51 research outputs found
Scientific, Technical and Economic Committee for Fisheries (STECF) - Report of the Working Group on Research Needs - Review of List of Surveys at Sea (Appendix XIV OF EU Commission Regulation N°1581/2004) with their Priorities (SGRN 07-01)
SGRN-07-01 was held on 12-16 February 2007 in Brussels. The report describes the operational prioritisation criteria for fisheries surveys at sea necessary for the compilation of a list of surveys at sea to be considered for co-funding by the new Data Collection Regulation (DCR). STECF expressed its opinion on the report during its the plenary meeting in April 2007.JRC.G.4-Maritime affair
Increased Chlorophyll Levels in the Southern Caspian Sea Following an Invasion of Jellyfish
A significant correlation was observed between satellite derived chlorophyll a (Chl a) concentrations and the biomass of the invasive comb jellyfish Mnemiopsis leidyi in the southern Caspian Sea. By consuming the herbivorous zooplankton, the predatory ctenophore M. leidyi may have caused levels of Chl a to rise to very high values (∼9 mg m−3) in the southern Caspian Sea. There might also be
several other factors concurrent with predation effects of
M. leidyi influencing Chl a
levels in this region, such as eutrophication and climatic changes
which play major roles in nutrient, phytoplankton, and zooplankton
variations. The decrease in pelagic fishes due to overfishing,
natural, and anthropogenic impacts might have provided a suitable
environment for M. leidyi to spread throughout
this enclosed basin
The contribution of nearshore fish aggregating devices (FADs) to food security and livelihoods in Solomon Islands
Fish aggregating devices, or FADs, are used widely in developing countries to concentrate pelagic fish, making them easier to catch. Nearshore FADs anchored close to the coast allow access for rural communities, but despite their popularity among policy makers, there is a dearth of empirical analysis of their contributions to the supply of fish and to fisheries management. In this paper we demonstrate that nearshore FADs increased the supply of fish to four communities in Solomon Islands. Estimated total annual fish catch ranged from 4300 to 12 000 kg across the study villages, with nearshore FADs contributing up to 45% of the catch. While it is clear that FADs increased the supply of fish, FAD catch rates were not consistently higher than other fishing grounds. Villages with limited access to diverse or productive fishing grounds seemingly utilized FADs to better effect. Villagers believed FADs increased household income and nutrition, as well as providing a source of fish for community events. FADs were also perceived to increase intrahousehold conflict and reduce fishers\u27 participation in community activities. FADs need to be placed within a broader rural development context and treated as another component in the diversified livelihoods of rural people; as with other livelihood options they bring trade-offs and risks
VMStools: Open-source software for the processing, analysis and visualization of fisheries logbook and VMS data
VMStools is a package of open-source software, build using the freeware environment R, specifically developed for the processing, analysis and visualisation of landings (logbooks) and vessel location data (VMS) from commercial fisheries. Analyses start with standardized data formats for logbook (EFLALO) and VMS (TACSAT), enabling users to conduct a variety of analyses using generic algorithms. Embedded functionality handles erroneous data point detection and removal, métier identification through the use of clustering techniques, linking logbook and VMS data together in order to distinguish fishing from other activities, provide high-resolution maps of both fishing effort and -landings, interpolate vessel tracks, calculate indicators of fishing impact as listed under the Data Collection Framework at different spatio-temporal scales. Finally data can be transformed into other existing formats, for example to populate regional databases like FishFrame. This paper describes workflow examples of these features while online material allows a head start to perform these analyses. This software incorporates state-of-the art VMS and logbook analysing methods standardizing the process towards obtaining pan-European, or even worldwide indicators of fishing distribution and impact as required for spatial planning. -------------------------------------------------------------------------------
ICES 2005/Theme Session N ICES CM 2005/N:16 The potential impact of commercial fishing activity on the ecology of deepwater chondrichthyans from the west of Scotland
Since the 1970s the deepwater shelf edge habitat west of the British Isles has been targeted by commercial fishers. The fishery is aimed at teleosts such as ling, black scabbardfish and roundnose grenadier. A smaller component of the catch is, however, composed of Chondrichthyes, i.e. the elasmobranchs (skates & rays) and holocephalans (chimaeras). Until the early 1990s these were discarded, but now they are either actively targeted or retained as by-catch and landed for human consumption. Elasmobranchs are particularly sensitive to high harvesting levels because of slow growth rates, high longevity and low fecundity. A recent combined assessment by ICES of the two most important commercial species, Centroscymnus coelolepis and Centrophorus squamosus indicated drastic decline to less than 50% original biomass. However, landings data are unreliable and fisheries independent, species-specific data that might be used to quantify the effects of fishing in these areas are sparse because of the technological challenges and expense involved in fishing to these depths. In this study, data from scientific deepwater trawl surveys collected by FRS Marine Laboratory were carried out from 1998-2004 and interrogated. These data were examined for any evidence of a decline in abundance and compared with published data from MAFF surveys in the same region between [1970][1971][1972][1973][1974][1975][1976][1977][1978]. Despite the short time series there were indications of declining trends in CPUE for a number of Squaliformes between 1998 and 2004 and the overall catch rates of sharks are dramatically lower than those recorded from pre-exploitation surveys in the 1970s. These results highlight the need to continue fisheries-independent surveys of this vulnerable ecosystem
Evaluating the effect of fishery closures: Lessons learnt from the Plaice Box
To reduce discarding of plaice Pleuronectes platessa in the North Sea flatfish fisheries, the major nursery areas were closed to large trawlers in 1995. The area closed was named the ‘Plaice Box’ (PB) and beam trawl effort fell by over 90% , while the exemption fleets of small flatfish beam trawlers, gill netters targeting sole (Solea solea) and shrimp (Crangon crangon) trawlers increased their effort. Contrary to the expectation, plaice landings and biomass declined. The initial support for the PB from the fisheries was lost, whereas other stakeholder groups claimed that any failure was due to the fact that fishing had never been completely prohibited in the area. To evaluate whether the PB has been an effective management measure, the changes in the ecosystem (plaice, demersal fish, benthos) and fisheries are analysed to test whether the observed changes are due to the PB or to changes in the environment unrelated to the PB. Juvenile growth rate of plaice decreased and juveniles moved to deeper waters outside the PB. Demersal fish biomass decreased, whereas the abundance of epibenthic predators (Asterias rubens and Cancer pagurus) increased in the PB. Endobenthos, in particular the main food items of plaice (polychaetes and small bivalves) remained stable or decreased both inside and outside the PB. Currently catches of both plaice and sole from within the PB are lower than in the late 1980s and the exemption fleet often prefers to fish outside the Plaice Box alongside much larger competitors. It is concluded that the observed changes are most likely related to changes in the North Sea ecosystem, which may be related to changes in eutrophication and temperature. It is less likely that they are related to the change in fishing. This case study highlights the importance setting testable objectives and an appropriate evaluation framework including both ecological and socio-economic indicators when implementing closed areas. Key words: Marine Protected Area, MPA, spatial management, fisheries management, discards, climate change, trawling impact, North Sea, benthos, ecosystem change, stakeholder perceptio
Finishing the euchromatic sequence of the human genome
The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead
Investigating Agreement between Different Data Sources Using Bayesian State-Space Models: An Application to Estimating NE Atlantic Mackerel Catch and Stock Abundance
Bayesian Markov chain Monte Carlo methods are ideally suited to analyses of situations where there are a variety of data sources,
particularly where the uncertainties differ markedly among the data and the estimated parameters can be correlated. The example
of Northeast Atlantic (NEA) mackerel is used to evaluate the agreement between available data from egg surveys, tagging, and
catch-at-age using multiple models within the Bayesian framework WINBUGS. The errors in each source of information are dealt
with independently, and there is extensive exploration of potential sources of uncertainty in both the data and the model. Model
options include variation by age and over time of both selectivity in the fishery and natural mortality, varying the precision and calculation
method for spawning-stock biomass derived from an egg survey, and the extent of missing catches varying over time. The
models are compared through deviance information criterion and Bayesian posterior predictive p-values. To reconcile mortality estimated
from the different datasets the landings and discards reported would have to have been between 1.7 and 3.6 times higher than
the recorded catches.JRC.G.4-Maritime affair
An unintended experiment in fisheries science: a marine area protected by war results in mexican waves in fish numbers-at-age
Marine protected areas (MPAs) are attaining increasing importance in the management of marine ecosystems. They are effective for conservation in tropical and subtropical areas (mainly coral and rocky reefs), but it is debated whether they are useful in the management of migratory fish stocks in open temperate regions. World War II created a large marine area within which commercial fishing was prevented for 6 years. Here we analyse scientific trawl data for three important North Sea gadoids, collected between 1928 and 1958. Using statistical models to summarise the data, we demonstrate the potential of MPAs for expediting the recovery of over-exploited fisheries in open temperate regions. Our age-structured data and population models suggest that wild fish stocks will respond rapidly and positively to reductions in harvesting rates and that the numbers of older fish in a population will react before, and in much greater proportion, than their younger counterparts in a kind of Mexican wave. Our analyses demonstrate both the overall increase in survival due to the lack of harvesting in the War and the form of the age-dependent wave in numbers. We conclude that large closed areas can be very useful in the conservation of migratory species from temperate areas and that older fish benefit fastest and in greater proportion. Importantly, any rise in spawning stock biomass may also not immediately result in better recruitment, which can respond more slowly and hence take longer to contribute to higher future harvestable biomass levels
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