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| 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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| 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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| 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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| 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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| 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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