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Registros recuperados: 6
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L'état des communautés exploitées au large des côtes de France. Application d'indicateurs à l'évaluation de l'impact de la pêche. ArchiMer
Bertrand, Jacques.
Since about twenty years, Ifremer have carried out fishery surveys along the French coasts. A dynamic indicator-based approach to the assessment of multi-stock fisheries has been applied to these data series. Reference points for non-commercial populations and community indicators are seldom available, but reference directions are well established: it is known whether fishing will increase or decrease the indicator, hence the direction that should be avoided. A set of simple indicators of fishing impacts on fish populations and communities were estimated from time-series data provided by scientific surveys (population abundance and average length, community total biomass and number, average length and weight, and size spectrum). Trends in these indicators...
Tipo: Text Palavras-chave: Approche écosystémique pour la gestion des pêches; Pêcheries multi-spécifiques; Campagnes scientifiques; Indicateurs.; Ecosystem approach to fisheries management; Multispecies fisheries; Scientific surveys; Indicators.
Ano: 2004 URL: http://archimer.ifremer.fr/doc/00326/43763/43320.pdf
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Combining indicator trends to assess ongoing changes in exploited fish communities: diagnostic of communities off the coasts of France ArchiMer
Rochet, Marie-joelle; Trenkel, Verena; Bellail, Robert; Coppin, Franck; Le Pape, Olivier; Mahe, Jean-claude; Morin, Jocelyne; Poulard, Jean-charles; Schlaich, Ivan; Souplet, Arnauld; Verin, Yves; Bertrand, Jacques.
We present a method for combining individual indicator results into a comprehensive diagnostic of fishing impacts on fish populations and communities. A conceptual framework for interpreting combined trends in a set of simple indicators is proposed, relying beforehand on qualitative expectations anchored in ecological theory. The initial state of the community is first assessed using published information. Which combinations of trends are acceptable or undesirable is decided, depending on the initial status. The indicators are then calculated from a time-series and their time trends are estimated as the slopes of linear models. Finally, the test results are combined within the predefined framework, providing a diagnostic on the dynamics of fishing impacts...
Tipo: Text Palavras-chave: Scientific surveys; Multispecies fisheries; Indicators; Ecosystem approach to fisheries management.
Ano: 2005 URL: http://archimer.ifremer.fr/doc/2005/publication-773.pdf
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Ecosystem trends: evidence for agreement between fishers' perceptions and scientific information ArchiMer
Rochet, Marie-joelle; Prigent, M; Bertrand, Jacques; Carpentier, Andre; Coppin, Franck; Delpech, Jean-paul; Fontenelle, G; Foucher, Eric; Mahe, Kelig; Rostiaux, Emilie; Trenkel, Verena.
The results of a survey on fishers' perceptions of recent changes in the eastern English Channel ecosystem carried out in 2006 were compared with fishery and bottom-trawl survey data. A hypothesis-testing framework was used, testing the null hypothesis that fishers' statements were true, which permitted evaluation of both agreement and disagreement. Overall good agreement between fishers' statements and scientific data was found, and both sources suggested that the fish community in the Channel is undergoing large changes, among which are decreases in some commercially important species; in addition, a number of human pressures impact the ecosystem. Fishers had an accurate perception of changes and their time-frames, but not necessarily of their causes....
Tipo: Text Palavras-chave: Stakeholder interview; Hypothesis testing; Fisher knowledge; Ecosystem approach to fisheries management; Eastern English Channel.
Ano: 2008 URL: http://archimer.ifremer.fr/doc/2008/publication-4474.pdf
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Notes on nine biological indicators estimable from trawl surveys with an illustrative assessment for North Sea cod ArchiMer
Cotter, John; Mesnil, Benoit; Witthames, Peter; Parker-humphreys, Matt.
This paper reviews a selection of nine indicators for assessing the biological state of a fish population monitored only by using trawl surveys in which catchability is assumed constant from time to time and place to place. The intention is to inform or remind of the range of possibilities and of associated practical and statistical issues. The indicators, grouped according to relationships with abundance, length, age, weight, and reproduction, are documented in a standard format covering estimation, interpretability, sensitivity, considerations for reference points where possible, and an example of their application. Lastly, selected indicators together with year-class curves fitted to abundance indices-at-age are applied to the North Sea cod to...
Tipo: Text Palavras-chave: Ecosystem approach to fisheries management; Year class curves; Weight index; Maturity stage; Age composition; Length based indicators; Biological indicators.
Ano: 2009 URL: http://archimer.ifremer.fr/doc/2009/publication-6901.pdf
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Fishing destabilizes the biomass flow in the marine size spectrum ArchiMer
Rochet, Marie-joelle; Benoit, E..
Fishing impacts on marine food webs are predicted by simulations of a size spectrum community model. In this model, predation is determined by predator and prey size and abundance, and drives predator growth and prey mortality. Fishing amplifies temporal oscillations in the biomass flow. Oscillations appear at lower fishing intensity and have wider amplitude when fishing is selective (removes a narrow size range) and/or when large fish are targeted, than when fishing is more balanced (catching a larger size range) or when small fish are targeted. A novel index of size diversity is developed, and is shown to be sensitive to both fishing intensity and selectivity. To avoid unstable food web dynamics with potential harmful consequences for fisheries, limiting...
Tipo: Text Palavras-chave: Size spectrum; Ecosystem approach to fisheries management; Biodiversity; Fishing selectivity; Community stability.
Ano: 2012 URL: http://archimer.ifremer.fr/doc/00053/16462/14025.pdf
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Fishing impact and environmental status in European seas: a diagnosis from stock assessments and ecosystem indicators ArchiMer
Gascuel, Didier; Coll, Marta; Fox, Clive; Guenette, Sylvie; Guitton, Jerome; Kenny, Andrew; Knittweis, Leyla; Nielsen, J. Rasmus; Piet, Gerjan; Raid, Tiit; Travers-trolet, Morgane; Shephard, Samuel.
Stock-based and ecosystem-based indicators are used to provide a new diagnosis of the fishing impact and environmental status of European seas. In the seven European marine ecosystems covering the Baltic and the North-east Atlantic, (i) trends in landings since 1950 were examined; (ii) syntheses of the status and trends in fish stocks were consolidated at the ecosystem level; and (iii) trends in ecosystem indicators based on landings and surveys were analysed. We show that yields began to decrease everywhere (except in the Baltic) from the mid-1970s, as a result of the over-exploitation of some major stocks. Fishermen adapted by increasing fishing effort and exploiting a wider part of the ecosystems. This was insufficient to compensate for the decrease in...
Tipo: Text Palavras-chave: Ecosystem approach to fisheries management; Ecosystem indicators; Good environmental status; Marine Strategy Framework Directive; Stock assessment; Trophic level.
Ano: 2016 URL: http://archimer.ifremer.fr/doc/00201/31256/29910.pdf
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