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| Registros recuperados: 96 | |
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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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| Rochet, Marie-joelle; Collie, Jeremy S.; Trenkel, Verena. |
| Competition and predation can play different roles in mediating the influence of external pressures, such as fishing or environmental variations, on marine communities. Pressure effects propagate through food webs along predation links. These predator-prey interactions may result in trophic cascades, but they can be buffered by competitive interactions. We investigated these mechanisms by taking a functional-group approach. Are functional groups affected by external pressures in a predictable way? Within functional groups, do all species respond in the same way, or does competitive release allow for compensation among species? We constructed a simple community model, with functional groups connected by predation links. Loop analysis was used to make... |
| Tipo: Text |
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| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00154/26492/25465.pdf |
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| Trenkel, Verena; Berthele, Olivier; Lorance, Pascal; Bertrand, Jacques; Brind'Amour, Anik; Cochard, Marie-laure; Coppin, Franck; Leaute, Jean-pierre; Mahe, Jean-claude; Morin, Jocelyne; Rochet, Marie-joelle; Salaun, Michele; Souplet, Arnauld; Verin, Yves. |
| Depuis une vingtaine d'années, l'Ifremer organise des campagnes de pêche scientifique en mer du Nord, Manche, Atlantique et Méditerranée concernant les ressources pélagiques, démersales et benthiques. L'objectif prioritaire est de produire des indices d'abondance des principales espèces commerciales. Elles recueillent également des données sur les espèces capturées non commerciales. Les campagnes sont réalisées selon des plans d'échantillonnage standardisés. L'engin de pêche et son gréement, la position des stations, le tri des captures, les prélèvements biologiques suivent des protocoles fixés. Chaque zone étudiée est découpée en fonction de la profondeur, de la latitude ou d'autres critères. L'échantillonnage prévoit un nombre de traits de chalut... |
| Tipo: Text |
Palavras-chave: Populations; Halieutique; Bulletin; Méditerranée; Golfe de Gascogne; Manche; Mer du Nord; France; Pêche; Campagnes à la mer; Atlas; Survey; Mediterranean Sea; Bay of Biscay; English Channel; North Sea; France; Populations; Fishery science; Bulletin; Atlas. |
| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/2009/rapport-6976.pdf |
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| Garcia, Serge M.; Bianchi, Gabriella; Charles, Anthony; Kolding, Jeppe; Rice, Jake; Rochet, Marie-joelle; Zhou, Shijie; Delius, Gustav; Reid, David; Van Zwieten, Paul A. M.; Atcheson, Megan; Bartley, Devin; Borges, Lisa; Bundy, Alida; Dagorn, Laurent; Dunn, Daniel C.; Hall, Martin; Heino, Mikko; Jacobsen, Brigitte; Jacobsen, Nis S.; Law, Richard; Makino, Mitsutaku; Martin, Felix; Skern-mauritzen, Mette; Suuronen, Petri; Symons, Despina. |
| The concept of the Ecosystem Approach has entered the fishery harvesting discussions both from fishery perspectives (Reykjavik Declaration; FAO 2003 Annex to the Code of Conduct and from the principles of the Ecosystem Approach adopted by the CBD in 1995. Both perspectives establish the need to maintain ecosystem structure and functioning, whether for sustainable use of biodiversity (CBD) or simply to keep exploited ecosystems healthy and productive (fisheries). In response, the “Balanced Harvest” (BH) concept was suggested by a group of scientists brought together by the IUCN Fisheries Experts Group during the CBD CoP 10 in 2010. The meeting and the BH concept as consolidated there highlighted some of the collateral ecological effects of current fishing... |
| Tipo: Text |
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| Ano: 2015 |
URL: http://archimer.ifremer.fr/doc/00255/36575/35113.pdf |
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| Daures, Fabienne; Rochet, Marie-joelle; Van Iseghem, Sylvie; Trenkel, Verena. |
| Thirty French fleets fishing primarily in the Bay of Biscay were defined based on techno-economic input criteria: i) 18 fishing gear or gear combinations ii) the location of fishing grounds visited during a year (<12 nautical miles from coast, beyond 12 nm or both) and iii) total vessel length (<20 m for trawlers and other gears <24 m). The fleets were then characterised in terms of horse power, economic dependence on a list of nine dominant commercial species (sole, Nephrops, sea bass, hake, monkfish, anchovy, cuttlefish, sardine and squid) and their contribution to the landings of these species from the Bay of Biscay. Most fleets derived the majority of their income from one or two among the nine species. Species dependencies changed little... |
| Tipo: Text |
Palavras-chave: Fishing methods; Fishing vessels; Fleet dynamics; Mixed fisheries; Catch distribution; Economy; Atlantic Ocean. |
| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/00000/11172/7530.pdf |
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| Rochet, Marie-joelle. |
| 1) Demographic traits These data are published data of age-specific mortality rates, age-specific lengths or weights, length and age at maturity, fecundity-length relationships, and egg size for 84 populations from 49 species of primarily commercial teleost fishes. The populations included are those for which all the life history traits under study have been estimated over a period shorter than 10 years. Traits were estimated from within the ten year window or averaged across it when data were available. Only studies in which reference population, sample size, techniques used for ageing fish and counting eggs, and models used for estimating mortality were reported are included. When only a size or age range was available, the midpoint between the extreme... |
| Tipo: Dataset |
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| Ano: 2015 |
URL: http://dx.doi.org/10.17882/39953 |
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| Cornou, Anne-sophie; Quinio-scavinner, Marion; Delaunay, Damien; Dimeet, Joel; Goascoz, Nicolas; Dube, Benoit; Fauconnet, Laurence; Rochet, Marie-joelle. |
| Ce document est une synthèse des informations collectées en 2014 à bord des navires de pêche professionnelle dans le cadre de l'action ObsMer. Cette action vise à observer in situ l'activité de pêche et l'ensemble de la capture, particulièrement la partie non retenue, en identifiant les espèces capturées, les tonnages par espèce et en prenant des mesures de tailles. |
| Tipo: Text |
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| Ano: 2015 |
URL: http://archimer.ifremer.fr/doc/00286/39722/38188.pdf |
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| Trenkel, Verena; Le Loch, Francois; Rochet, Marie-joelle. |
| In the summer of 2004, a video survey was carried out in the northern part of the central mud bank (Grande Vasiere) of the Bay of Biscay to study the small scale relationship between the dominant crustacean megafauna Nephrops norvegicus, Munida rugosa and Goneplax rhomboides and juvenile hake (Merluccius merluccius). Using a towed body, high-resolution videos were recorded in six sampling sites. Statistical modelling using generalised additive models (GAM) revealed variations in activity patterns for two species. More N. norvegicus were observed outside their burrows at dawn and somewhat at dusk (no observations during night) while G. rhomboides was less observed in the morning. In addition, reduced spatial overlap between G. rhomboides and N. norvegicus... |
| Tipo: Text |
Palavras-chave: Competition; Variations in activity patterns; Video; Benthos. |
| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/2007/publication-2614.pdf |
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| Rochet, Marie-joelle; Cadiou, Jean-francois; Trenkel, Verena. |
| During the VIITAL cruise in the Bay of Biscay in summer 2002, two devices for measuring the length of swimming fish were tested: 1) a mechanical crown that emitted a pair of parallel laser beams and that was mounted on the main camera and 2) an underwater auto-focus video camera. The precision and accuracy of these devices were compared and the various sources of measurement errors were estimated by repeatedly measuring fixed and mobile objects and live fish. It was found that fish mobility is the main source of error for these devices because they require that the objects to be measured are perpendicular to the field of vision. The best performance was obtained with the laser method where a video-replay of laser spots (projected on fish bodies) carrying... |
| Tipo: Text |
Palavras-chave: Auto focus method; Laser method; Error estimation; Measurement methods; Fish lenght. |
| Ano: 2006 |
URL: http://archimer.ifremer.fr/doc/2006/publication-978.pdf |
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| Piet, G; Jansen, H; Rochet, Marie-joelle. |
| This study describes the process of evaluating potential indicators for an ecosystem approach to fishery management in European waters by evaluating these indicators against existing criteria using questionnaires completed by experts. We (i) compare the use of a longer list of simple criteria with a shorter list of elaborate ones; (ii) compare evaluation results when screening criteria are applied to specific indicators vs. high-level headline indicators; and (iii) examine whether detailed questionnaires, with elaborate indicators and elaborate criteria, result in ranked scores that are less influenced by familiarity with the indicators. The results show that the ranked scores of indicators are affected by the level of detail, both in terms of criteria and... |
| Tipo: Text |
Palavras-chave: Questionnaire; Headline indicators; Evaluation criteria; Ecosystem approach. |
| Ano: 2008 |
URL: http://archimer.ifremer.fr/doc/2008/publication-4715.pdf |
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| Cornillon, Pierre-andré; Pontier, Dominique; Rochet, Marie-joelle. |
| Comparative methods are used to investigate the attributes of present species or higher taxa. Difficulties arise from the phylogenetic heritage: taxa are not independent and neglecting phylogenetic inertia can lead to inaccurate results. Within-species variations in life-history traits are also not negligible, but most comparative methods are not designed to take them into account. Taxa are generally described by a single value for each trait. We have developed a new model which permits the incorporation of both the phylogenetic relationships among populations and within-species variations. This is an extension of classical autoregressive models. This family of models was used to study the effect of fishing on six demographic traits measured on 77... |
| Tipo: Text |
Palavras-chave: Autoregressive method; Intraspecific variation; Fishing effect; Comparative method. |
| Ano: 2000 |
URL: http://archimer.ifremer.fr/doc/2000/publication-682.pdf |
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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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| Peronnet, Isabelle; Rochet, Marie-joelle; Badts, Vincent; Dimeet, Joel; Dintheer, Christian; Fauconnet, Laurence; Gaudou, Olivier; Larnicol, Alain; Morizur, Yvon; Tetard, Alain. |
| En 2010 des moyens importants ont continué d’être consacrés à l’observation à la mer tant par la Direction des Pêches Maritimes et de l’Aquaculture (DPMA) que par l’Ifremer, en particulier pour le développement de l’outil informatique pour ce dernier. Les points positifs pour cette année sont la refonte du plan d’échantillonnage et des documents contractuels qui définissent les marchés d’observation, dans une perspective de contrats pluri-annuels ; cet allongement des contrats est un pas vers la stabilisation des observateurs, à même de garantir à terme une meilleure implantation sur le terrain et une meilleure collaboration avec les professionnels ; la mise en place d’une véritable collaboration entre la DPMA, les prestataires d’observation, et l’Ifremer... |
| Tipo: Text |
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| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00032/14325/11606.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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| Registros recuperados: 96 | |
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