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...

FRD Trawl Database

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Fish captured in trawls by the SWFSC Fisheries Resources Division during surveys for coastal pelagic species. Most tows were targeted for sardine using a Nordic...

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

-specific quotas. The toplesstrawl design was developed to improve species-specific selectivity in such fisheries. In a topless trawl,the foot rope is located more forward than the headline to allow fish to escape upwards, whereas theheadline is located in front in traditional trawl designs. In this study we...... Atlantic, topless trawls have been introducedas legal cod-selective trawl designs. However, this study demonstrates that identical gear modificationsmade to similar trawls of different sizes and used in the same fishery can lead to different results....

50 CFR 660.337 - Trawl rationalization program - data collection requirements.

Science.gov (United States)

2010-10-01

... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Trawl rationalization program - data... COAST STATES West Coast Groundfish Fisheries § 660.337 Trawl rationalization program - data collection... guarantee that they will qualify for quota share under a future trawl rationalization program. The following...

77 FR 38266 - Sea Turtle Conservation; Shrimp Trawling Requirements; Public Hearing

Science.gov (United States)

2012-06-27

... withdraw the alternative tow time restriction and require all skimmer trawls, pusher-head trawls, and wing nets (butterfly trawls) rigged for fishing to use turtle excluder devices (TEDs) in their nets, which...

The footprint of bottom trawling in European waters

NARCIS (Netherlands)

Eigaard, Ole R.; Bastardie, Francois; Hintzen, Niels T.; Buhl-Mortensen, Lene; Buhl-Mortensen, Pål; Catarino, Rui; Dinesen, Grete E.; Egekvist, Josefine; Fock, Heino O.; Geitner, Kerstin; Gerritsen, Hans D.; González, Manuel Marín; Jonsson, Patrik; Kavadas, Stefanos; Laffargue, Pascal; Lundy, Mathieu; Gonzalez-Mirelis, Genoveva; Nielsen, J.R.; Papadopoulou, Nadia; Posen, Paulette E.; Pulcinella, Jacopo; Russo, Tommaso; Sala, Antonello; Silva, Cristina; Smith, Christopher J.; Vanelslander, Bart; Rijnsdorp, Adriaan D.

2017-01-01

Mapping trawling pressure on the benthic habitats is needed as background to support an ecosystem approach to fisheries management. The extent and intensity of bottom trawling on the European continental shelf (0-1000 m) was analysed from logbook statistics and vessel monitoring system data for

Optimisation of trawl energy efficiency under fishing effort constraint

OpenAIRE

Priour, Daniel; Khaled, Ramez

2009-01-01

Trawls energy efficiency is greatly affected by the drag, as well as by the swept area. The drag results in an increase of the energy consumption and the sweeping influences the catch. Methods of optimisation of the trawl design have been developed in order to reduce the volume of carburant per kg of caught fish and consequently the drag per swept area of the trawl. Based on a finite element method model for flexible netting structures, the tool modifies step by step a reference design. For e...

Food consumption estimates of Barents Sea harp seals

Directory of Open Access Journals (Sweden)

Kjell T Nilssen

2004-05-01

total consumption, other gadoids (dominated by cod, but also including haddock (Melanogrammus aeglefinus and saithe (Pollachius virens, herring, and "other fish". Using the same set of assumptions as in the previous estimate, the total consumption would have been 3.47 million tonnes, divided between various prey species as follows (in tonnes: polar cod 876,000, codfish (cod, saithe and haddock 359,700, "other fish" 618,800, herring 392,500, and crustaceans 1,204,200. Overall, the largest quantities of food were estimated to be consumed in the period June-September. In 1999, the total Barents Sea harp seal stock size was estimated to be 2.18 (95% CI, 1.79 to 2.58 million animals, which would give an annual food consumption in the range of 2,69 - 3.96 million tonnes (based on upper and lower 95% confidence limits and adjusted for a pup mortality rate of 0.3 if capelin is assumed to be abundant.

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

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

Directory of Open Access Journals (Sweden)

Simon J Allen

Full Text Available 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

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,...

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...

Summer Bottom Trawl Survey

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Sampling the coastal waters of the Gulf of Maine using the Northeast Fishery Science Center standardized bottom trawl has been problematic due to large areas of hard...

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....

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...

Global analysis of depletion and recovery of seabed biota after bottom trawling disturbance.

Science.gov (United States)

Hiddink, Jan Geert; Jennings, Simon; Sciberras, Marija; Szostek, Claire L; Hughes, Kathryn M; Ellis, Nick; Rijnsdorp, Adriaan D; McConnaughey, Robert A; Mazor, Tessa; Hilborn, Ray; Collie, Jeremy S; Pitcher, C Roland; Amoroso, Ricardo O; Parma, Ana M; Suuronen, Petri; Kaiser, Michel J

2017-08-01

Bottom trawling is the most widespread human activity affecting seabed habitats. Here, we collate all available data for experimental and comparative studies of trawling impacts on whole communities of seabed macroinvertebrates on sedimentary habitats and develop widely applicable methods to estimate depletion and recovery rates of biota after trawling. Depletion of biota and trawl penetration into the seabed are highly correlated. Otter trawls caused the least depletion, removing 6% of biota per pass and penetrating the seabed on average down to 2.4 cm, whereas hydraulic dredges caused the most depletion, removing 41% of biota and penetrating the seabed on average 16.1 cm. Median recovery times posttrawling (from 50 to 95% of unimpacted biomass) ranged between 1.9 and 6.4 y. By accounting for the effects of penetration depth, environmental variation, and uncertainty, the models explained much of the variability of depletion and recovery estimates from single studies. Coupled with large-scale, high-resolution maps of trawling frequency and habitat, our estimates of depletion and recovery rates enable the assessment of trawling impacts on unprecedented spatial scales.

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

Directory of Open Access Journals (Sweden)

Shengmao Zhang

Full Text Available 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.

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...

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

Marine AS. The project will examine krill escape mortality from the codend during a full scale field experiment, model size selectivity and escape mortality in codends including different designs and assess the size selectivity in the trawl body forward of the codend. Based on end results from the preceding...... examinations we will be able to predict size selectivity and escape mortality from the entire trawl body with the appurtenant mortality for different trawl designs......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...

Behaviour of fish by-catch in the mouth of a crustacean trawl.

Science.gov (United States)

Queirolo, D; Gaete, E; Montenegro, I; Soriguer, M C; Erzini, K

2012-06-01

The behaviour of fish by-catch was recorded and characterized by in situ observations in the mouth of a crustacean trawl using an underwater camera system with artificial light, at depths between 106 and 461 m, along the central coast of Chile. The groups or species studied were rattails (family Macrouridae), Chilean hake Merluccius gayi gayi, sharks (orders Carcharhiniformes and Squaliformes), skates (family Rajidae), flatfishes (genus Hippoglossina) and small benthopelagic and demersal fishes (orders Osmeriformes, Stomiiformes, Gadiformes, Ophidiiformes and Perciformes). The fish behaviour was categorized in terms of (1) position in the water column, (2) initial orientation with respect to the trawl, (3) locomotion and (4) swimming speed with respect to the trawl. Rattails, sharks, skates and flatfishes were passive in response to the trawl and showed similar behavioural patterns, with most fishes observed sitting or touching the bottom with no swimming or other activity. Merluccius gayi gayi was the most active species, displaying a wide combination of behavioural responses when the trawl approached. This species showed several behavioural patterns, mainly characterized by swimming forward at variable speed. A fraction of small bentho-pelagic and demersal fishes also showed an active behaviour but always at lower speed than the trawl. The species-specific differences in behaviour in the mouth of the trawl suggest that improvements at the level of the footrope can be made to reduce by-catch, especially of passive species. © 2012 The Authors. Journal of Fish Biology © 2012 The Fisheries Society of the British Isles.

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

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...... found with both trawling and eDNA, while three families were found only with eDNA and two families were found only with trawling. Key commercial fish species for Greenland were the most abundant species in both eDNA reads and biomass catch, and interpolation of eDNA abundances between sampling sites...

75 FR 13081 - Fisheries off West Coast States; Pacific Coast Groundfish Fishery; Trawl Rationalization Program

Science.gov (United States)

2010-03-18

... West Coast States; Pacific Coast Groundfish Fishery; Trawl Rationalization Program AGENCY: National... proposed Trawl Rationalization Program. We are interested in feedback concerning proposed regulations to... Pacific Fishery Management Council (Council) has been developing a trawl rationalization program that...

Epibenthic diversity and productivity on a heavily trawled Barents Sea bank (Tromsøflaket

Directory of Open Access Journals (Sweden)

Monika Kędra

2017-04-01

Full Text Available Shallow Arctic banks have been observed to harbour rich communities of epifaunal organisms, but have not been well-studied with respect to composition or function due to sampling challenges. In order to determine how these banks function in the Barents Sea ecosystem, we used a combination of video and trawl/dredge sampling at several locations on a heavily trawled bank, Tromsøflaket – located at the southwestern entrance to the Barents Sea. We describe components of the benthic community, and calculate secondary production of dominant epifaunal organisms. Forty-six epibenthic taxa were identified, and sponges were a significant part of the surveyed benthic communities. There were differences in diversity and production among areas, mainly related to the intensity of trawling activities. Gamma was the most diverse and productive area, with highest species abundance and biomass. Trawled areas had considerably lower species numbers, and significant differences in epifaunal abundance and biomass were found between all trawled and untrawled areas. Trawling seems to have an impact on the sponge communities: mean individual poriferan biomass was higher in untrawled areas, and, although poriferans were observed in areas subjected to more intensive trawling, they were at least five times less frequent than in untrawled areas.

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

The Kattegat in the inner Danish waters has been trawled for at least 80 yr, but so far only few attempts have been made to quantify the trawl effort, its spatial distribution and its potential ecological impact on the benthic fauna. GIS-analyses of VMS-data from trawling in the Kattegat by both ...

North Sea Scyphomedusae; summer distribution, estimated biomass and significance particularly for 0-group Gadoid fish

Science.gov (United States)

Hay, S. J.; Hislop, J. R. G.; Shanks, A. M.

Data on the by-catch of Scyphomedusae from pelagic trawls was collected during the routine ICES International 0-group Gadoid Surveys of the North Sea, in June and July of the years 1971-1986 (except 1984). These data are used to describe the distributions, abundances and biomasses of three common North Sea Scyphomedusae: Aurelia aurita (L.), Cyanea capillata (L.) and C. lamarckii (Péron & Lesuer). Information is also presented on inter-annual variability, size (umbrella diameter) frequencies and, for the Cyanea species, umbrella diameter: wet weight relationships. The general role and ecological significance of Scyphomedusae is discussed and, given the well known 'shelter' relationships between Scyphomedusae and certain 0-group fish, whiting ( Merlangius merlangus) and haddock ( Melanogrammus aeglefinus), in particular. The data were examined for evidence of such relationships. Aurelia aurita, although fairly widespread in the northern North Sea was virtually absent from the central North Sea but very abundant in coastal waters. This species was particularly abundant off the Scottish east coast and especially in the Moray Firth. Cyanea lamerckii was most abundant in the southern and eastern North Sea. More widespread than Aurelia, this species was also most abundant in coastal regions, particularly off the Danish west coast. Cyanea capillata, with a more northern distribution was also more widely distributed and abundant offshore. This species was most abundant in the area between the Orkney/Shetland Isles and the Norwegian Deep and in shelf waters of the north west approaches to the North Sea. As with C. lamarckii it was also, in some years, abundant off the Scottish east coast and west of Denmark. The abundance and the size frequency of the jellyfish show considerable inter-annual variability, and variability between regions of the North Sea. It is considered that hydrographic variability and differences in food supply to both medusae and to their sessile

77 FR 66577 - Fisheries Off West Coast States; Pacific Coast Groundfish Fishery; Trawl Rationalization Program...

Science.gov (United States)

2012-11-06

...-XC165 Fisheries Off West Coast States; Pacific Coast Groundfish Fishery; Trawl Rationalization Program... implemented as part of the trawl rationalization program. FOR FURTHER INFORMATION CONTACT: Jamie Goen, phone..., NMFS implemented a trawl rationalization program, a catch share program, for the Pacific coast...

FLEXSELECT: counter-herding device to reduce bycatch in crustacean trawl fisheries

DEFF Research Database (Denmark)

Melli, Valentina; Karlsen, Junita Diana; Feekings, Jordan P.

2018-01-01

FLEXSELECT is a simple counter-herding device which aims at reducing the bycatch of fish by scaring them away from the trawl path without affecting the catches of the target species. FLEXSELECT was tested in the Norway lobster (Nephrops norvegicus) directed trawl fishery, as this includes bycatch...

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

Science.gov (United States)

Hinz, Hilmar; Moranta, Joan; Balestrini, Stephen; Sciberras, Marija; Pantin, Julia R; Monnington, James; Zalewski, Alex; Kaiser, Michel J; Sköld, Mattias; Jonsson, Patrik; Bastardie, Francois; Hiddink, Jan Geert

2017-07-24

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 may both negatively and positively influence the quantity and quality of food available. Using δ 13 C and δ 15 N we investigated potential diet changes of three commercially exploited species across trawling gradients in the Kattegat (plaice, dab and Norway lobster (Nephrops)) and the Irish Sea (Nephrops). In the Kattegat, trawling affected primarily the biomass of benthic consumers, lowering competition. Nephrops showed significant positive relationships for δ 13 C and a domed relationship for δ 15 N with trawling. In the Irish Sea, intense trawling had a negative effect on benthic prey. δ 13 C and δ 15 N thus showed the inverse relationships to those observed in the Kattegat. Plaice from the Kattegat, showed a significant relationship with trawling intensity for δ 13 C, but not for δ 15 N. No relationship was found for dab. Changes of δ 13 C and δ 15 N correlated with changes in condition of species. The results show that the removal of demersal competitors and benthos by trawling can change the diets of commercial species, ultimately affecting their body condition.

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...

Deep-Sea Mega-Epibenthic Assemblages from the SW Portuguese Margin (NE Atlantic Subjected to Bottom-Trawling Fisheries

Directory of Open Access Journals (Sweden)

Sofia P. Ramalho

2017-11-01

Full Text Available Bottom-trawling fisheries are a common threat to the health of continental margins worldwide. Together with numerous environmental and biological processes, physical disturbance induced by trawlers can largely shape the benthic habitats and their associated assemblages. At the SW Portuguese Margin, crustacean bottom trawlers have exploited deep-sea habitats for a few decades, but its effects on the benthic biodiversity are practically unknown. During the spring-summer of 2013 and 2014, several Remotely Operated Vehicle (ROV video transects were used to investigate mega-epibenthic abundance, composition, and diversity in soft-sediment areas subjected to varying trawling pressures off Sines and Setúbal (200–800 m. Differences in mega-epibenthic assemblages were linked with environmental changes (depth, grain size, primary productivity and trawling disturbance. The effect of trawling was assessed between segments with similar habitat characteristics, i.e., muddy-sand bottoms between 300 and 500 m. Areas subjected to intensive trawling pressure showed a generally flattened seabed, with abundant recent trawl marks (up to 3 scars.100 m−1, indicating that the seabed physical integrity was compromised. Significant negative correlations were detected between various mega-epibenthic diversity indices [S, H′, and ET(20] and trawling pressure (h.cell−1.y−1. Furthermore, the distinct mega-epibenthic assemblages and absence of several sessile erect morphospecies at both low and highly disturbed locations by trawling off Sines, namely all seapen morphospecies found in non-trawled areas, demonstrates the negative influence of trawling fisheries on the benthic component of the study area. Also, low dissimilarity between assemblages from the main fishing grounds and the adjacent low-disturbance locations, suggests that the potentially negative influence of trawling can extend beyond the targeted areas (e.g., by the plumes of re-suspended sediments. The

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.

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 it i...

Impacts of Bottom Trawling and Litter on the Seabed in Norwegian Waters

Directory of Open Access Journals (Sweden)

Pål Buhl-Mortensen

2018-02-01

Full Text Available Bottom trawling and seabed littering are two serious threats to seabed integrity. We present an overview of the distribution of seabed litter and bottom trawling in Norwegian waters (the Norwegian Sea and the southern Barents Sea. Vessel Monitoring System (VMS records and trawl marks (TM on the seabed were used as indicators of pressure and impact of bottom trawling, respectively. Estimates of TM density and litter abundance were based on analyses of seabed videos from 1,778 locations, surveyed during 23 cruises, part of the Norwegian seabed mapping programme MAREANO. The abundance and composition of litter and the density of TM varied with depth, and type of sediments and marine landscapes. Lost or discarded fishing gear (especially lines and nets, and plastics (soft and hard plastic and rubber were the dominant types of litter. The distribution of litter reflected the distribution of fishing intensity (density of VMS records and density of TM at a regional scale, with highest abundance close to the coast and in areas with high fishing intensity, indicated from the VMS data. However, at a local scale patterns were less clear. An explanation to this could be that litter is transported with currents and accumulates in troughs, canyons, and local depressions, rather than reflecting the fisheries footprints directly. Also, deliberate dumping of discarded fishing gear is likely to occur away from good fishing grounds. Extreme abundance of litter, observed close to the coast is probably caused by such discarded fishing gear, but the contribution from aggregated populations on land is also indicated from the types of litter observed. The density of trawl marks is a good indicator of physical impact in soft sediments where the trawl gear leaves clear traces, whereas on harder substrates the impacts on organisms is probably greater than indicated by the hardly visible marks. The effects of litter on benthic communities is poorly known, but large litter

A geostatistical analysis of IBTS data for age 2 North Sea haddock ( Melanogrammus aeglefinus ) considering daylight effects

DEFF Research Database (Denmark)

Wieland, Kai; Rivoirard, J.

2001-01-01

to ordinary kriging being most pronounced for years characterized by a high portion of night hauls and a low mean catch rate at night. This demonstrates that external drift kriging with a day/night indicator but preferably with time of day is capable of compensating successfully for daylight effects...... are included in the estimation without any correction for possible daylight effects. In the present study, ordinary kriging was used to correct for sampling irregularities and external drift kriging with a day/night indicator or a cosine function of time of day was applied to account additionally for diurnal...... differences in the catch rates. Only minor differences between the standard indices and the abundance estimates obtained by ordinary kriging were found. In contrast, the external drift kriging, particularly with time of day, yielded higher estimates of mean abundance for all years with the differences...

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 retained...

Configuring the Mesh Size, Side Taper and Wing Depth of Penaeid Trawls to Reduce Environmental Impacts

Science.gov (United States)

Broadhurst, Matt K.; Sterling, David J.; Millar, Russell B.

2014-01-01

The effects of reducing mesh size while concomitantly varying the side taper and wing depth of a generic penaeid-trawl body were investigated to improve engineering performance and minimize bycatch. Five trawl bodies (with the same codends) were tested across various environmental (e.g. depth and current) and biological (e.g. species and sizes) conditions. The first trawl body comprised 41-mm mesh and represented conventional designs (termed the ‘41 long deep-wing'), while the remaining trawl bodies were made from 32-mm mesh and differed only in their side tapers, and therefore length (i.e. 1N3B or ‘long’ and ∼28o to the tow direction vs 1N5B or ‘short’ and ∼35o) and wing depths (‘deep’–97 T vs ‘shallow’–60 T). There were incremental drag reductions (and therefore fuel savings – by up to 18 and 12% per h and ha trawled) associated with reducing twine area via either modification, and subsequently minimizing otter-board area in attempts to standardize spread. Side taper and wing depth had interactive and varied effects on species selectivity, but compared to the conventional 41 long deep-wing trawl, the 32 short shallow-wing trawl (i.e. the least twine area) reduced the total bycatch by 57% (attributed to more fish swimming forward and escaping). In most cases, all small-meshed trawls also caught more smaller school prawns Metapenaeus macleayi but to decrease this effect it should be possible to increase mesh size slightly, while still maintaining the above engineering benefits and species selectivity. The results support precisely optimizing mesh size as a precursor to any other anterior penaeid-trawl modifications designed to improve environmental performance. PMID:24911786

trawl codends for blue whiting (Micromesistius

African Journals Online (AJOL)

Administrator

2010-12-27

Dec 27, 2010 ... Page 1 ... landing size; PE, polyethylene; PA, polyamide; LSMTPC, large square mesh top panel codend; SR, selection range. taceans by traditional Mediterranean trawls in seasonal .... Size structure of the population indicated retaining (thin line), escaping. (broken line) and entering (thick line) from the ...

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.

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

NARCIS (Netherlands)

Denderen, van Daniel; Bolam, Stefan G.; Hiddink, Jan Geert; Jennings, Simon; Kenny, Andrew; Rijnsdorp, Adriaan D.; Kooten, Van Tobias

2015-01-01

Bottom trawl fishing has widespread impacts on benthic habitats and communities. The benthic response to trawling seems to be smaller or absent in areas exposed to high natural disturbance, leading to the hypothesis that natural and trawl disturbance affect benthic communities in a similar way.

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...

Environmental DNA from Seawater Samples Correlate with Trawl Catches of Subarctic, Deepwater Fishes.

Directory of Open Access Journals (Sweden)

Philip Francis Thomsen

Full Text Available 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 found with both trawling and eDNA, while three families were found only with eDNA and two families were found only with trawling. Key commercial fish species for Greenland were the most abundant species in both eDNA reads and biomass catch, and interpolation of eDNA abundances between sampling sites showed good correspondence with catch sizes. Environmental DNA sequence reads from the fish assemblages correlated with biomass and abundance data obtained from trawling. Interestingly, the Greenland shark (Somniosus microcephalus showed high abundance of eDNA reads despite only a single specimen being caught, demonstrating the relevance of the eDNA approach for large species that can probably avoid bottom trawls in most cases. Quantitative detection of marine fish using eDNA remains to be tested further to ascertain whether this technique is able to yield credible results for routine application 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

Bycatch in 36 and 40 mm PA Turkish twin rigged beam trawl codends

African Journals Online (AJOL)

The Turkish twin rigged beam trawl which has two identical nets rigged side by side on the same beam targets mainly the Parapenaeus longirostris, although some bycatch fish species have also become target species. Thus, landings of the shrimp beam trawling fleet also include some commercially valuable fishes.

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

The paper develops a biological-economic evaluation tool to analyse the consequences for trawl fishers of implementing more selective fishing technologies. This is done by merging a dynamic biological population model and an economic cost-benefit evaluation framework to describe the consequences...... 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...... 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 byratches of several species. Four different kinds of selectivity scenarios are evaluated in comparison...

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

The paper develops a biological-economic evaluation tool to analyse the consequences for trawl fishers of implementing more selective fishing technologies. This is done by merging a dynamic biological population model and an economic cost-benefit evaluation framework to describe the consequences...... 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...... 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...

Quantity and biochemical composition of particulate organic matter in a highly trawled area (Thermaikos Gulf, Eastern Mediterranean Sea

Directory of Open Access Journals (Sweden)

Antonio Pusceddu

2015-11-01

Full Text Available Bottom trawling represents nowadays one of the most severe anthropogenic disturbances at sea, and determines large impacts on benthic communities and processes. Bottom trawling determines also local sediment resuspension and the effects of the injection of large amounts of surface sediments into the water column have been repeatedly investigated. Few studies have assessed the consequences of sediment resuspension caused by bottom trawling on the quantity, biochemical composition and bioavailability of suspended organic particles and how these eventually rival those exerted by natural storms. To provide insights on this poorly addressed issue, we investigated concentrations and biochemical composition of total and enzymatically digestible pools of particulate organic matter (POM in the Thermaikos Gulf (Mediterranean Sea under calm sea conditions, during intensive trawling activities, and after a severe storm. We show here that sediment resuspension caused by trawling can cause large effects on POM quantity, biochemical composition and bioavailability. Both during trawling and after the storm, the relative importance of the carbohydrate pools increased (in the upper water column and the total lipid concentrations decreased (in the intermediate and bottom layers when compared to values measured during calm conditions. These results would suggest that bottom trawling could inject in the upper water column POM pools more refractory in nature (e.g., carbohydrates than those present in calm or after-storm conditions. By contrast, we show also that the bioavailable fraction of biopolymeric C increased significantly during trawling in the upper water column of the shallowest stations and in the bottom water column layer of the deepest ones. These results provide evidence that bottom trawling can influence the overall trophic status of coastal waters, exerting effects similar or stronger than those caused by natural storms, though of variable amplitude

78 FR 40435 - Proposed Information Collection; Comment Request; Gulf of Alaska Trawl Fishery, Rationalization...

Science.gov (United States)

2013-07-05

... Collection; Comment Request; Gulf of Alaska Trawl Fishery, Rationalization Sociocultural Study AGENCY... management actions requiring equivalent information. Fisheries rationalization programs have an impact on... the implementation of a new, yet to be defined, rationalization program for the Gulf of Alaska trawl...

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

pressure. 2. We assessed the impact of bottom trawling on the food availability, condition and stomach contents of three flatfishes and the Norway lobster in an area in the Kattegat hat is characterized by a steep commercial bottom-trawling gradient due to the establishment of an area closed to all....... This pattern was mirrored in both the condition and stomach contents of plaice and for long-rough dab. 4. No effect of trawling on dab prey and condition was found. Conversely, the condition of the main target species – Norway lobster – increased as its biomass decreased with increased trawling intensities. 5...

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...

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.

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...

Underwater sound from vessel traffic reduces the effective communication range in Atlantic cod and haddock.

Science.gov (United States)

Stanley, Jenni A; Van Parijs, Sofie M; Hatch, Leila T

2017-11-07

Stellwagen Bank National Marine Sanctuary is located in Massachusetts Bay off the densely populated northeast coast of the United States; subsequently, the marine inhabitants of the area are exposed to elevated levels of anthropogenic underwater sound, particularly due to commercial shipping. The current study investigated the alteration of estimated effective communication spaces at three spawning locations for populations of the commercially and ecologically important fishes, Atlantic cod (Gadus morhua) and haddock (Melanogrammus aeglefinus). Both the ambient sound pressure levels and the estimated effective vocalization radii, estimated through spherical spreading models, fluctuated dramatically during the three-month recording periods. Increases in sound pressure level appeared to be largely driven by large vessel activity, and accordingly exhibited a significant positive correlation with the number of Automatic Identification System tracked vessels at the two of the three sites. The near constant high levels of low frequency sound and consequential reduction in the communication space observed at these recording sites during times of high vocalization activity raises significant concerns that communication between conspecifics may be compromised during critical biological periods. This study takes the first steps in evaluating these animals' communication spaces and alteration of these spaces due to anthropogenic underwater sound.

78 FR 3848 - Fisheries Off West Coast States; Pacific Coast Groundfish Fishery; Trawl Rationalization Program...

Science.gov (United States)

2013-01-17

... Rationalization Program; Emergency Rule Extension AGENCY: National Marine Fisheries Service (NMFS), National... Coast Groundfish Fishery Trawl Rationalization Program (program) regulations. This emergency rule... trawl rationalization program. Background on this rule was provided in the proposed rule, published on...

Recovery of Seamount Precious Coral Beds From Heavy Trawling Disturbance with Links to Carbonate Chemistry Changes

Science.gov (United States)

Roark, E. B.; Baco-Taylor, A.; Morgan, N. B.; Shamberger, K.; Miller, K.; Brooks, J.

2016-12-01

Increasing anthropogenic impacts in the deep sea make studies of resilience and recovery time critical, with deep-sea hard-substrate habitats and large-scale disturbances having received little attention. Seamount hard-substrate habitats in particular are thought to have low resilience due to the slow growth rates and recruitment limitations of key structure-forming taxa. Seamounts of the far Northwestern Hawaiian Islands and Emperor Chain have had some of the heaviest trawl impacts in the world, from both fish and precious coral fisheries, and include sites that are still trawled and recovering ones that have been protected since establishment of the EEZ in 1977. To test the hypothesis of low resilience we compare these impacted seamounts to untrawled sites. We used the AUV Sentry in 2014 and 2015 to image nine features (three per "treatment") and analyze for substrate and visible megafauna. Sites in the "still trawled" treatment were characterized by extensive areas of bare substrate with abundant trawl scars. Sites in the "recovering" and "never trawled" locations had abundant megafauna in hard substrate areas. Initial comparisons of transects at 700m depth for three sites indicate that Yuryaku in the "still trawled" treatment had lower diversity and abundance of megafauna compared to the "recovering" and "never trawled" locations with a dominance of sea urchins. The "recovering" and "never trawled" sites were dominated by cnidarians, fishes, and echinoderms, but differed in dominant species, diversity, abundances and occurrence of dead coral skeletons. These preliminary results suggest that the recovering sites have not returned to a pre-impact community type in the 38 years since they were trawled. The megafauna distribution, in particular that of deep-sea corals, was compared to environmental water column variables at the study sites across the Northwestern Hawaiian Islands. Deep-sea corals with calcium carbonate skeletons were found living below the

The NSW Steam Trawl Fishery on the South-East Continental Shelf of Australia, 1915-1961

DEFF Research Database (Denmark)

Jacobsen, A. Lif Lund

2014-01-01

How was modern fishing methods, in the form of steam trawling, introduced in Australia? And what were the consequences for the fish stocks found on the South-East Continental Shelf? Through historical catch records and archival resources, the history of the NSW Steam Trawl Industry from 1915...... that flathead biomass on the South-East Continental shelf was permanently reduced. The study furthermore reveals how the trawl industry was influenced by government policy, market conditions, war and fishing effort with little understanding of the marine resources which they relied on....

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

DEFF Research Database (Denmark)

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

2017-01-01

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...... of individuals per sample (density), we expect species density and density to be positively correlated. This correlation was confirmed by a simulation model and by statistical analysis of the bottom samples in which log species density was highly significantly related to log density (r = 0.75, df = 144, p ...

trawl bycatch in the fishing grounds of Bus

African Journals Online (AJOL)

ajl yemi

2011-11-30

. Biol. 86: 1455-1462. Watson RA, Dredge MLC, Mayer DG (1990). Spatial and seasonal variation in demersal trawl fauna associated with a prawn fishery on the CentralGreat Barrier Reef, Australia. Aust. J. Mar. Freshw. Res.

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.

78 FR 75268 - Fisheries Off West Coast States; Pacific Coast Groundfish Fishery; Trawl Rationalization Program...

Science.gov (United States)

2013-12-11

... Rationalization Program; Cost Recovery AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and... recovery program for the Pacific coast groundfish trawl rationalization program, as required by the...). Allocations to the limited entry trawl fleet for certain species were developed through a parallel process...

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...

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.T.

The present communication is a study on the impact of bottom trawling on the sediment characteristics along Veraval coast, which is the largest trawler port of India. Experimental bottom trawling was conducted from MFV Sagarkripa at five transects...

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 (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 than under severe hypoxia. These statistically significant trends demonstrate that the structuring influences of bottom trawling on deep-sea benthic communities can be observed even where communities are being shaped by strong environmental gradients.

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

2018-03-01

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.

Precision in systematic trawl surveys as assessed from replicate ...

African Journals Online (AJOL)

Local variability was analysed as random noise, modelled and later reapplied ... The main statistical techniques applied were less susceptible to outlier catches ... be used to estimate the vessel factor when intercalibrating trawl survey vessels.

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

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......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...

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. Copyright © 2014 Elsevier B.V. All rights reserved.

The NSW Steam Trawl Fishery on the South-East Continental Shelf of Australia, 1915–1961

DEFF Research Database (Denmark)

Lund Jacobsen, A. Lif

2014-01-01

How was modern fishing methods, in the form of steam trawling, introduced in Australia? And what were the consequences for the fish stocks found on the South-East Continental Shelf? Through historical catch records and archival resources, the history of the NSW Steam Trawl Industry from 1915...

75 FR 4684 - Fisheries off West Coast States; Pacific Coast Groundfish Fishery; Data Collection for the Trawl...

Science.gov (United States)

2010-01-29

... Coast groundfish fishery. The trawl rationalization program is intended to increase net economic benefits, create individual economic stability, provide full utilization of the trawl sector allocation... one time reporting will have a significant economic impact on small entities, as the estimated...

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...

Modelling and simulation of size selectivity in diamond mesh trawl cod-ends

DEFF Research Database (Denmark)

Herrmann, Bent

of the fishing gear. The cod-end is the rearmost part of a trawl where catch accumulates and in which most of the size selection is known to take place. To date, the main method used to assess the selectivity of trawl cod-ends has been to run sea trials followed by statistical analysis of the obtained......Within many fisheries there is a widespread discard of fish. Furthermore, there are several fisheries where fish are caught before reaching the optimal size, leading to an adverse exploitation of the resources. One way to achieve a more optimal exploitation is to improve the size selectivity...

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....

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....

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....

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....

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....

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....

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....

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....

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....

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....

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....

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....

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....

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....

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....

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....

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....

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....

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....

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....

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....

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....

NEFSC 2016 Fall Bottom Trawl Survey (HB1604, 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....

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....

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....

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....

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....

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....

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....

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....

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....

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....

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....

NEFSC 2016 Spring Bottom Trawl Survey (HB1601, 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....

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....

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.

Parasites as biological tags in marine fisheries research: European Atlantic waters.

Science.gov (United States)

Mackenzie, K; Hemmingsen, W

2015-01-01

Studies of the use of parasites as biological tags for stock identification and to follow migrations of marine fish, mammals and invertebrates in European Atlantic waters are critically reviewed and evaluated. The region covered includes the North, Baltic, Barents and White Seas plus Icelandic waters, but excludes the Mediterranean and Black Seas. Each fish species or ecological group of species is treated separately. More parasite tag studies have been carried out on Atlantic herring Clupea harengus than on any other species, while cod Gadus morhua have also been the subject of many studies. Other species that have been the subjects of more than one study are: blue whiting Micromesistius poutassou, whiting Merlangius merlangus, haddock Melanogrammus aeglefinus, Norway pout Trisopterus esmarkii, horse mackerel Trachurus trachurus and mackerel Scomber scombrus. Other species are dealt with under the general headings redfishes, flatfish, tunas, anadromous fish, elasmobranchs, marine mammals and invertebrates. A final section highlights how parasites can be, and have been, misused as biological tags, and how this can be avoided. It also reviews recent developments in methodology and parasite genetics, considers the potential effects of climate change on the distributions of both hosts and parasites, and suggests host-parasite systems that should reward further research.

Drone Use in Monioring Open Ocean Surface Debris, Including Paired Manta and Tucker Trawls for Relateing Sea State to Vertical Debris Distribution

Science.gov (United States)

Lattin, G.

2016-02-01

Monitoring debris at sea presents challenges not found in beach or riverine habitats, and is typically done with trawl nets of various apertures and mesh sizes, which limits the size of debris captured and the area surveyed. To partially overcome these limitations in monitoring floating debris, a Quadcopter drone with video transmitting and recording capabilities was deployed at the beginning and the end of manta trawl transects within the North Pacific Subtropical Gyre's eastern convergence zone. Subsurface tucker trawls at 10 meters were conducted at the same time as the manta trawls, in order to assess the effect of sea state on debris dispersal. Trawls were conducted on an 11 station grid used repeatedly since 1999. For drone observations, the operator and observer were stationed on the mother ship while two researchers collected observed debris using a rigid inflatable boat (RIB). The drone was flown to a distance of approximately 100 meters from the vessel in a zigzag or circular search pattern. Here we examine issues arising from drone deployment during the survey: 1) relation of area surveyed by drone to volume of water passing through trawl; 2) retrieval of drone-spotted and associated RIB spotted debris. 3) integrating post- flight image analysis into retrieved debris quantification; and 4) factors limiting drone effectiveness at sea. During the survey, debris too large for the manta trawl was spotted by the drone, and significant debris not observed using the drone was recovered by the RIB. The combination of drone sightings, RIB retrieval, and post flight image analysis leads to improved monitoring of debris at sea. We also examine the issue of the distribution of floating debris during sea states varying from 0-5 by comparing quantities from surface manta trawls to the tucker trawls at a nominal depth of 10 meters.

A knowledge platform to inform on the effects of trawling on benthic communities

Science.gov (United States)

Muntadas, Alba; Lample, Michel; Demestre, Montserrat; Ballé-Béganton, Johanna; de Juan, Silvia; Maynou, Francesc; Bailly, Denis

2018-02-01

For a successful implementation of an Ecosystem Approach to Fisheries (EAF) management, it is necessary that all stakeholders involved in fisheries management are aware of the implications of fishing impacts on ecosystems and agree with the adopted measures to mitigate these impacts. In this context, there is a need for tools to share knowledge on the ecosystem effects of fisheries among these stakeholders. When managing bottom trawl fisheries under an EAF framework, one of the main concerns is the direct and indirect consequences of trawling impacts on benthic ecosystems. We developed a platform using the ExtendSim® software with a user-friendly interface that combines a simulation model based on existing knowledge, data collection and representation of predicted trawling impacts on the seabed. The platform aims to be a deliberation support tool for fisheries' stakeholders and, simultaneously, raise public awareness of the need for good benthic community knowledge to appropriately inform EAF management plans. The simulation procedure assumes that trawling affects benthic communities with an intensity that depends on the level of fishing effort exerted on benthic communities and on the habitat characteristics (i.e. sediment grain size). Data to build the simulation comes from epifaunal samples from 18 study sites located in Mediterranean continental shelves subjected to different levels of fishing effort. In this work, we present the simulation outputs of a 50% fishing effort increase (and decrease) in four of the study sites which cover different habitats and different levels of fishing effort. We discuss the platform strengths and weaknesses and potential future developments.

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,...

76 FR 57679 - Fisheries of the Exclusive Economic Zone Off Alaska; Shallow-Water Species by Vessels Using Trawl...

Science.gov (United States)

2011-09-16

.... 101126522-0640-02] RIN 0648-XA704 Fisheries of the Exclusive Economic Zone Off Alaska; Shallow- Water... closure. SUMMARY: NMFS is opening directed fishing for shallow-water species by vessels using trawl gear... apportionment of the 2011 Pacific halibut bycatch allowance specified for the trawl shallow-water species...

75 FR 56017 - Fisheries of the Exclusive Economic Zone Off Alaska; Shallow-Water Species by Vessels Using Trawl...

Science.gov (United States)

2010-09-15

.... 0910131362-0087-02] RIN 0648-XZ06 Fisheries of the Exclusive Economic Zone Off Alaska; Shallow- Water Species... closure. SUMMARY: NMFS is opening directed fishing for shallow-water species by vessels using trawl gear... of the 2010 Pacific halibut bycatch allowance specified for the trawl shallow-water species fishery...

Assessing and mitigating of bottom trawling. Final BENTHIS project Report (Benthic Ecosystem Fisheries Impact Study)

DEFF Research Database (Denmark)

Rijnsdorp, Adriaan D; Eigaard, Ole Ritzau; Kenny, Andrew

2017-01-01

the fuel cost without affecting the catch rate of the target species. Replacing mechanical stimulation by tickler chains with electrical stimulation In the beam trawl fishery for sole, reduced footprint and penetration depth as well as the fuel cost. Electrical stimulation is also a promising innovation...... to reduce the bycatch and bottom contact in the beam trawl fishery for brown shrimps. Sea trials to replace bottom trawls with pots were inconclusive. Results suggest that creels may offer an alternative for small Nephrops fishers in the Kattegat. In waters off Greece, the catch rates were very low. Sea...... trials with the blue mussel fishery showed that fishers could reduce their footprint by deploying acoustic equipment to detect mussel concentrations that allow the fishers to more precisely target the mussel beds and hence reduce fishing in areas with low mussel density. A review of the various case...

Spring Coastal Pelagic Species Acoustic Trawl Survey (SH1404, EK60)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — 14 Acoustic transects were run offshore of Southern California between San Francisco and Cape Mendocino, CA with CTD casts conducted daily and trawls nightly based...

Trawl survey data are applied in fish stock assessment mainly to ...

African Journals Online (AJOL)

denise

Merluccius capensis (shallow-water Cape hake) and. M. paradoxus (deep-water Cape hake) off Namibia provide an ... published data), meaning that the horizontal trawl opening will .... Acoustic data were post-processed twice daily. Hake.

Bycatch of crustacean and fish bottom trawl fisheries from southern Portugal (Algarve

Directory of Open Access Journals (Sweden)

Maria Esmeralda Costa

2008-12-01

Full Text Available As part of two research projects for analysing bycatch and discards, we quantified catch composition, catch rates, bycatch and discards in two important commercial bottom trawl fisheries (crustacean and fish trawls off the southern coast of Portugal (Algarve. Stratified sampling by onboard observers took place from February 1999 to March 2001 and data were collected from 165 tows during 52 fishing trips. Commercial target species included crustaceans: blue and red shrimp (Aristeus antennatus, deep-water rose shrimp (Parapenaeus longirostris, Norway lobster (Nephrops norvegicus; and fishes: seabreams (Diplodus spp. and Pagellus spp., horse mackerels (Trachurus spp. and European hake (Merluccius merluccius. The trawl fisheries are characterised by considerable amounts of bycatch: 59.5% and 80.4% of the overall total catch for crustacean and fish trawlers respectively. A total of 255 species were identified, which belonged to 15 classes of organisms (137 vertebrates, 112 invertebrates and 6 algae. Crustacean trawlers had higher bycatch biodiversity. Bony fish (45.6% and 37.8% followed by crustaceans (14.6% and 11.5% were the dominant bycatch components of both crustacean and fish trawlers respectively. The influence of a number of factors (e.g. depth, fishing gear, tow duration and season on bycatch and discards is discussed.

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...

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.

Job satisfaction in the shrimp trawl fisheries of Chennai, India

NARCIS (Netherlands)

Bavinck, M.

2012-01-01

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

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

such as logbook data. Here, we take a different approach starting from the gear itself (design and dimensions) to estimate the physical interactions with the seabed at the level of the individual fishing operation. We defined 14 distinct towed gear groups in European waters (eight otter trawl groups, three beam...... 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...... to enable the prediction of gear footprint area and sediment penetration from vessel size. Application of these relationships with average vessel sizes and towing speeds provided hourly swept-area estimates by métier. Scottish seining has the largest overall gear footprint of ∼1.6 km2 h−1 of which 0.08 km2...

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...

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...

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…

Final report of the Working Group on electrical Trawling

NARCIS (Netherlands)

Haan, de D.; Molenaar, P.; Rijnsdorp, A.D.; Steenbergen, J.; Marlen, van B.

2017-01-01

WGELECTRA met three times (22–24/10/2014; 10–12/11/2015, and 17–19/01/2017) to discuss the ongoing research projects in Belgium, the Netherlands, and Germany and provide an overview of the state of the art knowledge of the ecological effects. Pulse trawls are used in the North Sea fishery for

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...

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...

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...

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…

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...

Comparative distribution of the fan mussel Atrina fragilis (Bivalvia, Pinnidae in protected and trawled areas of the north Aegean Sea (Thermaikos Gulf

Directory of Open Access Journals (Sweden)

K. FRYGANIOTIS

2013-02-01

Full Text Available The distribution of the fan mussel Atrina fragilis was studied at two contrasting areas of the north Aegean Sea (Thermaikos Gulf: one routinely trawled and one closed to trawlers for over 25 years. Significant differences were detected between the two areas with decreased values in density and size of A. fragilis individuals at the trawled area. As habitat differences, i.e. sediment composition and bathymetry, had non-significant effect, extensive trawling activities probably explain the observed results.

SWFSC FED Mid Water Trawl Juvenile Rockfish Survey, Surface Data, 1987-2015

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...

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...

Hydrodynamic characteristics of the oval cambered double slotted otter board in bottom trawl fisheries

Science.gov (United States)

Liu, J.; Huang, H. L.; Li, L. Z.; Qu, T. C.; Wu, Y.; Chen, S.; Yang, J. L.; Rao, X.

2017-07-01

The otter board is one of the main components of single boat trawl fisheries. An oval cambered double slotted otter board was developed for improving the expansion performance of trawl net in bottom trawl fisheries. A flume model experiment was conducted to measure the lift coefficient (C L), drag coefficient (C D), and lift to drag ratio (K) in different angles of attack (α). The experimental results are as follows : (1) The C L and K value show a trend of increasing at the beginning and then decreasing with the increase of angle of attack, the C D value reflects an upward trend as the angle of attack increases; (2) The D3 otter board (front flow deflector angle at 29°) showed a better hydrodynamic performance. When α=30°, the max lift coefficient (C Lmax) was 1.464, in this case C D = 0.554 and K=2.643. When α=15°, the max lift to drag ratio (K max) was 4.165, C L =0.633, and C D = 0.152. This suggests that the best working scope for the angle of attack is between 15°~30°, in which case, C L>0.633 and K>2.643. The mean value of the lift coefficient was 1.071 and the mean of the lift to drag ratio was 3.482. Comparative analysis of the hydrodynamic performance of different types of otter boards showed that the D3 otter board both had good expansion performance and efficiency, which can provide a reference basis for further optimization of the bottom trawl otter board.

SWFSC FED Mid Water Trawl Juvenile Rockfish Survey, CTD Data, 1987-2015

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...

50 CFR 660.381 - Limited entry trawl fishery management measures.

Science.gov (United States)

2010-10-01

... or tied along the length of the footrope). Other lines or ropes that run parallel to the footrope may... gear must have unprotected footropes at the trawl mouth, and must not have rollers, bobbins, tires... gear may not be enlarged by encircling it with chains or by any other means. Ropes or lines running...

Landscape effects on demersal fish revealed by field observations and predictive seabed modelling.

Science.gov (United States)

Elliott, Sophie A M; Sabatino, Alessandro D; Heath, Michael R; Turrell, William R; Bailey, David M

2017-01-01

Nature conservation and fisheries management often focus on particular seabed features that are considered vulnerable or important to commercial species. As a result, individual seabed types are protected in isolation, without any understanding of what effect the mixture of seabed types within the landscape has on ecosystem functions. Here we undertook predictive seabed modelling within a coastal marine protected area using observations from underwater stereo-video camera deployments and environmental information (depth, wave fetch, maximum tidal speeds, distance from coast and underlying geology). The effect of the predicted substratum type, extent and heterogeneity or the diversity of substrata, within a radius of 1500 m around each camera deployment of juvenile gadoid relative abundance was analysed. The predicted substratum model performed well with wave fetch and depth being the most influential predictor variables. Gadus morhua (Atlantic cod) were associated with relatively more rugose substrata (Algal-gravel-pebble and seagrass) and heterogeneous landscapes, than Melanogrammus aeglefinus (haddock) or Merlangius merlangus (whiting) (sand and mud). An increase in M. merlangus relative abundance was observed with increasing substratum extent. These results reveal that landscape effects should be considered when protecting the seabed for fish and not just individual seabed types. The landscape approach used in this study therefore has important implications for marine protected area, fisheries management and monitoring advice concerning demersal fish populations.

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....

Bycatch in 36 and 40 mm PA Turkish twin rigged beam trawl codends

African Journals Online (AJOL)

Jane

2011-07-20

Jul 20, 2011 ... Thus, landings of the shrimp beam trawling fleet also include some commercially valuable fishes. ... Fishing has significant direct and indirect effects on the habitat, diversity ..... Statistics 2006. State Institute of Statistics Prime.

Influence of Benthic Macrofauna as a Spatial Structuring Agent for Juvenile Haddock (Melanogrammus aeglefinus) on the Eastern Scotian Shelf, Atlantic Canada.

Science.gov (United States)

Rincón, Beatriz; Kenchington, Ellen L

2016-01-01

We examined the habitat of juvenile haddock on the eastern Scotian Shelf (off Nova Scotia, Canada) in relation to grab-sampled benthic macrofaunal invertebrate species assemblages in order to determine whether there were significant differences in benthic macrofauna between areas of historically persistent high and low juvenile haddock abundance. Our analyses were conducted over two spatial scales in each of two years: among banks (Emerald, Western and Sable Island), approximately 60 km distant from each other, and between areas of high and low juvenile haddock abundance at distances of 10 to 30 km-all in an area that had not experienced groundfishing in the decade prior to sampling. We also examined fine-scale (10s of metres) within-site variability in the macrofauna and used surficial sediment characteristics, along with hydrographic variables, to identify environmental correlates. PERMANOVA identified statistically significant differences in biomass, density and composition of the benthos associated with juvenile haddock abundance; however it was difficult to determine whether the results had biological relevance. Post hoc tests showed that these differences occurred only on Sable Island Bank where both fish and benthos may have been independently responding to sediment type which was most different there (100% sand in the area of low haddock abundance vs. 22% gravel in the area of high haddock abundance). In total, 383 benthic taxa representing 13 phyla were identified. Annelida was the most specious phylum (36.29% of taxa, representing 33 families), followed by Arthropoda (with Crustaceans, mostly Amphipoda, accounting for 25.07% of the total number of taxa). The strongest pattern in the macrofauna was expressed at the largest scale, between banks, accounting for approximately 25% of the variation in the data. Emerald Bank, deeper, warmer and saltier than the Western and Sable Island Banks, had a distinctive fauna.

Influence of Benthic Macrofauna as a Spatial Structuring Agent for Juvenile Haddock (Melanogrammus aeglefinus) on the Eastern Scotian Shelf, Atlantic Canada

Science.gov (United States)

2016-01-01

We examined the habitat of juvenile haddock on the eastern Scotian Shelf (off Nova Scotia, Canada) in relation to grab-sampled benthic macrofaunal invertebrate species assemblages in order to determine whether there were significant differences in benthic macrofauna between areas of historically persistent high and low juvenile haddock abundance. Our analyses were conducted over two spatial scales in each of two years: among banks (Emerald, Western and Sable Island), approximately 60 km distant from each other, and between areas of high and low juvenile haddock abundance at distances of 10 to 30 km–all in an area that had not experienced groundfishing in the decade prior to sampling. We also examined fine-scale (10s of metres) within-site variability in the macrofauna and used surficial sediment characteristics, along with hydrographic variables, to identify environmental correlates. PERMANOVA identified statistically significant differences in biomass, density and composition of the benthos associated with juvenile haddock abundance; however it was difficult to determine whether the results had biological relevance. Post hoc tests showed that these differences occurred only on Sable Island Bank where both fish and benthos may have been independently responding to sediment type which was most different there (100% sand in the area of low haddock abundance vs. 22% gravel in the area of high haddock abundance). In total, 383 benthic taxa representing 13 phyla were identified. Annelida was the most specious phylum (36.29% of taxa, representing 33 families), followed by Arthropoda (with Crustaceans, mostly Amphipoda, accounting for 25.07% of the total number of taxa). The strongest pattern in the macrofauna was expressed at the largest scale, between banks, accounting for approximately 25% of the variation in the data. Emerald Bank, deeper, warmer and saltier than the Western and Sable Island Banks, had a distinctive fauna. PMID:27649419

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...

Diel effects on bottom-trawl survey catch rates of shallow- and deep ...

African Journals Online (AJOL)

Fishing in depths shallower than 400 m outside daylight hours should therefore be avoided in order to reduce bias and ensure consistency in abundance estimates from surveys. Keywords: Benguela Current system, consistency of survey indices, efficiency of bottom-trawl surveys, negative binomial GAM, transect survey ...

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...

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.

Demersal trawling on the South African south and east coasts for the ...

African Journals Online (AJOL)

spamer

ralis was initiated in 1878, initially using a steam tug ... species composition, catch seasonality, catch per unit effort (cpue) and size-at-recruitment over the time ... Changes in the Eastern Cape demersal inshore trawl fishery operating out of Port ... MATERIAL AND METHODS ... The model parameters were estimated by mini-.

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...

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...

Inshore small-mesh trawling survey of the Cape south coast. Part 5 ...

African Journals Online (AJOL)

Inshore small-mesh trawling survey of the Cape south coast. Part 5. Crustacea, Stomatopoda, Isopoda and. Decapoda. B. Kensley and C.D. Buxton. Port Elizabeth Museum, Port Elizabeth. Forty-six species of Crustacea from the shallow marine waters of the southern Cape coast are listed. Five new records for the area.

Fish behaviour in responce to a midwater trawl footrope in temperate reservoirs

Czech Academy of Sciences Publication Activity Database

Sajdlová, Zuzana; Draštík, Vladislav; Jůza, Tomáš; Říha, Milan; Frouzová, Jaroslava; Čech, Martin; Vašek, Mojmír; Muška, Milan; Blabolil, Petr; Tušer, Michal; Kratochvíl, Michal; Peterka, Jiří; Mrkvička, Tomáš; Balk, Helge; Kubečka, Jan

2015-01-01

Roč. 172, December (2015), s. 105-113 ISSN 0165-7836 R&D Projects: GA MŠk(CZ) EE2.3.20.0204 Institutional support: RVO:60077344 Keywords : pair trawling * avoidance behaviour * SED echogram * open water * vertical track slope Subject RIV: EH - Ecology, Behaviour Impact factor: 2.230, year: 2015

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...

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...... species caught in the trawls. To address this issue, we developed a novel sorting box concept consisting of a four-panel section with a window on the top in order to improve the escape of cod and other bycatch species through an escape window while retaining the target catch of Norway lobster. The concept....... The reduction in bycatch decreased with decreasing mesh size and increasing height of the sorting box. Escape of Norway lobster through the escape window was limited. A modified version of the sorting box concept was implemented in the Kattegat fishery from 2009 onwards...

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.

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...

Job satisfaction in the shrimp trawl fisheries of Chennai, India

OpenAIRE

Bavinck, M.

2012-01-01

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...

Biomarkers in natural fish populations indicate adverse biological effects of offshore oil production.

Directory of Open Access Journals (Sweden)

Lennart Balk

Full Text Available Despite the growing awareness of the necessity of a sustainable development, the global economy continues to depend largely on the consumption of non-renewable energy resources. One such energy resource is fossil oil extracted from the seabed at offshore oil platforms. This type of oil production causes continuous environmental pollution from drilling waste, discharge of large amounts of produced water, and accidental spills.Samples from natural populations of haddock (Melanogrammus aeglefinus and Atlantic cod (Gadus morhua in two North Sea areas with extensive oil production were investigated. Exposure to and uptake of polycyclic aromatic hydrocarbons (PAHs were demonstrated, and biomarker analyses revealed adverse biological effects, including induction of biotransformation enzymes, oxidative stress, altered fatty acid composition, and genotoxicity. Genotoxicity was reflected by a hepatic DNA adduct pattern typical for exposure to a mixture of PAHs. Control material was collected from a North Sea area without oil production and from remote Icelandic waters. The difference between the two control areas indicates significant background pollution in the North Sea.It is most remarkable to obtain biomarker responses in natural fish populations in the open sea that are similar to the biomarker responses in fish from highly polluted areas close to a point source. Risk assessment of various threats to the marine fish populations in the North Sea, such as overfishing, global warming, and eutrophication, should also take into account the ecologically relevant impact of offshore oil production.

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...

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

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

Recent stock assessments of the Pandalus stock in the Skagerrak (ICES Division IIIa) and the Norwegian Deep (Division IVa east) have relied largely on a time-series of landings per unit effort (lpue) calculated from Danish logbook data. Because of fleet renewal and trawl-size changes, the relatio......Recent stock assessments of the Pandalus stock in the Skagerrak (ICES Division IIIa) and the Norwegian Deep (Division IVa east) have relied largely on a time-series of landings per unit effort (lpue) calculated from Danish logbook data. Because of fleet renewal and trawl-size changes...

50 CFR Figure 6 to Part 223 - TED Extension in Summer Flounder Trawl

Science.gov (United States)

2010-10-01

... 50 Wildlife and Fisheries 7 2010-10-01 2010-10-01 false TED Extension in Summer Flounder Trawl 6 Figure 6 to Part 223 Wildlife and Fisheries NATIONAL MARINE FISHERIES SERVICE, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE MARINE MAMMALS THREATENED MARINE AND ANADROMOUS SPECIES Pt. 223, Fig. 6 Figure 6 to Part 223—TED...

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...

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...

78 FR 7371 - Fisheries Off West Coast States; Pacific Coast Groundfish Fishery; Trawl Rationalization Program...

Science.gov (United States)

2013-02-01

... Rationalization Program; Cost Recovery AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and... Office rule goes final before the cost recovery program rule and if it would affect the appeals process... would implement a cost recovery program for the Pacific coast groundfish trawl rationalization program...

Otter trawls in Greece: Landing profiles and potential mιtiers

Directory of Open Access Journals (Sweden)

S. KATSANEVAKIS

2010-02-01

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.

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

both negatively and positively influence the quantity and quality of food available. Using δ 13C and δ 15N we investigated potential diet changes of three commercially exploited species across trawling gradients in the Kattegat (plaice, dab and Norway lobster (Nephrops)) and the Irish Sea (Nephrops...

Comparison of gill nets and fixed-frame trawls for sampling threadfin shad in tropical reservoirs

Czech Academy of Sciences Publication Activity Database

Prchalová, Marie; Neal, J. W.; Munoz-Hincapie, M.; Jůza, Tomáš; Říha, Milan; Peterka, Jiří; Kubečka, Jan

2012-01-01

Roč. 141, č. 4 (2012), s. 1151-1160 ISSN 0002-8487 R&D Projects: GA ČR(CZ) GPP505/12/P647 Institutional support: RVO:60077344 Keywords : threadfin shad * gillnet * trawl * gear selectivity * catchability * reservoir Subject RIV: EH - Ecology, Behaviour Impact factor: 1.546, year: 2012

Great lakes prey fish populations: a cross-basin overview of status and trends based on bottom trawl surveys, 1978-2012

Science.gov (United States)

Gorman, Owen T.

2012-01-01

The assessment of prey fish stocks in the Great Lakes have been conducted annually with bottom trawls since the 1970s by the Great Lakes Science Center, sometimes assisted by partner agencies. These stock assessments provide data on the status and trends of prey fish that are consumed by important commercial and recreational fishes. Although all these annual surveys are conducted using bottom trawls, they differ among the lakes in the proportion of the lake covered, seasonal timing, bottom trawl gear used, and the manner in which the trawl is towed (across or along bottom contours). Because each assessment is unique in one or more important aspects, direct comparison of prey fish catches among lakes is not straightforward. However, all of the assessments produce indices of abundance or biomass that can be standardized to facilitate comparisons of status and trends across all the Great Lakes. In this report, population indices were standardized to the highest value for a time series within each lake for the following principal prey species: cisco (Coregonus artedi), bloater (C. hoyi), rainbow smelt (Osmerus mordax), and alewife (Alosa pseudoharengus). Indices were also provided for round goby (Neogobius melanostomus), an invasive fish that has proliferated throughout the basin over the past 18 years. These standardized indices represent the best available long-term indices of relative abundance for these fishes across all of the Great Lakes. In this report, standardized indices are presented in graphical form along with synopses to provide a short, informal cross-basin summary of the status and trends of principal prey fishes. In keeping with this intent, tables, references, and a detailed discussion were omitted.

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

DEFF Research Database (Denmark)

Krag, Ludvig Ahm

have been published in scientific journals and Paper 3 has been submitted to Fisheries Research. This review will take a broader perspective and will examine the capturing process, which is the basis for the selection process. Moreover, it discusses the existing methods and knowledge in the fields...... different species, including cod, are caught together. Demersal trawling is the predominant fishing method in Denmark, as measured by both catch value and volume. Demersal trawls also account for the highest discard rates of juvenile fish, including cod. The focus of this work was on improving......, and openings. The results show that the morphology-based simulations of size selectivity of cod can be used to explain a large part of both the within-haul and the between-haul variations previously reported from sea trials. The method can further predict the selection parameters (L50 and SR) for cod...

AFSC/RACE/MACE: Results of 2012 Acoustic-trawl survey of the Shumagin Islands and Sanak Trough dy1201

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...

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

A framework to assess the impact of mobile fishing gear on the seabed and benthic ecosystem is presented. The framework that can be used at regional and local scales provides indicators for both trawling pressureand ecological impact. It builds on high-resolution maps of trawlingintensity and con...

Characterization of Atlantic cod spawning habitat and behavior in Icelandic coastal waters.

Directory of Open Access Journals (Sweden)

Timothy B Grabowski

Full Text Available The physical habitat used during spawning may potentially be an important factor affecting reproductive output of broadcast spawning marine fishes, particularly for species with complex, substrate-oriented mating systems and behaviors, such as Atlantic cod Gadus morhua. We characterized the habitat use and behavior of spawning Atlantic cod at two locations off the coast of southwestern Iceland during a 2-d research cruise (15-16 April 2009. We simultaneously operated two different active hydroacoustic gear types, a split beam echosounder and a dual frequency imaging sonar (DIDSON, as well as a remotely operated underwater vehicle (ROV. A total of five fish species were identified through ROV surveys: including cusk Brosme brosme, Atlantic cod, haddock Melanogrammus aeglefinus, lemon sole Microstomus kitt, and Atlantic redfish Sebastes spp. Of the three habitats identified in the acoustic surveys, the transitional habitat between boulder/lava field and sand habitats was characterized by greater fish density and acoustic target strength compared to that of sand or boulder/lava field habitats independently. Atlantic cod were observed behaving in a manner consistent with published descriptions of spawning. Individuals were observed ascending 1-5 m into the water column from the bottom at an average vertical swimming speed of 0.20-0.25 m s(-1 and maintained an average spacing of 1.0-1.4 m between individuals. Our results suggest that cod do not choose spawning locations indiscriminately despite the fact that it is a broadcast spawning fish with planktonic eggs that are released well above the seafloor.

Characterization of Atlantic cod spawning habitat and behavior in Icelandic coastal waters

Science.gov (United States)

Grabowski, Timothy B.; Boswell, Kevin M.; McAdam, Bruce J.; Wells, R. J. David; Marteinsdóttir, Gudrún

2012-01-01

The physical habitat used during spawning may potentially be an important factor affecting reproductive output of broadcast spawning marine fishes, particularly for species with complex, substrate-oriented mating systems and behaviors, such as Atlantic cod Gadus morhua. We characterized the habitat use and behavior of spawning Atlantic cod at two locations off the coast of southwestern Iceland during a 2-d research cruise (15–16 April 2009). We simultaneously operated two different active hydroacoustic gear types, a split beam echosounder and a dual frequency imaging sonar (DIDSON), as well as a remotely operated underwater vehicle (ROV). A total of five fish species were identified through ROV surveys: including cusk Brosme brosme, Atlantic cod, haddock Melanogrammus aeglefinus, lemon sole Microstomus kitt, and Atlantic redfish Sebastes spp. Of the three habitats identified in the acoustic surveys, the transitional habitat between boulder/lava field and sand habitats was characterized by greater fish density and acoustic target strength compared to that of sand or boulder/lava field habitats independently. Atlantic cod were observed behaving in a manner consistent with published descriptions of spawning. Individuals were observed ascending 1–5 m into the water column from the bottom at an average vertical swimming speed of 0.20–0.25 m s−1 and maintained an average spacing of 1.0–1.4 m between individuals. Our results suggest that cod do not choose spawning locations indiscriminately despite the fact that it is a broadcast spawning fish with planktonic eggs that are released well above the seafloor.

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.

Impact of natural (waves and currents) and anthropogenic (trawl) resuspension on the export of particulate matter to the open ocean: Application to the Gulf of Lion (NW Mediterranean)

Science.gov (United States)

Ferré, B.; Durrieu de Madron, X.; Estournel, C.; Ulses, C.; Le Corre, G.

2008-08-01

Modern sediment deposits on continental margins form a vast reservoir of particulate matter that is regularly affected by resuspension processes. Resuspension by bottom trawling on shelves with strong fishing activity can modify the scale of natural disturbance by waves and currents. Recent field data show that the impact of bottom trawls on fine sediment resuspension per unit surface is comparable with that of the largest storms. We assessed the impact of both natural and anthropogenic processes on the dispersal of riverborne particles and shelf sediments on the Gulf of Lion shelf. We performed realistic numerical simulations of resuspension and transport forced by currents and waves or by a fleet of bottom trawlers. Simulations were conducted for a 16-month period (January 1998-April 1999) to characterise the seasonal variability. The sediment dynamics takes into account bed armoring, ripple geometry and the cohesive and non-cohesive characteristics of the sediments. Essential but uncertain parameters (clay content, erosion fluxes and critical shear stress for cohesive sediment) were set with existing data. Resuspension by waves and currents was controlled by shear stress, whereas resuspension by trawls was controlled by density and distribution of the bottom trawler fleet. Natural resuspension by waves and currents mostly occurred during short seasonal episodes, and was concentrated on the inner shelf. Trawling-induced resuspension, in contrast, occurred regularly throughout the year and was concentrated on the outer shelf. The total annual erosion by trawls (5.6×10 6 t y -1, t for metric tonnes) was four orders of magnitude lower than the erosion induced by waves and currents (35.3×10 9 t y -1). However the net resuspension (erosion/deposition budget) for trawling (0.4×10 6 t y -1) was only one order of magnitude lower than that for waves and currents (9.2×10 6 t y -1). Off-shelf export concerned the finest fraction of the sediment (clays and fine silts

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

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...... 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 ... 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...

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

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...

Avoidance reactions of fish in the trawl mouth opening in a shallow and turbid lake at night

Czech Academy of Sciences Publication Activity Database

Jůza, Tomáš; Rakowitz, G.; Draštík, Vladislav; Blabolil, Petr; Herzig, A.; Kratochvíl, Michal; Muška, Milan; Říha, Milan; Sajdlová, Zuzana; Kubečka, Jan

2013-01-01

Roč. 147, October (2013), s. 154-160 ISSN 0165-7836 R&D Projects: GA MŠk(CZ) EE2.3.20.0204 Institutional support: RVO:60077344 Keywords : Lake Neusiedl * trawl * DIDSON * fish abundance * biomass Subject RIV: EH - Ecology, Behaviour Impact factor: 1.843, year: 2013

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...

AFSC/RACE/MACE: Results of 2013 Acoustic-trawl survey of the Shumagin Islands, Sanak Trough, and Morzhovoi Bay dy1302

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...

Bottom trawl assessment of Lake Ontario prey fishes

Science.gov (United States)

Weidel, Brian C.; Connerton, Michael J.; Holden, Jeremy

2018-01-01

Managing Lake Ontario fisheries in an ecosystem-context requires prey fish community and population data. Since 1978, multiple annual bottom trawl surveys have quantified prey fish dynamics to inform management relative to published Fish Community Objectives. In 2017, two whole-lake surveys collected 341 bottom trawls (spring: 204, fall: 137), at depths from 8-225m, and captured 751,350 fish from 29 species. Alewife were 90% of the total fish catch while Deepwater Sculpin, Round Goby, and Rainbow Smelt comprised the majority of the remaining total catch (3.8, 3.1, and 1.1% respectively). The adult Alewife abundance index for US waters increased in 2017 relative to 2016, however the index for Canadian waters declined. Adult Alewife condition, assessed by the predicted weight of a 165 mm fish (6.5 inches), declined in 2017 from record high values observed in spring 2016. Spring 2017 Alewife condition was slightly less than the 10-year average, but the fall value was well below the 10-year average, likely due to increased Age-1 Alewife abundance. The Age-1 Alewife abundance index was the highest observed in 40 years, and 8-times higher than the previous year. The Age-1 index estimates Alewife reproductive success the preceding year. The warm summer and winter of 2016 likely contributed to the large year class. In contrast the relatively cool 2017 spring and cold winter may result in a lower than average 2017 year class. Abundance indices for Rainbow Smelt, Cisco, and Emerald Shiner either declined or remained at low levels in 2017. Pelagic prey fish diversity continues to be low since a single species, Alewife, dominates the catch. Deepwater Sculpin were the most abundant benthic prey fish in 2017 because Round Goby abundance declined sharply from 2016. Slimy Sculpin density continued to decline and the 2017 biomass index for US waters was the lowest ever observed. Prior to Round Goby proliferation, juvenile Slimy Sculpin comprised ~10% of the Slimy Sculpin catch, but

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...

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...

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...

The size selectivity of the main body of a sampling pelagic pair trawl in freshwater reservoirs during the night

Czech Academy of Sciences Publication Activity Database

Říha, Milan; Jůza, Tomáš; Prchalová, Marie; Mrkvička, Tomáš; Čech, Martin; Draštík, Vladislav; Muška, Milan; Kratochvíl, Michal; Peterka, Jiří; Tušer, Michal; Vašek, Mojmír; Kubečka, Jan

2012-01-01

Roč. 127, September (2012), s. 56-60 ISSN 0165-7836 R&D Projects: GA MZe(CZ) QH81046 Institutional support: RVO:60077344 Keywords : quantitative sampling * gear selectivity * trawl * reservoirs Subject RIV: GL - Fishing Impact factor: 1.695, year: 2012

Recovery by the Norway lobster Nephrops norvegicus (L.) from the physiological stresses of trawling: Influence of season and live-storage position

DEFF Research Database (Denmark)

Lund, H. S.; Wang, T.; Chang, E. S.

2009-01-01

Live Norway lobsters (Nephrops norvegicus L.) were trawled at depths of 30 to 55 m off the coast of Jutland (Denmark) in late winter (March) and in summer (August) in 2006. Water temperatures at the bottom and surface of the sea were 7 °C and 2 °C during the winter, and 12 °C and 21 °C in the sum......Live Norway lobsters (Nephrops norvegicus L.) were trawled at depths of 30 to 55 m off the coast of Jutland (Denmark) in late winter (March) and in summer (August) in 2006. Water temperatures at the bottom and surface of the sea were 7 °C and 2 °C during the winter, and 12 °C and 21 °C...... in the summer, respectively. The recovery of specific physiological and metabolic variables from the intense stresses associated with capture (trawling and air-exposure during sorting) was followed in seawater at 5 °C in winter or 18 °C in summer. Recovery was compared in lobsters held individually in two......-base status. In winter, a potential metabolic lactic acidosis was compensated by a marked respiratory alkalosis, with significantly increased haemolymph pH and decreased CO2 total content and partial pressure. These effects disappeared gradually over 96 h. Summer lobsters showed combined metabolic...

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...

Use of high-frequency imaging sonar (DIDSON) to observe fish behaviour towards a surface trawl

Czech Academy of Sciences Publication Activity Database

Rakowitz, G.; Tušer, Michal; Říha, Milan; Jůza, Tomáš; Balk, H.; Kubečka, Jan

2012-01-01

Roč. 123, July (2012), s. 37-48 ISSN 0165-7836. [Fish Sampling with Active Methods. České Budějovice, 08.09.2010-11.09.2010] R&D Projects: GA ČR(CZ) GA206/07/1392 Grant - others:NFM(CZ) CZ 0091 Institutional support: RVO:60077344 Keywords : active sampling gear * trawl * fish avoidance behaviour * DIDSON * freshwater reservoir Subject RIV: EH - Ecology, Behaviour Impact factor: 1.695, year: 2012

Baseline study of the distribution of marine debris on soft-bottom habitats associated with trawling grounds in the northern Mediterranean

Directory of Open Access Journals (Sweden)

Pilar Sánchez

2013-06-01

Full Text Available The present study aims to analyse the local and regional variability in the density and typology of marine debris on fishing grounds on the northern Mediterranean continental shelf, and to test relationships between marine litter and trawl fishing activity. Moreover, the colonization of plastics was examined in order to study the importance of plastics as a source of impact on marine communities and their further environmental implications. This study surveyed 11 sites, associated with trawling grounds and subjected to different levels of fishing intensity, located in four areas of the Mediterranean: one in Italy, the Central Tyrrhenian coast, one in Greece, the eastern Ionian coast, and two in Spain, the Murcian and Catalan coasts. Samples were collected during an oceanographic cruise undertaken from the 21 May to the 24 June 2009. Results showed geographical variation in the density of marine debris which ranged from 0 to 405 pieces per hectare in the surveyed areas, plastics being the dominant components. Variability within sites was higher than between areas, indicating small-scale patchiness in the distribution of the debris over the seafloor. Though the study areas were within trawling grounds, the density of debris was not significantly correlated with fishing effort. More than 30% of plastics were between 10 and 20 cm width/length, and more than 40% of the plastics were colonized by a biofilm of microorganisms, suggesting indirect effects on benthic communities.

The mobilisation of sediment by demersal otter trawls.

Science.gov (United States)

O'Neill, F G; Summerbell, K

2011-05-01

The mobilisation of sediment by towed demersal fishing gears has been related to the release of nutrients, benthic infaunal mortality and the resuspension of phytoplankton cysts and copepod eggs. Hence, to understand the broader environmental and ecological implications of demersal fishing, it is important to be able to estimate accurately the amount of sediment put into the water column by towed gears. Experimental trials were carried out in the Moray Firth, Scotland, to measure the quantity of sediment remobilised by trawl gear components. It is demonstrated, for a given sediment type, that there is a relationship between the hydrodynamic drag of the gear element and the mass of sediment entrained behind it. A better understanding of this relationship and the hydrodynamic processes involved will lead to the development of accurate predictive models and aid the design of fishing gears of reduced impact. Crown Copyright © 2011. Published by Elsevier Ltd. All rights reserved.

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...

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...

Temporal modification in cardiac rhythmicity of Nephrops norvegicus (Crustacea: Decapoda in relation to trawl capture stress

Directory of Open Access Journals (Sweden)

Jacopo Aguzzi

2005-09-01

Full Text Available The effects of trawling on cardiac rhythmicity of Nephrops norvegicus (L. are still mostly unknown. Ultradian rhythms reported in previous studies may result from trawling capture stress, thus disappearing following acclimatisation to laboratory conditions. To test this hypothesis, 34 time series of cardiac activity data recorded in constant darkness were studied by Fourier analysis. Spectral decomposition of time series was obtained by defining the fundamental or circadian harmonic (CH in 24-h together with 9 submultiples of this period. The power content (PC of each harmonic was estimated in data segments of 24-h duration (days, giving graphic matrices of PC values over consecutive days. Values of PC for 9 submultiples were summed and studied in a block named ultradian band (UB. The modification in the PC of the CH and of the UB was evaluated during laboratory acclimatisation. A significant increase in the PC of the circadian harmonic component (CH over consecutive days of testing was observed. These findings suggest that, rather than being a product of dim light environmental fluctuations experienced by the animals from the deep waters of the continental slope, ultradian periodicity could well be caused by the stress of capture.

Trawling disturbance on benthic ecosystems and consequences on commercial species: a northwestern Mediterranean case study

Directory of Open Access Journals (Sweden)

Alba Muntadas

2014-03-01

Full Text Available Trawling is known to disturb benthic communities and habitats, which may in turn indirectly affect populations of commercial species that live in close association with the seabed. The degree of impact on both benthic communities and demersal species depends on the fishing effort level. This may vary over the year because of the fleet dynamics, which are in turn normally driven by the main target species’ life cycle. In this study we describe changes in benthic functional components of a northwestern Mediterranean fishing ground that represents a recruitment area for an important target species (red mullet, Mullus barbatus. This fishing ground experiences a varying intensity of fishing effort over the year and benthic functional components under different levels of trawling were compared with an unfished, control area. Traits related to sexual maturity and life span for infauna and body size and life span for epifauna were found to vary with fishing activity. Potential effects of these changes on ecological functioning and the impact on red mullet population are discussed. The development of fisheries management plans under an ecosystem based fisheries management (EBFM requires the links between target species and benthic communities’ disturbance due to fishing practices to be explicitly considered.

Screening for viral hemorrhagic septicemia virus in marine fish along the Norwegian coastal line.

Directory of Open Access Journals (Sweden)

Nina Sandlund

Full Text Available Viral hemorrhagic septicemia virus (VHSV infects a wide range of marine fish species. To study the occurrence of VHSV in wild marine fish populations in Norwegian coastal waters and fjord systems a total of 1927 fish from 39 different species were sampled through 5 research cruises conducted in 2009 to 2011. In total, VHSV was detected by rRT-PCR in twelve samples originating from Atlantic herring (Clupea harengus, haddock (Melanogrammus aeglefinus, whiting (Merlangius merlangus and silvery pout (Gadiculus argenteus. All fish tested positive in gills while four herring and one silvery pout also tested positive in internal organs. Successful virus isolation in cell culture was only obtained from one pooled Atlantic herring sample which shows that today's PCR methodology have a much higher sensitivity than cell culture for detection of VHSV. Sequencing revealed that the positive samples belonged to VHSV genotype Ib and phylogenetic analysis shows that the isolate from Atlantic herring and silvery pout are closely related. All positive fish were sampled in the same area in the northern county of Finnmark. This is the first detection of VHSV in Atlantic herring this far north, and to our knowledge the first detection of VHSV in silvery pout. However, low prevalence of VHSV genotype Ib in Atlantic herring and other wild marine fish are well known in other parts of Europe. Earlier there have been a few reports of disease outbreaks in farmed rainbow trout with VHSV of genotype Ib, and our results show that there is a possibility of transfer of VHSV from wild to farmed fish along the Norwegian coast line. The impact of VHSV on wild fish is not well documented.

Fish product mislabelling: failings of traceability in the production chain and implications for illegal, unreported and unregulated (IUU) fishing.

Science.gov (United States)

Helyar, Sarah J; Lloyd, Hywel Ap D; de Bruyn, Mark; Leake, Jonathan; Bennett, Niall; Carvalho, Gary R

2014-01-01

Increasing consumer demand for seafood, combined with concern over the health of our oceans, has led to many initiatives aimed at tackling destructive fishing practices and promoting the sustainability of fisheries. An important global threat to sustainable fisheries is Illegal, Unreported and Unregulated (IUU) fishing, and there is now an increased emphasis on the use of trade measures to prevent IUU-sourced fish and fish products from entering the international market. Initiatives encompass new legislation in the European Union requiring the inclusion of species names on catch labels throughout the distribution chain. Such certification measures do not, however, guarantee accuracy of species designation. Using two DNA-based methods to compare species descriptions with molecular ID, we examined 386 samples of white fish, or products labelled as primarily containing white fish, from major UK supermarket chains. Species specific real-time PCR probes were used for cod (Gadus morhua) and haddock (Melanogrammus aeglefinus) to provide a highly sensitive and species-specific test for the major species of white fish sold in the UK. Additionally, fish-specific primers were used to sequence the forensically validated barcoding gene, mitochondrial cytochrome oxidase I (COI). Overall levels of congruence between product label and genetic species identification were high, with 94.34% of samples correctly labelled, though a significant proportion in terms of potential volume, were mislabelled. Substitution was usually for a cheaper alternative and, in one case, extended to a tropical species. To our knowledge, this is the first published study encompassing a large-scale assessment of UK retailers, and if representative, indicates a potentially significant incidence of incorrect product designation.

Fish product mislabelling: failings of traceability in the production chain and implications for illegal, unreported and unregulated (IUU fishing.

Directory of Open Access Journals (Sweden)

Sarah J Helyar

Full Text Available Increasing consumer demand for seafood, combined with concern over the health of our oceans, has led to many initiatives aimed at tackling destructive fishing practices and promoting the sustainability of fisheries. An important global threat to sustainable fisheries is Illegal, Unreported and Unregulated (IUU fishing, and there is now an increased emphasis on the use of trade measures to prevent IUU-sourced fish and fish products from entering the international market. Initiatives encompass new legislation in the European Union requiring the inclusion of species names on catch labels throughout the distribution chain. Such certification measures do not, however, guarantee accuracy of species designation. Using two DNA-based methods to compare species descriptions with molecular ID, we examined 386 samples of white fish, or products labelled as primarily containing white fish, from major UK supermarket chains. Species specific real-time PCR probes were used for cod (Gadus morhua and haddock (Melanogrammus aeglefinus to provide a highly sensitive and species-specific test for the major species of white fish sold in the UK. Additionally, fish-specific primers were used to sequence the forensically validated barcoding gene, mitochondrial cytochrome oxidase I (COI. Overall levels of congruence between product label and genetic species identification were high, with 94.34% of samples correctly labelled, though a significant proportion in terms of potential volume, were mislabelled. Substitution was usually for a cheaper alternative and, in one case, extended to a tropical species. To our knowledge, this is the first published study encompassing a large-scale assessment of UK retailers, and if representative, indicates a potentially significant incidence of incorrect product designation.

Testing Nordmøre grids on the target and by-catch species of the commercial bottom trawl fishery in the Gulf of Cadiz

Directory of Open Access Journals (Sweden)

Mariángeles Gamaza

2015-12-01

Full Text Available Sorting grids have been tested worldwide in trawl fisheries. Here we report upon the first trials performed using Nordmøre sorting grids with four different bar spacings in the trawl fisheries of the Gulf of Cadiz targeting crustaceans as the main resource. A total of 288 valid hauls and 67 commercial species were caught. Escapement and escape size selectivity were evaluated for the most important target and by-catch species. A decrease in the percentage of biomass escape was recorded with increasing grid spacing for the two target species, deep-water rose shrimp (Parapenaeus longirostris and Norway lobster (Nephrops norvegicus, from 24% to 8% for the former and from 86 to 9% for the latter, with a 15-mm and 30-mm grid respectively. In general, high escape rates were found for most finfish and cephalopods. For hake (Merluccius merluccius, as the main by-catch species, the results showed an escape rate decreasing from 96% to 71% as the bar spacing increased. Our findings suggest the 30-mm grid would be effective for the deep-water crustacean trawlers but different mitigation measures will be required for other métiers in the multispecies trawl fishery of the Gulf of Cadiz.

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.

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...

The use of at‐sea‐sampling data to dissociate environmental variability in Norway lobster (Nephrops norvegicus) catches to improve resource exploitation efficiency within the Skagerrak/Kattegat trawl fishery

DEFF Research Database (Denmark)

Feekings, Jordan P.; Christensen, Asbjørn; Jonsson, Patrik

2015-01-01

Research into the influence of environmental variables on the behaviour of Norway lobster (Nephrops norvegicus), and hence catch rates, dates back to the 1960s (e.g., Höglund and Dybern, Diurnal and seasonal variations in the catch‐composition of Nephrops norvegicus (L.) at the Swedish west coast...... on commercial trawl catches of Nephrops norvegicus (L.). ICES J. Mar. Sci. 58:1318). Here, we aimed to dissociate environmental variability in Norway lobster catches to improve resource exploitation efficiency within the Skagerrak and Kattegat trawl fisheries by utilising data collected as part of an extensive...

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

Institute of Scientific and Technical Information of China (English)

WANG Yang; WANG Yingbin; ZHENG Ji

2015-01-01

The original purpose of Vessel Monitoring System (VMS) is for enforcement and control of vessel sailing. With the ap-plication 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 Zhou-shan 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 be-tween 2.5kn and 5.0kn 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 at-tention should be paid to its construction and application to fisheries stock assessment and management.

SEM/EDS and optical microscopy analyses of microplastics in ocean trawl and fish guts.

Science.gov (United States)

Wang, Zhong-Min; Wagner, Jeff; Ghosal, Sutapa; Bedi, Gagandeep; Wall, Stephen

2017-12-15

Microplastic particles from Atlantic and Pacific Ocean trawls, lab-fed fish guts and ocean fish guts have been characterized using optical microscopy and SEM/EDS in terms of size, morphology, and chemistry. We assessed whether these measurements could serve as a rapid screening process for subsequent identification of the likely microplastic candidates by micro-spectroscopy. Optical microscopy enabled morphological classification of the types of particles or fibers present in the sample, as well as the quantification of particle size ranges and fiber lengths. SEM/EDS analysis was used to rule out non-plastic particles and screen the prepared samples for potential microplastic, based on their element signatures and surface characteristics. Chlorinated plastics such as polyvinyl chloride (PVC) could be easily identified with SEM/EDS due to their unique elemental signatures including chlorine, as could mineral species that are falsely identified as plastics by optical microscopy. Particle morphology determined by optical microscopy and SEM suggests the fish ingested particles contained both degradation fragments from larger plastic pieces and also manufactured microplastics. SEM images of microplastic particle surfaces revealed characteristic cracks consistent with environmental exposure, as well as pigment particles consistent with manufactured materials. Most of the microplastic surfaces in the fish guts and ocean trawls were covered with biofilms, radiolarians, and crustaceans. Many of the fish stomachs contained micro-shell pieces which visually resembled microplastics. Copyright © 2017 Elsevier B.V. All rights reserved.

Influence of tow duration on catch performance of trawl survey in the Mediterranean Sea.

Directory of Open Access Journals (Sweden)

Antonello Sala

Full Text Available The aim of this study was to assess the effect of tow duration on catch per unit of swept area (CPUE, trawl catch performance, and the proportion of the species caught in a trawl survey. Longer tows are expected to have a greater probability of catching species. An average of 26 species were caught in the first 30 minutes, whereas only about one additional species was caught in the next 30 minutes in longer tows. The shorter tows involved a decrement in catch weight for 11 of the 12 target species sampled, demonstrating that tow duration did affect catch per unit of swept area CPUE. The shorter tows were associated with a significant reduction of the overall CPUE in terms of weight of the main target species and of the total catch (circa 60%. The same strong reduction of around 70% was found in particular for European hake (Merluccius merluccius and surmullet (Mullus spp and 50% for Nephrops (Nephrops norvegicus. The shorter tows were less efficient in catching large-sized hake, surmullet, Nephrops, Atlantic horse mackerel (Trachurus trachurus, and poor cod (Trisopterus minutus, even though the difference was significant only for Nephrops. Regardless of the p-value statistic, these findings suggest that the continuity of survey time series would be severely impaired by changing tow duration. Further work is required to explore a way to reduce tow duration without reducing CPUE.

From fishing to fish processing: Separation of fish from crustaceans in the Norway lobster-directed multispecies trawl fishery improves seafood quality

DEFF Research Database (Denmark)

Karlsen, Junita Diana; Krag, Ludvig Ahm; Albertsen, Christoffer Moesgaard

2015-01-01

Fishing gears have negative impacts on seafood quality, especially on fish in the mixed trawl fishery targeting Norway lobster (Nephrops norvegicus). In this fishery, which is worth about €80 millions in Denmark alone, the quality of fish can be significantly improved by simple gear changes....... A trawl codend divided into an upper and lower codend was designed to separate fish from Norway lobster during the fishing process by encourage fish to swim into the upper codend by using a frame at the entrance of the lower codend. Separate codends for fish and Norway lobster in the same gear provide...... with hard or spiny surfaces due to successful separation of fish and Norway lobster into the upper and lower codends, respectively, and by lower catch weight in the upper codend of the test codend compared with the standard codend. The decrease in damages may also improve quality indirectly by inflicting...

Fine-scale environmental effects on Cape hake survey catch rates in the Northern Benguela, using data from a trawl-mounted instrument package

DEFF Research Database (Denmark)

Kainge, Paulus Inekela; Wieland, Kai

2017-01-01

We investigated fine-scale effects of environmental variables associated with habitat distribution for 4 size groups of Cape hakes, Merluccius capensis and M. paradoxus, using generalized additive models (GAMs) with a negative binominal error distribution. This study took place during the Namibian...... hake trawl survey of 2016, and was made possible for the first time in Namibia by collecting oceanographic information with a trawl-mounted instrument package concurrently with the catch data. Depth, geographical position, bottom oxygen and bottom temperature had the most pronounced effect on the catch...... rates of both hake species, whereas solar zenith angle representing diel effects and surface layer chlorophyll appeared to be less important. The explained deviance for the best models ranged from 71.4% for M. capensis to 92.7% for M. paradoxus between 43 and 57 cm in length. Differences in catch rates...

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,...

Development of a low commercial value fish-sausage from the fish trawling “mix” category

Directory of Open Access Journals (Sweden)

Juliana de Lima Brandão GUIMARÃES

2018-05-01

Full Text Available Abstract The decreasing stock of the main species consumed in Brazil has stimulated studies regarding the use and development of products using low commercial value species. The shrimp trawling modality produces a large volume of a “mix” category comprising low commercial value fish. However, it is necessary to develop products with greater practicality to meet the current demands of the Brazilian consumer. The aim of the present study was to develop a sausage using a low commercial value fish, the Brazilian flathead (Percophis brasiliensis , caught in the fish trawling “mix” category landed in Niterói/RJ, and perform physico-chemical, microbiological, toxicological and sensorial analyses. The centesimal composition of the analyzed fish were as follows: humidity 73.78%, proteins 16.17%, carbohydrates 3.75%, total lipids 4.41% and ash 1.78%. The microbiological and toxicological results were within the legislation standards. Twenty varieties of fatty acids (AG were detected, with the most frequent being palmitic acid (22.81%. Among the omega-3 series, the most frequent were eicosapentaenoic acid (5.36% and docosahexaenoic acid (15.95%. Regarding minerals, the most noteworthy were sodium, calcium and iron (1114.24 mg, 112.32 mg and 1.73 mg respectively. The sausage showed 87.30% acceptability. The results demonstrate that the low commercial value fish Brazilian flathead resulted in a viable product for use in fish technology, with excellent nutritional results.

The vertical distribution of fish in the open water area of a deep temperate mesotrophic lake assessed by hydroacoustics and midwater trawling

Czech Academy of Sciences Publication Activity Database

Jůza, Tomáš; Frouzová, Jaroslava; Brämick, U.; Draštík, Vladislav; Mrkvička, Tomáš; Kubečka, Jan

2012-01-01

Roč. 97, č. 6 (2012), s. 509-525 ISSN 1434-2944 R&D Projects: GA AV ČR(CZ) IAA600960901 Institutional support: RVO:60077344 Keywords : smelt * vendace * trawling * hydroacoustics * Lake Werbellin Subject RIV: EH - Ecology, Behaviour Impact factor: 0.870, year: 2012

Determining the impacts of trawling on benthic function in European waters : a biological traits approach

DEFF Research Database (Denmark)

Bolam, Stefan; Kenny, Andrew; Garcia, Clement

characteristics, have allowed us to better understand the interactions between the benthic fauna and their environment at a functional level. We present the initial findings of work conducted under the auspices of the EU-funded project ‘BENTHIS’ which aims to improve our understanding of the impacts of trawling...... on benthic ecosystem functioning over much larger spatial scales than previously undertaken. Biological traits information from 887 stations across European waters (Norwegian, UK, Belgian, Dutch, Danish waters, the Mediterranean and Black Sea) were analysed to: i) quantify the relationships between infaunal...

The influence of the trawl mouth opening size and net colour on catch efficiency during sampling of early fish stages

Czech Academy of Sciences Publication Activity Database

Jůza, T.; Čech, Martin; Kubečka, Jan; Vašek, Mojmír; Peterka, Jiří; Matěna, Josef

2010-01-01

Roč. 105, č. 3 (2010), s. 125-133 ISSN 0165-7836 R&D Projects: GA ČR(CZ) GP206/09/P266; GA AV ČR(CZ) 1QS600170504 Institutional research plan: CEZ:AV0Z60170517 Keywords : trawl efficiency * fry density * perch Subject RIV: EH - Ecology, Behaviour Impact factor: 1.656, year: 2010

Analyses of changes in spatial distribution of the beam trawl fleet and their effects on the plaice and sole stock, 1990 - 2005

NARCIS (Netherlands)

Quirijns, F.J.; Rijnsdorp, A.D.; Grift, R.E.

2006-01-01

Management measures directed at limiting fishing effort may have had an influence on the behaviour of the beam trawl fleet that negatively affected the North Sea plaice and sole stocks. This study analyses trends in fleet behaviour and fishing pressure in relation to management measures proposed by

A study of fish behaviour in the extension of a demersal trawl using a multi-compartment separator frame and SIT camera system

DEFF Research Database (Denmark)

Krag, Ludvig Ahm; Madsen, Niels; Karlsen, Junita

2009-01-01

A rigid separator frame with three vertically stacked codends was used to study fish behaviour in the extension piece of a demersal trawl. A video camera recorded fish as they encountered the separator frame. Ten hauls were conducted in a mixed species fishery in the northern North Sea. Fish...

Great Lakes prey fish populations: a cross-basin overview of status and trends based on bottom trawl surveys, 1978-2013

Science.gov (United States)

Gorman, Owen T.; Weidel, Brian C.

2014-01-01

The assessment of Great Lakes prey fish stocks have been conducted annually with bottom trawls since the 1970s by the Great Lakes Science Center, sometimes assisted by partner agencies. These stock assessments provide data on the status and trends of prey fish that are consumed by important commercial and recreational fishes. Although all these annual surveys are conducted using bottom trawls, they differ among the lakes in the proportion of the lake covered, seasonal timing, trawl gear used, and the manner in which the trawl is towed (across or along bottom contours). Because each assessment is unique, population indices were standardized to the highest value for a time series within each lake for the following prey species: Cisco (Coregonus artedi), Bloater (C. hoyi), Rainbow Smelt (Osmerus mordax), Alewife (Alosa pseudoharengus), and Round Goby (Neogobius melanostomus). In this report, standardized indices are presented in graphical form along with synopses to provide a short, informal cross-basin summary of the status and trends of principal prey fishes. There was basin-wide agreement in the trends of age-1 and older biomass for all prey species, with the highest concordance occurring for coregonids and Rainbow Smelt, and weaker concordance for Alewife. For coregonids, the highest biomass occurred from the mid-1980s to the mid-1990s. Rainbow Smelt biomass declined slowly and erratically during the last quarter century. Alewife biomass was generally higher from the early 1980s through 1990s across the Great Lakes, but since the early 1990s, trends have been divergent across the lakes, though there has been a downward trend in all lakes since 2005. Recently, Lake Huron has shown resurgence in biomass of Bloater, achieving 75% of its maximum record in 2012 due to recruitment of a succession of strong and moderate year classes that appeared in 2005-2011. Also, strong recruitment of the 2010 year class of Alewife has led to a sharp increase in biomass of Alewife in

Aspects of the biology of the Atlantic Midshipman, Porichthys porosissimus (Teleostei, Batrachoididae: an important by-catch species of shrimp trawling off southern Brazil

Directory of Open Access Journals (Sweden)

Marcelo Vianna

2000-01-01

Full Text Available Trawl fishing for pink shrimp (Farfantepenaeus brasiliensis and F. paulensis catches large quantities of by-catch fish, discarded due to their having no commercial vaue. As these species have rarely been studied, the impact of fisheries on these populations is not known. This contribution studies the biology of a species of no commercial value, the Atlantic midshipman Porichthys porosissimus. The last haul /Tom a commercial trawler, operating on the northern coast of São Paulo State and the southern coast of Rio de Janeiro State, was preserved (/Tom being discarded and identified at the species leveI. It was observed that this fishery affects the juvenile population which is intluenced by the seasonal variation of the water masses. Growth parameters were estimated: L∞ = 37.0 cm, K = 0.285 year-1. Instantaneous mortality coefficients were estimated: 2=2.14, M=0.63, F= 1.51, S= 11.8 and E=0.71. Considering the intensive activity of the shrimp trawl tleet operating in this area, the deleterious action of trawling is considered as of high impact. The stock management measures applied for pink shrimp are without effect regarding P. porosissimus. which has its spawning period before the closed season and its recruitment peak after it. The results show overfishing and the need to apply measures to reduce trawling action, such as adequate policies, introduction of selectivity devices and the creation of exclusion zones for trawl fishing.A pesca de arrasto para a captura do camarão-rosa (Fm:fantepenaeus brasi/iensis e F. paulensis captura grande quantidade de peixes considerados fauna acompanhante que são descartados por não possuírem valor comercial. Assim, pouco aparecem em trabalhos de biologia pesqueira com dados de desembarque, sendo a ação pesqueira sobre estas populações pouco conhecida. Neste estudo, um arrasto mensal de um barco de pesca foi desembarcado sem que nada do material capturado fosse descartado. Analisou-se Porichthys

Elasmobranch bycatch in the Italian Adriatic pelagic trawl fishery

Science.gov (United States)

Fortuna, Caterina Maria; Moro, Fabrizio; Sala, Antonello

2018-01-01

Elasmobranchs are among the most threatened long-lived marine species worldwide, and incidental capture is a major source of mortality. The northern central Adriatic Sea, though one of the most overfished basins of the Mediterranean Sea, supports a very valuable marine biodiversity, including elasmobranchs. This study assesses the impact of the northern central Adriatic pelagic trawl fishery on common smooth-hound (Mustelus mustelus), spiny dogfish (Squalus acanthias), common eagle ray (Myliobatis aquila), and pelagic stingray (Pteroplatytrygon violacea) by examining incidental catches recorded between 2006 and 2015. The distribution of bycatch events was evaluated using geo-referenced data. Generalized Linear Models were computed to standardize the catch of the four species and to predict the relative abundance of bycatch events. Data analysis shows that most bycatch events involving all four species occurred in the northern Adriatic Sea. The models predicted significant, distinct temporal patterns of standardized catches in line with previous investigations. Water depth, season, and fishing region were the best predictors to explain bycatch events. The present data suggest that the northern Adriatic may be an important nursery area for several elasmobranchs. They also highlight the urgent need for a better understanding of the interactions between elasmobranchs and fisheries to develop and apply suitable, ad hoc management measures. PMID:29377920

Elasmobranch bycatch in the Italian Adriatic pelagic trawl fishery.

Directory of Open Access Journals (Sweden)

Sara Bonanomi

Full Text Available Elasmobranchs are among the most threatened long-lived marine species worldwide, and incidental capture is a major source of mortality. The northern central Adriatic Sea, though one of the most overfished basins of the Mediterranean Sea, supports a very valuable marine biodiversity, including elasmobranchs. This study assesses the impact of the northern central Adriatic pelagic trawl fishery on common smooth-hound (Mustelus mustelus, spiny dogfish (Squalus acanthias, common eagle ray (Myliobatis aquila, and pelagic stingray (Pteroplatytrygon violacea by examining incidental catches recorded between 2006 and 2015. The distribution of bycatch events was evaluated using geo-referenced data. Generalized Linear Models were computed to standardize the catch of the four species and to predict the relative abundance of bycatch events. Data analysis shows that most bycatch events involving all four species occurred in the northern Adriatic Sea. The models predicted significant, distinct temporal patterns of standardized catches in line with previous investigations. Water depth, season, and fishing region were the best predictors to explain bycatch events. The present data suggest that the northern Adriatic may be an important nursery area for several elasmobranchs. They also highlight the urgent need for a better understanding of the interactions between elasmobranchs and fisheries to develop and apply suitable, ad hoc management measures.

Selectivity of Standard, Narrow and Square Mesh Panel Trawl Codends for Hake (Merluccius merluccius) and Poor Cod (Trisopterus minutus capelanus)

OpenAIRE

ÖZBİLGİN, Hüseyin; TOSUNOĞLU, Zafer; AYDIN, Celalettin; KAYKAÇ, Hakan; TOKAÇ, Adnan

2005-01-01

The selectivity of 3 trawl codends, (1) a commercially used standard codend, (2) a narrow codend (100 meshes on its circumference instead of 200) and (3) a square mesh top panel codend, was tested for hake (Merluccius merluccius) and poor cod (Trisopterus minutus capelanus) between 8 and 24 October 2003, in the Aegean Sea. Data were collected using the covered codend technique, and analysed by means of a logistic equation with the maximum likelihood method. The results show that the commer...

Underway meteorological, navigational, optical, physical, profile, time series and trawl data collected aboard NOAA Ship Gordon Gunter in the Gulf of Mexico from 2014-08-21 to 2014-09-30 (NODC Accession 0122396)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0122396 contains raw underway meteorological, navigational, optical, physical, profile, time series and trawl data logged by the Scientific Computer...

Underway meteorological, navigational, optical, physical, time series and trawl data collected aboard NOAA Ship Bell M. Shimada in the North Pacific Ocean from 2013-04-06 to 2013-04-30 (NCEI Accession 0115912)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0115912 contains raw underway meteorological, navigational, optical, physical, time series and trawl data logged by the Scientific Computer System...

Underway meteorological, navigational, optical, physical, profile, time series and trawl data collected aboard NOAA Ship Gordon Gunter in the North Atlantic Ocean from 2014-03-11 to 2014-04-28 (NODC Accession 0118186)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0118186 contains raw underway meteorological, navigational, optical, physical, profile, time series and trawl data logged by the Scientific Computer...

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

DEFF Research Database (Denmark)

Feekings, Jordan P.

Discarding of aquatic organisms is a global problem in the world’s fisheries, where more than 7 million tonnes are caught and subsequently discarded each year. The understanding of what drives discarding can help provide mitigation measures in the future. Altering management measures which result...... in high discard rates/ratios may prove beneficial not only to the economic viability of the fishery but also to the biological functioning of the ecosystem. The present Ph.D. thesis, titled “Discarding Discards: Identification of influential factors and possible mitigation tools in demersal trawl...... an examination of the efficiency of technical regulations currently in force and retrospective analyses of the efficiency of such measures in the past. The thesis consists of a review and 4 papers. Paper I is an investigation of the factors that can potentially influence the discarding of commercial species...

DIAGNOSIS OF SHRIMP TRAWLING IN THE STATE OF PERNAMBUCO, BRAZIL

Directory of Open Access Journals (Sweden)

Carlos Eduardo Rangel Andrade

2016-09-01

Full Text Available With a technical approach, this diagnosis aims to fill a gap in the overview of the activity, considering its technical aspects that manage the fishing effort of shrimping of Penambuco. From October 2013 to August 2014, the fishing grounds were identified used in this activity, as well as the fishing method, the number of boats and fishermen acting, type of boat and gears used. Analyses were performed with the major communities operating in this fishery (Recife, Jaboatão dos Guararapes, Barra de Sirinhaém and São Jose da Coroa Grande. The analyzes of the catch were tested using one-way ANOVA (α 5%. They observed two traditional types: the beach seining and trawing. It was cataloged about 50 vessels in the activity, with approximately 100 fishermen. They are caught mainly three types of shrimp: pink (Farfantepenaeus spp., Seabob (Xiphopenaeus kroyeri and white (Lithopenaeus schmitii. Statistical data concentrated in the metropolitan area of Recife and Barra de Sirinhaém. There seems to be a direct relationship rainfall with shrimp production because with increased rainfall, there is a higher volume of landing fishery. Barra de Sirinhaém is the main area used in the State. Keywords: ‘mangote’; trawling fishing; pink shrimp; Farfantepenaeus spp.

Escape windows to improve the size selectivity in the Baltic cod trawl fishery

DEFF Research Database (Denmark)

Madsen, Niels; Holst, René; Foldager, L.

2002-01-01

A rapid decrease of the stock of Baltic cod (Gadus morhua) has provided the incentive to improve the size selectivity in the trawl fishery. Use of escape windows is permitted in the legislation to give means of improving the size selectivity of cod as an alternative to a traditional standard codend....... The history of the use of escape windows in the Baltic Sea cod fishery is reviewed. The present escape windows do not function optimally. The objective of this new experiment was to compare an improved design of escape window, which is placed in the upper panel, with that of standard codend. Three standard...... of the codend selectivity was formulated to analyse the results and determine the effects of codend type, mesh size and other recorded variables. L50 and SR increased significantly with the mesh size. L50 was significantly increased and SR significantly reduced for a window codend with the same window mesh size...

The seascape of demersal fish nursery areas in the North Mediterranean Sea, a first step towards the implementation of spatial planning for trawl fisheries.

Directory of Open Access Journals (Sweden)

Francesco Colloca

Full Text Available The identification of nursery grounds and other essential fish habitats of exploited stocks is a key requirement for the development of spatial conservation planning aimed at reducing the adverse impact of fishing on the exploited populations and ecosystems. The reduction in juvenile mortality is particularly relevant in the Mediterranean and is considered as one of the main prerequisites for the future sustainability of trawl fisheries. The distribution of nursery areas of 11 important commercial species of demersal fish and shellfish was analysed in the European Union Mediterranean waters using time series of bottom trawl survey data with the aim of identifying the most persistent recruitment areas. A high interspecific spatial overlap between nursery areas was mainly found along the shelf break of many different sectors of the Northern Mediterranean indicating a high potential for the implementation of conservation measures. Overlap of the nursery grounds with existing spatial fisheries management measures and trawl fisheries restricted areas was also investigated. Spatial analyses revealed considerable variation depending on species and associated habitat/depth preferences with increased protection seen in coastal nurseries and minimal protection seen for deeper nurseries (e.g. Parapenaeus longirostris 6%. This is partly attributed to existing environmental policy instruments (e.g. Habitats Directive and Mediterranean Regulation EC 1967/2006 aiming at minimising impacts on coastal priority habitats such as seagrass, coralligenous and maerl beds. The new knowledge on the distribution and persistence of demersal nurseries provided in this study can support the application of spatial conservation measures, such as the designation of no-take Marine Protected Areas in EU Mediterranean waters and their inclusion in a conservation network. The establishment of no-take zones will be consistent with the objectives of the Common Fisheries Policy

The seascape of demersal fish nursery areas in the North Mediterranean Sea, a first step towards the implementation of spatial planning for trawl fisheries.

Science.gov (United States)

Colloca, Francesco; Garofalo, Germana; Bitetto, Isabella; Facchini, Maria Teresa; Grati, Fabio; Martiradonna, Angela; Mastrantonio, Gianluca; Nikolioudakis, Nikolaos; Ordinas, Francesc; Scarcella, Giuseppe; Tserpes, George; Tugores, M Pilar; Valavanis, Vasilis; Carlucci, Roberto; Fiorentino, Fabio; Follesa, Maria C; Iglesias, Magdalena; Knittweis, Leyla; Lefkaditou, Eugenia; Lembo, Giuseppe; Manfredi, Chiara; Massutí, Enric; Pace, Marie Louise; Papadopoulou, Nadia; Sartor, Paolo; Smith, Christopher J; Spedicato, Maria Teresa

2015-01-01

The identification of nursery grounds and other essential fish habitats of exploited stocks is a key requirement for the development of spatial conservation planning aimed at reducing the adverse impact of fishing on the exploited populations and ecosystems. The reduction in juvenile mortality is particularly relevant in the Mediterranean and is considered as one of the main prerequisites for the future sustainability of trawl fisheries. The distribution of nursery areas of 11 important commercial species of demersal fish and shellfish was analysed in the European Union Mediterranean waters using time series of bottom trawl survey data with the aim of identifying the most persistent recruitment areas. A high interspecific spatial overlap between nursery areas was mainly found along the shelf break of many different sectors of the Northern Mediterranean indicating a high potential for the implementation of conservation measures. Overlap of the nursery grounds with existing spatial fisheries management measures and trawl fisheries restricted areas was also investigated. Spatial analyses revealed considerable variation depending on species and associated habitat/depth preferences with increased protection seen in coastal nurseries and minimal protection seen for deeper nurseries (e.g. Parapenaeus longirostris 6%). This is partly attributed to existing environmental policy instruments (e.g. Habitats Directive and Mediterranean Regulation EC 1967/2006) aiming at minimising impacts on coastal priority habitats such as seagrass, coralligenous and maerl beds. The new knowledge on the distribution and persistence of demersal nurseries provided in this study can support the application of spatial conservation measures, such as the designation of no-take Marine Protected Areas in EU Mediterranean waters and their inclusion in a conservation network. The establishment of no-take zones will be consistent with the objectives of the Common Fisheries Policy applying the ecosystem

Underway meteorological, navigational, optical, physical, profile, time series and trawl data collected aboard NOAA Ship Bell M. Shimada in the North Pacific Ocean from 2013-09-09 to 2013-09-16 (NODC Accession 0116842)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0116842 contains raw underway meteorological, navigational, optical, physical, profile, time series and trawl data logged by the Scientific Computer...

Marine Fish and Shellfish Survey data from otter trawls in the Chukchi Sea from the OCEAN HOPE 3 and OSHORO MARU from 16 August 1990 to 31 July 1992 (NODC Accession 9400061)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Marine Fish and Shellfish Survey data were collected from otter trawls in the Chukchi Sea from the OCEAN HOPE. Data were collected by the University of Alaska from...

A comparative study of Northern Ireland's estuaries based on the results of beam trawl fish surveys

Science.gov (United States)

Harrison, Trevor D.; Armour, Neil D.; McNeill, Michael T.; Moorehead, Peter W.

2017-11-01

The fish communities of Northern Ireland's estuaries were described and compared using data collected with a modified beam trawl over a six year period from 2009 to 2014. Multivariate analyses identified four estuary groups based on variations in their physico-chemical attributes. These groups broadly corresponded with the distribution and variation of estuary geomorphic types identified around the Irish coast. The dominant fish species captured were also among the main species reported in other North East Atlantic estuaries. A significant link between the estuary types and their fish communities was found; each estuary group contained a somewhat distinctive fish community. The fish communities also showed a significant relationship with the physico-chemical characteristics of the estuaries. Differences in fish species composition are attributed to habitat and environmental preferences of key estuary-associated species.

Diamond vs. square mesh codend in a multi-species trawl fishery of the western Mediterranean: effects on catch composition, yield, size selectivity and discards

OpenAIRE

Ordines, F. (Francesc); Massutí, E. (Enric); Guijarro, B. (Beatriz); Mas, R. (Ramon)

2006-01-01

Selectivity studies usually describe the effects on target species, whereas information on by-catch and discards is scarce. Nevertheless, large quantities of undersized individuals and invertebrates are discarded in the Mediterranean multi-species bottom trawl fishery. The present work analyses the data from two surveys carried out on the shallow and deep continental shelf (50–78 m, and 147–189 m, respectively) off the Balearic Islands (western Mediterranean). In these surveys, the traditiona...

Experimental investigation and numerical analysis to develop low-energy large-midwater trawls

Science.gov (United States)

Lee, Jihoon; Kim, Taeho; Lee, Chun-Woo; Park, Subong

2017-12-01

Fuel consumption in fisheries is a primary concern because of its effects on the environment and the costs incurred by fishermen. Many studies have been conducted to reduce the fuel consumption in fishing operations. Fuel consumption due to fishing gear during a fishing operation is generally related to the hydrodynamic resistance on the gear. This means that fuel consumption is proportional to the drag created by the towing speed. Based on numerical methods, this study suggests a new approach to reduce fuel consumption in fisheries. The results of the simulation are in good agreement with those of model experiments. The total as well as partial resistance forces on the gear are calculated by simulation. The simulation results suggest improved materials and gear structure for reducing the hydrodynamic forces on the gear while maintaining gear performance. The method for assessing the gear performance involves measuring the height and width of the net mouth. Furthermore, this study investigates the efficiency of a low-energy trawl from an economic point of view. The findings of this study will be useful in reducing greenhouse gas (GHG) emissions in fishing operations, and thereby contribute toward lowering fishing costs by saving fuel.

Fishing effects in northeast Atlantic shelf seas : patterns in fishing effort, diversity and community structure. III. International trawling effort in the North Sea : an analysis of spatial and temporal trends

DEFF Research Database (Denmark)

Jennings, S.; Alsväg, J.; Cotter, A.J.R.

1999-01-01

of beam trawling effort increases from north to south. Plots of annual fishing effort by ICES statistical rectangle (211 boxes of 0.5 degrees latitude x 1 degrees longitude) indicate that the majority of fishing effort in the North Sea are concentrated in a very few rectangles. Thus mean annual total...

Bayesian spatio-temporal discard model in a demersal trawl fishery

Science.gov (United States)

Grazia Pennino, M.; Muñoz, Facundo; Conesa, David; López-Quílez, Antonio; Bellido, José M.

2014-07-01

Spatial management of discards has recently been proposed as a useful tool for the protection of juveniles, by reducing discard rates and can be used as a buffer against management errors and recruitment failure. In this study Bayesian hierarchical spatial models have been used to analyze about 440 trawl fishing operations of two different metiers, sampled between 2009 and 2012, in order to improve our understanding of factors that influence the quantity of discards and to identify their spatio-temporal distribution in the study area. Our analysis showed that the relative importance of each variable was different for each metier, with a few similarities. In particular, the random vessel effect and seasonal variability were identified as main driving variables for both metiers. Predictive maps of the abundance of discards and maps of the posterior mean of the spatial component show several hot spots with high discard concentration for each metier. We argue how the seasonal/spatial effects, and the knowledge about the factors influential to discarding, could potentially be exploited as potential mitigation measures for future fisheries management strategies. However, misidentification of hotspots and uncertain predictions can culminate in inappropriate mitigation practices which can sometimes be irreversible. The proposed Bayesian spatial method overcomes these issues, since it offers a unified approach which allows the incorporation of spatial random-effect terms, spatial correlation of the variables and the uncertainty of the parameters in the modeling process, resulting in a better quantification of the uncertainty and accurate predictions.

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...

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...

Underway meteorological, navigational, optical, physical, profile, time series and trawl data collected aboard NOAA Ship Bell M. Shimada in the Coastal Waters of SE Alaska and North Pacific Ocean from 2013-06-06 to 2013-09-09 (NCEI Accession 0116843)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0116843 contains raw underway meteorological, navigational, optical, physical, profile, time series and trawl data logged by the Scientific Computer...

Physical, chemical, marine fish, shellfish, and other data from bottle casts and bottom trawls from the JEFF AND TINA as part of the EPA/FLOWER GARDENS project from 1980-10-11 to 1981-07-27 (NODC Accession 8200169)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Physical, chemical, marine fish, shellfish, and other data from bottle casts and bottom trawls from the JEFF AND TINA from 11 October 1980 to 27 July 1981. Data were...

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.

Influence of the hydrodynamic conditions on the accessibility of Aristeus antennatus and other demersal species to the deep water trawl fishery off the Balearic Islands (western Mediterranean)

OpenAIRE

Amores, Ángel; Rueda, Lucía; Monserrat, Sebastià; Guijarro, Beatriz; Pasqual, Catalina; Massutí, Enric

2013-01-01

Monthly catches per unit of effort (CPUE) of adult red shrimp (. Aristeus antennatus), reported in the deep water bottom trawl fishery developed on the Sóller fishing ground off northern Mallorca (Western Mediterranean), and the mean ocean surface vorticity in the surrounding areas are compared between 2000 and 2010. A good correlation is found between the rises in the surrounding surface vorticity and the drops in the CPUE of the adult red shrimp. This correlation could be explained by assum...

Deepwater Horizon MC252 water column data from the Environmental Response Management Application (ERMA) containing workplan cruise samples, plankton trawl surveys, fish surveys, and related data collected between 2000-06-13 and 2011-10-06 for the DWH response in the Northern Gulf of Mexico (NCEI Accession 0163816)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This Archival Information Package (AIP) contains Environmental Resource Management Application (ERMA) GIS layers that represent trawl locations, Southeast Area...

The influence of the trawl mouth opening size and net colour on catch efficiency during sampling of early stages of perch (Perca fluviatilis) and pikeperch (Sander lucioperca) in the bathypelagic layer of a canyon-shaped reservoir

Czech Academy of Sciences Publication Activity Database

Jůza, Tomáš; Čech, Martin; Kubečka, Jan; Vašek, Mojmír; Peterka, Jiří; Kratochvíl, Michal; Frouzová, Jaroslava; Matěna, Josef

2012-01-01

Roč. 123, July (2012), s. 21-25 ISSN 0165-7836 R&D Projects: GA ČR(CZ) GA206/06/1371; GA ČR(CZ) GP206/09/P266 Institutional support: RVO:60077344 Keywords : Římov Reservoir * percids avoidance reaction * ichthyoplankton trawl Subject RIV: EH - Ecology, Behaviour Impact factor: 1.695, year: 2012

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.

Preliminary estimates of the abundance and fidelity of dolphins associating with a demersal trawl fishery.

Science.gov (United States)

Allen, Simon J; Pollock, Kenneth H; Bouchet, Phil J; Kobryn, Halina T; McElligott, Deirdre B; Nicholson, Krista E; Smith, Joshua N; Loneragan, Neil R

2017-07-10

The incidental capture of wildlife in fishing gear presents a global conservation challenge. As a baseline to inform assessments of the impact of bycatch on bottlenose dolphins (Tursiops truncatus) interacting with an Australian trawl fishery, we conducted an aerial survey to estimate dolphin abundance across the fishery. Concurrently, we carried out boat-based dolphin photo-identification to assess short-term fidelity to foraging around trawlers, and used photographic and genetic data to infer longer-term fidelity to the fishery. We estimated abundance at ≈ 2,300 dolphins (95% CI = 1,247-4,214) over the ≈ 25,880-km 2 fishery. Mark-recapture estimates yielded 226 (SE = 38.5) dolphins associating with one trawler and some individuals photographed up to seven times over 12 capture periods. Moreover, photographic and genetic re-sampling over three years confirmed that some individuals show long-term fidelity to trawler-associated foraging. Our study presents the first abundance estimate for any Australian pelagic dolphin community and documents individuals associating with trawlers over days, months and years. Without trend data or correction factors for dolphin availability, the impact of bycatch on this dolphin population's conservation status remains unknown. These results should be taken into account by management agencies assessing the impact of fisheries-related mortality on this protected species.

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

. Motivated by Sydney’s insufficient supplies of fish, the objective of early fisheries management in the state of New South Wales (NSW) was to improve the industry. Driven by state developmentalism, efforts were focused on increasing the productivity of already existing coastal fisheries through fisheries......As many of the world’s fish stocks are fully or over-exploited there is an urgent need for governments to provide robust fisheries management. However, governments are often slow to implement necessary changes to fisheries practices. The will to govern is an essential factor in successful marine...... 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...

Survival of fish after escape from a 40 mm stretched diamond mesh trawl codend in the Aegean Sea

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Faik Ozan Düzbastilar

2010-11-01

Full Text Available This study aimed to determine the survival rates of three fish species, the brown comber (Serranus hepatus, black goby (Gobius niger and annular seabream (Diplodus annularis, after their escape from a 40 mm stretched diamond mesh polyethylene (PE codend. Experiments were carried out in the eastern Mediterranean in September 2007 using a conventional bottom trawl with 600 meshes around the mouth. A constant 15 min towing duration was used for all hauls. The towing speed varied between 2.0 and 2.5 knots. Codend covers, supported by two hoops, were used to retain escaping fish. At the end of each haul, these covers were detached from the codend, fixed to the sea floor at depths of 19 to 28 m, and then observed by the divers for a period of seven days. On the eighth day, all of the covers were lifted up and the survivors and mortalities were counted and measured. The mean survival percentages of open codend and experimental cages were found to be 97.1% and 98.3% for brown comber, 69.0% and 77.2% for black goby, and 97.5% and 98.6% for annular seabream respectively.

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

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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.

From Fishing to Fish Processing: Separation of Fish from Crustaceans in the Norway Lobster-Directed Multispecies Trawl Fishery Improves Seafood Quality.

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Junita D Karlsen

Full Text Available Fishing gears have negative impacts on seafood quality, especially on fish in the mixed trawl fishery targeting Norway lobster (Nephrops norvegicus. In this fishery, which is worth about €80 millions in Denmark alone, the quality of fish can be significantly improved by simple gear changes. A trawl codend divided into an upper and lower codend was designed to separate fish from Norway lobster during the fishing process by encourage fish to swim into the upper codend by using a frame at the entrance of the lower codend. Separate codends for fish and Norway lobster in the same gear provide the opportunity to selectively reduce small low-value fish, which will reduce catch weight and sorting time onboard the vessel. For this horizontally divided test codend and a standard codend, in which the catch was mixed, quality assessments were performed on the same batches of fish during three steps of the value chain: i aboard the fishing vessel; ii at the Fishermen's Collection Central, and iii in the production plant. Four species of fish and fillets from fish caught in the upper codend of the test codend were of significantly better quality for several of the assessed parameters compared with those caught in the standard codend: i newly caught fish showed significantly less scale loss and discolourations and had significantly better texture; ii landed fish had significantly better skin appearance and texture and significantly fewer discolourations; and iii fillets showed significantly fewer blood spots and had significantly better texture. There were no differences in injuries for newly caught fish or gaping and bruises for fillets between the test and standard codends. The decrease in catch-related damages in the test codend is explained by little contact between fish and animals with hard or spiny surfaces due to successful separation of fish and Norway lobster into the upper and lower codends, respectively, and by lower catch weight in the upper

75 FR 32993 - Fisheries Off West Coast States; Pacific Coast Groundfish Fishery Management Plan; Amendments 20...

Science.gov (United States)

2010-06-10

.../processor (C/P) trawl fleets. The trawl rationalization program is intended to increase net economic benefits, create individual economic stability, provide full utilization of the trawl sector allocation..., creates individual economic stability, provides for full utilization of the trawl sector allocation...

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.

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

International Nuclear Information System (INIS)

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

2008-01-01

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 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

Partitioning the contributions of mega-, macro- and meiofauna to benthic metabolism on the upper continental slope of New Zealand: Potential links with environmental factors and trawling intensity

Science.gov (United States)

Leduc, Daniel; Pilditch, Conrad A.; Nodder, Scott D.

2016-02-01

Understanding and predicting change in deep-sea benthic ecosystem function remains a major challenge. Here, we conducted analyses combining data on the abundance and biomass of benthic fauna and sediment community oxygen consumption (SCOC) on New Zealand's continental margin to estimate and compare the contributions of meio-, macro-, and megafauna to total benthic metabolism and identify potential links with environmental factors and trawling intensity. We focussed on two regions in close proximity-the high surface primary productivity Chatham Rise and low surface productivity Challenger Plateau. Mean megafauna biomass was twenty times greater on Chatham Rise than Challenger Plateau, likely reflecting differences in food supply between the two regions; this contrast in megafaunal biomass was mainly due to differences in mean body weight rather than abundance. Meio- and macrofauna made similar contributions to SCOC and together accounted for 12% of benthic metabolism on average. In contrast, the estimated contribution of megafauna never exceeded 1.5%. Significant positive correlations between faunal respiration and food availability indicate a link between food supply and benthic community function. Our analyses also show that fauna made a greater contribution to SCOC in conditions of high food availability, and that microorganisms (i.e., the proportion of SCOC not accounted for by the fauna) tended to be more dominant at sites with low food availability. These findings provide support for the concept that large organisms are more strongly affected by a reduction in food resources than small organisms, which in turn underlies one of the most widely described patterns in the deep-sea benthos, i.e., the reduction in organism body size with depth. Because metabolism in deep-sea sediments is typically dominated by microorganisms and small fauna, the absence of a relationship between bottom trawling intensity and the respiration of benthic fauna in the present study may

Micronekton sampling gear Intercalibration Experiment Survey #1 (MIE-1) (SE0413L2, EK60)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The goal of the cruise was to collect micronekton samples using three different type of midwater trawl: Cobb trawl, Isaacs Kidd Midwater Trawl (IKMT), and a Hokkaido...

A Covered Cod-End and Tow-Path Evaluation of Midwater Trawl Gear Efficiency for Catching Delta Smelt (Hypomesus transpacificus

Directory of Open Access Journals (Sweden)

Lara Mitchell

2017-12-01

Full Text Available https://doi.org/10.15447/sfews.2017v15iss4art3For nearly 50 years, the California Department of Fish and Wildlife has used a midwater trawl to intensively monitor fish populations in the San Francisco Estuary during the fall, sampling over 100 locations each month. The data collected have been useful for calculating indices of fish abundance and for detecting and documenting the decline of the endangered fish species delta smelt (Hypomesus transpacificus. However, efforts to calculate estimates of absolute abundance have been hampered by the lack of information on gear efficiency, in particular questions about contact selectivity and the effect of tow method on catches. To answer these questions we conducted a study that used a covered cod end on a net towed either near the surface, referred to as a surface tow, or throughout the water column, referred to as an oblique tow. A contact selectivity model was fit to estimate the probability that a delta smelt that has come into contact with the net is retained in the cod end of the net conditional on its body length. Full retention of delta smelt was found to occur around 60 mm fork length. Delta smelt catch densities for the surface tows were an order of magnitude greater than densities in the oblique tows, suggesting a surface orientation at the sub-adult life stage. These results represent an important step in being able to calculate absolute abundance estimates of the delta smelt population size using decades’ worth of monitoring data.

Monitoring cod catches of the Dutch demersal fleet in 2016

NARCIS (Netherlands)

Hal, van R.; Machiels, M.A.M.

2017-01-01

This report presents the results of the cod monitoring program 2016. The research was commissioned by the Dutch Ministry of Economic Affairs within the EZ-program Beleidsondersteunend Onderzoek. Cod catches of the vessels in the fleet segments BT2 (beam trawl and pulse trawl) and TR (otter trawls

Ploughing the deep sea floor.

Science.gov (United States)

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

2012-09-13

Bottom trawling is a non-selective commercial fishing technique whereby heavy nets and gear are pulled along the sea floor. The direct impact of this technique on fish populations and benthic communities has received much attention, but trawling can also modify the physical properties of seafloor sediments, water–sediment chemical exchanges and sediment fluxes. Most of the studies addressing the physical disturbances of trawl gear on the seabed have been undertaken in coastal and shelf environments, however, where the capacity of trawling to modify the seafloor morphology coexists with high-energy natural processes driving sediment erosion, transport and deposition. Here we show that on upper continental slopes, the reworking of the deep sea floor by trawling gradually modifies the shape of the submarine landscape over large spatial scales. We found that trawling-induced sediment displacement and removal from fishing grounds causes the morphology of the deep sea floor to become smoother over time, reducing its original complexity as shown by high-resolution seafloor relief maps. Our results suggest that in recent decades, following the industrialization of fishing fleets, bottom trawling has become an important driver of deep seascape evolution. Given the global dimension of this type of fishery, we anticipate that the morphology of the upper continental slope in many parts of the world’s oceans could be altered by intensive bottom trawling, producing comparable effects on the deep sea floor to those generated by agricultural ploughing on land.

75 FR 41123 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea Subarea

Science.gov (United States)

2010-07-15

... nonpelagic trawl fishing industry. Modified Nonpelagic Trawl Gear Nonpelagic trawl gear uses a pair of long lines called sweeps to herd fish into the net. These lines drag across the bottom and may adversely... flatfish species. In 2008 and 2009, the AFSC and NOAA Office for Law Enforcement worked with the fishing...

Biological aspects of the Sailfin dory Zenopsis conchifer (Lowe, 1852 caught by deep-sea trawling fishery off southern Brazil

Directory of Open Access Journals (Sweden)

Rodrigo Silvestre Martins

2012-06-01

Full Text Available Biological aspects of sailfin dory, Zenopsis conchifer, were studied from 839 individuals obtained from deep-sea commercial bottom trawling off southern Brazil at depths up to 526 m in 2002 and 2003. Samples included fish from 101 mm Lt and 15 g up to 640 mm Lt and 2,9 g. The sex-ratio was 50% at 150 mm Lt and between 300-350 mm Lt, with females outnumbering males in the remaining size classes. Reproductive activity seems to peak between July and August (austral winter. Size at attainment of 50% maturity (Lt50 was 311 mm Lt in females. The mean length and maturity of the specimens increased with depth, suggesting that larger fish concentrate in deeper waters.Aspectos biológicos do peixe-galo-de-profundidade, Zenopsis conchifer, foram estudados a partir de 839 peixes amostrados na pesca comercial de arrasto de profundidade (até 526 m no sul do Brasil entre 2002 e 2003. As amostras incluíram peixes entre 101 mm TL e 15 g até 640 mm TL e 2.952 g. A proporção sexual foi próxima à paridade na classe de tamanho de 150 mm TL e entre 300-350 mm TL, sendo que as fêmeas predominaram nas demais classes. A atividade reprodutiva apresentou um pico durante o inverno. O tamanho de primeira maturação (TL50 nas fêmeas foi de 311 mm TL. Os comprimentos corporais e a maturidade sexual aumentaram com a profundidade, sugerindo que os maiores exemplares se concentram águas profundas.

Selectivity of commercial, larger mesh and square mesh trawl codends for deep water rose shrimp Parapenaeus longirostris (Lucas, 1846 in the Aegean Sea

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Hakan Kaykaç

2009-09-01

Full Text Available We investigated the differences between size selectivity of a commercial codend (40 mm diamond mesh – 40D, a larger mesh codend (48 mm diamond mesh – 48D, and a square mesh codend (40 mm square mesh – 40S for Parapenaeus longirostris in international waters of the Aegean Sea. Selectivity data were collected by using a covered codend method and analysed taking between-haul variation into account. The results indicate significant increases in L50 values in relation to an increase in mesh size and when the square mesh is used in the commercial trawl codend. The results demonstrate that the commercially used codend (40D is not selective enough for P. longirostris in terms of length at first maturity. Changing from a 40D to a 48D codend significantly improves selection, with an increase of about 15% in the L50 values (carapace length 14.5 mm for 40D and 16.6 mm for 48D. Similarly, 40 mm square mesh, which has recently been legislated for EU Mediterranean waters, showed a 12.4% higher mean L50 value (16.3 mm than 40 mm diamond mesh for this species. However, despite these improvements, the 48D and 40S codends still need further improvements to obtain higher selectivity closer to the length at first maturity (20 mm carapace length.

Comparative technical aspects of the Nephrops norvegicus (L. fishery in the northern Mediterranean Sea

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Francesc Sarda

1998-12-01

Full Text Available A comparative study of the technical characteristics of the Norway lobster fishery in the Mediterranean Sea is presented. The different trawl vessels, trawl gears, trawling manoeuvres, and status of the statistics compiled by the administrations are described. The main conclusions are that catchability has increased with technological advances, official landings statistics are flawed in most of the Mediterranean, and fishing methods differed from country to country.

Influence of the hydrodynamic conditions on the accessibility of the demersal species to the deep water trawl fishery off the Balearic Islands (western Mediterranean)

Science.gov (United States)

Amores, A.; Rueda, L.; Monserrat, S.; Guijarro, B.; Pasqual, C.; Massutí, E.

2013-12-01

Ocean mean surface vorticity from gridded multi-mission satellite altimetry data was explored in the Western Mediterranean basin for the period 2000-2010, with the aim of comparing its variability with several species of the deep water fishery in the area. Monthly catches per unit of effort (CPUE) of adult red shrimp (Aristeus antennatus), reported in the deep water bottom trawl fishery developed off northern Mallorca Island displayed a good correlation with surface vorticity. This correlation could be explained by assuming that most of the surface vorticity episodes could reach the bottom, increasing the seabed velocities and producing sediment resuspensions, which could affect the near bottom water turbidity. A. antennatus would respond to this increased turbidity by moving downwards to the deeper waters. This massive displacement of red shrimp specimens away from the fishing grounds would consequently decrease their accesibility to fishing exploitation. This relationship between vorticity and catches also holds for other species , considered as by-catch of the deep water fishery in the area. Results appear to support the suggestion that the water turbidity generated by the vorticy episodes is significant enough to affect the dynamics of the demersal species. The way the surface vorticity observed can affect the bottom sediments is also investigated using a year-long moored near-bottom currentmeter and a sediment trap sited in the fishing grounds.

Atividade reprodutiva de peixes (Teleostei e o defeso da pesca de arrasto no litoral norte de Santa Catarina, Brasil Reproductive activity of fish (Teleostei and closed season to shrimp trawling off ther northern coast of Santa Catarina, Brazil

Directory of Open Access Journals (Sweden)

Leda M. de Souza

2007-12-01

Full Text Available Desembarques de arrasto visando à pesca do camarão sete-barbas, Xiphopenaeus kroyeri, foram acompanhados de 2005 a 2007 no município de São Francisco do Sul, Santa Catarina. Setenta e seis espécies de teleósteos foram registradas como captura incidental e seus indivíduos foram avaliados quanto ao estádio de maturação e Índice de Atividade Reprodutiva. Constatou-se que indivíduos de metade das espécies são capturados com gônadas maduras, em estações que variaram conforme a espécie. Em Isopisthus parvipinnis a atividade enquadrou-se na categoria "muito intensa" na primavera de 2005 e no verão de 2007; em Menticirrhus americanus, Stellifer sp., Pomadasys corvinaeformis, Stellifer brasiliensis, Syacium papillosum, Larimus breviceps, Diapterus rhombeus, Symphurus tessellatus, Chirocentrodon bleekerianus, Pellona harroweri, Anchoa tricolor e Selene setapinnis apenas em uma estação, dependendo da espécie. O verão de 2007, seguido da primavera de 2005, foram as estações em que o arrasto incidiu sobre maior número de espécies em atividade reprodutiva "intensa" ou "muito intensa". No verão de 2007 o arrasto camaroeiro incidiu sobre um conjunto de espécies em atividade reprodutiva maior que na mesma estação em 2006. Atribui-se esse fato à proibição legal do arrasto de camarão no trimestre de outubro-dezembro de 2006, favorecendo a atividade reprodutiva das espécies na estação subseqüente. Recomenda-se que a gestão da pesca camaroeira na região mantenha o defeso de arrasto na primavera, assim beneficiando não apenas as espécies de peixes que desovam nesta estação, mas também aquelas que se preparam para a desova no verão.Shrimp trawling was monitored in southern Brazil in order to study the reproductive status of teleosts occurring as by-catch. From 2005 to 2007 seventy-six fish species were found in this kind of fisheries. Gonad stages were evaluated and the Reproductive Activity Index was calculated. Mature

Assessment of Marine Litter in the Barents Sea, a Part of the Joint Norwegian–Russian Ecosystem Survey

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Bjørn E. Grøsvik

2018-03-01

Full Text Available This study presents a large-scale monitoring of marine litter performed in the joint Norwegian–Russian ecosystem monitoring surveys in the period from 2010 to 2016 and contribute to documentation of the extent of marine litter in the Barents Sea. The distribution and abundance of marine litter were calculated by recordings of bycatch from the pelagic trawling in upper 60 m, from bottom trawling close to the sea floor, and floating marine debris at surface by visual observations. The study is comprehensive regarding coverage and number with registrations from 2,265 pelagic trawls and 1,860 bottom trawls, in addition to surface registration between the stations. Marine litter has been recorded from 301 pelagic and 624 of the bottom trawl catches. In total, 784 visual observations of floating marine debris were recorded during the period. Marine litter has been categorized according to volume or weight of the material types plastic, wood, metal, rubber, glass, paper, and textile. Marine litter is observed in the entire Barents Sea and distribution vary with material densities, ocean currents and depth. Plastic dominated number of observations with marine litter, as 72% of surface observations, 94% of pelagic trawls, and 86% of bottom trawls contained plastic. Observations of wood constituted 19% of surface observations, 1% of pelagic trawls, and 17% of bottom trawls with marine litter. Materials from other categories such as metal, rubber, paper, textile, and glass were observed sporadically. Recordings of wood dominated surface observations (61.9 ± 21.6% by volume and on seafloor (59.4 ± 35.0% by weight, while plastic dominated marine litter observations in upper 60 m depth (86.4 ± 16.5% by weight over these 7 years. Based on recordings and volume or area covered, mean levels of plastic in the upper 60 m of the Barents Sea were found to 0.011 mg m−3 (pelagic and 2.9 kg km−2 at sea floor over the study period. Average levels of marine

Analysis and standardization of landings per unit effort of red shrimp Aristeus antennatus from the trawl fleet of Barcelona (NW Mediterranean

Directory of Open Access Journals (Sweden)

Valeria Mamouridis

2014-03-01

Full Text Available Monthly landings and effort data from the Barcelona trawl fleet (NW Mediterranean were selected to analyse and standardize the landings per unit effort (LPUE of the red shrimp (Aristeus antennatus using generalized additive models. The dataset covers a span of 15 years (1994-2008 and consists of a broad spectrum of predictors: fleet-dependent (e.g. number of trips performed by vessels and their technical characteristics, such as the gross registered tonnage, temporal (inter- and intra-annual variability, environmental (North Atlantic Oscillation [NAO] index and economic (red shrimp and fuel prices variables. All predictors individually have an impact on LPUE, though some of them lose their predictive power when considered jointly. That is the case of the NAO index. Our results show that six variables from the whole set can be incorporated into a global model with a total explained deviance (ED of 43%. We found that the most important variables were effort-related predictors (trips, tonnage, and groups with a total ED of 20.58%, followed by temporal variables, with an ED of 13.12%, and finally the red shrimp price as an economic predictor with an ED of 9.30%. Taken individually, the main contributing variable was the inter-annual variability (ED=12.40%. This high ED value suggests that many factors correlated with inter-annual variability, such as environmental factors (the NAO in specific years and fuel price, could in turn affect LPUE variability. The standardized LPUE index with the effort variability removed was found to be similar to the fishery-independent abundance index derived from the MEDITS programme.

Structure and dynamics of demersal fish assemblages over three ...

African Journals Online (AJOL)

Open Access DOWNLOAD FULL TEXT ... In this study, we analysed data from scientific trawl surveys carried out on the ... Keywords: biodiversity, ecosystem indicators, fishing impact, historical data, marine ecology, trawling surveys ...

Habitat Mapping Cruise - Tunicates (HB0806, EK60)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Objectives: Use otter trawls (if available), beam trawls (if not), Naturalist Dredge, SEABOSS photography/bottom grab equipment, CTDs, and large (10-30 liter) Niskin...

Macrozooplankton community structure off East Antarctica (80 150°E) during the Austral summer of 1995/1996

Science.gov (United States)

Hosie, G. W.; Schultz, M. B.; Kitchener, J. A.; Cochran, T. G.; Richards, K.

2000-08-01

Zooplankton data from routine 0-200 m oblique trawls and targeted trawls were analysed using cluster analysis and non-metric multidimensional scaling to define the communities in Eastern Antarctica (80-150°E), their distribution patterns, indicator species, and species affinities. Three communities were defined based on routine trawls. The Main Oceanic Community comprising herbivorous copepods, chaetognaths, and the euphausiid Thysanoessa macrura dominated the area west of 120°E. The area east of 120°E was dominated by Salpa thompsoni. The third community located in the neritic zone was dominated by Euphausia crystallorophias. Antarctic krill Euphausia superba did not form a distinct community in its own right, unlike previous observations in Prydz Bay. Krill were distributed throughout most of the survey area but generally in higher abundances towards the shelf break. Overall, krill abundance was low compared with previous net surveys in Prydz Bay. Three main types of assemblages were identified based on target trawls. The first group was dominated by krill (mean 1149 individuals per 1000 m 3) which represented >99% of Group 1 catches in terms of numbers and biomass. Group 2 comprised the bulk of target trawls and comprised a wide diversity of species typical of the main oceanic community, with a mean abundance approximately half of that observed in the routine trawls. The third group comprised trawls in the neritic zone dominated by E. crystallorophias. No salp-dominated aggregation was found. While E. superba did not dominate a distinct community geographically as seen in previous Prydz Bay surveys, it did dominate discrete layers or aggregations, showing that both horizontal and vertical separation of communities exist.

AFSC/ABL: Lynn Canal Overwinter Acoustic Survey, 2004-2005

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...

Composite fish diversity off southern California

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This map shows composite diversity averaged between 4 data sets: RecFIN recreational hook and line, SCCWRP trawls, NMFS benthic trawls, and kelp diver surveys....

Benthic Habitat Dataset

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Beam trawl (2 m) and otter trawl (36' Yankee) demersal and epibenthic catches from targeted areas of interest including mid-Atlantic shelf and vicinity of Hudson...

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...

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...... and acoustic research surveys. Horizontal distribution maps for the 2001–2010 cohorts of juvenile cod are further generated by applying a statistical log-Gaussian Cox process model to the standard trawl survey data. The analyses indicate size-dependent horizontal and distinct vertical and diurnal distribution...... in deep sea localities down to a 100 m depth and at oxygen concentrations between 2–4 ml O2.l−1. The vertical, diurnally stratified and repeated trawling and hydroacoustic target strength-depth distributions obtained from the special surveys show juvenile cod concentrations in frontal zone water layers...

Derived concentration factors for caesium-137 in edible species of North Sea fish

International Nuclear Information System (INIS)

Steele, A.K.

1990-01-01

Concentration factor (CF=Bq kg -1 fillet/Bg kg -1 filtered sea water) values for 137 Cs in fillets of cod (Gadus morhua), haddock (Merlanogrammus aeglefinus), plaice (Pleuronectes platessa) and whiting (Merlangius merlangius), were derived from fish and filtered seawater concentrations. Samples were collected in twelve sampling boxes in the North Sea over an eight-year period - 1978-1985. The range of results with species, between species, and between surveys are discussed. Mean CF values of 92, 58, 39 and 150 were found in cod, haddock, plaice and whiting respectively. These support the International Atomic Energy Authority recommended CF value of 100 for fish in generalised dose assessments. (author)

75 FR 78343 - Fisheries Off West Coast States; Pacific Coast Groundfish Fishery Management Plan; Amendments 20...

Science.gov (United States)

2010-12-15

... increase net economic benefits, create individual economic stability, provide full utilization of the trawl... economic benefits and create individual economic stability. Response. Start dates for the Pacific whiting... net economic benefits, create economic stability, provide full utilization of the trawl sector...

Co-location of passive gear fisheries in offshore wind farms in the German EEZ of the North Sea: A first socio-economic scoping

DEFF Research Database (Denmark)

Stelzenmüller, V.; Diekmann, Rabea; Bastardie, Francois

2016-01-01

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

The economic and financial performance of Bahrain's Fisheries Sector

International Nuclear Information System (INIS)

Abdulqader, E.A.A.

2007-01-01

This work is based on an extensive socio-economic survey conducted at all Bahrain landing sites in the period July-November, 2002. Based on boat size and the type of fishing gear used, eight fisheries sectors were determined, these included small boats using wire traps, shrimp trawls, gillnets, hooks and lines and barrier traps. It also included large boats using wire traps, shrimp trawls and gillnets. The economic and financial performances of these sectors were evaluated. The ratio of net catch flow to total earnings was used to measure the economic performance, while the return over investment was used to measure the financial performance. Higher economic returns (except for gillnet and shrimp trawl fisheries) were found in the case of small boats where smaller investments are found. This indicated that an over-fishing condition exists in Bahrain's fisheries, which is clearly found in the case of the shrimp trawl fishery. (author)

Comparing fish bycatch of shrimp trawlers with catches made by ...

African Journals Online (AJOL)

This present study identifies resource use overlap and conflict by comparing species composition, distribution patterns and abundance of bottom trawl fish bycatches and artisanal fish catches in the bay. Bottom trawl surveys were undertaken during the dry Northeast Monsoon (NEM) season and during the wet Southeast ...

75 FR 10757 - Proposed Information Collection; Comment Request; Alaska Region Amendment 80 Permits and Reports

Science.gov (United States)

2010-03-09

... to the Fishery Management Plan for Groundfish of the Bering Sea and Aleutian Islands Management Area... facilitates the formation of harvesting cooperatives in the head-and-gut trawl catcher/processor sector... non-AFA trawl catcher/processor sector or to be used in Amendment 80 cooperative formation) are...

Biology of the cirrate octopod grimpoteuthis glacialis (cephalopoda ...

African Journals Online (AJOL)

Robson, 1930), of dorsal mantle length 20–165 mm during a 1996 trawling survey near the Antarctic Peninsula allowed the basic biology of the species to be examined. Their presence in bottom trawls at depths of 333–879 m, but their absence from ...

Improving escape panel selectivity in Nephrops directed fisheries by actively stimulating fish behaviour

DEFF Research Database (Denmark)

Krag, Ludvig Ahm; Herrmann, Bent; Feekings, Jordan P.

2017-01-01

The efficiency of escape panels inserted in trawls relies on fish actively attempting to escape through them. However, several studies indicate that most fish drift towards the aft end of the trawl, passing the escape panel through which they easily could have escaped, without making contact with...

Continental shelf sediment dynamics in the Anthropocene: A global shift

Science.gov (United States)

Oberle, Ferdinand K. J.; Puig, Pere; Martin, Jacobo

2017-04-01

Recent technological advances in remote sensing and deep marine sampling have revealed the extent and magnitude of the anthropogenic impacts to the seafloor. In particular, bottom trawling, a fishing technique consisting of dragging a net and fishing gear over the seafloor to capture bottom-dwelling living resources has gained attention due to its destructive effects on the seabed. Trawling gear produces acute impacts on biota and the physical substratum of the seafloor by disrupting the sediment column structure, overturning boulders, resuspending sediments and imprinting deep scars on muddy bottoms. Also, the repetitive passage of trawling gear over the same areas creates long-lasting, cumulative impacts that modify the cohesiveness and texture of sediments. It can be asserted nowadays that due to its recurrence, mobility and wide geographical extent, industrial trawling has become a major force driving seafloor change and affecting not only its physical integrity on short spatial scales but also imprinting measurable modifications to the geomorphology of entire continental margins.

78 FR 13161 - Fisheries of the Exclusive Economic Zone Off Alaska; Gulf of Alaska; Final 2013 and 2014 Harvest...

Science.gov (United States)

2013-02-26

... halibut PSC trawl limits between the trawl gear deep-water and the shallow-water species fishery... specifications set forth in Tables 1 through 31 of this document reflect the outcome of this process, as required... for pollock, sablefish, deep-water flatfish, rex sole, Pacific ocean perch, northern rockfish...

Collecting marine litter during regular fish surveys

NARCIS (Netherlands)

Sluis, van der M.T.; Hal, van R.

2014-01-01

This report presents the results of the marine litter monitoring on the IBTS survey of 2014 and the BTS survey of 2013. Since 2013 marine litter is collected during the International Bottom Trawl Survey (IBTS) and Dutch Beam Trawl Survey (BTS) following a protocol developed by ICES. The composition

76 FR 17107 - Fisheries of the Exclusive Economic Zone Off Alaska; Application for an Exempted Fishing Permit

Science.gov (United States)

2011-03-28

... development and testing of a salmon excluder device for the Bering Sea pollock trawl fishery. This activity is... salmon bycatch by the pollock trawl industry during the EFP period could potentially approach or exceed... experimental design requires this quantity of salmon to ensure statistically valid results. The applicant also...

Size selectivity of commercial (300 MC) and larger square mesh top ...

African Journals Online (AJOL)

In the present study, size selectivity of a commercial (300 MC) and a larger square mesh top panel (LSMTPC) codend for blue whiting (Micromesistius poutassou) were tested on a commercial trawl net in the international waters between Turkey and Greece. Trawling, performed during daylight was carried out at depths ...

50 CFR 600.725 - General prohibitions.

Science.gov (United States)

2010-10-01

.... Longline. F. Recreational fishery F. Hook and line, rod and reel, spear. 9. Atlantic Bluefish Fishery (FMP.... Purse seine, seine. C. Mixed species pot and trap fishery C. Pot, trap. D. Bluefish, croaker, flounder... Bluefish Fishery (FMP): A. Bluefish, croaker, and flounder trawl fishery A. Trawl. B. Pelagic longline and...

Distribution patterns, stock size and life-history strategies of cape ...

African Journals Online (AJOL)

The problems and advantages of bottom trawl and acoustic surveys are discussed in the context of fluctuations in estimates of the size of the stock between 1991 and 1994 and the prevailing environmental conditions. It is concluded that combined acoustic and bottom trawl surveys are the only effective means of surveying ...

Abundance, distribution and diversity of gelatinous predators along the northern Mid-Atlantic Ridge: A comparison of different sampling methodologies.

Directory of Open Access Journals (Sweden)

Aino Hosia

Full Text Available The diversity and distribution of gelatinous zooplankton were investigated along the northern Mid-Atlantic Ridge (MAR from June to August 2004.Here, we present results from macrozooplankton trawl sampling, as well as comparisons made between five different methodologies that were employed during the MAR-ECO survey. In total, 16 species of hydromedusae, 31 species of siphonophores and four species of scyphozoans were identified to species level from macrozooplankton trawl samples. Additional taxa were identified to higher taxonomic levels and a single ctenophore genus was observed. Samples were collected at 17 stations along the MAR between the Azores and Iceland. A divergence in the species assemblages was observed at the southern limit of the Subpolar Frontal Zone. The catch composition of gelatinous zooplankton is compared between different sampling methodologies including: a macrozooplankton trawl; a Multinet; a ringnet attached to bottom trawl; and optical platforms (Underwater Video Profiler (UVP & Remotely Operated Vehicle (ROV. Different sampling methodologies are shown to exhibit selectivity towards different groups of gelatinous zooplankton. Only ~21% of taxa caught during the survey were caught by both the macrozooplankton trawl and the Multinet when deployed at the same station. The estimates of gelatinous zooplankton abundance calculated using these two gear types also varied widely (1.4 ± 0.9 individuals 1000 m-3 estimated by the macrozooplankton trawl vs. 468.3 ± 315.4 individuals 1000 m-3 estimated by the Multinet (mean ± s.d. when used at the same stations (n = 6. While it appears that traditional net sampling can generate useful data on pelagic cnidarians, comparisons with results from the optical platforms suggest that ctenophore diversity and abundance are consistently underestimated, particularly when net sampling is conducted in combination with formalin fixation. The results emphasise the importance of considering

Abundance, distribution and diversity of gelatinous predators along the northern Mid-Atlantic Ridge: A comparison of different sampling methodologies

Science.gov (United States)

Falkenhaug, Tone; Baxter, Emily J.

2017-01-01

The diversity and distribution of gelatinous zooplankton were investigated along the northern Mid-Atlantic Ridge (MAR) from June to August 2004.Here, we present results from macrozooplankton trawl sampling, as well as comparisons made between five different methodologies that were employed during the MAR-ECO survey. In total, 16 species of hydromedusae, 31 species of siphonophores and four species of scyphozoans were identified to species level from macrozooplankton trawl samples. Additional taxa were identified to higher taxonomic levels and a single ctenophore genus was observed. Samples were collected at 17 stations along the MAR between the Azores and Iceland. A divergence in the species assemblages was observed at the southern limit of the Subpolar Frontal Zone. The catch composition of gelatinous zooplankton is compared between different sampling methodologies including: a macrozooplankton trawl; a Multinet; a ringnet attached to bottom trawl; and optical platforms (Underwater Video Profiler (UVP) & Remotely Operated Vehicle (ROV)). Different sampling methodologies are shown to exhibit selectivity towards different groups of gelatinous zooplankton. Only ~21% of taxa caught during the survey were caught by both the macrozooplankton trawl and the Multinet when deployed at the same station. The estimates of gelatinous zooplankton abundance calculated using these two gear types also varied widely (1.4 ± 0.9 individuals 1000 m-3 estimated by the macrozooplankton trawl vs. 468.3 ± 315.4 individuals 1000 m-3 estimated by the Multinet (mean ± s.d.) when used at the same stations (n = 6). While it appears that traditional net sampling can generate useful data on pelagic cnidarians, comparisons with results from the optical platforms suggest that ctenophore diversity and abundance are consistently underestimated, particularly when net sampling is conducted in combination with formalin fixation. The results emphasise the importance of considering sampling methodology

Abundance, distribution and diversity of gelatinous predators along the northern Mid-Atlantic Ridge: A comparison of different sampling methodologies.

Science.gov (United States)

Hosia, Aino; Falkenhaug, Tone; Baxter, Emily J; Pagès, Francesc

2017-01-01

The diversity and distribution of gelatinous zooplankton were investigated along the northern Mid-Atlantic Ridge (MAR) from June to August 2004.Here, we present results from macrozooplankton trawl sampling, as well as comparisons made between five different methodologies that were employed during the MAR-ECO survey. In total, 16 species of hydromedusae, 31 species of siphonophores and four species of scyphozoans were identified to species level from macrozooplankton trawl samples. Additional taxa were identified to higher taxonomic levels and a single ctenophore genus was observed. Samples were collected at 17 stations along the MAR between the Azores and Iceland. A divergence in the species assemblages was observed at the southern limit of the Subpolar Frontal Zone. The catch composition of gelatinous zooplankton is compared between different sampling methodologies including: a macrozooplankton trawl; a Multinet; a ringnet attached to bottom trawl; and optical platforms (Underwater Video Profiler (UVP) & Remotely Operated Vehicle (ROV)). Different sampling methodologies are shown to exhibit selectivity towards different groups of gelatinous zooplankton. Only ~21% of taxa caught during the survey were caught by both the macrozooplankton trawl and the Multinet when deployed at the same station. The estimates of gelatinous zooplankton abundance calculated using these two gear types also varied widely (1.4 ± 0.9 individuals 1000 m-3 estimated by the macrozooplankton trawl vs. 468.3 ± 315.4 individuals 1000 m-3 estimated by the Multinet (mean ± s.d.) when used at the same stations (n = 6). While it appears that traditional net sampling can generate useful data on pelagic cnidarians, comparisons with results from the optical platforms suggest that ctenophore diversity and abundance are consistently underestimated, particularly when net sampling is conducted in combination with formalin fixation. The results emphasise the importance of considering sampling methodology

Cooperation between scientists, NGOs and industry in support of sustainable fisheries: the South African hake Merluccius spp. trawl fishery experience.

Science.gov (United States)

Field, J G; Attwood, C G; Jarre, A; Sink, K; Atkinson, L J; Petersen, S

2013-10-01

This paper examines the increasingly close interaction between natural and social scientists, non-governmental organizations (NGO) and industry, in pursuit of responsible ecosystem-based management of fisheries. South Africa has committed to implementing an ecosystem approach to fisheries management. Management advice stems from multi-stakeholder representation on government-led scientific and management working groups. In the hake Merluccius capensis and Merluccius paradoxus fishery, the primary management measure is an annual total allowable catch (TAC), the level of which is calculated using a management procedure (MP) that is revised approximately every 4 years. Revision of the MP is a consultative process involving most stakeholders, and is based on simulation modelling of projected probable scenarios of resource and fishery dynamics under various management options. NGOs, such as the Worldwide Fund for Nature in South Africa (WWF-SA), have played an important role in influencing consumers, the fishing industry and government to develop responsible fishing practices that minimize damage to marine ecosystems. Cooperation between industry, government and scientists has helped to improve sustainability and facilitated the meeting of market-based incentives for more responsible fisheries. Research includes ecosystem modelling, spatial analysis and ecosystem risk assessment with increasing research focus on social and economic aspects of the fishery. A four-year cooperative experiment to quantify the effect of trawling on benthic community structure is being planned. The food requirements of top predators still need to be included in the TAC-setting formulae and more social and economic research is needed. This paper also demonstrates how NGO initiatives such as Marine Stewardship Council certification and the Southern African Sustainable Seafood Initiative, a traffic light system of classifying seafood for consumers, have contributed to responsible fishing

Trawling for Subsidies

DEFF Research Database (Denmark)

Svendsen, Gert Tinggaard; Brandt, Urs Steiner

2009-01-01

groups traditionally perceived as opponents may have mutual interests. Solving the current deadlocks in the EU fishery negotiations highlights the need to reveal the true incentives that motivate stakeholders such as the symbiosis and alignment of interests identified here....... their budgets both for altruistic reasons (to restore fish stocks) and for private reasons (by increasing demand for their services). We analyze the outcome of a game where the biologists and the fishermen are informed about the true stock size while the decision-maker is not. Our model shows that interest...

Diel variation in the catch of fishes and penaeid shrimps in a tropical estuary

Science.gov (United States)

Stoner, Allan W.

1991-07-01

In Laguna Joyuda, Puerto Rico, 24-h trawl surveys were conducted to test the hypothesis that there is no diel variation in the catch rate of fishes and penaeid shrimps in a turbid, microtidal estuary relatively free of visual predation. The null hypothesis was not rejected for the two most abundant fishes in the lagoon, Eucinostomus gula (Gerreidae) and Achirus lineatus (Bothidae). Conversely, the total number of fishes, Diapterus rhombeus (Gerreidae), and the engraulids Anchoa cubana and A. hepsetus were collected in significantly higher numbers during hours of darkness. Total penaeid catch was significantly higher in night than in day collections. The most abundant species were Penaeus notialis and P. subtilis, both of which appeared to be strong daytime burrowers. Small penaeids demonstrated greater diel variation in trawl capture rate than larger (subadult) shrimps. Diel variation in capture rate was related to habitat associations of individual species. Fauna resident in the very turbid lagoon demonstrated no diel variation in activity patterns and trawl susceptibility. Those species which spend only the early part of their lives in the lagoon, or live in both turbid and clear water, had significant diel variation in activity and trawl catchability.

Size structure of a heavily fished benthic/demersal community by shrimp trawling in the Colombian Caribbean Sea Estructura de tamaños de una comunidad bentónica/demersal fuertemente impactada por la pesca de arrastre camaronero en el Mar Caribe de Colombia

Directory of Open Access Journals (Sweden)

Paúl Gómez-Canchong

2011-01-01

Full Text Available The benthic and demersal communities in the Colombian Caribbean Sea (CCS are heavily fished by the shrimp trawling fishery, which presents very high discard levels. Here, we conducted an analysis of the size structure of these benthic and demersal communities in the northern and southern zones of the CCS. Sampling was conducted onboard shrimp trawlers throughout an entire year. No significant differences were found in the size distributions of the two zones, among sites within southern ecoregions, or among the analyzed cruises. This homogeneity in size structure is remarkable since the zones analyzed possess very different species compositions and environmental conditions. The observed size structures were adequately described by non-linear distributions rather than the traditionally employed linear normalized biomass size spectra. It is hypothesized that the non-linearity is due to the effect of fishing and particularly, of discarding. This study emphasizes the need for a greater understanding of the impacts that trawl fishing has on community size structure and the applicability of this knowledge towards fishery resource management in ecosystems with high diversity.Las comunidades bentónico-demersales en el Mar Caribe de Colombia (MCC son fuertemente explotadas por la pesca de arrastre camaronero, presentando niveles de descarte muy altos. Se efectuó un análisis de la estructura de tamaños de estas comunidades bentónico-demersales en las zonas norte y sur del MCC. Se realizaron muéstreos a bordo de las embarcaciones de arrastre de camarón a lo largo de un año. No se encontraron diferencias significativas entre las distribuciones de tamaños de las diferentes zonas, ecorregiones de la zona sur y cruceros analizados. Esta homogeneidad en la estructura de tamaños es destacable ya que las areas analizadas difieren en composición de especies y condiciones medioambientales. Las estructuras de tamaño observadas, fueron descritas

Status and trends in the fish community of Lake Superior, 2012

Science.gov (United States)

Gorman, Owen T.; Evrard, Lori M.; Cholwek, Gary A.; Vinson, Mark

2012-01-01

The Great Lakes Science Center has conducted daytime nearshore bottom trawl surveys of Lake Superior (15-80 m bathymetric depth zone) each spring since 1978 and an offshore survey (>80 m) since 2011 to provide long-term trends of relative abundance and biomass of the fish community. In 2012, 72 nearshore and 34 offshore stations were sampled with a 12-m Yankee bottom trawl.

Common sole in the northern and central Adriatic Sea: Spatial management scenarios to rebuild the stock

Science.gov (United States)

Scarcella, Giuseppe; Grati, Fabio; Raicevich, Saša; Russo, Tommaso; Gramolini, Roberto; Scott, Robert D.; Polidori, Piero; Domenichetti, Filippo; Bolognini, Luca; Giovanardi, Otello; Celić, Igor; Sabatini, Laura; Vrgoč, Nedo; Isajlović, Igor; Marčeta, Bojan; Fabi, Gianna

2014-05-01

The northern and central Adriatic Sea represents an important spawning and aggregation area for common sole (Solea solea) and provides for around 20% of the Mediterranean landings. In this area, this resource is mainly exploited with rapido trawl and set nets. The stock is not yet depleted and faces a situation of growth overfishing. The comparison between the spatial distribution by age of S. solea and the geographic patterns of the rapido trawl fishing effort evidenced an overlapping of this fishing activity with the area where juveniles concentrate (age groups 0-2). The majority of spawners inhabits specific offshore areas, here defined as ‘sole sanctuaries', where high concentrations of debris and benthic communities make difficult trawling with rapido. The aim of this study was to evaluate existing spatial management regimes and potential new spatial and temporal closures in the northern and central Adriatic Sea using a simple modelling tool. Two spatial simulations were carried out in order to verify the effectiveness of complementary methods for the management of fisheries: the ban of rapido trawling from October to December within 6 nautical miles and 9 nautical miles of the Italian coast. The focus of the simulation is that the effort of the rapido trawl is moved far from the coast during key sole recruitment periods, when the juveniles are moving from the inshore nursery area toward the offshore feeding grounds. The management scenarios showed that a change in selectivity would lead to a clear increase in the spawning stock biomass and an increase in landings of S. solea in the medium-term. The rapido trawl activity could be managed by using a different logic, bearing in mind that catches and incomes would increase with small changes in the spatial pattern of the fishing effort. The present study highlights the importance of taking into account spatial dimensions of fishing fleets and the possible interactions that can occur between fleets and target

Anthropogenic impact in the Santa Maria di Leuca cold-water coral province (Mediterranean Sea): Observations and conservation straits

Science.gov (United States)

D'Onghia, G.; Calculli, C.; Capezzuto, F.; Carlucci, R.; Carluccio, A.; Grehan, A.; Indennidate, A.; Maiorano, P.; Mastrototaro, F.; Pollice, A.; Russo, T.; Savini, A.; Sion, L.; Tursi, A.

2017-11-01

The Santa Maria di Leuca (SML) cold-water coral (CWC) province is a proposed priority conservation area according to several conservation initiatives in the Mediterranean Sea. Part of it is a Fisheries Restricted Area (FRA). Anthropogenic impacts due to fishing on this FRA were investigated using a towed camera system during 2005. The geographic distribution of fishing effort in the SML CWC province was examined through an observers' program of longline and trawl fishing activities during 2009 and 2010 and Vessel Monitoring by satellite System (VMS) data from 2008 to 2013. Using the video system, it was possible to observe evidence of impacts in the FRA due to longlines, proved by remains of lines on the bottoms and/or entangled in corals, and those due to trawl nets, proved by trawl door scars on the bottom. The application of Generalized Liner Models indicates that the impacts due to longline were significantly related to a geographic site characterized by carbonate mounds while those from trawl net were significantly related to the soft bottoms, consisting of bioturbated fine-grained sediments. The presence of waste of various types was also observed in the FRA; plastic was the most widespread waste and was significantly related to a macrohabitat characterized by the presence of corals. The geographic distribution of fishing effort for each type of fishing were rather superimposed in the two years of the observers' program and six years of VMS data with a significantly greater fishing effort outside the FRA than inside this area. The trawlers generally fished on the muddy bottoms of the upper and middle slope within the SML CWC province and near and inside the northward limit of the FRA. The longliners fished mainly on the shelf in north and off the FRA. The coral by-catch was only recorded during 2009 in 26% of the trawl hauls. No coral by-catch was recorded from longlining in either year. The catches from longlining mainly consisted of Chelidonichthys lucerna

Influence of the hydrodynamic conditions on the accessibility of Aristeus antennatus and other demersal species to the deep water trawl fishery off the Balearic Islands (western Mediterranean)

Science.gov (United States)

Amores, Angel; Rueda, Lucía; Monserrat, Sebastià; Guijarro, Beatriz; Pasqual, Catalina; Massutí, Enric

2014-10-01

Monthly catches per unit of effort (CPUE) of adult red shrimp (Aristeus antennatus), reported in the deep water bottom trawl fishery developed on the Sóller fishing ground off northern Mallorca (Western Mediterranean), and the mean ocean surface vorticity in the surrounding areas are compared between 2000 and 2010. A good correlation is found between the rises in the surrounding surface vorticity and the drops in the CPUE of the adult red shrimp. This correlation could be explained by assuming that most of the surface vorticity episodes could reach the bottom, increasing the seabed velocities and producing sediment resuspension, which could affect the near bottom water turbidity. A. antennatus would respond to this increased turbidity disappearing from the fishing grounds, probably moving downwards to the deeper waters. This massive displacement of red shrimp specimens away from the fishing grounds would consequently decrease their accessibility to fishing exploitation. Similar although more intense responses have been observed during the downslope shelf dense water current episodes that occurred in a submarine canyon, northeast of the Iberian peninsula. The proposed mechanism suggesting how the surface vorticity observed can affect the bottom sediments is investigated using a year-long moored near-bottom current meter and a sediment trap moored near the fishing grounds. The relationship between vorticity and catches is also explored for fish species (Galeus melastomus, Micromesistius poutassou, Phycis blennoides) and other crustacean (Geryon longipes and Nephrops norvegicus), considered as by-catch of the deep water fishery in the area. Results appear to support the suggestion that the water turbidity generated by the vorticity episodes is significant enough to affect the dynamics of the demersal species.

Criteria for sustainable fisheries on juveniles illustrated for Mediterranean hake: control the juvenile harvest, and safeguard spawning refugia to rebuild population fecundity

Directory of Open Access Journals (Sweden)

John F. Caddy

2015-09-01

Full Text Available The paper provides a broad overview of issues relevant to management of fisheries for juvenile fish in contrast to the many stock assessments following Beverton and Holt’s (1957 approach for rational exploitation of mature fishes. A perspective on assessing these fisheries is illustrated for juvenile European hake, Merluccius merluccius, in the northwestern Mediterranean. Here, a constant natural mortality (M assumption is incorrect, as is the assumption that high fecundities are necessarily adequate for stock replacement. The high Ms-at-age for juveniles generated by the reciprocal model are shown to be a logical counterpart to the high fecundity of hake. Charnov’s criterion of intergenerational reproductive replacement is used to test for a sustainable population, analogous to a limit reference point warning of the dangers of overfishing beyond population replacement. Once peak mortality rates of age 2 hake exceed F(2=1.1-1.2, which is currently the case, reproductive replacement may be at risk. Adult exploitation by inshore trawls is low, and maturing hake surviving the fine-mesh trawl fishery migrate offshore with a reduced vulnerability to fine-mesh gears. Early research suggested that rough bottom near the shelf edge once formed a refugium protecting offshore spawners from trawling, and led to abundant recruitment of juveniles nearer shore. It may not do so if offshore fishing effort by reinforced bottom trawls, gill nets and longlines is uncontrolled. Restoring offshore refugia to protect spawners and controlling peak fishing mortality of juveniles would be a precautionary strategy aimed at restoring previous levels of recruitment to the small-mesh trawl fishery.

Fishing activities

Science.gov (United States)

Oberle, Ferdinand; Puig, Pere; Martin, Jacobo; Micallef, Aaron; Krastel, Sebastian; Savini, Alessandra

2018-01-01

Unlike the major anthropogenic changes that terrestrial and coastal habitats underwent during the last centuries such as deforestation, river engineering, agricultural practices or urbanism, those occurring underwater are veiled from our eyes and have continued nearly unnoticed. Only recent advances in remote sensing and deep marine sampling technologies have revealed the extent and magnitude of the anthropogenic impacts to the seafloor. In particular, bottom trawling, a fishing technique consisting of dragging a net and fishing gear over the seafloor to capture bottom-dwelling living resources has gained attention among the scientific community, policy makers and the general public due to its destructive effects on the seabed. Trawling gear produces acute impacts on biota and the physical substratum of the seafloor by disrupting the sediment column structure, overturning boulders, resuspending sediments and imprinting deep scars on muddy bottoms. Also, the repetitive passage of trawling gear over the same areas creates long-lasting, cumulative impacts that modify the cohesiveness and texture of sediments. It can be asserted nowadays that due to its recurrence, mobility and wide geographical extent, industrial trawling has become a major force driving seafloor change and affecting not only its physical integrity on short spatial scales but also imprinting measurable modifications to the geomorphology of entire continental margins.

Haematozoans from deep water fishes trawled off the Cape Verde Islands and over the Porcupine Seabight, with a revision of species within the genus Desseria (Adeleorina: Haemogregarinidae).

Science.gov (United States)

Davies, Angela J; Hosein, Shazia; Merrett, Nigel R

2012-02-01

Archived blood smears from 32 of 113 fishes in 18 families and 12 orders, trawled from deep North Atlantic waters off the Cape Verde Islands in 1999 and over the Porcupine Seabight in 2001 were found to harbour haematozoans. These included four species of haemogregarines (Adeleorina, Haemogregarinidae) and a species of trypanosome (Trypanosomatina, Trypanosomatidae) located in Porcupine Seabight fishes. Also present were Haemohormidium-like structures of uncertain status found in samples from this location and from the Cape Verde Islands. Although material was limited, two of the haemogregarines were provisionally named Desseria harriottae sp. n. from Harriotta raleighana Goode et Bean (Chimaeriformes, Rhinochimaeridae), and Haemogregarina bathysauri sp. n. from Bathysaurus ferox Günther (Aulopiformes, Bathysauridae). The two remaining haemogregarines were identified as Desseria marshalllairdi (Khan, Threlfall et Whitty, 1992) from Halosauropsis macrochir (Günther) (Notacanthiformes, Halosauridae), and Haemogregarina michaeljohnstoni (Davies et Merrett, 2000) from Cataetyx laticeps Koefoed (Ophidiformes, Bythitidae). The name H. michaeljohnstoni was proposed to replace Haemogregarinajohnstoni Davies et Merrett, 2000 from C. laticeps and to avoid confusion with Hepatozoon johnstoni (Mackerras, 1961) Smith, 1996 from varanid lizards, originally named Haemogregarina johnstoni Mackerras, 1961. The trypanosome formed a mixed parasitaemia with D. harriottae in H. raleighana and was provisionally named Trypanosoma harriottae sp. n. No blood parasites had been described previously from cartilaginous fishes of the Holocephali, making the finds in H. raleighana unique. Haemohormidium-like structures were located in erythrocytes in one fish, Coryphaenoides armatus (Hector), among the Cape Verde Islands samples and in 12 species of fishes from the Porcupine Seabight; all these hosts were bony fishes. Finally, the haemogregarine species listed in the genus Desseria Siddall

Metodologia para a monitorização e gestão da pesca de arrasto em Portugal. O exemplo do SIG GEOCRUST 1.0

Directory of Open Access Journals (Sweden)

Joana Simões

2003-12-01

Full Text Available A METHODOLOGY FOR THE MONITORING AND MANAGEMENT OF TRAWL FISHERIES IN PORTUGAL. THE SIG EXAMPLE OF GEOCRUST 1.0. This paper aims to present the Geographical Information System GEOCRUST 1.0, a computer programme developed within the fishery research project DGXIV 99/059, Use of Satellite GPS data to map effort and landings of the Portuguese crustacean fleet (GEOCRUST, in the University of Algarve. This stand-alone application was developed essentially to map fishing effort and catch per unit effort (CPUE information for the Portuguese crustacean trawl fleet, operating off the Southwest and South coasts of Portugal. The data available for this study included GPS vessels’ geographical positions and speed, transmitted via satellite to the Portuguese fisheries inspection authorities, and their catch reported to the Portuguese Directorate-General of Fisheries. GEOCRUST 1.0 was developed in ®VISUAL BASIC 6.0 using two ActiveX control: ADODB, to connect with the ®MSACCESS 2000 database and ®MAPOBJECTS 2.0 PRO, to communicate with the maps and provide GIS facilities. The application includes seven modules with the following objectives: Module 1 – to map and edit the original VMS data for a single vessel or group of vessels, for different periods of time; Module 2 – to analyse the trawl speed of each vessel; Module 3 – to define the boundaries of all fishing trips performed by vessel along the year; Module 4 – to identify and define the trawl hauls, within each fishing trip; Module 5 – to issue maps of fishing effort and CPUE; Module 6 – for exploratory data analysis and to extract data from the DB for further use in other computer packages and Module 7 – to recreate the activity of a single vessel, group of vessels or the total fleet, for a fixed period of time. This GIS application, fully developed by programming, has the advantage of being able to be used on its own without any need for external software support. The system developed

The Quantity of Free Amino Acid and the Structure of the Component Composition of Soup Stock

OpenAIRE

光崎, 龍子; 森, 真弓; 鈴木, 啓子; 遠藤, 千鶴

2001-01-01

The following conclusions were obtained from the examination of the free amino acid content and its composition in katsuobushi1 (arabushi^2, hongare^3/pole-and-line, hongare/trawl), shaved-katsuobushi in a package, and granule stock. 1. Arabushi, hongare/pole-and-line and hongare/trawl contained a lot of histamine, anserine, and taurine, shaved-katsuobushi in a package contained a lot of histamine, glutamine, and taurine, and granule stocks contained a lot of glutamine. 2. Shaved-katsuobushi ...

Tejnefiskeri efter jomfruhummer. Et litteraturstudie

DEFF Research Database (Denmark)

Frandsen, Rikke; Krag, Ludvig Ahm; Andersen, Bo Sølgaard

The Danish quota for Norway lobster is fished by use of trawl. In the past 5 years, between 10 and 70 % of the quota has not been exploited. This is partly on account of restricted quotas on some of the other species that are targeted in this mixed species fishery. Furthermore, in order to protect...... cod, trawling is banned in some areas including areas known as Norway lobster grounds. Creels are highly selective gears both with regards to sizes and species and they lead to high quality landings. Compared to trawling, stationary gears such as creels also have much less impact on the benthic...... habitat and reduce fuel consumption. Commercial creeling for Norway lobster is for example found in Sweden, Norway, Scotland, and the Faroe Islands. However, all available literature report low catch rates and the viability of the fishery therefore depends upon fuel savings and the opportunity to achieve...

The substantial first impact of bottom fishing on rare biodiversity hotspots: a dilemma for evidence-based conservation.

Science.gov (United States)

Cook, Robert; Fariñas-Franco, Jose M; Gell, Fiona R; Holt, Rohan H F; Holt, Terry; Lindenbaum, Charles; Porter, Joanne S; Seed, Ray; Skates, Lucie R; Stringell, Thomas B; Sanderson, William G

2013-01-01

This study describes the impact of the first passage of two types of bottom-towed fishing gear on rare protected shellfish-reefs formed by the horse mussel Modiolus modiolus (L.). One of the study sites was trawled and the other was scallop-dredged. Divers collected HD video imagery of epifauna from quadrats at the two study sites and directed infaunal samples from one site. The total number of epifaunal organisms was significantly reduced following a single pass of a trawl (90%) or scallop dredge (59%), as was the diversity of the associated community and the total number of M. modiolus at the trawled site. At both sites declines in anthozoans, hydrozoans, bivalves, echinoderms and ascidians accounted for most of the change. A year later, no recovery was evident at the trawled site and significantly fewer infaunal taxa (polychaetes, malacostracans, bivalves and ophuroids) were recorded in the trawl track. The severity of the two types of impact reflected the undisturbed status of the habitats compared to previous studies. As a 'priority habitat' the nature of the impacts described on M. modiolus communities are important to the development of conservation management policy and indicators of condition in Marine Protected Areas (EU Habitats Directive) as well as indicators of 'Good Environmental Status' under the European Union Marine Strategy Framework Directive. Conservation managers are under pressure to support decisions with good quality evidence. Elsewhere, indirect studies have shown declines of M. modiolus biogenic communities in fishing grounds. However, given the protected status of the rare habitat, premeditated demonstration of direct impact is unethical or illegal in Marine Protected Areas. This study therefore provides a unique opportunity to investigate the impact from fishing gear whilst at the same time reflecting on the dilemma of evidence-based conservation management.

The substantial first impact of bottom fishing on rare biodiversity hotspots: a dilemma for evidence-based conservation.

Directory of Open Access Journals (Sweden)

Robert Cook

Full Text Available This study describes the impact of the first passage of two types of bottom-towed fishing gear on rare protected shellfish-reefs formed by the horse mussel Modiolus modiolus (L.. One of the study sites was trawled and the other was scallop-dredged. Divers collected HD video imagery of epifauna from quadrats at the two study sites and directed infaunal samples from one site. The total number of epifaunal organisms was significantly reduced following a single pass of a trawl (90% or scallop dredge (59%, as was the diversity of the associated community and the total number of M. modiolus at the trawled site. At both sites declines in anthozoans, hydrozoans, bivalves, echinoderms and ascidians accounted for most of the change. A year later, no recovery was evident at the trawled site and significantly fewer infaunal taxa (polychaetes, malacostracans, bivalves and ophuroids were recorded in the trawl track. The severity of the two types of impact reflected the undisturbed status of the habitats compared to previous studies. As a 'priority habitat' the nature of the impacts described on M. modiolus communities are important to the development of conservation management policy and indicators of condition in Marine Protected Areas (EU Habitats Directive as well as indicators of 'Good Environmental Status' under the European Union Marine Strategy Framework Directive. Conservation managers are under pressure to support decisions with good quality evidence. Elsewhere, indirect studies have shown declines of M. modiolus biogenic communities in fishing grounds. However, given the protected status of the rare habitat, premeditated demonstration of direct impact is unethical or illegal in Marine Protected Areas. This study therefore provides a unique opportunity to investigate the impact from fishing gear whilst at the same time reflecting on the dilemma of evidence-based conservation management.

Population biology and distribution of the portunid crab Callinectes ornatus (Decapoda: Brachyura) in an estuary-bay complex of southern Brazil

OpenAIRE

Timoteo T. Watanabe; Bruno S. Sant'Anna; Gustavo Y. Hattori; Fernando J. Zara

2014-01-01

Trawl fisheries are associated with catches of swimming crabs, which are an important economic resource for commercial as well for small-scale fisheries. This study evaluated the population biology and distribution of the swimming crab Callinectes ornatus (Ordway, 1863) in the Estuary-Bay of São Vicente, state of São Paulo, Brazil. Crabs were collected from a shrimp fishing boat equipped with a semi-balloon otter-trawl net, on eight transects (four in the estuary and four in the bay) from Mar...

Lake-wide distribution of Dreissena in Lake Michigan, 1999

Science.gov (United States)

Fleischer, Guy W.; DeSorcie, Timothy J.; Holuszko, Jeffrey D.

2001-01-01

The Great Lakes Science Center has conducted lake-wide bottom trawl surveys of the fish community in Lake Michigan each fall since 1973. These systematic surveys are performed at depths of 9 to 110 m at each of seven index sites around Lake Michigan. Zebra mussel (Dreissena polymorpha) populations have expanded to all survey locations and at a level to sufficiently contribute to the bottom trawl catches. The quagga (Dreissena bugensis), recently reported in Lake Michigan, was likely in the catches though not recognized. Dreissena spp. biomass ranged from about 0.6 to 15 kg/ha at the various sites in 1999. Dreissenid mussels were found at depths of 9 to 82 m, with their peak biomass at 27 to 46 m. The colonization of these exotic mussels has ecological implications as well as potential ramifications on the ability to sample fish consistently and effectively with bottom trawls in Lake Michigan.

The fish and fisheries of Jones Bank and the wider Celtic Sea

Science.gov (United States)

Martinez, I.; Ellis, J. R.; Scott, B.; Tidd, A.

2013-10-01

The Celtic Sea is a diverse fishing ground that supports important commercial fisheries for a range of demersal fish, large and small-bodied pelagic fish and a variety of cephalopods and other shellfish. A regional overview of the main commercial fish stocks of the Celtic Sea and of the fish that occur in the vicinity of Jones Bank are provided through analyses of landings data from English and Welsh vessels, and from scientific trawl surveys. Dedicated smaller scale sampling via trawl surveys combined with baited cameras on and around the Jones Bank were also analysed to investigate the importance of sandbank habitats with attention paid to the differences in the species occurring on the top of the bank in comparison to adjacent off-bank habitats. Official landing statistics for UK (English and Welsh) vessels indicated that the predominant commercial demersal species in ICES Divisions VIIg,h (in terms of quantities landed) were anglerfish, megrim, pollack and skates (Rajidae). There were, however, regional differences in the distribution of fish and fisheries, and the area surrounding Jones Bank (ICES Rectangles 28E1 and 28E2) supports fisheries for megrim, anglerfish, skates, hake, ling and turbot, with otter trawl, gillnet and beam trawl the main gears used. Recent survey data collected with GOV (Grande Ouverture Verticale) trawl from the Celtic Sea (ICES Divisions VIIe-h, 2007-2010) were used to highlight the broad scale distribution of the main fish assemblages in the Celtic Sea. Analyses of the fish and cephalopod catches from these surveys indicated that there were four broad assemblages in the area, including (i) a region around the Cornwall (which will also be partly influenced by the necessity to use rockhopper ground gear on these rough grounds), (ii) the shallower regions of the north-western Celtic Sea (including parts of the Bristol Channel), (iii) the deeper parts of the outer shelf and (iv) the central Celtic Sea. These data also provided

The Use of Simulators in Rules of the Road Training

Science.gov (United States)

2013-12-01

RoAoLMSR s llil>oal yacht s llil>oal yacht Tanker132k Tanker132k T anker!IO< Tug Barge Pushing Sand Tug Barge Pushing Sand on Starbo ... I 40...Boat Pilot Vessel Powe1Boat Cabin Cruiser Sailboat Yacht Sailboat Yacht Smoke Float Smoke Float Smoke Float Smoke Float Tanker 132k Tanker...2 Sailboat Yacht Smoke Float 2 Smoke Float 3 Smoke Float 4 Tanker 132k 2 Tanker 40k Tanker BOk T onker lnlond 2 Trawling trawling 2 Tug3

Colonial life under the Humboldt Current System: deep-sea corals from O'Higgins I seamount

OpenAIRE

Cañete,Juan I; Haussermann,Verena

2012-01-01

A benthic community constituted by an assemblage of at least four species of deep-sea corals collected in only one trawl carried-out on the summit of the O'Higgins I seamount, central Chile. The corals were collected in only one trawl carried-out during a Chilean-Japanese cruise onboard the R/V" Koyo Maru" in December 29, 2004. Presence of oxygenated and cold Antarctic Intermediate Water (>400 m depth) on the plateau was recorded under of the Equatorial Subsurface Water associated to the o...

Colonial life under the Humboldt Current System: deep-sea corals from O'Higgins I seamount La vida colonial bajo el sistema de la corriente de Humboldt: corales de aguas profundas en el monte submarino O'Higgins I

OpenAIRE

Juan I Cañete; Verena Haussermann

2012-01-01

A benthic community constituted by an assemblage of at least four species of deep-sea corals collected in only one trawl carried-out on the summit of the O'Higgins I seamount, central Chile. The corals were collected in only one trawl carried-out during a Chilean-Japanese cruise onboard the R/V" Koyo Maru" in December 29, 2004. Presence of oxygenated and cold Antarctic Intermediate Water (>400 m depth) on the plateau was recorded under of the Equatorial Subsurface Water associated to the oxyg...

Colonial life under the Humboldt Current System: deep-sea corals from O'Higgins I seamount

OpenAIRE

Cañete, Juan I; Haussermann, Verena

2012-01-01

A benthic community constituted by an assemblage of at least four species of deep-sea corals collected in only one trawl carried-out on the summit of the O'Higgins I seamount, central Chile. The corals were collected in only one trawl carried-out during a Chilean-Japanese cruise onboard the R/V" Koyo Maru" in December 29, 2004. Presence of oxygenated and cold Antarctic Intermediate Water (>400 m depth) on the plateau was recorded under of the Equatorial Subsurface Water associated to the oxyg...

Status of rainbow smelt in the U.S. waters of Lake Ontario, 2013

Science.gov (United States)

Weidel, Brian C.; Connerton, Michael J.

2014-01-01

Rainbow Smelt Osmerus mordax are the second most abundant pelagic prey fish in Lake Ontario after Alewife Alosa psuedoharengus. The 2013, USGS/NYSDEC bottom trawl assessment indicated the abundance of Lake Ontario age-1 and older Rainbow Smelt decreased by 69% relative to 2012. Length frequency-based age analysis indicated that age-1 Rainbow Smelt constituted approximately 50% of the population, which is similar to recent trends where the proportion of age-1 has ranged from 95% to 42% of the population. While they constituted approximately half of the catch, the overall abundance index for age 1 was one of the lowest observed in the time series, potentially a result of cannibalism from the previous year class. Combined data from all bottom trawl assessments along the southern shore and eastern basin indicate the proportion of the fish community that is Rainbow Smelt has declined over the past 30 years. In 2013 the proportion of the pelagic fish catch (only pelagic species) that was Rainbow Smelt was the second lowest in the time series at 3.1%. Community diversity indices, based on bottom trawl catches, indicate that Lake Ontario fish community diversity, as assessed by bottom trawls, has sharply declined over the past 36 years and in 2013 the index was the lowest value in the time series. Much of this community diversity decline is driven by changes in the pelagic fish community and dominance of Alewife.

Oceanographic conditions structure forage fishes into lipid-rich and lipid-poor communities in lower Cook Inlet, Alaska, USA

Science.gov (United States)

Abookire, Alisa A.; Piatt, John F.

2005-01-01

Forage fishes were sampled with a mid-water trawl in lower Cook Inlet, Alaska, USA, from late July to early August 1996 to 1999. We sampled 3 oceanographically distinct areas of lower Cook Inlet: waters adjacent to Chisik Island, in Kachemak Bay, and near the Barren Islands. In 163 tows using a mid-water trawl, 229 437 fishes with fork length lipid-poor gadids (walleye pollock and Pacific cod), and significantly increased in lipid-rich species such as Pacific sand lance, Pacific herring, and capelin. ?? Inter-Research 2005.

Estimating spatio-temporal dynamics of size-structured populations

DEFF Research Database (Denmark)

Kristensen, Kasper; Thygesen, Uffe Høgsbro; Andersen, Ken Haste

2014-01-01

with simple stock dynamics, to estimate simultaneously how size distributions and spatial distributions develop in time. We demonstrate the method for a cod population sampled by trawl surveys. Particular attention is paid to correlation between size classes within each trawl haul due to clustering...... of individuals with similar size. The model estimates growth, mortality and reproduction, after which any aspect of size-structure, spatio-temporal population dynamics, as well as the sampling process can be probed. This is illustrated by two applications: 1) tracking the spatial movements of a single cohort...

Responsible fisheries summary: 2000-2001 annual report

Energy Technology Data Exchange (ETDEWEB)

NONE

2001-05-01

The energy required to harvest fish from the sea is greater than that required for the production of any other primary food product. Increasing energy efficiency in the fishing industry makes sense, especially in light of the recent increases in fossil fuel prices and the increased concern expressed about greenhouse gas emissions. As a result, Fisheries and Oceans Canada collaborated with partners from the fishing industry, and with support provided by Natural Resources Canada, Program of Energy Research and Development (PERD) to initiate several projects aimed at improving the energy efficiency of fishing gear and related components. During the period April 2000 to March 2001, five projects were completed and two more were initiated. The goals were the determination of the effectiveness of new gear prototypes and fishing techniques towards a reduction in energy consumption. Detailed experimental protocols, gear prototypes, flume tank testing, at-sea trials, analysis of results, and reporting to industry and stakeholders are some of the facets common to most of the projects. Potential fuel savings, in the range of 2,330,000 liters annually for the shrimp trawler fleet were identified by testing new composite trawl netting. Potential fuel savings of 850,000 liters in Silver Hake could be realized by using new small diameter high tenacity braided polyethylene twines in trawl netting, when compared to standard polyethylene. A reduction of approximately 13 per cent in fuel consumption per kilogram of fish harvested is possible, as demonstrated by the testing of new Triplex Trawl design, with three codends rather than one. Operational costs and fuel consumption are both reduced through the use of the new Millennium trawl design using small mesh size in forepart and body of trawl, as shown by the Greenland Halibut (Turbot) selectivity experiments. Meshing is reduced, as is the by-catch of small Turbot. Potential benefits of lighter weight materials of construction were

Mortality of red mullet (Mullus barbatus Linnaeus, 1758 on the Montenegrin shelf (South Adriatic

Directory of Open Access Journals (Sweden)

Joksimović A.

2009-01-01

Full Text Available Red mullet, Mullus barbatus Linnaeus, 1758, is an economically very important species in trawl fisheries in the Adriatic Sea. Material for analysis was collected from October 2002 until May 2004 with a bottom trawl net from commercial trawlers on the Montenegrin shelf. Mortality of this species was analyzed for the first time in this area, sepa­rately for males and females and for both sexes together. Until now, only the spatial distribution and catch per unit of effort (CPUE of Mullus barbatus have been studied in Montenegrin waters. Estimated total mortality rates were Zmales = 0.653 and Zfemales = 0.712. The average mortality rate for both sexes was Z m+f = 0.749, while the natural mortality rate was Mm+f = 0.342. Values of Z in the Montenegrin shelf area are considerably lower than Z values for the Croatian and Italian parts of the Adriatic Sea, indicating that on the Montenegrin shelf fishing of this species is significantly less intensive than in other trawl-fishing areas of the Adriatic Sea.

Lake Ontario benthic prey fish assessment, 2015

Science.gov (United States)

Weidel, Brian C.; Walsh, Maureen; Holden, Jeremy P.; Connerton, Michael J.

2016-01-01

Benthic prey fishes are a critical component of the Lake Ontario food web, serving as energy vectors from benthic invertebrates to native and introduced piscivores. Since the late 1970’s, Lake Ontario benthic prey fish status was primarily assessed using bottom trawl observations confined to the lake’s south shore, in waters from 8 – 150 m (26 – 492 ft). In 2015, the Benthic Prey Fish Survey was cooperatively adjusted and expanded to address resource management information needs including lake-wide benthic prey fish population dynamics. Effort increased from 55 bottom trawl sites to 135 trawl sites collected in depths from 8 - 225m (26 – 738 ft). The spatial coverage of sampling was also expanded and occurred in all major lake basins. The resulting distribution of tow depths more closely matched the available lake depth distribution. The additional effort illustrated how previous surveys were underestimating lake-wide Deepwater Sculpin, Myoxocephalus thompsonii, abundance by not sampling in areas of highest density. We also found species richness was greater in the new sampling sites relative to the historic sites with 11 new fish species caught in the new sites including juvenile Round Whitefish, Prosopium cylindraceum, and Mottled sculpin, Cottus bairdii. Species-specific assessments found Slimy Sculpin, Cottus cognatus abundance increased slightly in 2015 relative to 2014, while Deepwater Sculpin and Round Goby, Neogobius melanostomus, dramatically increased in 2015, relative to 2014. The cooperative, lake-wide Benthic Prey Fish Survey expanded our understanding of benthic fish population dynamics and habitat use in Lake Ontario. This survey’s data and interpretations influence international resource management decision making, such as informing the Deepwater Sculpin conservation status and assessing the balance between sport fish consumption and prey fish populations. Additionally a significant Lake Ontario event occurred in May 2015 when a single

Pacific halibut bycatch in Pacific cod fisheries in the Bering Sea: an analysis to evaluate area-time management

Science.gov (United States)

Adlerstein, Sara A.; Trumble, Robert J.

1998-03-01

Mortality of discarded Pacific halibut bycatch from Pacific cod fisheries in the Bering Sea leads to significant losses in the halibut setline and in the Pacific cod fisheries. The commercial halibut fishery loses yield because of catch limit reductions to compensate the resource for lost spawning potential and because halibut killed as bycatch will not be available for subsequent harvest, and the cod fisheries may lose harvest if they reach a bycatch mortality limit before reaching allowed catch. In this study, significant differences in Pacific halibut bycatch rates and associated yield losses were found among months and areas of the Bering Sea in the longline and trawl fisheries for Pacific cod in 1990-1992. Bycatch rates were usually highest in late spring and early summer and in areas close to the Unimak Pass. With the exception of 1992, yield loss in the longline fishery was around 1 kg per kg of bycatch mortality, irrespective of where or when bycatch occurred. In the trawl fishery, loss of halibut yield varied from 1 to 4 kg per kg of bycatch mortality. Highest halibut net yield losses per tonne of groundfish harvest usually coincided with highest bycatch rates. When both fisheries operated in one area, trawl bycatch often imposed higher yield losses than longline bycatch, despite lower bycatch rates. Bycatch was affected by the strong 1987 halibut year class. Highest bycatch and yield loss rates occurred in the trawl fishery in 1990 and 1991 when the population was dominated by halibut age-3 and -4, and in the longline fishery in 1992 as fish reached age-5.

Short spatio-temporal variations in the population dynamics and biology of the deep-water rose shrimp Parapenaeus longirostris (Decapoda: Crustacea in the western Mediterranean

Directory of Open Access Journals (Sweden)

Beatriz Guijarro

2009-03-01

Full Text Available The deep-water rose shrimp Parapenaeus longirostris is a demersal decapod crustacean that is commercially exploited by trawl fleets. The present work compares its population dynamics, biology and condition in two locations (southern and north-western Mallorca in the Balearic Islands, western Mediterranean, separated by a distance of 120 km with different environmental conditions and explores the relationships between the species and certain environmental factors. Six multidisciplinary bimonthly surveys were carried out during 2003 and 2004 in these two locations (between 150 and 750 m depth in order to collect data on the demersal species with bottom trawl, the hydrography (temperature and salinity with CTD casts, and trophic resources (zooplankton in the water column and suprabenthos with Bongo net and Macer-GIROQ sledge respectively and sediments with a Shipeck dredge. The trawl fleets from both locations were monitored by monthly on board sampling and daily landings obtained from sales bills. Additional data was obtained from other trawl surveys. Temporal differences were detected both annually, with a decreasing trend over the last years in species abundance, and seasonally, in the biological indexes analysed. Bathymetric differences were also found in abundance, mean length, sex-ratio and condition of females. There were clear differences between the two locations studied, with higher abundance, condition and mean length and a lower length at first maturity for females in the north-western location. Trophic conditions could act as a link between geo-physical and biological changes. These short spatio-temporal differences could be due to the higher productivity found at this location, with higher density of preferred prey for the studied species together with adequate seafloor topography, sediment composition and hydrographical characteristics.

Spatial and temporal changes in benthic communities of the Galician continental shelf after the Prestige oil spill

International Nuclear Information System (INIS)

Serrano, Alberto . E-mail aserrano@st.ieo.es; Sanchez, Francisco; Preciado, Izaskun; Parra, Santiago; Frutos, Inmaculada

2006-01-01

Two years after the Prestige oil spill (POS) an assessment of the effects on benthic fauna was carried out using the data obtained in five multidisciplinary surveys. Otter trawl, beam trawl, suprabenthic sled and box corer were used to study the main benthic compartments, along eight transects perpendicular to the coastline. Beam trawl was also employed to quantify the amount of tar aggregates on the continental shelf. No significant correlations between tar aggregates and species richness, biomass and diversity of benthic communities were found. This result was corroborated when the role of depth, season, latitude and sediment characteristics was examined by canonical ordination, in which POS-related variables had low influence on spatial distribution patterns. Depth and sediment grain diameter profoundly influence epibenthic communities. Sediment organic content is a third key variable for the infaunal, suprabenthic and lower-sized epibenthic communities, but not for the larger epibenthic communities. Nevertheless, a decrease in the densities of several epibenthic indicators was detected the first year after spill, followed by a noteworthy recovery in 2004. Non-macroscopic toxicity and some oceanographic agents are suggested as possible causes of these shifts

PENDEKATAN GEOSTATISTIKA DALAM PENDUGAAN KELIMPAHAN IKAN DEMERSAL DENGAN METODE SWEPT AREA DI PERAIRAN UTARA JAWA TENGAH

Directory of Open Access Journals (Sweden)

Moh. Natsir

2016-03-01

This research is intended to apply geostatistical analysis in fish abundance estimation in the north Java waters. Geostatistical is a series of methods to examine one or more spatially distributed variables through structure analysis of the data. Trawl data obtained using the bottom trawl operated by Bawal Putih vessel. Data processing includes the standardization of catch, geographic position transformation to UTM format, variogram model fitting and abundance prediction using the model. Analysis of trawl data structure was done by using geostatistical analysis, estimation results of the experimental semi-variogram were then used to infer the characteristics of demersal fish abundance in the north of central Java waters. Results of structural analysis and models fitting using geostatistical analysis showed that the most suitable model with all data used were spherical model with different parameters from each model. The models are then used to estimate the value of fish abundance on the points that there is no abundance information through kriging interpolation process. Results of cross-validation of the estimated abundance using kriging with actual values shows that R2 values varied for each data set. Geostatistical prediction results showed smaller coefficients of variation compare to arithmetic calculations.

Spatial and temporal changes in benthic communities of the Galician continental shelf after the Prestige oil spill

Energy Technology Data Exchange (ETDEWEB)

Serrano, Alberto [Instituto Espanol de Oceanografia, P.O. Box 240, 39080 Santander (Spain)]. E-mail aserrano@st.ieo.es; Sanchez, Francisco [Instituto Espanol de Oceanografia, P.O. Box 240, 39080 Santander (Spain); Preciado, Izaskun [Instituto Espanol de Oceanografia, P.O. Box 240, 39080 Santander (Spain); Parra, Santiago [Instituto Espanol de Oceanografia, P.O. Box 130, 15080 La Coruna (Spain); Frutos, Inmaculada [Instituto Espanol de Oceanografia, P.O. Box 130, 15080 La Coruna (Spain)

2006-07-01

Two years after the Prestige oil spill (POS) an assessment of the effects on benthic fauna was carried out using the data obtained in five multidisciplinary surveys. Otter trawl, beam trawl, suprabenthic sled and box corer were used to study the main benthic compartments, along eight transects perpendicular to the coastline. Beam trawl was also employed to quantify the amount of tar aggregates on the continental shelf. No significant correlations between tar aggregates and species richness, biomass and diversity of benthic communities were found. This result was corroborated when the role of depth, season, latitude and sediment characteristics was examined by canonical ordination, in which POS-related variables had low influence on spatial distribution patterns. Depth and sediment grain diameter profoundly influence epibenthic communities. Sediment organic content is a third key variable for the infaunal, suprabenthic and lower-sized epibenthic communities, but not for the larger epibenthic communities. Nevertheless, a decrease in the densities of several epibenthic indicators was detected the first year after spill, followed by a noteworthy recovery in 2004. Non-macroscopic toxicity and some oceanographic agents are suggested as possible causes of these shifts.

Evidence for predatory control of the invasive round goby

Science.gov (United States)

Madenjian, C.P.; Stapanian, M.A.; Witzel, L.D.; Einhouse, D.W.; Pothoven, S.A.; Whitford, H.L.

2011-01-01

We coupled bioenergetics modeling with bottom trawl survey results to evaluate the capacity of piscivorous fish in eastern Lake Erie to exert predatory control of the invading population of round goby Neogobius melanostomus. In the offshore (>20 m deep) waters of eastern Lake Erie, burbot Lota lota is a native top predator, feeding on a suite of prey fishes. The round goby invaded eastern Lake Erie during the late 1990s, and round goby population size increased dramatically during 1999–2004. According to annual bottom trawl survey results, round goby abundance in offshore waters peaked in 2004, but then declined during 2004–2008. Coincidentally, round goby became an important component of burbot diet beginning in 2003. Using bottom trawling and gill netting, we estimated adult burbot abundance and age structure in eastern Lake Erie during 2007. Diet composition and energy density of eastern Lake Erie burbot were also determined during 2007. This information, along with estimates of burbot growth, burbot mortality, burbot water temperature regime, and energy densities of prey fish from the literature, were incorporated into a bioenergetics model application to estimate annual consumption of round goby by the adult burbot population. Results indicated that the adult burbot population in eastern Lake Erie annually consumed 1,361 metric tons of round goby. Based on the results of bottom trawling, we estimated the biomass of yearling and older round goby in offshore waters eastern Lake Erie during 2007–2008 to be 2,232 metric tons. Thus, the adult burbot population was feeding on round goby at an annual rate equal to 61% of the estimated round goby standing stock. We concluded that the burbot population had high potential to exert predatory control on round goby in offshore waters of eastern Lake Erie.

Ecologically Important Areas for Pacific Fishery Management Council's June 2005 Preferred Alternative, Groundfish EFH Final EIS

Data.gov (United States)

Pacific States Marine Fisheries Commission — These data depict ecologically important areas that were developed through a collaborative process involving Oceana; groundfish trawl fishermen, organized by the...

Estrutura populacional de Callinectes ornatus Ordway (Crustacea, Portunidae no Balneário Shangri-Lá, Pontal do Paraná, Paraná, Brasil

Directory of Open Access Journals (Sweden)

Baptista Cassiana

2003-01-01

Full Text Available Swimming crabs are commonly found in the otter-trawl shrimp fishery by-catch, which operate intensively in the Coastal Plain of Leste Beach, where is located Shangri-lá Beach (25°37'30"S and 48°25'08"W, Paraná State. This work aimed to study the population structure of Callinectes ornatus Ordway, 1863, the most abundant swimming crab in this beach. Between March 2000 and April 2001, fortnightly visits were accomplished in Shangri-lá at the fish market, where all swimming crabs of one otter-trawl were collected. The following data from each individual of C. ornatus were obtained: sex, carapace width (excluding lateral spines, weight, and the gonadal maturation stage, based on its color and size. Juveniles and mature males were dominant, mean sexual proportion was 2.2:1 (males:females. Two recruitment periods were detected, but few ovigerous females were obtained. Size at sexual maturation was estimated at 55mm for males, and 48 mm for females. Both sexes presented positives allometric growths. The results indicate that an important portion of C. ornatus population is captured in the otter-trawl shrimp fishery in Shangri-lá Beach (Paraná. Such information is important for futures plans of by-catch management in that area.

Reproductive features of the deep-water rose shrimp, Parapenaeus longirostris (Crustacea: Penaeidae, in the Strait of Sicily

Directory of Open Access Journals (Sweden)

M.L. BIANCHINI

2010-02-01

Full Text Available The deep‑water rose shrimp, Parapenaeus longirostris (Lucas, 1846, is one of the most valuable and heavily exploited demersal species of the Mediterranean bottom trawl fisheries. The basic life traits of this shrimp, in particular its reproductive aspects, are regularly monitored during experimental trawl surveys carried out in the Mediterranean Sea. Gonadic condition and maturity status for estimating the size at onset of sexual maturity are commonly assessed in females, using macroscopic color scales, histologically validated only in a few geographical areas. In this study, histological analyses were performed on rose shrimps collected from a trawl survey carried out in the Strait of Sicily, in order to support the empirical 4‑stage macroscopic scale locally employed. Ovaries from females of different sizes, ranging between 16 mm and 40 mm carapace length, were collected and used for microscopic examination of their structure, for oocytes counts and for oocyte diameter frequency distributions; oocytes diameter was measured by imaging analysis. The collected data were also used to estimate other basic vital parameters of the rose shrimp population. The histological observations show a broad correspondence between ovarian development and macroscopic features; therefore, the classifications derived by the empirical scale remain suitable for estimating the maturity parameters.

Community structure and diversity of demersal fish assemblages: the role of fishery

Directory of Open Access Journals (Sweden)

Mary Labropoulou

2004-04-01

Full Text Available Seasonal experimental trawl surveys were carried out in the Northern Aegean and Thracian seas (NE Mediterranean, Greece, from summer 1990 to autumn 1993, during which a total of 172 fish species were caught. In these areas, fishing pressure is very high, since approximately 50% of the Greek otter trawl fleet operates there, producing more than 57% of the total demersal landings. Different statistics were used to assess spatial structure, seasonal changes and diversity of the demersal fish assemblages on the continental shelf and upper slope. The following measures were applied to the species abundance matrix: species diversity, species richness, evenness and dominance. The analysis of 501 bottom trawls revealed that, in general, species diversity, richness and evenness decreased with water depth, with the highest values at depths 200 m. The effect of depth on the diversity patterns observed was always significant, while seasonal trends were similar with those described for the overall diversity characteristics in each area. Classification and ordination methods showed the existence of 4 groups associated with the continental shelf and upper slope in each area. Classification of the top ranking species at each group and area revealed that commercially important species were dominant in the shallowest zone (

Estimating the size of juvenile fish populations in southeastern coastal-plain estuaries

International Nuclear Information System (INIS)

Kjelson, M.A.

1977-01-01

Understanding the ecological significance of man's activities upon fishery resources requires information on the size of affected fish stocks. The objective of this paper is to provide information to evaluate and plan sampling programs designed to obtain accurate and precise estimates of fish abundance. Nursery habitats, as marsh--tidal creeks and submerged grass beds, offer the optimal conditions for estimating natural mortality rates for young-of-the-year fish in Atlantic and Gulf of Mexico coast estuaries. The area-density method of abundance estimation using quantitative gears is more feasible than either mark-recapture or direct-count techniques. The blockage method provides the most accurate estimates, while encircling devices enable highly mobile species found in open water to be captured. Drop nets and lift nets allow samples to be taken in obstructed sites, but trawls and seines are the most economical gears. Replicate samples are necessary to improve the precision of density estimates, while evaluation and use of gear-catch efficiencies is feasible and required to improve the accuracy of density estimates. Coefficients of variation for replicate trawl samples range from 50 to 150 percent, while catch efficiencies for both trawls and seines for many juvenile fishes range from approximately 30 to 70 percent

Benthic prey fish assessment, Lake Ontario 2013

Science.gov (United States)

Weidel, Brian C.; Walsh, Maureen; Connerton, Michael J.

2014-01-01

The 2013 benthic fish assessment was delayed and shortened as a result of the U.S. Government shutdown, however the assessment collected 51 of the 62 planned bottom trawls. Over the past 34 years, Slimy Sculpin abundance in Lake Ontario has fluctuated, but ultimately decreased by two orders of magnitude, with a substantial decline occurring in the past 10 years. The 2013 Slimy Sculpin mean bottom trawl catch density (0.001 ind.·m-2, s.d.= 0.0017, n = 52) and mean biomass density (0.015 g·m-2 , s.d.= 0.038, n = 52) were the lowest recorded in the 27 years of sampling using the original bottom trawl design. From 2011-2013, the Slimy Sculpin density and biomass density has decreased by approximately 50% each year. Spring bottom trawl catches illustrate Slimy Sculpin and Round Goby Neogobius melanostoma winter habitat overlaps for as much as 7 months out of a year, providing opportunities for competition and predation. Invasive species, salmonid piscivory, and declines in native benthic invertebrates are likely all important drivers of Slimy Sculpin population dynamics in Lake Ontario. Deepwater Sculpin Myoxocephalus thompsonii, considered rare or absent from Lake Ontario for 30 years, have generally increased over the past eight years. For the first time since they were caught in this assessment, Deepwater Sculpin density and biomass density estimates declined from the previous year. The 2013 abundance and density estimates for trawls covering the standard depths from 60m to 150m was 0.0001 fish per square meter and 0.0028 grams per square meter. In 2013, very few small (recruitment. Nonnative Round Gobies were first detected in the USGS/NYSDEC Lake Ontario spring Alewife assessment in 2002. Since that assessment, observations indicate their population has expanded and they are now found along the entire south shore of Lake Ontario, with the highest densities in U.S. waters just east of the Niagara River confluence. In the 2013 spring-based assessment, both the

77 FR 71786 - New England Fishery Management Council; Public Meeting

Science.gov (United States)

2012-12-04

..., gear requirements for small-mesh bottom trawl vessels fishing on Georges Bank, and several other issues.... Special Accommodations This meeting is physically accessible to people with disabilities. Requests for...

US AMLR Program fish dataset

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The AERD conducts semiannual bottom-trawl research surveys to characterize the populations and biological features of Antarctic demersal finfish species. These...

EOP TDRs (Temperature-Depth-Recordings) Data

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Temperature-depth-recorders (TDRs) were attached to commercial longline and research Cobb trawl gear to obtain absolute depth and temperature measurement during...

Hake Survey ADCP (2005)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Shipboard acoustic Doppler current profiler data collected during the Integrated Acoustic and Trawl Surveys of Pacific Hake. Processing by: Stephen Pierce, Oregon...

Hake Survey ADCP (1998)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Shipboard acoustic Doppler current profiler data collected during the Integrated Acoustic and Trawl Surveys of Pacific Hake. Processing by: Stephen Pierce, Oregon...

Hake Survey ADCP (1995)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Shipboard acoustic Doppler current profiler data collected during the Integrated Acoustic and Trawl Surveys of Pacific Hake. Processing by: Stephen Pierce, Oregon...

Hake Survey ADCP (2001)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Shipboard acoustic Doppler current profiler data collected during the Integrated Acoustic and Trawl Surveys of Pacific Hake. Processing by: Stephen Pierce, Oregon...

Atlantic Herring Acoustic Surveys

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC Advanced Sampling Technologies Research Group conducts annual fisheries acoustic surveys using state-of-the-art acoustic, midwater trawling, and underwater...

Hake Survey ADCP (2003)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Shipboard acoustic Doppler current profiler data collected during the Integrated Acoustic and Trawl Surveys of Pacific Hake. Processing by: Stephen Pierce, Oregon...

AFSC/RACE/SAP/Armistead: 1975 - 2016 eastern Bering Sea Crab Distribution For Web

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The Resource Assessment and Conservation Engineering Division (RACE) of the Alaska Fisheries Science Center (AFSC) conducts bottom trawl surveys to monitor the...

Fisheries Online Information System - Fishing vessel based survey of young-of-year groundfish along the Newport Hydrographic Line

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The Northwest Fisheries Science Center (NWFSC) conducts a comprehensive groundfish bottom trawl survey encompassing the U.S. West Coast between the borders with...

Ecosystems Surveys Branch Gear Efficiency Study

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — An experiment aimed at quantifying the herding efficiency of flatfish for the Northeast Fisheries Science Center (NEFSC) survey trawl bridles was conducted during...

Population parameters of the Pacific flagfin mojarra Eucinostomus currani (Perciformes: Gerreidae captured by shrimp trawling fishery in the Gulf of California

Directory of Open Access Journals (Sweden)

Juana López-Martínez

2011-06-01

Full Text Available Shrimp trawling fishery in the Gulf of California captures a wide variety of non-target species of fish, crustaceans, and mollusks that are relatively unknown. The Pacific flagfin mojarra Eucinostomus currani is a frequently found species in these catches, nevertheless, nothing is currently known about its population dynamics. To contribute to the knowledge on this fish species, we studied the size structure, growth, mortality, and the recruitment pattern during the 2004-2005 seasons. A total of 6 078 mojarra were captured from 350 samples, with minimum and maximum lengths of 4.5cm and a maximum of 21.0cm. The average total length of the four major cohorts was 11.4, 13.7, 15.6 and 18.0cm, corresponding to ages 0.9, 1.2, 1.6 and 2.2 years, respectively, being the most abundant the 1.2 year-old group. The instant growth coefficient indicated moderate growth rates (K S=0.81/year, K E=0.85/year, corresponding to individuals living between 3.5 to 3.7 years. The estimated asymptotic lengths was L∞=21.8cm. In general, the population could be considered healthy: natural mortality (M=1.53/year; total mortality (Z=2.73 /year; condition factor (K=0.01072; fishery mortality (F=1.2/ year and exploitation rate (E=0.43/year. The maximum reproduction period almost coincided with the closed season for shrimp fishing (March to August, thus we concluded that survival of the species is ensured because reproduction is indirectly protected. Rev. Biol. Trop. 59 (2: 887-897. Epub 2011 June 01.La pesquería de camarón del Golfo de California captura una amplia variedad de especies incidentales, relativamente no conocidas que incluye peces, crustáceos y moluscos. La mojarra bandera del Pacífico Eucinostomus currani es frecuentemente encontrada en las capturas del camarón y no hay información sobre su dinámica poblacional. La estructura de tallas, crecimiento, mortalidad y patrón de reclutamiento fueron determinados durante la temporada 2004-2005. De manera que

Growth, reproduction, mortality, distribution, and biomass of freshwater drum in Lake Erie

Science.gov (United States)

Bur, Michael T.

1984-01-01

Predominant age-groups in the Lake Erie freshwater drum Aplodinotus grunnienspopulation were 3, 4, and 5 as determined from gill net, trap net, bottom trawl, and midwater trawl samples. Age and growth calculations indicated that females grew faster than males. However, the length-weight relation did not differ between sexes and was described by the equation: log W = −5.4383 + 3.1987 log L. Some males became sexually mature at age 2 and all were mature by age 6. Females matured 1 year later than males. Three sizes of eggs were present in ovaries; the average total number was 127,000 per female for 20 females over a length range of 270 to 478 mm. Seasonal analysis of the ovary-body weight ratio indicated that spawning extended from June to August. A total annual mortality rate of 49% for drum aged 4 through 11 was derived from catch-curve analysis. Freshwater drum were widely distributed throughout Lake Erie in 1977–1979, the greatest concentration being in the western basin. They moved into warm, shallow water (less than 10 m deep) during summer, and returned to deeper water in late fall. Summer biomass estimates for the western basin, based on systematic surveys with bottom trawls, were 9,545 t in 1977 and 2,333 t in 1978.

Bathymetric and longitudinal distribution analyysis of the rockfish Helicolenus Dactylopterus (Delaroche, 1809 in the southern Tyrrhenian Sea (central Mediterranean

Directory of Open Access Journals (Sweden)

T. ROMEO

2009-06-01

Full Text Available This study provides information on bathymetric and longitudinal distribution heterogeneity of the rockfish Helicolenus dactylopterus in the southern Tyrrhenian Sea. Data were drawn from experimental bottom trawl (1996-2002 plus bottom trap (2001-02 surveys. The frequency of occurrence and mean relative density (N/km2 and biomass (kg/km2 indexes were calculated for two survey seasons (spring and autumn, four geographic sectors and three depth strata. MANOVA was used to test fish abundance among years, sectors and strata. Analysis of the length-frequency distributions was carried out by two-way (gears and depths ANOVA, post hoc multiple comparisons for testing differences among depths and Student’s t test for testing differences between gears. Length-weight relationship was also estimated and the allometric coefficient was tested with the Student’s t test. The results showed a significant positive bathymetric gradient of sizes both for trawl and trap surveys; at same depths, fish caught by traps were significantly longer than those caught by trawl. In spring surveys, significant differences were found among strata for both abundance indexes; in autumn surveys, significant differences between depth strata were found only for density indices. The distribution and abundance patterns of H. dactylopterus along the southern Tyrrhenian Sea was homogeneous among sectors. Length-weight relationship showed a significant positive allometric growth.

Benthic marine debris, with an emphasis on fishery-related items, surrounding Kodiak Island, Alaska, 1994-1996

Science.gov (United States)

Hess, N.A.; Ribic, C.A.; Vining, I.

1999-01-01

Composition and abundance of benthic marine debris were investigated during three bottom trawl surveys in inlet and offshore locations surrounding Kodiak Island, Alaska, 1994-1996. Debris items were primarily plastic and metal regardless of trawl location. Plastic bait jars, fishing line, and crab pots were the most common fishery-related debris items and were encountered in large amounts in inlets (20-25 items km-2), but were less abundant outside of inlets (4.5-11 items km-2). Overall density of debris was also significantly greater in inlets than outside of inlets. Plastic debris densities in inlets ranged 22-31.5 items km-2, 7.8-18.8 items km-2 outside of inlets. Trawls in inlets contained almost as much metal debris as plastic debris. Density of metal debris ranged from 21.2 to 23.7 items km-2 in inlets, a maximum of 2.7 items km-2 outside of inlets. Inlets around the town of Kodiak had the highest densities of fishery-related and total benthic debris. Differences in benthic debris density between inlets and outside of inlets and differences by area may be due to differences in fishing activity and water circulation patterns. At the current reduced levels of fishing activity, however, yearly monitoring of benthic debris appears unnecessary. Copyright (C) 1999.

Industry Based Monkfish Survey

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Monkfish industry leaders expressed concerns that the NEFSC bottom trawl surveys did not sample in all monkfish habitats; particularly the deeper water outside the...

AFSC/ABL: 2008 Chum Salmon Bycatch Sample Analysis Bering Sea

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — A genetic analysis of samples from the chum salmon (Oncorhynchus keta) bycatch of the 2008 Bering Sea walleye pollock (Theragra chalcogramma) trawl fishery was...

NEFSC 2002 Deepwater Biodiversity (AL0207, EK500)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The primary objective is to collect fish, cephalopod, and crustacean specimens from the bottom and midwaters at maximum depths possible with available trawl wire....

AFSC/ABL: 2007 Chum Salmon Bycatch Sample Analysis Bering Sea

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — A genetic analysis of samples from the chum salmon (Oncorhynchus keta) bycatch of the 2007 Bering Sea walleye pollock (Theragra chalcogramma) trawl fishery was...

75 FR 36318 - List of Fisheries for 2011

Science.gov (United States)

2010-06-25

... and a biodegradable release mechanism to allow crabs to escape from pots that become separated from... a double-rig otter trawl, which normally includes a lazy line attached to each bag's codend. The...

NEFSC 2004 Deepwater Biodiversity (DE0408, EK500)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The primary objective is to collect fish, cephalopod, and crustacean specimens from the bottom and midwaters at maximum depths possible with available trawl wire....

GLOBEC NEP MOCNESS Plankton (MOC1) Data, 2000-2002

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — GLOBEC (GLOBal Ocean ECosystems Dynamics) NEP (Northeast Pacific) California Current Program MOCNESS Plankton (MOC1) Data The MOCNESS is based on the Tucker Trawl...

AFSC/ABL: 2012 Chum Salmon Bycatch Sample Analysis Bering Sea

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — A genetic analysis of samples from the chum salmon (Oncorhynchus keta) bycatch from the 2012 Bering Sea walleye pollock (Gadus chalcogrammus) trawl fishery was...

AFSC/ABL: 2009 Chum Salmon Bycatch Sample Analysis Bering Sea

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — A genetic analysis of samples from the chum salmon (Oncorhynchus keta) bycatch of the 2009 Bering Sea walleye pollock (Theragra chalcogramma) trawl fishery was...

AFSC/ABL: 2011 Chum Salmon Bycatch Sample Analysis Bering Sea

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — A genetic analysis of samples from the chum salmon (Oncorhynchus keta) bycatch from the 2011 Bering Sea walleye pollock (Theragra chalcogramma) trawl fishery was...

NEFSC 2014 Deepwater Biodiversity (PC1404, EK60)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The primary objective is to collect fish, cephalopod, and crustacean specimens from the bottom and midwaters at maximum depths possible with available trawl wire....

IFQ Halibut/Sablefish and CDQ Halibut Permit Program

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Under the IFQ Halibut/Sablefish Permit Program and CDQ Halibut Permit Program permits are issued for harvesting and receiving/processing halibut, and non-trawl...

AFSC/ABL: 2006 Chum Salmon Bycatch Sample Analysis Bering Sea

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — A genetic analysis of samples from the chum salmon (Oncorhynchus keta) bycatch of the 2006 Bering Sea walleye pollock (Theragra chalcogramma) trawl fishery was...

75 FR 5541 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands; Final 2009...

Science.gov (United States)

2010-02-03

...\\ BSAI trawl limited access fisheries Red king crab C. opilio C. bairdi (animals) Halibut mortality (mt..., skates, and octopus. Classification This action is authorized under 50 CFR 679.20 and is exempt from...

AFSC/ABL: 2005 Chum Salmon Bycatch Sample Analysis Bering Sea

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — A genetic analysis of samples from the chum salmon (Oncorhynchus keta) bycatch of the 2005 Bering Sea walleye pollock (Theragra chalcogramma) trawl fishery was...

Molecular identification of polymers and anthropogenic particles extracted from oceanic water and fish stomach - A Raman micro-spectroscopy study.

Science.gov (United States)

Ghosal, Sutapa; Chen, Michael; Wagner, Jeff; Wang, Zhong-Min; Wall, Stephen

2018-02-01

Pacific Ocean trawl samples, stomach contents of laboratory-raised fish as well as fish from the subtropical gyres were analyzed by Raman micro-spectroscopy (RMS) to identify polymer residues and any detectable persistent organic pollutants (POP). The goal was to access specific molecular information at the individual particle level in order to identify polymer debris in the natural environment. The identification process was aided by a laboratory generated automated fluorescence removal algorithm. Pacific Ocean trawl samples of plastic debris associated with fish collection sites were analyzed to determine the types of polymers commonly present. Subsequently, stomach contents of fish from these locations were analyzed for ingested polymer debris. Extraction of polymer debris from fish stomach using KOH versus ultrapure water were evaluated to determine the optimal method of extraction. Pulsed ultrasonic extraction in ultrapure water was determined to be the method of choice for extraction with minimal chemical intrusion. The Pacific Ocean trawl samples yielded primarily polyethylene (PE) and polypropylene (PP) particles >1 mm, PE being the most prevalent type. Additional microplastic residues (1 mm - 10 μm) extracted by filtration, included a polystyrene (PS) particle in addition to PE and PP. Flame retardant, deca-BDE was tentatively identified on some of the PP trawl particles. Polymer residues were also extracted from the stomachs of Atlantic and Pacific Ocean fish. Two types of polymer related debris were identified in the Atlantic Ocean fish: (1) polymer fragments and (2) fragments with combined polymer and fatty acid signatures. In terms of polymer fragments, only PE and PP were detected in the fish stomachs from both locations. A variety of particles were extracted from oceanic fish as potential plastic pieces based on optical examination. However, subsequent RMS examination identified them as various non-plastic fragments, highlighting the importance

Influence of mesoscale features on micronekton and large pelagic fish communities in the Mozambique Channel

Science.gov (United States)

Potier, Michel; Bach, Pascal; Ménard, Frédéric; Marsac, Francis

2014-02-01

We investigated the diversity and distribution of two communities, micronekton organisms and large predatory fishes, sampled in mesoscale features of the Mozambique Channel from 2003 to 2009, by combining mid-water trawls, stomach contents of fish predators and instrumented longline fishing surveys. The highest species richness for assemblages was found in divergences and fronts rather than in the core of eddies. Despite an unbalanced scheme, diversity indices did not differ significantly between cyclonic and anticyclonic eddies, divergences and fronts. We found that eddies and associated physical cues did not substantially affect the distribution of micronektonic species which are mainly driven by the diel vertical migration pattern. Top predators exhibited a more complex response. Swordfish (Xiphias gladius) associated better with mesoscale features than tunas, with a clear preference for divergences which is consistent with the diel vertical migrations and occurrence of its main prey, the flying squids Sthenoteuthis oualaniensis (Ommastrephidae). On the other hand, the probability of presence of yellowfin tuna was not tied to any specific eddy structure. However, the highest values of positive yellowfin CPUEs were associated with low horizontal gradients of sea-level anomalies. We also showed a non-linear response of positive yellowfin CPUEs with respect to the depth of the minimal oxygen content. The larger the distance between the hooks and the minimal oxygen layer, towards the surface or at greater depths, the higher the CPUE, highlighting that yellowfin congregated in well-oxygenated waters. Micronekton sampled by mid-water trawls and stomach contents exhibited different species composition. The highly mobile organisms were not caught by trawling whereas they remain accessible to predators. The combination of stomach contents and mid-water trawls undoubtedly improved our understanding of the micronekton assemblage distribution. Our results provide some

Behavior of different trawl codend concepts

DEFF Research Database (Denmark)

Madsen, Niels; Hansen, Kurt; Madsen, Nina A.H.

2015-01-01

codend. The codends were tested in a flume tank with flow of 1.8 knots/h. A simulated catch of 500 kg was placed in the tested codend. A motion tracking system was used with four track markers placed on each of three successive cross-sections and a single marker at the end of the codend. This made...

Oil spillage recovery by vacuum trawl

International Nuclear Information System (INIS)

Birkett, H.

1992-01-01

In this invention, floating oil is sucked from the surface of the sea under a skirt and into a tubular floating boom, along whose interior it is carried to water-oil separation means. The suction is produced by one or more ejectors which are supplied with sea water under pressure and may be located inside the boom, or immediately below it and connected into a separate pipe. The boom is used to enclose an oil slick and drawn tighter to increase the thickness of the oil layer. The oil enters the boom through holes in its upper half and then flows to the ejector(s) along separate internal tubes or between buoyancy balls. A fraction of the oil-water mixture withdrawn from the boom is pressurised and returned to ejector(s) and the rest is diverted to the separation means. (author)

Sea turtle in-water population survey and tagging data

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Capture efforts, using several different fishing gear (pound nets, long haul seines, gill nets, and trawls) were conducted to evaluate the growth rates, sex ratios,...

West Coast Regional Office Permits

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NOAA Fisheries implemented a license limitation program for the trawl and fixed gear sectors of Pacific Coast commercial groundfish fishery on January 1, 1993. The...

AFSC/ABL: 2007-2013 Chinook Salmon Bycatch Sample

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — A genetic analyses of samples from the Chinook salmon (Oncorhynchus tshawytscha) bycatch from the 2007-2013 Bering Sea-Aleutian Island and Gulf of Alaska trawl...

AFSC/ABL: Chum salmon bycatch genetic stock identification 1994-1995 Bering Sea

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — In some years, the Bering Sea trawl fishery incidentally harvests (bycatch) large numbers of chum salmon. Because chum salmon were declining in some western Alaska...

Gear Selectivity Survey - Haddock

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Cooperative Haddock/Atlantic Cod Separator Trawl Experiment (URI Sea Grant/Fishing Industry) Haddock and cod associate in space and time in the waters of the...

Fishery potential along the Indian coastal waters between Porbandar and Ratnagiri

Digital Repository Service at National Institute of Oceanography (India)

Gajbhiye, S.N.; Mehta, P.; Mustafa, S.; Nair, V.R.

As part of the ongoing marine pollution monitoring programme the coastal stretch between Porbandar and Ratnagiri was considered to assess the fishery potential. Regular experimental trawling was done off Porbandar, Veraval, Diu, Hazira, Daman...

AFSC/ABL: 2010 Chum Salmon Bycatch Sample Analysis Bering Sea

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — A genetic analysis of samples from the chum salmon (Oncorhynchus keta) bycatch of the 2010 Bering Sea groundfish trawl fishery was undertaken to determine the...

Pacific Coast Groundfish Individual Fishing Quota Database

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — On January 11, 2011, NOAA Fisheries implemented a new fishery management system for the West Coast Groundfish Trawl Catch Share Program as specified in the...

Deep Water Survey Data

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The deep water biodiversity surveys explore and describe the biodiversity of the bathy- and bentho-pelagic nekton using Midwater and bottom trawls centered in the...

Pop / Mart Juur

Index Scriptorium Estoniae

Juur, Mart, 1964-

2003-01-01

Heliplaatidest: Dave Gahan "Paper Monsters", Paddy McAloon "I Trawl the Megahertz", Jukka Gustavson Organ Fusion Band "Between Fire And Ice", Tanel Ruben & Victoria "A Sentimental Call", Opiate "Sometimes", The Mooney Suzuki "Electric Sweat"

Bottom fish assemblages at the shelf and continental slope off East Greenland

DEFF Research Database (Denmark)

Jørgensen, Ole A; Hvingel, Carsten; Møller, P.R.

2015-01-01

During 2006 and 2008 two bottom trawl surveys were conducted at East Greenland to 72°N covering depths down to 1500 m. In the 149 trawl hauls in total 113 fish species were recorded of which 37 were considered pelagic and excluded from the analyses. As a first step the abundance data for the 76...... benthic species were used for analyses of the fish fauna diversity and fish assemblages. Nine assemblages were found by a standard type of cluster analysis. A Bayesian multinomial logit model was then applied to calculate vectors of probabilities defining the likelihood of each haul belonging to each...... distribution, species composition, temperature and depth. Three of the assemblages were located in the cold Iceland Sea while six were found in the somewhat warmer Irminger Sea...

Conductivity, Water Temperature, and others collected from R/V Pelican in Gulf of Mexico from 2013-05-16 to 2013-05-18 (NCEI Accession 0156661)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The main goals of this cruise were as follows: (1) Recover six moorings, including one sound source, and three trawl resistant bottom mounts concentrated in the...

NWFSC Groundfish Data for U.S. West Coast (2003-2005)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The data available for downloading is summarized data from the 2003-2005 U.S. West Coast Bottom Trawl Survey (WCGTS) of Groundfish Resources off Washington, Oregon...

AFSC/NMML: Cetacean line-transect survey in the eastern Bering Sea shelf; 1999, 2000, 2002, and 2004

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Visual surveys for cetaceans were conducted on the eastern Bering Sea shelf along transect lines, in association with the AFSC.s echo integration trawl surveys for...

50 CFR 660.383 - Open access fishery management measures.

Science.gov (United States)

2010-10-01

.... south to the U.S./Mexico border) is permitted within the non-trawl RCA with fixed gear only under the..., President Jackson Seamount, Cordell Bank (50-fm (91-m) isobath), Harris Point, Richardson Rock, Scorpion...

Food Habits Database (FHDBS)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC Food Habits Database has two major sources of data. The first, and most extensive, is the standard NEFSC Bottom Trawl Surveys Program. During these...

NEFSC Survey Indices of Abundance

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Northeast Fisheries Survey Bottom trawl survey indices of abundance such as stratified mean number per tow or mean weight per tow by species stock. Includes indices...

A bio-economic appraisal of pair trawl fisheries off southeastern Brazil Uma análise bio-econômica da pesca de parelhas no sudeste do Brasil

Directory of Open Access Journals (Sweden)

Luiz Arnaud Britto de Castro

2001-01-01

Full Text Available A study of the pair trawl fisheries was made in an attempt to introduce bio-economic models into fishery management in southern and southeastern Brazil. The biological parameters of demersal fishes found in the literature were used to mount the bio-economic model. Since there are no historical data on the economics of the fishery industry, the present market values of fish and of the diverse items that compose the costs of the catch have been used. The results show that the fleet was oversized in the period 1976-1981. The number of boats was reduced from 28 pairs to only 11 in 1996, but was still considered too big. The size of the fleet is reflected in the economic results of the analysis which shows negative returns. However, the fact that some of the fixed costs are not actually spent by the owners of the boats, as many of them have no insurance and most of the boats are already completely paid off and do not accrue costs on the capital invested must all be taken into account. On the other hand, the income figures used in this analysis did not take into account the value of the by-catch landed.Numa primeira tentativa de introduzir modelos bio-econômicos no gerenciamento pesqueiro no sudeste e sul do Brasil realizou-se um estudo da pesca de parelhas. Para isso construiu-se um modelo utilizando os parâmetros biológicos disponíveis na literatura. Como não há registros históricos de dados econômicos da pesca, foram utilizados os valores atuais do pescado e dos diversos insumos utilizados nessa atividade. Os resultados indicam que a frota estava superdimensionada no período de 1976-1981. De fato, daquela época até 1996, essa frota reduziu-se de 28 parelhas para apenas 11, um número ainda excessivo. O superdimensionamento da frota reflete-se nos resultados econômicos da análise, na forma de retornos financeiros negativos. Entretanto, deve-se levar em conta que alguns dos custos fixos não representam efetivo desembolso por parte dos

AFSC/RACE/EcoFOCI - Physical oceanographic data collected in support of EcoFOCI assessment surveys and ecosystem observations in the Bering, Beaufort, and Chukchi Seas and the Gulf of Alaska - 1995 to Present

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Pressure, temperature and salinity data. Data are available in 1 meter intervals in conjunction with the MARMAP 20/60 bongo array, CalVET, and Tucker trawl. Maximum...

AFSC/FMA/Vessel Assessment Logging

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Vessels fishing trawl gear, vessels fishing hook-and-line and pot gear that are also greater than 57.5 feet overall, and shoreside and floating processing facilities...

Coral genetic - Taxonomic and genetic identification of deep-sea corals in bycatch and field surveys -linked to groundfish survey dataset

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Data for this project will reside in the West Coast Groundfish Bottom Trawl Survey Data Base. This proposal relates to a continuation and augmentation of our efforts...

Physical, chemical, and other data from the Gulf of Mexico as part of the Deepwater project from 01 August 1999 to 01 August 2002 (NODC Accession 0002207)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Physical, chemical, and other data were collected using trawl, SeaWifs and other instruments from the GYRE from the Gulf of Mexico. Data were collected from August...

AFSC/FMA/NPRB Alternative Catch Monitoring Table and ccolumn Definitions

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — These data arise from a field study of groundfish catch monitoring in Kodiak, AK trawl fisheries. Two monitoring components were included in the study: 1) at-sea...

St Andrews Bay, Florida, Juvenile Reeffish Survey from 2002-07-05 to 2015-08-13 (NCEI Accession 0156994)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains Excel and CSV files containing fish length of Juvenile Reeffish. Trawls were made during the summer months in shallow seagrass beds to monitor...

Effect of lunar periodicity on the abundance of crabs from the Goa Coast

Digital Repository Service at National Institute of Oceanography (India)

Chatterji, A; Ansari, Z.A; Ingole, B.S.; Sreepada, R.A; Kanti, A; Parulekar, A

Lunar periodicity showed a significant influence on the occurrence of edible crabs (@iPortunus pelagicus, Charybdis cruciata and Portunus sanguinolentus@@). High density of these crabs was recorded in the trawl catches during full moon and new moon...

AFSC/ABL: Salisbury Sound sponge recovery

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — In 1995, an area of the seafloor near Salisbury Sound was trawled to identify immediate effects on large, erect sponges and sea whips. Video transects were made in...

Obsolete - AFSC/RACE/Eco-FOCI: 2010 Eastern Bering Sea Juvenile Survey

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Data collected on this cruise included the following: We conducted a juvenile fish and benthic fish prey survery in the eastern Bering Sea (61 3-meter beam trawls,...

AFSC/RACE/EcoFOCI: 2010 Eastern Bering Sea Juvenile Survey - 1MF10

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Data collected on this cruise included the following: We conducted a juvenile fish and benthic fish prey survery in the eastern Bering Sea (61 3-meter beam trawls,...

Cetacean line-transect survey conducted in the eastern Bering Sea shelf by Alaska Fisheries Science Center, National Marine Mammal Laboratory from NOAA Ship Miller Freeman from 1999-07-07 to 2004-06-30 (NCEI Accession 0131862)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Visual surveys for cetaceans were conducted on the eastern Bering Sea shelf along transect lines, in association with the AFSC’s echo integration trawl surveys for...

75 FR 60867 - Fisheries off West Coast States; Pacific Coast Groundfish Fishery Management Plan; Amendments 20...

Science.gov (United States)

2010-10-01

... individual economic stability, provide full utilization of the trawl sector allocation, consider... rationalization program is intended to increase net economic benefits, create individual economic stability... of concern; improving economic performance; helping to maintain community stability; improving safety...

Groundfish Ecology Cruises

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This program involved a series of one day cruises on a commercial trawl and longline vessel. Cruises were conducted once per month from 2001-2005. The objectives of...

Comparative analysis of environmental impacts of agricultural production systems, agricultural input efficiency, and food choice

Science.gov (United States)

Clark, Michael; Tilman, David

2017-06-01

Global agricultural feeds over 7 billion people, but is also a leading cause of environmental degradation. Understanding how alternative agricultural production systems, agricultural input efficiency, and food choice drive environmental degradation is necessary for reducing agriculture’s environmental impacts. A meta-analysis of life cycle assessments that includes 742 agricultural systems and over 90 unique foods produced primarily in high-input systems shows that, per unit of food, organic systems require more land, cause more eutrophication, use less energy, but emit similar greenhouse gas emissions (GHGs) as conventional systems; that grass-fed beef requires more land and emits similar GHG emissions as grain-feed beef; and that low-input aquaculture and non-trawling fisheries have much lower GHG emissions than trawling fisheries. In addition, our analyses show that increasing agricultural input efficiency (the amount of food produced per input of fertilizer or feed) would have environmental benefits for both crop and livestock systems. Further, for all environmental indicators and nutritional units examined, plant-based foods have the lowest environmental impacts; eggs, dairy, pork, poultry, non-trawling fisheries, and non-recirculating aquaculture have intermediate impacts; and ruminant meat has impacts ∼100 times those of plant-based foods. Our analyses show that dietary shifts towards low-impact foods and increases in agricultural input use efficiency would offer larger environmental benefits than would switches from conventional agricultural systems to alternatives such as organic agriculture or grass-fed beef.

Raja asterias population assessment in FAO GFCM GSA17 area

Directory of Open Access Journals (Sweden)

C. FERRÀ

2016-09-01

Full Text Available Population structure and distribution of the starry ray, Raja asterias, were described based on data collected during yearly rapido trawl surveys (SoleMon, between 2005 and 2014 in the Northern and Central Adriatic Sea. A total of 306 individuals were caught, sex ratio was 1.04:1 in favor of males and length-weight relationships were obtained for the whole sample. Following the MEDITS scale, maturity was estimated, observing a higher number of immature individuals. Relative abundance significantly increased during the recent period with the highest values recorded at 5-30 m depths. Such increase could be related to the response of R. asterias to climatic change or to the decrease  in fishing pressure in the area. Clear spatial segregation of individuals depending on their life stage was observed, with immature individuals inhabiting the coastal areas and adults more abundant at depths greater than 40 m. The comparison of the result of the present study with MEDITS survey outcomes in terms of  distribution patterns, persistence areas of adults and juveniles and abundances indices, evidences that SoleMon survey seems to be more suitable in defining such features of the stock, likely due to the greater catchability of the rapido trawl in respect to the MEDITS trawl net. However, further investigations are needed to identify factors affecting the increasing abundance of this species, and develop an action plan for spatial management of fishing activities.

Measurements and Counts for Larval and Juvenile Beryx Specimens

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Larval alfonsin (Beryx species) were collected in the vicinity of the Southeast Hancock Seamount. A three-net Tucker trawl (I m2 effective mouth opening and 0.333 mm...

75 FR 5945 - Proposed Information Collection; Comment Request; Pacific Coast Groundfish, Rationalization...

Science.gov (United States)

2010-02-05

... Collection; Comment Request; Pacific Coast Groundfish, Rationalization Sociocultural Study AGENCY: National... requiring equivalent information. Fisheries rationalization programs have an impact on those individuals... rationalization program for the Pacific Coast Groundfish limited entry trawl fishery in January 2011. This...

Evaluation of alternative age-based methods for estimating relative abundance from survey data in relation to assessment models

DEFF Research Database (Denmark)

Berg, Casper Willestofte; Nielsen, Anders; Kristensen, Kasper

2014-01-01

Indices of abundance from fishery-independent trawl surveys constitute an important source of information for many fish stock assessments. Indices are often calculated using area stratified sample means on age-disaggregated data, and finally treated in stock assessment models as independent...... observations. We evaluate a series of alternative methods for calculating indices of abundance from trawl survey data (delta-lognormal, delta-gamma, and Tweedie using Generalized Additive Models) as well as different error structures for these indices when used as input in an age-based stock assessment model...... the different indices produced. The stratified mean method is found much more imprecise than the alternatives based on GAMs, which are found to be similar. Having time-varying index variances is found to be of minor importance, whereas the independence assumption is not only violated but has significant impact...

Environmental impacts from Danish fish products

DEFF Research Database (Denmark)

Thrane, Mikkel

This dissertation presents an assessment of the environmental impacts from Danish fish products in a life cycle perspective (from sea to table). The assessment is carried out in three steps ? and includes a MECO analysis, a quantitative LCA and a qualitative LCA. The results are used to discuss...... current environmental policies addressing the fishery, landing and auction, the fish processing industry, wholesale, transport, retail, and use.It is concluded that considerable improvement potentials exist in the fishing stage, which also represents the largest environmental impact potential compared....... It is suggested that passive and semi-active fishing methods such as Danish seine, purse seine, gillnet and long line represent a significant improvement potential compared to trawl. And it is shown that the energy consumption can be reduced with a factor 15 by substituting beam trawl with Danish seine...

Deep-sea spiny lobster, Puerulus sewelli Ramadan: Its commercial potentialities

Digital Repository Service at National Institute of Oceanography (India)

Rao, P.V.; George, M.J.

Recent exploratory cruises carried out along and outside the continental shelf off the west coast of India have brought to light the existence of spiny lobster in considerable numbers The trawling operations conducted in areas of depths between 200...

Threadfin shad Dorosoma petenense density and biomass of four Puerto Rico reservoirs – seasonal differences and comparison among temperate and tropical reservoirs

Czech Academy of Sciences Publication Activity Database

Wesley Neal, J.; Prchalová, Marie

2014-01-01

Roč. 78, 3-4 (2014), s. 229-240 ISSN 1211-376X R&D Projects: GA ČR(CZ) GPP505/12/P647 Institutional support: RVO:60077344 Keywords : trawl * sampling * variability * seasonal effect Subject RIV: EH - Ecology, Behaviour

78 FR 21114 - Magnuson-Stevens Act Provisions; General Provisions for Domestic Fisheries; Application for...

Science.gov (United States)

2013-04-09

... for Sustainable Fisheries, Northeast Region, NMFS (Assistant Regional Administrator), has made a... University Cooperative Extension of Suffolk County, NY. Regulations under the Magnuson-Stevens Fishery... limits to conduct onboard sampling. This project proposes to evaluate bottom trawl modifications as a...

Abundance, composition and distribution of solid wastes in the ...

African Journals Online (AJOL)

... 2013 at 68 stations in six depth strata using the bottom trawl swept area method. ... (42%), longlines and hooks (7%), plastic bags (4%), floats (2%), and clothing (1%). ... solid waste pollution is not at present a major problem in Lake Victoria.

Fish Assemblages in Three Northwest Florida Urbanized Bayous before and after Two Hurricanes

Science.gov (United States)

A six-year survey (1993 - 1998) is summarized for fish collected from chemically-contaminated, urbanized bayous in northwest Florida. Fifty-two monthly collections (January - November) were conducted by trawls and seines at 22 sites located in three adjacent bayous associated wi...

Fishery potential of the Gulf of Kachchh

Digital Repository Service at National Institute of Oceanography (India)

Nair, V.R.; Govindan, K.; Ramaiah, Neelam; Gajbhiye, S.N.

Fishery potential of the interior Gulf of Kachchh and adjacent creek regions was reported for the first time as baseline data for future ecological assessment. The experimental trawling and gill netting indicated that the inner Gulf (av. 7.8 kg...

Call to protect deep-sea coral, sponge ecosystems

Science.gov (United States)

Showstack, Randy

2004-03-01

More than 1100 scientists are signatories to a 15 February consensus statement calling for the protection of deep sea coral and sponge ecosystems. The statement indicates that ``the greatest human threat'' to these ecosystems ``is commercial fishing, especially bottom trawling.''

Ocean robotics in support of fisheries research and management

CSIR Research Space (South Africa)

Swart, S

2016-12-01

Full Text Available South Africa’s small pelagic fishery is an important component of the country’s commercial fisheries sector, second in value only to the demersal trawl fishery. Management of this sector relies on frequent hydro-acoustic surveys, which provide...

The cirrate, or finned, octopods are deep-sea animals about which ...

African Journals Online (AJOL)

spamer

Cephalopod Biodiversity, Ecology and Evolution. Payne, A. I. L. .... collected by the large bottom trawl used for the fish- ..... it is not clear what is the functional significance of .... VOSS, G. L. 1988a — Evolution and phylogenetic relationships of.

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...

BTS 2007: Resultaten en reisverslagen

NARCIS (Netherlands)

Boois, de I.J.; Bol, R.A.

2007-01-01

In 2007 is de beam trawl survey (BTS) uitgevoerd met de Tridens II en de Isis in opdracht van het ministerie van LNV. In dit rapport staan de resultaten van de survey alsmede de reisverslagen van de reizen op beide schepen

76 FR 79620 - Fisheries of the Exclusive Economic Zone Off Alaska; Gulf of Alaska; Proposed 2012 and 2013...

Science.gov (United States)

2011-12-22

.... Apportionment of trawl PSC limits between the deep-water and shallow-water fisheries, limits for non-exempt... specifications. The draft 2011 SAFE reports indicate that the biomass trend for shallow-water flatfish, deep... inshore and offshore processing components in the [[Page 79621

The South African chokka squid Loligo vulgaris reynaudii is caught ...

African Journals Online (AJOL)

spamer

during the 1970s and early 1980s that official statistics started to reveal ... a South African offshore component fishing off both .... 2: Annual landings of Loligo vulgaris reynaudii, 1971–1997, by the trawl fishery, both South African and foreign ...

78 FR 56641 - Fisheries Off West Coast States; Pacific Coast Groundfish Fishery Management Plan; Commercial...

Science.gov (United States)

2013-09-13

... rationalization program, including the shorebased IFQ program, was intended to increase net economic benefits, create individual economic stability, provide full utilization of the trawl sector allocation, consider..., Pacific cod and yellowtail rockfish and would likely have a favorable economic impact to groundfish...

75 FR 26702 - Fisheries off West Coast States; Pacific Coast Groundfish Fishery Management Plan; Amendments 20...

Science.gov (United States)

2010-05-12

... increase net economic benefits, create individual economic stability, provide full utilization of the trawl... (Amendments 20 and 21) is intended to increase net economic benefits, create individual economic stability... licenses, quota share accounts, vessel accounts, further tracking and monitoring components, and economic...

Contribution to the study of deep coastal detritic bottoms: the algal communities of the continental shelf off the Balearic Islands, Western Mediterranean

Directory of Open Access Journals (Sweden)

S. JOHER

2015-09-01

Full Text Available Three main algal-dominated coastal detritic communities from the continental shelf off Mallorca and Menorca (Balearic Islands, Western Mediterranean are described herein: maërl beds dominated by Spongites fruticulosus and forests of Laminaria rodriguezii located in the Menorca channel, and Peyssonnelia inamoena beds found along the Southern coast of Menorca. There seems to be a gradient of disturbance from the highly disturbed Peyssonnelia beds to the almost undisturbed L. rodriguezii forests. Whether this gradient is the result of current and past anthropogenic pressure (e.g. trawling intensity or is driven by natural environmental factors needs further assessment. Finally, the location of the target communities by means of ROV dives combined with the use of a Box-Corer dredge and beam trawl proved to be a good methodology in the study of the composition and structure of these deep water detritic communities.

Cephalopods distribution in the southern Aegean Sea

Directory of Open Access Journals (Sweden)

E. LEFKADITOU

2003-06-01

Full Text Available The present study concerns faunal composition and distribution of cephalopods in the southern Aegean Sea (35Ζ 13’ 19’’- 37Ζ 55’ 25’’ N, 23Ζ 00’ 15’’ - 28Ζ 15’ 37’’ E. Samples were collected from 708 hauls, obtained by an experimental bottom trawl net during eight surveys carried out in the summers of the years 1994-2001, as well as by commercial trawl net during four surveys carried out in September 1995, December 1995, May and September 1996. The hauls were performed at depths ranging from 16 to 778 m. A total of 34 species of cephalopod in 12 families were identified, including 11 oegopsid squid, 3 myopsid squid, 7 octopod, 3 cuttlefish and 10 sepiolid. Trawling with the experimental net resulted in the capturing of some uncommon pelagic species, such as Ctenopteryx siculaand Octopoteuthis sicula, which were recorded for the first time in the Aegean Sea. Most of the species showed a wide depth and geographical range. The species: Sepia officinalis, Sepietta neglecta, Sepietta obscuraand Sepiola rondeletiwere caught only on the continental shelf, whereas the Ancistroteuthis lichtensteini, Bathypolypous sponsalis, Brachioteuthis riisei, Chiroteuthis veranyi, Ctenopteryx sicula, Heteroteuthis dispar, Histioteuthis reversa, Neorossia caroli and Pyroteuthis margaritiferawere found only on the slope. The rest of the species extended in both continental shelf and slope. The spatial distribution of different species groups is discussed in relation to the hydrology and topography of the study area and the species ecology.

Survey gear calibration independent of spatial fish distribution

DEFF Research Database (Denmark)

Lewy, Peter; Nielsen, J. Rasmus; Hovgård, Holger

2004-01-01

Trawl surveys provide important information for evaluation of relative stock abundance fluctuations over time. Therefore, when survey gears or vessels are changed, it is important to compare the efficiency and selectivity of old and new gears and vessels. A method for estimation of conversion fac...

Sonar sound groups and increased terminal buzz duration reflect task complexity in hunting bats

DEFF Research Database (Denmark)

Hulgard, K.; Ratcliffe, J. M.

2016-01-01

to prey under presumably more difficult conditions. Specifically, we found Daubenton's bats, Myotis daubentonii, produced longer buzzes when aerial-hawking versus water-trawling prey, but that bats taking revolving air- and water-borne prey produced more sonar sound groups than did the bats when taking...

The Cape horse mackerel Trachurus trachurus capensis is the most ...

African Journals Online (AJOL)

denise

25 cm being sampled by the latter. Also, the .... Parallel trawl comparison tests .... fish (>27 cm). The modal length of the fish in both. 268. A Decade of Namibian Fisheries Science. South African Journal of Marine Science 23. 2001. B. A C W u.

A statistical model for estimation of fish density including correlation in size, space, time and between species from research survey data

DEFF Research Database (Denmark)

Nielsen, J. Rasmus; Kristensen, Kasper; Lewy, Peter

2014-01-01

Trawl survey data with high spatial and seasonal coverage were analysed using a variant of the Log Gaussian Cox Process (LGCP) statistical model to estimate unbiased relative fish densities. The model estimates correlations between observations according to time, space, and fish size and includes...

Assessing the suitability of commercial fisheries data for local-scale ...

African Journals Online (AJOL)

... are suitable for systematic spatial planning on a local scale and can be used for future spatial management and conservation. Keywords: chokka-squid, conservation planning, demersal trawl, linefish, logbooks, observer data, shark longline, small pelagic, vessel monitoring system. African Journal of Marine Science 2014, ...

76 FR 56985 - Magnuson-Stevens Fishery Conservation and Management Act Provisions; Fisheries of the...

Science.gov (United States)

2011-09-15

... to estimate total haddock catch by the herring midwater trawl fleet in these herring management areas.... 110627355-1539-02] RIN 0648-BB08 Magnuson-Stevens Fishery Conservation and Management Act Provisions... the NE Multispecies Fishery Management Plan (FMP), which increases the haddock incidental catch cap...

Geostatistical modelling of the spatial life history of post-larval deepwater hake Merluccius paradoxus in the Benguela Current Large Marine Ecosystem

DEFF Research Database (Denmark)

Jansen, T; Kristensen, K; Fairweather, T. P.

2017-01-01

paradoxus are not reflected in the current assessment and management practices for the Benguela Current Large Marine Ecosystem. In this study, we compiled data from multiple demersal trawl surveys from the entire distribution area and applied state-of the-art geostatistical population modelling (Geo...

75 FR 67809 - Magnuson-Stevens Act Provisions; Fisheries Off West Coast States; Pacific Coast Groundfish...

Science.gov (United States)

2010-11-03

... economic benefits, create individual economic stability, provide full utilization of the trawl sector... taken in the U.S. exclusive economic zone (EEZ) off the coasts of Washington, Oregon, and California... holistic alternatives relative to the biological and socio-economic environment and consistent with the...

Oceanographic Trawl Data - Ocean Survival of Salmonids

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — A study to evaluate the role of changing ocean conditions on growth and survival of juvenile salmon from the Columbia River basin as they enter the Columbia River...

50 CFR 660.112 - Trawl fishery-prohibitions.

Science.gov (United States)

2010-10-01

... reports of groundfish landings, containing all data, and in the exact manner, required by the regulation.../Biogenic Area, Farallon Islands/Fanny Shoal, Half Moon Bay, Monterey Bay/Canyon, Point Sur Deep, Big Sur... prohibited from fishing, landing, or processing primary season Pacific whiting with a catcher/processor...

reproductive biology of the moony, Monodacty/us ja/cijormis, in ...

African Journals Online (AJOL)

assistance with the trawling and acknowledge the fInancial sup- port of the South African National Committee for Oceano- graphic Research. References. BADENHORST, A. & BOYD, A.J. 1980. ... King's Beach, Algoa Bay, accounting for 10% of the nwnbers landed (Lasiak, in press). Being of no commercial significance,.

Fishing long-fingered bats (Myotis capaccinii) prey regularly upon exotic fish

DEFF Research Database (Denmark)

Aizpurua, Ostaizka; Garin, Inazio; Alberdi, Antton

2013-01-01

The long-fingered bat Myotis capaccinii is a European trawling bat reported to feed on fish in several Mediterranean locations, but the ecological circumstances of this behavior have not yet been studied. To elucidate the importance of fishing in this bat's diet, we evaluated the frequency...

Modeling marine surface microplastic transport to assess optimal removal locations

NARCIS (Netherlands)

Sherman, Peter; Van Sebille, Erik

2016-01-01

Marine plastic pollution is an ever-increasing problem that demands immediate mitigation and reduction plans. Here, a model based on satellite-tracked buoy observations and scaled to a large data set of observations on microplastic from surface trawls was used to simulate the transport of plastics

Environmental eff ects on the availability of shallow and deep-water hake to the demersaltrawl survey in Namibian waters

DEFF Research Database (Denmark)

Kainge, Paulus Inekela

at different size groups (juvenile, small, medium and large) of the two hake species. Most of the years, the environmental data were collected independent of the fishing operations usually on few selected transects with limited spatial overlap between the CTD and the trawl stations. The results, however...

Short Communication: An Update on Initiatives to Reduce Prawn ...

African Journals Online (AJOL)

While prawn trawling contributes substantially to the economies of some Western Indian Ocean countries, there is usually a considerable bycatch, much of which is wastefully discarded. Conflict between trawlers and other fisheries sectors often occurs, for example when trawlers catch species which are targeted by these ...

75 FR 52306 - Submission for OMB Review; Comment Request

Science.gov (United States)

2010-08-25

... Management Plan for Groundfish of the Bering Sea and Aleutian Islands Management Area (BSAI FMP), primarily allocates BSAI non-pollock trawl groundfish fisheries among fishing sectors and facilitates the formation of... Amendment 80 cooperative formation) are restricted from being used outside of the Amendment 80 sector...

TANZANIA JOURNAL OF SCIENCE SHORT COMMUNICATION

African Journals Online (AJOL)

Mgina

Page 1 ... caves (Table 2). Table 1: Known first landing of coelacanth in countries around the WIO region. The questionmark indicates ... Landing. Bottom type. Fishery type. Vessel Name Source. 1938. East London, S. Africa. Rocky. Trawl. Nerine. Smith 1939. 1952. --, Comoro. Volcanic slopes Lining ? Dinofish.com. 1991.

78 FR 53419 - Fisheries of the Exclusive Economic Zone Off Alaska; Groundfish of the Gulf of Alaska; Amendment...

Science.gov (United States)

2013-08-29

...) combine management of available trawl halibut PSC limits in the second season deep-water and shallow-water... annual GOA groundfish harvest specifications process. Section 679.21(d)(5) authorizes NMFS to seasonally...- line catcher vessel gears with the largest reductions. Amendment 95 would also maintain the process...

Occurrence of age-0 year dwarf pikeperch Sander lucioperca in late summer – an overlooked phenomenon in reservoirs

Czech Academy of Sciences Publication Activity Database

Jůza, Tomáš; Mrkvička, Tomáš; Blabolil, Petr; Čech, Martin; Peterka, Jiří; Vašek, Mojmír; Kubečka, Jan

2013-01-01

Roč. 83, č. 5 (2013), s. 1444-1452 ISSN 0022-1112 R&D Projects: GA MŠk(CZ) EE2.3.20.0204 Institutional support: RVO:60077344 Keywords : extremely small pikeperch * fry trawling * population dynamics Subject RIV: EH - Ecology, Behaviour Impact factor: 1.734, year: 2013

50 CFR 660.160 - Catcher/processor (C/P) Coop Program.

Science.gov (United States)

2010-10-01

... Pacific whiting, canary rockfish, darkblotched rockfish, Pacific Ocean perch, widow rockfish; (ii) Species... issuance for C/P endorsement—(i) Eligibility criteria for C/P endorsement. Only current owners of a current... with the current limited entry trawl permit accrues to the current permit owner. NMFS will not...

Time-zoning for the safe-guarding of capture fisheries: a closed season in Tamil Nadu, India

NARCIS (Netherlands)

Bavinck, M.; de Klerk, L.; van Dijk, D.; Rothuizen, J.V.; Blok, A.N.; Bokhorst, J.R.; van Haastrecht, E.K.; van de Loo, T.J.C.; Quaedvlieg, J.G.J.; Scholtens, J.

2008-01-01

A closed fishing season is arguably the most important fisheries regulation measure implemented by the government of India in the new millennium. Applied mainly to the inshore trawl fishing fleet, the planners’ intention was a safe-guarding of capture fisheries. This article, which is based on

Spatiotemporal distributions of threadfin shad in tropical reservoirs

Czech Academy of Sciences Publication Activity Database

Neal, J. W.; Prchalová, Marie

2012-01-01

Roč. 32, č. 5 (2012), s. 929-940 ISSN 0275-5947 R&D Projects: GA ČR(CZ) GPP505/12/P647 Institutional support: RVO:60077344 Keywords : threadfin shad * trawl * distribution * tropical reservoir Subject RIV: EH - Ecology, Behaviour Impact factor: 1.179, year: 2012

76 FR 58469 - Endangered Species; File Nos. 16526, 16323, 16436, 16422, 16438, 16431, 16507, 16547, 16375...

Science.gov (United States)

2011-09-21

... gastric lavaged. Stony Brook University (Keith Dunton, Responsible Party) [File No. 16422], School of... Wildlife Service, 11110 Kimages Road, Charles City, VA 23030 (Responsible Party) [File No. 16547] requests... tag. Young of the year fish would be captured using trawls, and measured and weighed; larval fish...

Investigating the effects of mobile bottom fishing on benthic biota: a systematic review protocol

NARCIS (Netherlands)

Hughes, K.M.; Kaiser, M.J.; Jennings, S.; Rijnsdorp, A.D.

2014-01-01

Background Mobile bottom fishing, such as trawling and dredging, is the most widespread direct human impact on marine benthic systems. Knowledge of the impacts of different gear types on different habitats, the species most sensitive to impacts and the potential for habitats to recover are often

76 FR 15301 - Pacific Fishery Management Council; Public Meeting

Science.gov (United States)

2011-03-21

... Council Direction for 2011 Management Measures for Analysis 5. Essential Fish Habitat Review 6. Adoption... Review 3. Periodic Essential Fish Habitat Review Process 4. Formation of Risk Pools under the Trawl... Service Report 2. Exempted Fishing Permit for 2011 Aerial Survey 3. CPS Survey Methodology D. Habitat...

Effects of environmental variables on survey catch rates and distribution by size of shallow- and deep-water Cape hakes, Merluccius capensis and Merluccius paradoxus off Namibia

DEFF Research Database (Denmark)

Kainge, Paulus Inekela; van der Plas, A. K.; Bartholomae, C. H.

2017-01-01

In order to study the effects of temperature, oxygen, salinity and time of day on survey trawl catches, we modeled observed catches of juvenile, small, medium and large hakes per station as functions of zenith angle of the sun, geographical position, year, temperature, salinity, oxygen and depth....

Vertical migration and dispersion of sprat ( Sprattus sprattus ) and herring ( Clupea harengus ) schools at dusk in the Baltic Sea

DEFF Research Database (Denmark)

Nilsson, Lars Anders Fredrik; Thygesen, Uffe Høgsbro; Lundgren, Bo

2003-01-01

, and that the dissolution of schools can be modelled by diffusion, i.e. active repulsion is not required. The field measurements were obtained during 3 days in March at one location in the Baltic Sea and included continuous hydroacoustical monitoring, trawl samples, and hydrographical CTD data. Echogram patterns were...

75 FR 52308 - Submission for OMB Review; Comment Request

Science.gov (United States)

2010-08-25

... in the Exclusive Economic Zone under the Fishery Management Plan for Groundfish of the Bering Sea and.... 1801 et seq. (MSA). Amendment 80 to the FMP primarily allocated several Bering Sea and Aleutian Islands Management Area non-pollock trawl groundfish fisheries among fishing sectors, and facilitated the formation...

A new deep-sea species of Barathronus Goode & Bean from Brazil, with notes on Barathronus bicolor Goode & Bean (Ophidiiformes: Aphyonidae)

DEFF Research Database (Denmark)

Nielsen, Jørgen; Mincarone, Michael M.; Di Dario, Fabio

2015-01-01

A new species of Barathronus (Ophidiiformes: Aphyonidae) is described from a single, mature male specimen (101 mm SL) bottom trawled on the continental slope of Rio Grande do Norte, northeastern Brazil, between 1,964 and 2,045 m depth. The new species is diagnosed among congeners by the following...

Growth, biomass, and production of two small barbs (Barbus humilis and B. tanapelagius, Cyprinidae) and their role in the food web of Lake Tana (Ethiopia)

NARCIS (Netherlands)

Dejen, E.; Vijverberg, J.; Nagelkerke, L.A.J.; Sibbing, F.A.

2009-01-01

Growth, biomass and production of two small barbs (Barbus humilis and Barbus tanapelagius) and their role in the food web of Lake Tana were investigated. From length–frequency distribution of trawl monitoring surveys growth coefficient, F' values were estimated at 3.71–4.17 for B. humilis and

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

... a timely fashion and would delay the reallocation of Pacific cod specified from trawl catcher... catcher vessel Pacific cod fishery is currently open, it is important to immediately inform the industry... and efficient operation of this fishery, to allow the industry to plan for the fishing season, and to...

Distribution of squid and fish in the pelagic zone of the Cosmonaut Sea and Prydz Bay region during the BROKE-West campaign

NARCIS (Netherlands)

Van de Putte, Anton P.; Jackson, George D.; Pakhomov, Evgeny; Flores, Hauke; Volckaert, Filip A. M.

The composition and distribution of squid and fish collected by Rectangular Midwater Trawls in the upper 200 m were investigated during the BROKE-West (Baseline Research on Oceanography, Krill and the Environment-West) survey (January-March 2006) in CCAMLR Subdivision 58.4.2 of the Southern Ocean. A

Distribution of squid and fish in the pelagic zone of the Cosmonaut Sea and Prydz Bay region during the BROKE-West campaign

NARCIS (Netherlands)

Putte, van de A.P.; Jackson, G.D.; Pakhomov, E.; Florentino De Souza Silva, A.P.; Volckaert, F.A.M.

2010-01-01

The composition and distribution of squid and fish collected by Rectangular Midwater Trawls in the upper 200 m were investigated during the BROKE-West (Baseline Research on Oceanography, Krill and the Environment-West) survey (January-March 2006) in CCAMLR Subdivision 58.4.2 of the Southern Ocean. A

Bayesian analysis of allozyme markers indicates a single genetic ...

African Journals Online (AJOL)

Kingklip Genypterus capensis inhabit deep continental shelf and slope waters off southern Africa and are now largely harvested as a bycatch in trawl and longline fisheries for Cape hakes Merluccius spp. Regional differences in growth, vertebral count and otolith morphology indicate that kingklip may consist of three stocks.

How the bat got its buzz

DEFF Research Database (Denmark)

Ratcliffe, John M; Elemans, Coen P H; Jakobsen, Lasse

2013-01-01

Since the discovery of echolocation in bats, the final phase of an attack on a flying insect, the 'terminal buzz', has proved enigmatic. During the buzz, bats increase information update rates by producing vocalizations up to 220 times s(-1). The buzz's ubiquity in hawking and trawling bats impli...

75 FR 31321 - Fisheries of the Exclusive Economic Zone Off Alaska; Rock Sole, Flathead Sole, and “Other...

Science.gov (United States)

2010-06-03

.... 0910131363-0087-02] RIN 0648-XW74 Fisheries of the Exclusive Economic Zone Off Alaska; Rock Sole, Flathead... participating in the Amendment 80 limited access fishery in the Bering Sea and Aleutian Islands management area... the trawl rock sole, flathead sole, and ``other flatfish'' fishery category by vessels participating...

78 FR 30869 - New England Fishery Management Council; Public Meeting

Science.gov (United States)

2013-05-23

... Omnibus Essential Fish Habitat Amendment 2 (OA2) which will include: Development of appropriate bridle length caps to be used on no- groundcable trawl gear within two potential adverse effects habitat... issues that will be discussed during the June 11, 2013 joint meeting of the Groundfish and Habitat...

The biology of the skates raja wallacei and r.pullopunctata (batoidea ...

African Journals Online (AJOL)

Aspects of the biology of Raja wallacei and R. pullopunctata were investigated using data collected in 1995 and 1996 from research and commercial trawls on the Agulhas Bank, South Africa. Age and growth parameters were investigated by examination of bands on the vertebral centrum. Estimates of Von Bertalanffy ...

Management implications of the biodiversity and socio-economic impacts of shrimp trawler by-catch in Bahía de Kino, Sonora, México.

Science.gov (United States)

Meltzer, Lorayne; Blinick, Naomi S; Fleishman, Abram B

2012-01-01

The shrimp fishery is the most economically important fishery in Mexico. The trawler-based portion of this fishery results in high rates of by-catch. This study quantifies and describes the biodiversity of by-catch associated with trawling in the Bahía de Kino region of Sonora, Mexico. Data were collected from 55 trawls, on six boats, over 14 nights, during November of 2003, 2004, 2006-2009. By-catch rates within trawl samples averaged 85.9% measured by weight. A total of 183 by-catch species were identified during the course of this study, including 97 species of bony fish from 43 families, 19 species of elasmobranchs from 12 families, 66 species of invertebrates from eight phyla, and one species of marine turtle; seven of the documented by-catch species are listed on the IUCN Red List, CITES, or the Mexican NOM-059-ECOL-2010; 35 species documented in the by-catch are also targeted by local artisanal fishers. Some of the species frequently captured as juveniles in the by-catch are economically important to small-scale fishers in the region, and are particularly sensitive to overexploitation due to their life histories. This study highlights the need for further research quantifying the impacts of high levels of by-catch upon small-scale fishing economies in the region and presents strong ecological and economic rationale for by-catch management within the shrimp fishery of the Gulf of California. Site-specific by-catch management plans should be piloted in the Bahía de Kino region to address the growing momentum in national and international fisheries policy regimes toward the reduction of by-catch in shrimp fisheries.

Shrimp by-catch reduction using a short funnel net, in the Gulf of Tehuantepec, South Pacific, Mexico

Directory of Open Access Journals (Sweden)

Saúl Sarmiento-Náfate

2007-12-01

Full Text Available Reduction of the by-catch in shrimp fishery is an important goal worldwide. In order to compare by-catch using the conventional trawling net and a newly designed short funnel net, nine cruises were carried out by the commercial fleet operating in the Gulf of Tehuantepec, Mexico. A total of 480 trawls were done (mean duration: 85 min. The experimental trawls using the modified net produced a 21.13-28.86 % by-catch reduction (confidence interval 95 %, a 3 % increase of shrimp catch, and a significant reduction on net recovery time. Rev. Biol. Trop. 55 (3-4: 889-897. Epub 2007 December, 28.La reducción de la fauna de acompañamiento del camarón (FAC es uno de los temas de discusión más importantes en la pesca mundial. Con la finalidad de contribuir en este tópico, se diseñó y utilizó una red de arrastre variando la longitud del túnel, y se comparó su efecto con el de una red tradicional; durante 9 cruceros de la flota comercial en el Golfo de Tehuantepec, México. Se realizó un total de 480 lances con promedio de 85 min cada uno. Los arrastres de la red modificada mostraron mejores resultados, con variación entre 21.13 a 28.86 %, con un 95 % de confianza de reducción de FAC, un incremento de 3 % en la captura de camarón, y una disminución del tiempo de recuperación, lo que sugiere un incremento en la eficiencia gracias al nuevo diseño.

A new species of the genus Linuparus White, from the South China Sea (Crustacea Decapoda)

NARCIS (Netherlands)

Bruce, A.J.

1965-01-01

The palinurid genus Linuparus White, 1847, has been represented by a single recent species, Linuparus trigonus (Von Siebold). The trawl survey of the northern shelf region of the South China Sea at present being carried out by the R.V. "Cape St. Mary" of the Fisheries Research Station, Hong Kong,

Growth, biomass, and production of two small barbs (Barbus humilis and B. tanapelagius, Cyprinidae) and their role in the food web of Lake Tana (Ethiopia)

NARCIS (Netherlands)

Dejen, E.; Vijverberg, J.; Nagelkerke, L.A.J.; Sibbing, F.A.

2009-01-01

Growth, biomass and production of two small barbs (Barbus humilis and Barbus tanapelagius) and their role in the food web of Lake Tana were investigated. From length–frequency distribution of trawl monitoring surveys growth coefficient, Φ′ values were estimated at 3.71–4.17 for B. humilis and

78 FR 36150 - Fisheries of the Exclusive Economic Zone Off Alaska; Tanner Crab Area Closure in the Gulf of...

Science.gov (United States)

2013-06-17

... rule would make a minor technical revision to the modified nonpelagic trawl gear construction... of the gear off the sea floor. This proposed rule also would make a minor technical revision to the... Marmot Bay Tanner Crab Protection Area as recommended by the Council in proposed Amendment 89. Due to the...

50 CFR 660.711 - General catch restrictions.

Science.gov (United States)

2010-10-01

... following are prohibited species: (1) Any species of salmon. (2) Great white shark. (3) Basking shark. (4..., or 3 individual sharks of the species in the management unit, whichever is greater. (3) Trawl and pot... or 2 individual sharks of the species in the management unit, whichever is greater. (c) Marlin...

Feeding habits, daily ration and vertical migration of the cape horse ...

African Journals Online (AJOL)

The feeding periodicity, rate of gut evacuation and vertical migration of horse mackerel were investigated from midwater and bottom trawl collections taken during five diel sampling periods between 1993 and 1995 at fixed positions on the South Coast. Horse mackerel feed only during the day, mostly in late afternoon prior ...

Osteichthyes: Sciaenidae

African Journals Online (AJOL)

common in the sea from the surf zone of sandy beaches ..... varying relative abundance of the major prey species on account of movements ..... length distribution of A. h%/epidotus trawled in Algoa Bay showed a ... plankton picker, A. hololepidotus is probably an active ..... abundance and diversity of the Swartkops estuary.

Scanning for PIT-tagged flatfish in a coastal area using a sledge equipped with an RFID antenna

DEFF Research Database (Denmark)

Sparrevohn, Claus Reedtz; Aarestrup, Kim; Stenberg, Claus

2014-01-01

A radio frequency identification (RFID) antenna system, build into a sledge that can be towed behind a vessel like a trawl and thereby has the potential to detect the position of a passive inductor technology (PIT)-tagged fish in a wide variety of habitats, is presented. By scanning for hatchery...

75 FR 55689 - Fisheries of the Exclusive Economic Zone Off Alaska; Reallocation of Yellowfin Sole in the Bering...

Science.gov (United States)

2010-09-14

... fisheries data in a timely fashion and would delay the reallocation of yellowfin sole from the BSAI trawl... is important to immediately inform the industry as to the revised allocations. Immediate notification... industry to plan for the fishing season, and to avoid potential disruption to the fishing fleet as well as...

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

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

Recognizing cephalopod boreholes in shells and the northward spread of Octopus vulgaris Cuvier, 1797 (Cephalopoda, Octopodoidea)

NARCIS (Netherlands)

Hiemstra, Auke-Florian

2015-01-01

Octopuses prey on molluscs by boring through their shell. Among the regular naticid borings, traces of cephalopod predation should be found soon on Dutch beaches. Bottom trawling has declined, and by the effects of global warming Octopus will find its way back to the North Sea where it lived before.

The Cape horse mackerel Trachurus trachurus capensis is an ...

African Journals Online (AJOL)

spamer

The extent to which this feeding behaviour is relevant to South African .... 1). These fish were either processed on board or blast-frozen ... 1998. 265. Table II: Stomach sample collection information of horse mackerel caught in bottom trawls during the South and West ..... Agulhas Bank, where the thermocline is deep and.

Dragmacidins: new protein phosphatase inhibitors from a southern australian deep-water marine sponge, spongosorites sp

Science.gov (United States)

Capon; Rooney; Murray; Collins; Sim; Rostas; Butler; Carroll

1998-05-01

A Spongosorites sp. collected during trawling operations off the southern coast of Australia returned the new alkaloid dragmacidin E (3), the structure of which was secured by detailed spectroscopic analysis. Dragmacidin E (3), and its co-metabolite dragmacidin D (1) have been identified as potent inhibitors of serine-threonine protein phosphatases.

Length-weight relationships, condition factors and relative weight of ...

African Journals Online (AJOL)

The aim of this study was to record the length-weight relationship parameters and condition factors for some commercially important fish of Bushehr coastal waters of Persian Gulf. The length-weight relationships were calculated for five species caught during fishing surveys using different types of fishing gears (trawls, pots ...

Reproductive status of opisthoteuthis sp . Over an annual cycle ...

African Journals Online (AJOL)

The reproductive biology of deepwater cephalopods has received relatively little attention. The cirrate octopus Opisthoteuthis sp. is a regular bycatch in deep benthic trawls from 800 to 1 200 m deep west of Scotland. Specimens were sampled throughout the seasonal cycle. Mature females occurred over a broad size range ...

Le Débat des semences

International Development Research Centre (IDRC) Digital Library (Canada)

Équilibrer les obligations issues de traités ...... Bien que les opinions diffèrent sur le caractère moral et la sécurité des cultures ...... Anonyme, citant William Haseltine, P.D.G. de Human Génome Sciences, Inc., Company Hopes Gène Trawl Will ...

77 FR 69796 - Fisheries of the Exclusive Economic Zone Off Alaska; Application for an Exempted Fishing Permit

Science.gov (United States)

2012-11-21

... concentrations of salmon and pollock for addressing experimental design criteria. The activities under the EFP... test a salmon excluder device for the Central Gulf of Alaska pollock trawl fishery. This activity is... approach the Central GOA Chinook salmon PSC limits of 18,316 Chinook salmon. If the EFP Chinook salmon were...

Chaos and stability of age-0 fish assemblages in a temperate deep reservoir: unpredictable success and stable habitat use

Czech Academy of Sciences Publication Activity Database

Jůza, Tomáš; Vašek, Mojmír; Kratochvíl, Michal; Blabolil, Petr; Čech, Martin; Draštík, Vladislav; Frouzová, Jaroslava; Muška, Milan; Peterka, Jiří; Prchalová, Marie; Říha, Milan; Tušer, Michal; Kubečka, Jan

2014-01-01

Roč. 724, č. 1 (2014), s. 217-234 ISSN 0018-8158 R&D Projects: GA MŠk(CZ) EE2.3.20.0204 Institutional support: RVO:60077344 Keywords : horizontal migration * Římov reservoir * trawling * seining * fry distribution Subject RIV: EH - Ecology, Behaviour Impact factor: 2.275, year: 2014

Patterns in abundance, population structure and biology of knife ...

African Journals Online (AJOL)

The deep-water trawl fishery along the KwaZulu-Natal coast of South Africa targets several crustacean species, with the knife (or pink) prawn Haliporoides triarthrus contributing most of the catch. Logbook data of fishing effort and catch between 1988 and 2010 were used to assess the distribution and abundance of H.

A trouser bag experiment that quantify by-catch species escaping ...

African Journals Online (AJOL)

Sea fishing trials were conducted to quantify by-catch species escaping from a modified shrimp trawl codend and retained in a trouser bag. Modification was by inserting a rectangular aluminum frame excluder device with bar spacing of 20mm at the anterior bunt. Thirty replicate landings showed that; Drepane africana have ...

notes on the bathypelagic fauna of the seas around south africa

African Journals Online (AJOL)

dwell during daylight hours in the darkness of the mid-depths of the ocean, .... there has long been much active scientific collecting and a large deep-sea ... first author is responsible for the work on invertebrates and hydrography, and ...... Mechanical analysis on the working behaviour of mid water trawl. Bull. Japan. Soc. sci.

77 FR 20339 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Management...

Science.gov (United States)

2012-04-04

... intended to facilitate an increase in the processing capabilities of the fleet to improve the retention and... non- AFA trawl C/P subsector set forth in section 219(a)(7) of the BSAI Catcher Processor Capacity... PSC sideboard limit by the number of seasons, and into two species complexes: the shallow-water and...

78 FR 77659 - Pacific Fishery Management Council; Public Meeting

Science.gov (United States)

2013-12-24

... Technical Advisory Committee (GEMTAC) will hold a work session, which is open to the public. DATES: The... will hold a work session January 22 and 23 in Portland to discuss development of an impact analysis for... further analysis a range of alternatives for electronic monitoring (EM) of the West Coast groundfish trawl...