine species guilds showed the greatest richness, whereas freshwater migrants were the most numerous. Among the feeding guilds, the zoobenthivores were the most diverse, whereas the piscivores were the most abundant. The results indicate that fishing pressure primarily affects small- (20-30 cm and medium-sized (30-50 cm individuals, although the catch of P. squamosissimus was composed primarily of adults. However, the catches of both B. rousseauxii and B. vaillantii were composed primarily of juveniles.

  11. L’écodéveloppement participatif en question

    Directory of Open Access Journals (Sweden)

    Lucie Dejouhanet

    2010-03-01

    Full Text Available Si les politiques forestières indiennes ont évolué d’un paradigme directif à un paradigme participatif, les aires protégées sont encore gérées par des textes de loi qui privilégient la séparation entre activités humaines et espaces à protéger. L’écodéveloppement, soutenu par la Banque Mondiale, se voulait un moyen de favoriser des activités alternatives à l’exploitation des ressources et de faire participer les populations à la protection de leur environnement. Lancé en 2001 dans la réserve naturelle de Parambikulam au Kérala, ses résultats quelques années après sont peu concluants. Alors qu’un rapport de 2003 accuse le délitement social des populations concernées, cet article insiste davantage sur l’inadaptation des projets des comités d’écodéveloppement au contexte des villages ; le cliché essentialiste attaché aux populations adivasi constitue une vision a-historique qui ne permet pas de penser le développement aujourd’hui. L’écodéveloppement, s’il veut atteindre ses objectifs, doit permettre une réelle négociation entre acteurs des aires protégées et proposer des compromis réalistes entre limitation des activités et survie des populations.While Indian forest policies have evolved from a directive paradigm to a participative one, protected areas are still managed by legislative acts, which advocate a clear separation between human activities and areas to be protected. Eco-development financed by the World Bank was planned as a tool for developing alternative activities to resource exploitation and for involving local populations in environment protection through participation. Started in 2001 in the Wildlife Sanctuary of Parambikulam in Kerala, its results few years after are rather inconclusive. While a report in 2003 was accusing the social disintegration of concerned people, I am more stressing on the inappropriateness of EDC to villages’ context. The essentialist clich

  12. 75 FR 3416 - Fisheries in the Western Pacific; Pelagic Fisheries; Vessel Identification Requirements

    Science.gov (United States)

    2010-01-21

    ... National Oceanic and Atmospheric Administration 50 CFR Part 665 RIN 0648-AX38 Fisheries in the Western Pacific; Pelagic Fisheries; Vessel Identification Requirements AGENCY: National Marine Fisheries Service... INFORMATION CONTACT: Jarad Makaiau, Sustainable Fisheries, NMFS PIR, 808-944-2108. SUPPLEMENTARY...

  13. 75 FR 1023 - International Fisheries Regulations; Fisheries in the Western Pacific; Pelagic Fisheries; Hawaii...

    Science.gov (United States)

    2010-01-08

    ... CFR Part 665 [Docket No. 080225267-91393-03] RIN 0648-AW49 International Fisheries Regulations; Fisheries in the Western Pacific; Pelagic Fisheries; Hawaii-based Shallow-set Longline Fishery; Correction AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration...

  14. 75 FR 42610 - Fisheries Off West Coast States; Coastal Pelagic Species Fisheries; Closure

    Science.gov (United States)

    2010-07-22

    ... National Oceanic and Atmospheric Administration 50 CFR Part 660 RIN 0648-XX54 Fisheries Off West Coast States; Coastal Pelagic Species Fisheries; Closure AGENCY: National Marine Fisheries Service (NMFS... live bait fishery or incidental to other fisheries; the incidental harvest of Pacific sardine...

  15. 76 FR 58720 - Fisheries Off West Coast States; Coastal Pelagic Species Fisheries; Closure

    Science.gov (United States)

    2011-09-22

    ... National Oceanic and Atmospheric Administration 50 CFR Part 660 RIN 0648-XA709 Fisheries Off West Coast States; Coastal Pelagic Species Fisheries; Closure AGENCY: National Marine Fisheries Service (NMFS... bait fishery or incidental to other fisheries; the incidental harvest of Pacific sardine is limited...

  16. 76 FR 40836 - Fisheries Off West Coast States; Coastal Pelagic Species Fisheries; Closure

    Science.gov (United States)

    2011-07-12

    ... National Oceanic and Atmospheric Administration 50 CFR Part 660 RIN 0648-XA554 Fisheries Off West Coast States; Coastal Pelagic Species Fisheries; Closure AGENCY: National Marine Fisheries Service (NMFS... live bait fishery or incidental to other fisheries; the incidental harvest of Pacific sardine...

  17. 75 FR 59156 - Fisheries Off West Coast States; Coastal Pelagic Species Fisheries; Closure

    Science.gov (United States)

    2010-09-27

    ... National Oceanic and Atmospheric Administration 50 CFR Part 660 RIN 0648-XY79 Fisheries Off West Coast States; Coastal Pelagic Species Fisheries; Closure AGENCY: National Marine Fisheries Service (NMFS... bait fishery or incidental to other fisheries; the incidental harvest of Pacific sardine is limited...

  18. 77 FR 50952 - Fisheries Off West Coast States; Coastal Pelagic Species Fisheries; Closure

    Science.gov (United States)

    2012-08-23

    ... National Oceanic and Atmospheric Administration 50 CFR Part 660 RIN 0648-XC166 Fisheries Off West Coast States; Coastal Pelagic Species Fisheries; Closure AGENCY: National Marine Fisheries Service (NMFS... live bait fishery or incidental to other fisheries; the incidental harvest of Pacific sardine...

  19. 78 FR 51097 - Fisheries Off West Coast States; Coastal Pelagic Species Fisheries; Closure

    Science.gov (United States)

    2013-08-20

    ... National Oceanic and Atmospheric Administration 50 CFR Part 660 RIN 0648-XC783 Fisheries Off West Coast States; Coastal Pelagic Species Fisheries; Closure AGENCY: National Marine Fisheries Service (NMFS... live bait fishery or incidental to other fisheries; the incidental harvest of Pacific sardine...

  20. 76 FR 52888 - Western Pacific Pelagic Fisheries; American Samoa Longline Gear Modifications To Reduce Turtle...

    Science.gov (United States)

    2011-08-24

    ... definition of ``Western Pacific pelagic management unit species'' remove the entries for ``northern bluefin... Pacific green sea turtles. This final rule also makes administrative clarifications to the names of... Pacific Fishery Management Council (Council) prepared Amendment 5 to the Fishery Ecosystem Plan for...

  1. Distribution and abundance of pelagic shrimps from the deep scattering layer of the eastern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Karuppasamy, P.K.; Menon, N.G.; Nair, K.K.C.; Achuthankutty, C.T.

    The sonic scattering layer (SSL) or deep scattering layer (DSL) of the eastern Arabian Sea of India is found in depths between surfaces to 750 m with varying thicknesses and in multiple layers. There is a distinct resident community of pelagic...

  2. 76 FR 11969 - Fisheries Off West Coast States; Coastal Pelagic Species Fisheries; Annual Specifications

    Science.gov (United States)

    2011-03-04

    ... decrease the future stock of the species, as well as harvest limits, thereby reducing future potential... States; Coastal Pelagic Species Fisheries; Annual Specifications AGENCY: National Marine Fisheries... this species on July 1, 2011. Vessels with Pacific sardine catch must be at shore and in the process...

  3. Property and performance amelioration of pelagic clay from the East Pacific

    Institute of Scientific and Technical Information of China (English)

    Peiping ZHANG; Shufeng LIU; Xuefa SHI; Huahua LU; Juanjuan LIU; Xiaoguo CHI

    2008-01-01

    To make use of the pelagic clay as polymer filling, the properties of clay sediments from the ocean investigation zone of China in the East Pacific were studied by the SSA, XRF, ICP/MAS, FHR, XRD, SEM, DTA/TG and granularity distributing etc. , and experiments were settled to improve the whiteness and activation of the clay based on these data. Compared with land clay, pelagic clay holds many particular features, such as fine particles and incompact accumulation, worse crystallization and more defects, high activity, complex mineral and chemical components, and low whiteness etc. Processing the purified pelagic clay with acids and zinc, then baked it at different temperatures, the whiteness of clay can be increased from 23.8% to 73.1%, and the optimized conditions is : consistency of vitriol 25%, ratio of clay to water 4:1, reaction time 4h, reaction temperature 90℃, dosage of zinc 2.0 g/L, and baking temperature 700℃. And the SSA of whited clay is increased too. Using the dry milling method to modify the pelagic clay with organic reagents, the optimized technique is KH550, concentration 1.5%, reaction time 20 min. XRD,FTIR and SEM testing indicate that the mechanism of organic activation was mainly surface absorbing and chemical combination secondly.

  4. Selective ingestion of pelagic versus benthic algae by the cockle Cerastoderma edule (Linne, 1758)

    NARCIS (Netherlands)

    Rueda, J.L.; Smaal, A.C.

    2002-01-01

    The pre-ingestive selection of microphytobenthic algae by the cockle Cerastoderma edule was studied in comparison with diets containing the pelagic diatom Phaeodactylum tricornutum. Treatments with the different diets covered a range of seston concentrations and organic content similar to field

  5. Upper Cretaceous pelagic red beds,implications for paleoclimate and pale oc eanography

    Institute of Scientific and Technical Information of China (English)

    LubaJansa; O.Tuysuz; R.W.Scott

    2004-01-01

    Members of IGCP 463, Upper Cretaceous Oceanic Red Beds: Response to Ocean/Climate Global Change (CORBs) held their second workshop near the Black Sea in Bartin, Turkey. In addition to discussion of results and plans, the participants examined exposures of pelagic red beds in northern Turkev.

  6. 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.

  7. Deep-sea crustacean trawling fisheries in Portugal: quantification of effort and assessment of landings per unit effort using a Vessel Monitoring System (VMS)

    Science.gov (United States)

    Bueno-Pardo, Juan; Ramalho, Sofia P.; García-Alegre, Ana; Morgado, Mariana; Vieira, Rui P.; Cunha, Marina R.; Queiroga, Henrique

    2017-01-01

    Mapping and quantifying bottom trawling fishing pressure on the seafloor is pivotal to understand its effects on deep-sea benthic habitats. Using data from the Vessel Monitoring System of crustacean trawlers along the Portuguese margin, we have identified the most exploited areas and characterized the most targeted habitats and water depths. We estimated a total trawling effort of 69596, 66766, and 63427 h y‑1 for the years 2012, 2013, and 2014 respectively which, considering the total landings estimated for this gear, yield values of 20.76, 21.06, and 19.11 kg of landed fish per trawled hour. The main trawling pressure is exerted in the South and Southwest Portuguese margins, on muddy and muddy-sand bottoms between 200 and 700 m water depths, while in the North and Central-West coasts a minor effort, at shallower waters and across a wider range of habitats, is also applied. The most landed species are crustaceans such as rose shrimp and Norway lobster, although this varies importantly between the different regions of Portugal, being fish and cephalopods the main captures in the Northern ports. We discuss the consequences of trawling for the impacted communities as well as the characteristics of the commercialization of these captures in Portugal.

  8. Deep-sea crustacean trawling fisheries in Portugal: quantification of effort and assessment of landings per unit effort using a Vessel Monitoring System (VMS)

    Science.gov (United States)

    Bueno-Pardo, Juan; Ramalho, Sofia P.; García-Alegre, Ana; Morgado, Mariana; Vieira, Rui P.; Cunha, Marina R.; Queiroga, Henrique

    2017-01-01

    Mapping and quantifying bottom trawling fishing pressure on the seafloor is pivotal to understand its effects on deep-sea benthic habitats. Using data from the Vessel Monitoring System of crustacean trawlers along the Portuguese margin, we have identified the most exploited areas and characterized the most targeted habitats and water depths. We estimated a total trawling effort of 69596, 66766, and 63427 h y−1 for the years 2012, 2013, and 2014 respectively which, considering the total landings estimated for this gear, yield values of 20.76, 21.06, and 19.11 kg of landed fish per trawled hour. The main trawling pressure is exerted in the South and Southwest Portuguese margins, on muddy and muddy-sand bottoms between 200 and 700 m water depths, while in the North and Central-West coasts a minor effort, at shallower waters and across a wider range of habitats, is also applied. The most landed species are crustaceans such as rose shrimp and Norway lobster, although this varies importantly between the different regions of Portugal, being fish and cephalopods the main captures in the Northern ports. We discuss the consequences of trawling for the impacted communities as well as the characteristics of the commercialization of these captures in Portugal. PMID:28098211

  9. Estimating abundances of 0-group western Baltic cod by using pound net fisheries

    DEFF Research Database (Denmark)

    Bauer, Robert; Stepputtis, Daniel; Storr-Paulsen, Marie

    2010-01-01

    Nearshore 0-group western Baltic cod are frequently caught as bycatch in the commercial pound net fishery. Pound net fishermen from the Danish Isle of Funen and Lolland and the German Isle of Fehmarn have recorded their catches of small cod between September and December 2008. Abundance patterns...

  10. The invasive ctenophore Mnemiopsis leidyi poses no direct threat to Baltic cod eggs and larvae

    DEFF Research Database (Denmark)

    Jaspers, Cornelia; Titelman, Josefin; Hansson, Lars Johan

    2011-01-01

    Since its invasion in to the Baltic Sea in 2006, the ctenophore Mnemiopsis leidyi has been suspected of seriouspredation on the early life stages of Baltic cod (Gadus morhua callarias L.) due to a temporal and spatial overlap inthe most important cod spawning ground, the Bornholm Basin. We conduc...

  11. Hazard Analysis and identification of Critical Control Points of collagen extraction from cod by-products

    NARCIS (Netherlands)

    Aalberts, C.H.J.

    2004-01-01

    The aim of the European research project “UTILISATION AND STABILISATION OF BY-PRODUCTS FROM COD SPECIES” (QLK1-CT-2000-01017 QLRT-2001-02829) is to investigate whether collagen from fish by-products could serve as an important raw material in high quality food. Since Atlantic cod is a major commodit

  12. Prediction of selectivity from morphological conditions: Methodology and a case study on cod (Gadus morhua)

    DEFF Research Database (Denmark)

    Herrmann, Bent; Krag, Ludvig Ahm; Frandsen, Rikke

    2009-01-01

    The FISHSELECT methodology. tools, and software were developed and used to measure the morphological parameters that determine the ability of cod to penetrate different mesh types, sizes, and openings. The shape of one cross-section at the cod's head was found to explain 97.6% of the mesh...

  13. Proteome reference map of the skin mucus of Atlantic cod (Gadus morhua) revealing immune competent molecules

    NARCIS (Netherlands)

    Rajan, B.; Fernandes, J.M.O.; Caipang, C.M.A.; Kiron, V.; Rombout, J.H.W.M.; Brinchmann, M.

    2011-01-01

    The skin mucosal proteome of Atlantic cod (Gadus morhua) was mapped using a 2D PAGE, LC–MS/MS coupled approach. Mucosal proteins from naive fish were identified primarily by similarity searches across various cod EST databases. The identified proteins were clustered into 8 groups based on gene ontol

  14. Preparation, characterization, and in vitro cytotoxicity of COM and COD crystals with various sizes.

    Science.gov (United States)

    Sun, Xin-Yuan; Ouyang, Jian-Ming; Liu, Ai-Jie; Ding, Yi-Ming; Gan, Qiong-Zhi

    2015-12-01

    Calcium oxalate crystals in urine often differ in size and crystal phase between healthy humans and patients with kidney stones. In this work, calcium oxalate monohydrate (COM) and dihydrate (COD) with sizes of about 50 nm, 100 nm, 1 μm, 3 μm, and 10 μm were prepared by varying reactant concentration, reaction temperature, solvent, mixing manner, and stirring speed. These crystals mainly had a smooth surface and no obvious pore structure, except COM-1 μm. In cell culture medium, the zeta potential of crystals became increasingly negative with increasing size, and the absolute value of zeta potential of COD was greater than the same-sized COM. Results of cell viability and PI staining assays showed that the order of injury degree in African green monkey renal epithelial (Vero) cells caused by different sizes of COD was COD-50 nm>COD-100 nm>COD-1 μm>COD-3 μm>COD-10 μm, and that of different sizes of COM was COM-1 μm>COM-50~COM-100 nm>COM-3 μm>COM-10 μm. COM-1 μm presented the highest cytotoxicity in Vero cells, which was associated with its rougher surface, larger specific surface area (SBET), and larger pore volume. Overall, these findings indicated that the physical properties of crystals play an important role in their cytotoxicity.

  15. Evaluation of Electrical Stunning of Atlantic Cod (Gadus morhua) and Turbot (Psetta maxima) in Seawater

    NARCIS (Netherlands)

    Lambooij, E.; Digre, H.; Erikson, U.; Reimert, H.G.M.; Burggraaf, D.; Vis, van de J.W.

    2013-01-01

    The aim of this study was to assess electrical stunning of Atlantic cod and turbot in seawater to develop a protocol for the process of stunning and killing. An induced general epileptiform insult (unconscious) had a duration of 40 ± 27 s (n =14) in cod (2.6 ± 0.5 kg) and 34 ± 18 s (n = 19) in turbo

  16. A genomic island linked to ecotype divergence in Atlantic cod

    DEFF Research Database (Denmark)

    Hansen, Jakob Hemmer; Eg Nielsen, Einar; Therkildsen, Nina O.;

    2013-01-01

    gene flow and large effective population sizes, properties which theoretically could restrict divergence in local genomic regions. We identify a genomic region of strong population differentiation, extending over approximately 20 cM, between pairs of migratory and stationary ecotypes examined at two......The genomic architecture underlying ecological divergence and ecological speciation with gene flow is still largely unknown for most organisms. One central question is whether divergence is genome‐wide or localized in ‘genomic mosaics’ during early stages when gene flow is still pronounced....... Empirical work has so far been limited, and the relative impacts of gene flow and natural selection on genomic patterns have not been fully explored. Here, we use ecotypes of Atlantic cod to investigate genomic patterns of diversity and population differentiation in a natural system characterized by high...

  17. Lessons for fisheries management from the EU cod recovery plan

    DEFF Research Database (Denmark)

    Kraak, S.B.M.; Bailey, N.; Cardinale, M.;

    2013-01-01

    Member States to 'buy back' or increase fishing effort for fleet segments engaged in cod-avoidance measures. The stipulated fishing mortality reductions have not been achieved. On the positive side, the 'buy-back' instrument has led to increased uptake of selective gear and implementation of permanent...... in targeted fisheries, although fishers experienced them as prohibiting the full uptake of other quotas. Recommendations for future plans include (i) management through catch rather than landings quotas, (ii) the internalisation of the costs of exceeding quotas, (iii) use of more selective gear types, (iv......) the development of appropriate metrics as a basis for regulatory measures and for evaluations, (v) participatory governance, (vi) fishery-based management, (vii) flexibility in fishing strategy at vessel level...

  18. Alternative adaptive immunity strategies: coelacanth, cod and shark immunity.

    Science.gov (United States)

    Buonocore, Francesco; Gerdol, Marco

    2016-01-01

    The advent of high throughput sequencing has permitted to investigate the genome and the transcriptome of novel non-model species with unprecedented depth. This technological advance provided a better understanding of the evolution of adaptive immune genes in gnathostomes, revealing several unexpected features in different fish species which are of particular interest. In the present paper, we review the current understanding of the adaptive immune system of the coelacanth, the elephant shark and the Atlantic cod. The study of coelacanth, the only living extant of the long thought to be extinct Sarcopterygian lineage, is fundamental to bring new insights on the evolution of the immune system in higher vertebrates. Surprisingly, coelacanths are the only known jawed vertebrates to lack IgM, whereas two IgD/W loci are present. Cartilaginous fish are of great interest due to their basal position in the vertebrate tree of life; the genome of the elephant shark revealed the lack of several important immune genes related to T cell functions, which suggest the existence of a primordial set of TH1-like cells. Finally, the Atlantic cod lacks a functional major histocompatibility II complex, but balances this evolutionary loss with the expansion of specific gene families, including MHC I, Toll-like receptors and antimicrobial peptides. Overall, these data point out that several fish species present an unconventional adaptive immune system, but the loss of important immune genes is balanced by adaptive evolutionary strategies which still guarantee the establishment of an efficient immune response against the pathogens they have to fight during their life.

  19. [Omega-3: from cod-liver oil to nutrigenomics].

    Science.gov (United States)

    Caramia, G

    2008-08-01

    The leading role of cod-liver oil on rickets was a relevant factor in the knowledge of this disease. In 1922 the preventive and therapeutic value of cod-liver oil and sunlight against rickets in young infants was confirmed. The seasonal variation in the incidence of rickets, the role of skin pigmentation, of diet and the fact that breast milk was not an adequate source of vitamin D were understood. The discovery of essential fatty acids omega-6 and omega-3 have shown that deficiencies, mainly of omega-3 long chain polyunsaturated fatty acids, result in visual and cognitive impairment and disturbances in mental functions in infants and also in cognitive function in adults, as fatty acids are beneficial to vascular health and may forestall cerebrovascular disease and thus dementia. An adequate ratio of n-6 and n-3 fatty acids may promote a healthier balance of eicosanoids, which would protect membrane function with a nutraceutical function. Dietary lipids not only influence the biophysical state of the cell membranes but, via direct and indirect routes, they also act on multiple pathways including signalling, gene and protein activities, protein modifications and they probably play important role in modulating protein aggregation. Significant advances have been made in understanding the relation between dietary factors and inflammation, which is a central component of many chronic diseases, including coronary artery disease, rheumatoid arthritis, cancer prevention. However, the identification of those who will or will not benefit from dietary intervention strategies remains a major obstacle. Adequate knowledge about how the responses depend on an individual's genetic background (nutrigenetic effects), the cumulative effects of food components on genetic expression profiles through nutrigenomics mechanism, may assist in identifying responders and non-responders. Thus, fish and fish oil consumption might encourage brain development and gene expression to brain

  20. An Oscillating Jet in the Cape Cod Bay

    Science.gov (United States)

    Poulin, F. J.; Flierl, G. R.

    2004-05-01

    During the spring months, the Cape Cod Bay is a roaming ground for the North Atlantic right whale, perhaps the most endangered whale species in the world. The whales are observed to travel along the topographic steps that run parallel to the shore, eating plankton patches that form in the coastal water. In this region, off the coast of Provincetown, there is an oscillatory current with the same period as that of the ambient tides. The location of the current and its periodicity suggest that the topography and tides play fundamental roles in generating the jet. This current, depending on its velocity profile, may become unstable and generate vortices. It is likely that the local surface convergences and divergences in the tidal flows and vortices are related to the aggregation of the copepods (Calanus Finmarchicus), which are the right whale's primary food source. Understanding the dynamics of this jet is essential to predicting the spatial and temporal patterns of the codepods, which will in turn help us understand the likely locations and feeding history of the whales. In this talk we discuss results of the first phase of this study, that of the oscillatory jet in the Cape Cod Bay. This jet is rather complicated since it involves complex topography and coastlines, bottom and lateral friction, stratification and numerous other effects. Rather than study this system in fine detail, we investigate an idealized model that captures the essential features. In the context of this model, we first compute possible profiles for the oscillating jet. We then solve the linear stability problem to determine how the growth rates depend on the various parameters. Finally, and most importantly, we study the nonlinear problem to observe the time evolution of the instability process along with its equilibration. This provides some insight into how the instabilities are related to fluid transport across the shelf.

  1. Long-term effects of the transient COD concentration on the performance of microbial fuel cells.

    Science.gov (United States)

    Mateo, S; Gonzalez Del Campo, A; Lobato, J; Rodrigo, M; Cañizares, P; Fernandez-Morales, F J

    2016-07-08

    In this work, the long-term effects of transient chemical oxygen demands (COD) concentrations over the performance of a microbial fuel cell were studied. From the obtained results, it was observed that the repetitive change in the COD loading rate during 12 h conditioned the behavior of the system during periods of up to 7 days. The main modifications were the enhancement of the COD consumption rate and the exerted current. These enhancements yielded increasing Coulombic efficiencies (CEs) when working with COD concentrations of 300 mg/L, but constant CEs when working with COD concentrations from 900 to 1800 mg/L. This effect could be explained by the higher affinity for the substrate of Geobacter than that of the nonelectrogenic organisms such as Clostridia. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:883-890, 2016.

  2. Automatic feeding and Harvesting of Juvenile Atlantic Cod (Gadus Morhua L. in a Pond

    Directory of Open Access Journals (Sweden)

    V. Øiestad

    1987-01-01

    Full Text Available Large scale production of juvenile Atlantic cod has been carried out since 1980 in a saltwater pond. A break-through was obtained in 1983 with high survival rates of cod larvae to metamorphosis. In 1985 we made progress in two fiels, reduced cannibalism and automatic harvesting. Juvenile cod formed large schools while fed dry pellets in the currents set up by five propellers. An underwater loudspeaker was programmed to give sound pulses just before feeding. During harvesting dry pellets were released inside a fish trap while giving the sound signals the cod juveniles were conditioned to. The cod readily entered the trap and a computer-controlled fish pump transported the fish from the fish trap into a storing tank and grading grids. The trap gradually emptied the pond of fish and more than 80

  3. Spatio-temporal dynamics of cod nursery areas in the Baltic Sea

    DEFF Research Database (Denmark)

    Hinrichsen, Hans-Harald; Dewitz, B. von; Lehmann, M.

    2017-01-01

    In this study the drift of eastern Baltic cod larvae and juveniles spawned within the historical eastern Baltic cod spawning grounds was investigated by detailed drift model simulations for the years 1971–2010, to examine the spatio-temporal dynamics of environmental suitability in the nursery...... areas of juvenile cod settlement. The results of the long-term model scenario runs, where juvenile cod were treated as simulated passively drifting particles, enabled us to find strong indications for long-term variations of settlement and potentially the reproduction success of the historically...... in the Baltic Sea. Furthermore, transport of juveniles surviving to the age of settlement with origin in the Bornholm Basin contributed on average 13 and 11% to the total settlement in the Arkona Basin and in the Gdansk Deep, respectively. The time-series of the simulated occupied juvenile cod habitat...

  4. Elucidation of different cold-adapted Atlantic cod (Gadus morhua) trypsin X isoenzymes.

    Science.gov (United States)

    Stefansson, Bjarki; Sandholt, Gunnar B; Gudmundsdottir, Ágústa

    2017-01-01

    Trypsins from Atlantic cod (Gadus morhua), consisting of several isoenzymes, are highly active cold-adapted serine proteases. These trypsins are isolated for biomedical use in an eco-friendly manner from underutilized seafood by-products. Our group has explored the biochemical properties of trypsins and their high potential in biomedicine. For broader utilization of cod trypsins, further characterization of biochemical properties of the individual cod trypsin isoenzymes is of importance. For that purpose, a benzamidine purified trypsin isolate from Atlantic cod was analyzed. Anion exchange chromatography revealed eight peaks containing proteins around 24kDa with tryptic activity. Based on mass spectrometric analysis, one isoenzyme gave the best match to cod trypsin I and six isoenzymes gave the best match to cod trypsin X. Amino terminal sequencing of two of these six trypsin isoenzymes showed identity to cod trypsin X. Three sequence variants of trypsin X were identified by cDNA analysis demonstrating that various forms of this enzyme exist. One trypsin X isoenzyme was selected for further characterization based on abundance and stability. Stepwise increase in catalytic efficiency (kcat/Km) of this trypsin X isoenzyme was obtained with substrates containing one to three amino acid residues. The study demonstrates that the catalytic efficiency of this trypsin X isoenzyme is comparable to that of cod trypsin I, the most abundant and highly active isoenzyme in the benzamidine cod trypsin isolate. Differences in pH stability and sensitivity to inhibitors of the trypsin X isoenzyme compared to cod trypsin I were detected that may be important for practical use.

  5. [Influence of substrate COD on methane production in single-chambered microbial electrolysis cell].

    Science.gov (United States)

    Teng, Wen-Kai; Liu, Guang-Li; Luo, Hai-Ping; Zhang, Ren-Duo; Fu, Shi-Yu

    2015-03-01

    The chemical oxygen demand (COD) of substrate can affect the microbial activity of both anode and cathode biofilm in the single-chamber methanogenic microbial electrolysis cell (MEC). In order to investigate the effect of COD on the performance of MEC, a single chamber MEC was constructed with biocathode. With the change of initial concentration of COD (700, 1 000 and 1 350 mg x L(-1)), the methane production rate, COD removal and energy efficiency in the MEC were examined under different applied voltages. The results showed that the methane production rate and COD removal increased with the increasing COD. With the applied voltage changing from 0.3 to 0.7 V, the methane production rate increased at the COD of 700 mg x L(-1), while it increased at first and then decreased at the COD of 1000 mg x L(-1) and 1350 mg x L(-1). A similar trend was observed for the COD removal. The cathode potential reached the minimum (- 0.694 ± 0.001) V as the applied voltage was 0.5 V, which therefore facilitated the growth of methanogenic bacteria and improved the methane production rate and energy efficiency of the MEC. The maximum energy income was 0.44 kJ ± 0.09 kJ (1450 kJ x m(-3)) in the MEC, which was obtained at the initial COD of 1000 mg x L(-1) and the applied voltage of 0.5 V. Methanogenic MECs could be used for the treatment of wastewaters containing low organic concentrations to achieve positive energy production, which might provide a new method to recover energy from low-strength domestic wastewater.

  6. The role of the male copulatory organs in the colonization of the pelagic by shrimp-like eucarids

    Science.gov (United States)

    Lunina, Anastasia; Vereshchaka, Alexander

    2017-03-01

    Five major taxa of shrimp-like eucarid are recognized: the order Euphausiacea, the suborder Dendrobranchiata, and three infraorders of the suborder Pleocyemata (Caridea, Procarididea, and Stenopodidea). These animals are very successful in the colonization of the pelagic but the role of the sexual structures (the appendix masculina and the petasma) in this process remains uncertain. We revise the vertical distribution of pelagic species and genera within the shrimp-like eucarids and the presence and types of the male copulatory organs. We further test the hypothesis that the pelagic habitat is associated with the elaborated male copulatory organs and discuss possible mechanisms of association. We also consider possible effects of the depth and coastal factors. In the turbulent and fluid pelagic, successful copulation depends on the perfect fixation and possible stimulation of mates during spermatophore transfer and thus on the development and elaboration of the copulatory structures. The presence of the appendix masculina is necessary for copulation in the pelagic and thus for colonization of the pelagic. The 'family success' in colonizing the pelagic depends on the presence of the elaborate petasma, whilst the 'species success' is not so obviously related to the presence of this organ. The colonization of the water column by the eucarids may basically occur at the family level and be associated with the elaboration of the petasma. Within monophyletic pelagic groups, a greater development of the petasma is observed in the epi- and mesopelagic; some reduction of this organ in the bathypelagic may be related to the reduction in current velocities and turbulence. Simplification of the petasma is also observed in coastal waters. The proposed hypothesis is invariant to phylogenetic models and suggests an explanation to why (but not in which consequence) the elaborated copulative organs have been developed/retained in the pelagic or reduced/lost in the benthic.

  7. Impact of discards of beam trawl fishing on the nematode community from the Tagus estuary (Portugal)

    Energy Technology Data Exchange (ETDEWEB)

    Franco, M.A. [Marine Biology Section, Biology Department, Ghent University, Krijgslaan 281 (S8), 9000 Gent (Belgium); Oceanography Institute, Faculty of Sciences, University of Lisbon, Campo Grande, 1749-016 Lisboa (Portugal); Steyaert, M. [Marine Biology Section, Biology Department, Ghent University, Krijgslaan 281 (S8), 9000 Gent (Belgium); Cabral, H.N. [Oceanography Institute, Faculty of Sciences, University of Lisbon, Campo Grande, 1749-016 Lisboa (Portugal); Tenreiro, R.; Chambel, L. [Instituto de Ciencia Aplicada e Tecnologia, Faculty of Sciences, University of Lisbon, Campo Grande, 1749-016 Lisboa (Portugal); Vincx, M. [Marine Biology Section, Biology Department, Ghent University, Krijgslaan 281 (S8), 9000 Gent (Belgium); Costa, M.J. [Oceanography Institute, Faculty of Sciences, University of Lisbon, Campo Grande, 1749-016 Lisboa (Portugal); Vanaverbeke, J. [Marine Biology Section, Biology Department, Ghent University, Krijgslaan 281 (S8), 9000 Gent (Belgium)], E-mail: jan.vanaverbeke@ugent.be

    2008-10-15

    The impact of dead discards, originating from beam trawl fishing on the nematode community from the Tagus estuary was investigated in terms of vertical distribution of the dominant nematode groups. Sediment cores were collected from a mud-flat from the Tagus estuary. Crangoncrangon (Linnaeus, 1758) carcasses were added to the surface of the cores, simulating the settling of dead discards on the sediment. The vertical distribution of the dominant nematode groups was determined up to 4 cm deep at four different moments in time post deposition (0, 2, 4 and 6 h) and compared to control cores. The C.crangon addition to the sediment led to the formation of black spots and therefore oxygen depleted areas at the sediment surface. The Chromadora/Ptycholaimellus group, normally dominant at the surface layer, migrated downwards due to their high sensibility to toxic conditions. Sabatieria presented the opposite trend and became the dominant group at the surface layer. Since Sabatieria is tolerant to oxygen stressed conditions and high sulphide concentrations, we suggest that it migrated opportunistically towards an unoccupied niche. Daptonema, Metachromadora and Terschellingia did not show any vertical migration, reflecting their tolerance to anoxic and high sulphidic conditions. Our study showed that an accumulation of dead discards at the sediment surface might therefore alter the nematode community vertical distribution. This effect is apparently closely related to toxic conditions in the sediment, induced by the deposition of C.crangon at the sediment surface. These alterations might be temporal and reflect an adaptation of the nematode community to dynamic intertidal environments.

  8. Impact of discards of beam trawl fishing on the nematode community from the Tagus estuary (Portugal).

    Science.gov (United States)

    Franco, M A; Steyaert, M; Cabral, H N; Tenreiro, R; Chambel, L; Vincx, M; Costa, M J; Vanaverbeke, J

    2008-10-01

    The impact of dead discards, originating from beam trawl fishing on the nematode community from the Tagus estuary was investigated in terms of vertical distribution of the dominant nematode groups. Sediment cores were collected from a mud-flat from the Tagus estuary. Crangoncrangon (Linnaeus, 1758) carcasses were added to the surface of the cores, simulating the settling of dead discards on the sediment. The vertical distribution of the dominant nematode groups was determined up to 4cm deep at four different moments in time post deposition (0, 2, 4 and 6h) and compared to control cores. The C.crangon addition to the sediment led to the formation of black spots and therefore oxygen depleted areas at the sediment surface. The Chromadora/Ptycholaimellus group, normally dominant at the surface layer, migrated downwards due to their high sensibility to toxic conditions. Sabatieria presented the opposite trend and became the dominant group at the surface layer. Since Sabatieria is tolerant to oxygen stressed conditions and high sulphide concentrations, we suggest that it migrated opportunistically towards an unoccupied niche. Daptonema, Metachromadora and Terschellingia did not show any vertical migration, reflecting their tolerance to anoxic and high sulphidic conditions. Our study showed that an accumulation of dead discards at the sediment surface might therefore alter the nematode community vertical distribution. This effect is apparently closely related to toxic conditions in the sediment, induced by the deposition of C.crangon at the sediment surface. These alterations might be temporal and reflect an adaptation of the nematode community to dynamic intertidal environments.

  9. Increasing sediment accumulation rates in La Fonera (Palamós) submarine canyon axis and their relationship with bottom trawling activities

    Science.gov (United States)

    Puig, P.; Martín, J.; Masqué, P.; Palanques, A.

    2015-10-01

    Previous studies conducted in La Fonera (Palamós) submarine canyon (NW Mediterranean) found that trawling activities along the canyon flanks cause resuspension and transport of sediments toward the canyon axis. 210Pb chronology supported by 137Cs dating applied to a sediment core collected at 1750 m in 2002 suggested a doubling of the sediment accumulation rate since the 1970s, coincident with the rapid industrialization of the local trawling fleet. The same canyon area has been revisited a decade later, and new data are consistent with a sedimentary regime shift during the 1970s and also suggest that the accumulation rate during the last decade could be greater than expected, approaching ~2.4 cm yr-1 (compared to ~0.25 cm yr-1 pre-1970s). These results support the hypothesis that commercial bottom trawling can substantially affect sediment dynamics and budgets on continental margins, eventually initiating the formation of anthropogenic depocenters in submarine canyon environments.

  10. Steam trawling on the south-east continental shelf of Australia. An environmental history of fishing, management and science in NSW, 1865 -1961

    DEFF Research Database (Denmark)

    Jacobsen, A. Lif Lund

    2010-01-01

    resource management. Studies of historical documents from State and Commonwealth fisheries authorities involved in the steam trawl fishery on the south-east continental shelf of Australia illustrate different expressions of intentional management and how a more ecological responsible view has emerged...... scientific recommendations. The Second World War provided financial relief for the industry, as the Royal Australian Navy leased the ageing trawler fleet for minesweeping. After the war a complex system of overlapping State and Commonwealth authority evolved. Different management objectives and lack...... of catches caused by overfishing forced the steam trawling companies to gradually close down between 1954 and 1961. The history of the management of the steam trawling fishery shows the considerable difficulties associated with implementing responsible resource management in a multi-governmental system...

  11. Biology and population dynamics of by-catch fish species of the bottom trawl fishery in the western Mediterranean

    Directory of Open Access Journals (Sweden)

    F. ORDINES

    2014-09-01

    Full Text Available The teleosts Chelidonichthys cuculus, Trigloporus lastoviza, Serranus cabrilla and Trachinus draco, are important by-catch species, in terms of landed biomass and commercial value, from the continental shelf bottom trawl fishery off the Balearic Islands (western Mediterranean. The main biological parameters of these species were calculated from monthly biological samplings, and were used along with three years pseudo-cohorts (2008-2010 obtained from monitoring on-board of the bottom trawl fleet, to assess their exploitation level through Virtual Population Analysis (VPA and Yield per Recruit (Y/R analysis. Time series of fishery independent indicators based on MEDITS surveys data such as the evolution of the abundance and biomass, the distribution range, and the Conservation Status of Fish b (CSFb, were also analyzed. All four species analyzed showed growth overfishing. The reductions of the fishing effort required to reach the Y/RF0,1 reference point were lower, 66-73% depending on the species, to those reported for the target species M. merluccius (87%, but higher than that reported for M. surmuletus (53%, in the study area in the period 2000-2010. The abundance and biomass, and the distribution range did not show any trend for the period 2001-2011, whereas the CSFb showed signs of recovery that may be due to the displacement of the trawl fishing effort from the shelf to the slope during the last decade. Our results underline the necessary incorporation of monitoring and assessment of by-catch species to the management of fisheries as their populations can show a more pronounced overexploitation than target ones.

  12. Differences in salinity tolerance and gene expression between two populations of Atlantic cod (Gadus morhua) in response to salinity stress

    DEFF Research Database (Denmark)

    Larsen, Peter Foged; Eg Nielsen, Einar; Meier, Kristian

    2012-01-01

    in salinity tolerance and gene expression among Atlantic cod (Gadus morhua) from two populations distributed across a steep salinity gradient, we observed high mortality (45% North Sea cod and 80% Baltic Sea cod) in a reciprocal common garden setup. Quantitative RT-PCR assays for expression of hsp70 and Na....... The findings strongly suggest that Atlantic cod are adapted to local saline conditions, despite relatively low levels of neutral genetic divergence between populations...

  13. Infaunal community responses to a gradient of trawling disturbance and a long-term Fishery Exclusion Zone in the Southern Tyrrhenian Sea

    Science.gov (United States)

    Mangano, M. Cristina; Kaiser, Michel J.; Porporato, Erika M. D.; Lambert, Gwladys I.; Rinelli, Paola; Spanò, Nunziacarla

    2014-03-01

    Historically the majority of Mediterranean trawl fisheries occur on the continental shelf with a smaller proportion focused on the shelf slope and deep sea areas. Understanding how trawl fisheries affect the wider ecosystem is an important component of the ecosystem-based approach to fisheries management. In this context the current study examined the impact of the otter trawl fishery on the infaunal communities found on the continental shelf and upper slope off the coast of Sicily and Calabria, Italy. A total of thirty six sites were sampled across a gradient of fishing intensity and from within a large bay from which trawling has been excluded for 22 years. Fishing intensities were ascertained post-hoc from vessel monitoring system data. Seabed characteristics of the sites studied were uniform across the continental shelf and slope areas that were studied, such that the only factor that varied was fishing intensity. The density index (DI) and total number of species (S) were significantly higher in the fishery closure area compared with other continental shelf sites. In particular, bioturbating decapod fauna occurred only within the fishery closure area. Fished sites were dominated primarily by burrowing deposit feeding worms, small bivalves and scavenging biota. In contrast, the response to fishing on the upper slope was less clear. This observation was treated with caution as the power to detect fishing effects was lower for the upper slope sites as a result of possible illegal fishing that had compromised two of the four replicate sites within the closed area. While the present study was able to quantify the effect of the demersal trawl fleet on the benthic infauna of the continental shelf, the effects of trawling on the upper shelf slope remain unclear and warrant further study.

  14. Redox condition of the late Neoproterozoic pelagic deep ocean: 57Fe Mössbauer analyses of pelagic mudstones in the Ediacaran accretionary complex, Wales, UK

    Science.gov (United States)

    Sato, Tomohiko; Sawaki, Yusuke; Asanuma, Hisashi; Fujisaki, Wataru; Okada, Yoshihiro; Maruyama, Shigenori; Isozaki, Yukio; Shozugawa, Katsumi; Matsuo, Motoyuki; Windley, Brian F.

    2015-11-01

    We report geological and geochemical analysis of Neoproterozoic pelagic deep-sea mudstones in an accretionary complex in Lleyn, Wales, UK. Ocean plate stratigraphy at Porth Felen, NW Lleyn, consists of mid-ocean ridge basalt (> 4 m), bedded dolostone (2 m), black mudstone (5 m), hemipelagic siliceous mudstone (1 m,) and turbiditic sandstone (15 m), in ascending order. The absence of terrigenous clastics confirms that the black and siliceous mudstone was deposited in a pelagic deep-sea. Based on the youngest U-Pb age (564 Ma) of detrital zircons separated from overlying sandstone, the deep-sea black mudstone was deposited in the late Ediacaran. The 5 m-thick black mudstone contains the following distinctive lithologies: (i) black mudstone with thin pyritic layers (0.8 m), (ii) alternation of black mudstone and gray/dark gray siliceous mudstone (2.4 m), (iii) thinly-laminated dark gray shale (1 m), and (iv) black mudstone with thin pyritic layers (1 m). 57Fe Mössbauer spectroscopy confirms that these black mudstones contain pyrite without hematite. In contrast, red bedded claystones (no younger than 542 Ma) in the neighboring Braich section contain hematite as their main iron mineral. These deep-sea mudstones in the Lleyn Peninsula record a change of redox condition on the pelagic deep-sea floor during the Ediacaran. The black mudstone at Porth Felen shows that deep-sea anoxia existed in the late Ediacaran. The eventual change from a reducing to an oxidizing deep-sea environment likely occurred in the late Ediacaran (ca. 564-542 Ma).

  15. Slave to the rhythm: seasonal signals in otolith microchemistry reveal age of eastern Baltic cod (Gadus morhua)

    DEFF Research Database (Denmark)

    Hüssy, Karin; Gröger, J.; Heidemann, F.

    2016-01-01

    Annual growth zones in cod otoliths from the eastern Baltic stock are less discrete than in other cod stocks leading to biased age reading, which recently led to a failure of age-based assessment in the eastern Baltic cod stock. In this study, we explored the applicability of minor and trace elem...

  16. Organic biomarkers in deep-sea regions affected by bottom trawling: pigments, fatty acids, amino acids and carbohydrates in surface sediments from the La Fonera (Palamós Canyon, NW Mediterranean Sea

    Directory of Open Access Journals (Sweden)

    E. Sañé

    2012-12-01

    Full Text Available Deep-sea ecosystems are in general adapted to a limited variability of physical conditions, resulting in high vulnerability and slow recovery rates from anthropogenic perturbations such as bottom trawling. Commercial trawling is the most recurrent and pervasive of human impacts on the deep-sea floor, but studies on its consequences on the biogeochemistry of deep-sea sediments are still scarce. Pigments, fatty acids, amino acids and carbohydrates were analyzed in sediments from the flanks of the La Fonera (Palamós submarine canyon (NW Mediterranean Sea, where a commercial bottom trawling fishery has been active for more than 70 yr. More specifically, we investigated how trawling-induced sediment reworking affects the quality of sedimentary organic matter which reaches the seafloor and accumulates in the sediment column, which is fundamental for the development of benthic communities. Sediment samples were collected during two oceanographic cruises in spring and autumn 2011. The sampled sites included trawl fishing grounds as well as pristine (control areas. We report that bottom trawling in the flanks of the La Fonera Canyon has caused an alteration of the quality of the organic matter accumulated in the upper 5 cm of the seafloor. The use of a wide pool of biochemical tracers characterized by different reactivity to degradation allowed us to discriminate the long-term effects of trawled-induced sediment reworking from the natural variability caused by the seasonal cycle of production and sinking of biogenic particles. Differences between untrawled and trawled areas were evidenced by labile amino acids, while differences between spring and autumn samples were detected only by the more labile indicators chlorophyll a and mono-unsaturated fatty acids. These results suggest that changes in the biochemical composition of the sedimentary organic matter caused by bottom trawling can be more relevant than those associated with natural

  17. Pelagic Nekton Distribution - Improving ecosystem-based fisheries management and integrated ecosystem assessments by linking long-term climatic forcing and the Pelagic Nekton Community in the Northern California Current

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Pelagic nekton communities are among the most ecologically and economically important components of marine ecosystems worldwide. From sardines and anchovies to squid...

  18. Analyses of trawling track and fishing activity based on the data of vessel monitoring system (VMS): A case study of the single otter trawl vessels in the Zhoushan fishing ground

    Science.gov (United States)

    Wang, Yang; Wang, Yingbin; Zheng, Ji

    2015-02-01

    The original purpose of Vessel Monitoring System (VMS) is for enforcement and control of vessel sailing. With the application of VMS in fishing vessels, more and more population dynamic studies have used VMS data to improve the accuracy of fisheries stock assessment. In this paper, we simulated the trawl trajectory under different time intervals using the cubic Hermite spline (cHs) interpolation method based on the VMS data of 8 single otter trawl vessels (totally 36000 data items) fishing in Zhoushan fishing ground from September 2012 to December 2012, and selected the appropriate time interval. We then determined vessels' activities (fishing or non-fishing) by comparing VMS speed data with the corresponding speeds from logbooks. The results showed that the error of simulated trajectory greatly increased with the increase of time intervals of VMS data when they were longer than 30 minutes. Comparing the speeds from VMS with those from the corresponding logbooks, we found that the vessels' speeds were between 2.5 kn and 5.0 kn in fishing. The cHs interpolation method is a new choice for improving the accuracy of estimation of sailing trajectory, and the VMS can be used to determine the vessels' activities with the analysis of their trajectories and speeds. Therefore, when the fishery information is limited, VMS can be one of the important data sources for fisheries stock assessment, and more attention should be paid to its construction and application to fisheries stock assessment and management.

  19. Mercury concentration trend as a possible result of changes in cod population demography.

    Science.gov (United States)

    Ruus, Anders; Hjermann, Dag Ø; Beylich, Bjørnar; Schøyen, Merete; Øxnevad, Sigurd; Green, Norman W

    2017-07-20

    Mercury (Hg) in Atlantic cod (Gadus morhua) is one of many parameters that are monitored through OSPAR's Joint Assessment and Monitoring Programme. Time series for cod in the Inner Oslofjord (Norway) go back to 1984. Until 2014, annual median Hg-concentrations in cod from the Inner Oslofjord showed both significant upward long-term (whole time series) and short-term (recent 10 years) trends (when 2015 was included, the short-term trend was not significant). However, the median length of the cod sampled also showed upward trends. This may have been caused by low cod recruitment in the area since the start of the 2000s, as indicated by beach seine surveys. To investigate how length would impact the trend analysis, the Hg-concentrations in the cod were normalised to 50 cm. No significant short-term trend in Hg-concentrations could be detected for length-normalised concentrations. The results indicated that most of the upward trend in Hg-concentrations could be attributed to the sampling of larger fish. The reasons for the apparent change in the cod population demography are not conclusive, however, sampling bias must also be considered. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. A review of the battle for food in the Barents Sea: Cod vs. marine mammals

    Directory of Open Access Journals (Sweden)

    Bjarte eBogstad

    2015-03-01

    Full Text Available Cod, harp seal and minke whale are the main top predators in the Barents Sea ecosystem. In the last decade, the abundance of cod has increased considerably, and is at a record high level. In spite of this, the growth and condition of cod has remained rather stable, although some decrease is seen in size at age of large, mature cod. During the same period, the abundance of harp seals has declined whereas the minke whale stock has been at a stable level. The body condition (blubber thickness of these two mammal stocks has, however, decreased, with the strongest decrease observed for harp seals. A possible hypothesis for explaining this is that cod outperform the marine mammal stocks in the competition for food. The main advantages for cod are most likely larger availability of food (mainly capelin during winter-spring than for marine mammals, as well as a wider range of prey species being available to cod than to marine mammals. Harp seals are more dependent on prey items found close to the ice edge than the other two predator stocks are, which could partly explain why the performance of harp seals is worse than that of the two other main top predators in the area.

  1. Atlantic Cod (Gadus morhua benefits from the availability of seagrass (Zostera marina nursery habitat

    Directory of Open Access Journals (Sweden)

    Richard J. Lilley

    2014-12-01

    Full Text Available The Atlantic cod (Gadus morhua is a species of significant economic and historic importance but infamous for its decline. Apart from overfishing, the causes of this decline and its subsequent lack of recovery remain largely unresolved. Indeed, the degree to which specific habitats are important for this species remains unquantified at the scale of North Atlantic. Here, the literature on the role of eelgrass meadows (Zostera marina as valuable nursery habitat for the Atlantic cod is reviewed and synthesized. Evidence is presented on relative densities of Atlantic cod in shallow water environments and in eelgrass meadows in comparison to alternative habitats. In addition, evidence pertaining to the ’viability gains’ attributed to the use of eelgrass meadows as nursery habitat (growth and survival by juvenile Atlantic cod is analyzed. Although juvenile Atlantic cod use of Z. marina is found to be facultative, when possible, available literatures indicates that they may select Z. marina as a nursery habitat where they are found in high density (average of at least 246 ha−1. From their use of Z. marina habitat the juvenile Atlantic cod receives viability benefits from it, improving their chances of reaching maturation. This paper provides strong evidence that eelgrass meadows are of significant importance to contributing to Atlantic cod stocks.

  2. Trends in trawl and purse seine catch rates in the north-eastern Mediterranean

    Directory of Open Access Journals (Sweden)

    A. MACHIAS

    2012-12-01

    Full Text Available Data on fishing effort expressed in vessel days at sea and corresponding landing/day for a large number of species have been collected by the Institute of Marine Biological Resources (IMBR since the second half of 1995. Data were collected over a grid of 21 stations throughout the Greek seas. In the present study we analyzed the monthly days at sea as well as catch per day for trawlers and purse seiners from 1996 to 2000, by general linear models and trend analysis. The following vessel size groups per gear were considered: (a trawlers smaller and larger than 20m; (b purse-seiners smaller and larger than 15m. Collected data were also aggregated for five fishing sub-areas: the North Aegean, the Central Aegean, the South Aegean, Cretan waters and the Ionian Sea. Trend analysis of landing/day time series indicated that demersal and pelagic resources are declining in the main fishing grounds. Declining landing/day trends are regarded as indicators of overfishing, especially in the light of the fact that high catch rates are maintained by fishing in ‘hot spots’. The results of the present analysis provide, for the first time, important information on the sustainability of the fisheries in the north-eastern Mediterranean, an area characterized by a complete lack of accurate long-term data on effort and catch per effort

  3. Progress in development of selective shrimp trawls in tropical seawaters%热带海域选择性虾拖网渔具的研究进展

    Institute of Scientific and Technical Information of China (English)

    张健; 石建高; 陈小康

    2011-01-01

    Development of selective shrimp trawl is regarded as one of most promising technical measures to solve the bycatch and discard of shrimp trawling, especially tropic shrimp trawl fisheries, one of the most prominent issues in global marine fisheries. In the southeastern US shrimp trawl fisheries and Australian prawn trawl fisheries,two typical tropic shrimp trawl fisheries, more attention has been paid to development of species selective devices including Turtle Exclusion Devices (TED) and Bycatch Reduction Devices (BRD) than development of size selection, because of the simultaneous existing of bycatch and mortality of large-scale marine organism ( especially sea turtles) and finfish. In this paper, the developmental history of selective shrimp trawls in both fisheries was reviewed and different BRDs and TEDs designs occupied in different periods and regions were summarized and compared. Then the general and special characters of these selective trawls were discussed and some of legal technical conservation measures to reduce bycatch were described. It is considered that the successful experience in development of selective shrimp trawls in tropic shrimp trawls fisheres would be the necessary gist for future research and legislation on selective shrimp trawls in Chinese fisheries.%捕虾拖网,特别是热带海域捕虾拖网渔业的兼捕和抛弃是全球最为突出的渔业问题,而选择性渔具的开发是解决这一问题的主要技术手段.美国东南沿海和澳大利亚沿海对虾拖网渔业是典型的热带海域捕虾拖网渔业,在这些海域的捕虾拖网渔业中,大型海洋生物(海龟)和鱼类兼捕共存的特点使得选择性研究主要是以种类选择性为主,选择性装置研究也主要集中在海龟释放装置(TED)和鱼类兼捕减少装置(BRD)上.通过归纳和对比这两种渔业中所开展的选择性研究,找出选择性虾拖网研究的共性和个性,结合不同渔业中有关兼捕减少的法律法

  4. Threshold-dependent climate effects and high mortality limit recruitment and recovery of the Kattegat cod

    DEFF Research Database (Denmark)

    Lindegren, Martin; Eero, Margit

    2013-01-01

    Cod in the Kattegat is one of the most dramatic examples of stock collapse, where despite large management efforts, almost no signs of recovery have been observed. We investigate how multiple physical and biological factors could potentially influence recruitment and recovery of Kattegat cod, using...... non-additive threshold models. In contrast to previous studies on recruitment dynamics of Kattegat cod Gadus morhua, we found that recruitment variability may be explained by a combination of the size of the spawning stock and external conditions (i.e. sea surface temperature and oxygen concentrations...

  5. Bay-scale population structure in coastal Atlantic cod in Labrador and Newfoundland, Canada

    DEFF Research Database (Denmark)

    Ruzzante, D.E.; Wroblewski, J.S.; Taggart, C.T.;

    2000-01-01

    of population structure suggest that important barriers to gene flow exist among five components that include two inshore (Gilbert and Trinity Bay) and three offshore cod aggregations on the north-east Newfoundland Shelf and the Grand Bank. D-A and D-SW estimates of genetic distance that involve Gilbert Bay cod...... fishery collapse. Harvesting strategies for northern cod should recognize the existence of genetic diversity between inshore and offshore components as well as among coastal components. (C) 2000 The Fisheries Society of the British Isles...

  6. Sensory characteristics of different cod products related to consumer preferences and attitudes

    DEFF Research Database (Denmark)

    Sveinsdottir, K.; Martinsdottir, E.; Green-Petersen, Ditte

    2009-01-01

    to fish consumption, attitudes and preferences of the eight cod products. However, it was demonstrated that within each country, different segments of consumers existed with different preferences, motives/barriers and demographic background. The results indicated various potential to increase fish...... the liking in terms of different consumer attitudes and demographics. The QDA discriminated well between the products. The farmed cod products Were considerably different from wild cod, with More light and even colour, meaty texture, odour and flavour. Country differences were considerable with regard...

  7. Mapping the spawning grounds of North Sea cod ( Gadus morhua ) by direct and indirect means

    DEFF Research Database (Denmark)

    Fox, C.J.; Taylor, M.; Dickey-Collas, M.

    2008-01-01

    Despite recent evidence for sub-stock structuring, North Sea cod are assessed as a single unit. As a consequence, knowledge of sub-stock trends is poor. In particular, there are no recent evaluations of which spawning grounds are active. Here we report results from the first ichthyoplankton survey...... with known spawning locations from the period 1940 to 1970. We were, however, unable to directly detect significant numbers of cod eggs at the historic spawning ground off Flamborough (northeast coast of England). The results demonstrate that most of the major spawning grounds of cod in the North Sea...

  8. Penentuan Kadar COD (Chemical Oxygen Demand) Pada Limbah Cair Pabrik Kelapa Sawit, Pabrik Karet Dan Domestik

    OpenAIRE

    Nurhasanah

    2009-01-01

    Telah dilakukan penentuan kadar COD pada limbah cair pabrik kelapa sawit, industri karet, dan domestik dengan metode titrimetri. Dari hasil analisa COD diperoleh kadar limbah kelapa sawit sebesar 206,33mg/l, limbah industri karet sebesar 31,74 mg/l, dan limbah domestik sebesar 162,68 mg/l. dimana menurut Standart baku mutu yang telah ditetapkan oleh Menteri Lingkungan Hidup Nomor: Kep-51/MENLH/10/1995, kadar maksimum COD dalam air limbah industri kelapa sawit sebesar 350 mg/l, dalam indust...

  9. Biogeography and environmental genomics of the Roseobacter-affiliated pelagic CHAB-I-5 lineage

    DEFF Research Database (Denmark)

    Billerbeck, Sara; Wemheuer, Bernd; Voget, Sonja

    2016-01-01

    The identification and functional characterization of microbial communities remains a prevailing topic in microbial oceanography as information on environmentally relevant pelagic prokaryotes is still limited. The Roseobacter group, an abundant lineage of marine Alphaproteobacteria, can constitut...

  10. 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...

  11. A bio-socioeconomic model for the management of the small pelagic fishery in northwest Peninsular Malaysia

    OpenAIRE

    1993-01-01

    The article was extracted from the author's dissertation entitled "Management of small pelagic fisheries on the northwest coast of Peninsular Malaysia: a bio-socioeconomic simulation analysis". The basic structure and uses of this simulation model are presented here.

  12. Radiation and speciation of pelagic organisms during periods of global warming : the case of the common minke whale, Balaenoptera acutorostrata

    NARCIS (Netherlands)

    Pastene, Luis A.; Goto, Mutsuo; Kanda, Naohisa; Zerbini, Alexandre N.; Kerem, Dan; Watanabe, Kazuo; Bessho, Yoshitaka; Hasegawa, Masami; Nielsen, Rasmus; Larsen, Finn; Palsboll, Per J.

    2007-01-01

    How do populations of highly mobile species inhabiting open environments become reproductively isolated and evolve into new species? We test the hypothesis that elevated ocean-surface temperatures can facilitate allopatry among pelagic populations and thus promote speciation. Oceanographic modelling

  13. A nitrogen and phosphorus dynamic model of mesocosm pelagic ecosystem in the Jiaozhou Bay in China

    Institute of Scientific and Technical Information of China (English)

    LI Keqiang; WANG Xiulin; LIANG Shengkang; SHI Xiaoyong; ZHU Chenjian; CHEN Hu

    2008-01-01

    A nitrogen and phosphorus dynamic model of mesocosm pelagic ecosystem was established according to the summary and synthesis of the models available, in which seven state variables (DIN, PO4-P, DON, DOP, phytoplankton, zooplankton and detritus)were included. Logically it had five modules-phytoplankton, zooplankton, dissolved inorganic nutrients, dissolved organic nutrients and detritus. The results showed that this model could simulate the variations of DIN, PO4-P, DON, DOP, POC and phytoplankton biomass in pelagic ecosystem in mesocosm properly, based on the site experiment data in the Jiaozhou Bay in the autumn of 1999 and the summer of 2000. Not only the logical structure but also the model parameters were feasible, and about 20 parameters were made to fit for the Jiaozhou Bay during the simulation. All of these are necessary to study the control mechanism of nutrients biogeochemical cycling in the Jiaozhou Bay and other China' s coastal waters.

  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. 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

  16. 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.

  17. 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.

  18. Resurrection of the family Aetobatidae (Myliobatiformes) for the pelagic eagle rays, genus Aetobatus.

    Science.gov (United States)

    White, William T; Naylor, Gavin J P

    2016-07-21

    Molecular and morphological data show that the pelagic eagle rays of the genus Aetobatus form a distinct family-level grouping separate from the true eagle rays, Aetomylaeus and Myliobatis (family Myliobatidae). The family Aetobatidae is herein resurrected to include the pelagic eagle rays and definitions are provided for this family and for the Myliobatidae. The key characters separating Aetobatidae from Myliobatidae are: pectoral fins joining head at level of eyes (vs. below level of eyes), internasal flap deeply notched (vs. nearly straight), free rear tip of pectoral fins broadly rounded (vs. angular), spiracles dorsolateral on head and visible in dorsal view (spiracles lateral on head and not visible in dorsal view), dorsal fin with obvious free rear tip (vs. no free rear tip evident, posterior margin joining dorsal surface of tail).

  19. Complete mitochondrial genome of the pelagic stingray Pteroplatytrygon violacea (Myliobatiformes: Dasyatidae).

    Science.gov (United States)

    Yang, Chao-Pin; Zhi, Ting-Ting; Zhang, Shuai; Yan, Shuai; Yang, Tingbao

    2016-01-01

    The pelagic stingray Pteroplatytrygon violacea is the only pelagic species of the Dasyatidae (Chondrichthyes: Elasmobranchii), which is widely distributed in all tropical, subtropical and temperate oceans. In this study, the complete mitochondrial genome of Pteroplatytrygon violacea was determined. It is 17,665 bp in length and contains 13 protein-coding genes, 2 ribosomal RNA genes, 22 transfer RNA genes and 1 control region, with the typical gene order and direction of transcription of vertebrates. The overall nucleotide compositions of the whole mitogenome are 30.8% A, 26.9% C, 28.6% T and 13.7% G. The ND2 and CO1 sequences are highly similar to the corresponding sequences of this species available in NCBI collected from the Atlantic sea.

  20. 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...