43 research outputs found
De See weer frie âŠ
A method is discussed to indicate principal areas for fisheries in the light of recent developments in European policies for the future development of marine offshore resources
Report of the Trinational Doggerbank Survey 2016, cruise WH 396 of the FRV Walther Herwig III July 04 - 15, 2016
World Ocean Review 2013 : Living with the ocean : 2. The Future of Fish - The Fisheries of the Future
Catchability of pelagic trawls for sampling deep-living nekton in the mid-North Atlantic
Material collected in summer 2004 from the Mid-Atlantic Ridge between Iceland and the Azores with three pelagic trawls was used to estimate relative catchabilities of common fish, cephalopod, decapod, and jellyfish species. Catchability is defined as the ratio of numbers caught between two trawls, standardized for towed distance. Taxon-specific catchability coefficients were estimated for two large pelagic trawls with graded meshes, using a smaller pelagic trawl with a uniform mesh size as the reference trawl. Two of the trawls were equipped with multiple openingâclosing codends that allowed sampling of different depth layers. Generalized linear and mixed models suggest that most of the taxa have catchabilities much lower than expected from the area of opening alone, indicating that only a few species are herded by the large mesh at the mouth of larger trawls. Catchability coefficients across taxa show a very large spread, indicating that the sampled volume for the larger trawls with graded meshes was highly
taxon-specific. Part of this variability can be explained by body size and taxonomic group, the latter probably reflecting differences in body form and behaviour. The catchability estimates presented here form the basis for combining data for quantitative analyses of community structure
Species richness in North Atlantic fish: Process concealed by pattern
International audiencePrevious analyses of marine fish species richness based on presenceâabsence data have shown changes with latitude and average species size, but little is known about the underlying processes. To elucidate these processes we use metabolic, neutral and descriptive statistical models to analyse how richness responds to maximum species length, fish abundance, temperature, primary production, depth, latitude and longitude, while accounting for differences in species catchability, sampling effort and mesh size
Are we ready to track climate-driven shifts in marine species across international boundaries? - A global survey of scientific bottom trawl data
Marine biota are redistributing at a rapid pace in response to climate change and shifting seascapes. While changes in fish populations and community structure threaten the sustainability of fisheries, our capacity to adapt by tracking and projecting marine species remains a challenge due to data discontinuities in biological observations, lack of data availability, and mismatch between data and real species distributions. To assess the extent of this challenge, we review the global status and accessibility of ongoing scientific bottom trawl surveys. In total, we gathered metadata for 283,925 samples from 95 surveys conducted regularly from 2001 to 2019. We identified that 59% of the metadata collected are not publicly available, highlighting that the availability of data is the most important challenge to assess species redistributions under global climate change. Given that the primary purpose of surveys is to provide independent data to inform stock assessment of commercially important populations, we further highlight that single surveys do not cover the full range of the main commercial demersal fish species. An average of 18 surveys is needed to cover at least 50% of species ranges, demonstrating the importance of combining multiple surveys to evaluate species range shifts. We assess the potential for combining surveys to track transboundary species redistributions and show that differences in sampling schemes and inconsistency in sampling can be overcome with spatio-temporal modeling to follow species density redistributions. In light of our global assessment, we establish a framework for improving the management and conservation of transboundary and migrating marine demersal species. We provide directions to improve data availability and encourage countries to share survey data, to assess species vulnerabilities, and to support management adaptation in a time of climate-driven ocean changes.En prensa6,86
Bottom trawl fishing footprints on the worldâs continental shelves
Publication history: Accepted - 23 August 2018; Published online - 8 October 2018.Bottom trawlers land around 19 million tons of fish and invertebrates
annually, almost one-quarter of wild marine landings. The extent of
bottom trawling footprint (seabed area trawled at least once in a
specified region and time period) is often contested but poorly
described. We quantify footprints using high-resolution satellite vessel
monitoring system (VMS) and logbook data on 24 continental shelves
and slopes to 1,000-m depth over at least 2 years. Trawling footprint
varied markedly among regions: from <10% of seabed area in Australian
and New Zealand waters, the Aleutian Islands, East Bering Sea,
South Chile, and Gulf of Alaska to >50% in some European seas.
Overall, 14% of the 7.8 million-km2 study area was trawled, and
86% was not trawled. Trawling activity was aggregated; the most
intensively trawled areas accounting for 90% of activity comprised
77% of footprint on average. Regional swept area ratio (SAR; ratio
of total swept area trawled annually to total area of region, a metric
of trawling intensity) and footprint area were related, providing an
approach to estimate regional trawling footprints when highresolution
spatial data are unavailable. If SAR was â€0.1, as in 8 of
24 regions, therewas >95% probability that >90%of seabed was not
trawled. If SAR was 7.9, equal to the highest SAR recorded, there
was >95% probability that >70% of seabed was trawled. Footprints
were smaller and SAR was â€0.25 in regions where fishing rates consistently
met international sustainability benchmarks for fish stocks,
implying collateral environmental benefits from sustainable fishing.Funding for meetings of the study group and salary
support for R.O.A. were provided by the following: David and Lucile Packard
Foundation; the Walton Family Foundation; the Alaska Seafood Cooperative;
American Seafoods Group US; Blumar Seafoods Denmark; Clearwater Seafoods
Inc.; Espersen Group; Glacier Fish Company LLC US; Gortons Seafood; Independent
Fisheries Limited N.Z.; Nippon Suisan (USA), Inc.; Pesca Chile S.A.;
Pacific Andes International Holdings, Ltd.; San Arawa, S.A.; Sanford Ltd. N.Z.;
Sealord Group Ltd. N.Z.; South African Trawling Association; Trident Seafoods;
and the Food and Agriculture Organisation of the United Nations. Additional
funding to individual authors was provided by European Union Project
BENTHIS EU-FP7 312088 (to A.D.R., O.R.E., F.B., N.T.H., L.B.-M., R.C., H.O.F.,
H.G., J.G.H., P.J., S.K., M.L., G.G.-M., N.P., P.E.P., T.R., A.S., B.V., and M.J.K.); the
Instituto PortuguĂȘs do Mar e da Atmosfera, Portugal (C.S.); the International
Council for the Exploration of the Sea Science Fund (R.O.A. and K.M.H.); the
Commonwealth Scientific and Industrial Research Organisation (C.R.P. and
T.M.); the National Oceanic and Atmospheric Administration (R.A.M.); New
Zealand Ministry for Primary Industries Projects BEN2012/01 and DAE2010/
04D (to S.J.B. and R.F.); the Institute for Marine and Antarctic Studies, University
of Tasmania and the Department of Primary Industries, Parks, Water and
Environment, Tasmania, Australia (J.M.S.); and UK Department of Environment,
Food and Rural Affairs Project MF1225 (to S.J.)