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| Registros recuperados: 96 | |
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| Mesnil, Benoit; Rochet, Marie-joelle. |
| With political commitment to restore stocks to levels where they can produce maximum sustainable yield (MSY), fisheries managers request evaluations of management plans that include options for an FMSY policy. The procedure to estimate FMSY with dynamic-pool, stock assessment models is well established for common stock-recruitment relationships (S-RR). In this paper, we extend this capacity to another S-RR, a piecewise function known as the hockey stick, which is frequently assumed when the data do not support more elaborate functions. However, the hockey stick is not continuous, which makes it problematic for this application, where differentiable functions are required. The bent-hyperbola model proves to be an adequate continuous equivalent to the hockey... |
| Tipo: Text |
Palavras-chave: Bent hyperbola; F-MSY; Hockey stick; MSY; Stock-recruitment. |
| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00016/12735/9667.pdf |
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| Benoit, Eric; Rochet, Marie-joelle. |
| A new time-dependent continuous model of biomass size spectra is developed. In this model, predation is the single process governing the energy flow in the ecosystem, as it causes both growth and mortality. The ratio of predator to prey is assumed to be distributed: predators may feed on a range of prey sizes. Under these assumptions, it is shown that linear size spectra are stationary solutions of the model. Exploited fish communities are simulated by adding fishing mortality to the model: it is found that realistic fishing should affect the curvature and stability of the size spectrum rather than its slope. |
| Tipo: Text |
Palavras-chave: Predation; Mortality; Growth; Biomass size spectrum; Allometry. |
| Ano: 2004 |
URL: http://archimer.ifremer.fr/doc/2004/publication-665.pdf |
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| Rochet, Marie-joelle; Trenkel, Verena; Rice, Jake. |
| Currently many multi-year management plans are being developed either for rebuilding depleted stocks or for avoiding difficult negotiations when management decisions must be revisited on a regular basis. Management plans are commonly evaluated by intensive model simulations that describe the ecological and economic dynamics, and the management loop. Under the results-based management paradigm, the fishing industry or particular fishing sectors will develop their own management plans, potentially leading to a huge number of plans to be evaluated. Guidelines for evaluating the plans on a qualitative level before launching quantitative evaluations will be essential. Here we propose a framework for evaluating management strategies in a qualitative way. A... |
| Tipo: Text |
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| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00029/13988/11166.pdf |
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| Rice, Jake; Rochet, Marie-joelle. |
| We develop a framework for the objective selection of a suite of indicators for use in fisheries management. The framework encompasses eight steps, and provides guidance on pitfalls to be avoided at each step. Step I identifies user groups and their needs, featuring the setting of operational objectives, and Step 2 identifies a corresponding list of candidate indicators. Step 3 assigns weights to nine screening criteria for the candidate indicators: concreteness, theoretical basis, public awareness, cost, measurement, historic data, sensitivity, responsiveness, and specificity. Step 4 scores the indicators against the criteria, and Step 5 summarizes the results. Steps 3-5 offer technical aspects on which guidance is provided, including scoring standards... |
| Tipo: Text |
Palavras-chave: Scoring; Objectives; Indicators; Guidelines; Framework; Ecosystem; Criteria. |
| Ano: 2005 |
URL: http://archimer.ifremer.fr/doc/2005/publication-484.pdf |
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| Trenkel, Verena; Rochet, Marie-joelle; Sari, Tewfik. |
| There exists an urgent need in fisheries science for simple models for assessing the impact of fishing on the dynamics of fish communities. We present a new class of predator prey models that describe the relationship between predators and their prey by piecewise-linear differential equations. Interactions are governed by threshold values for population abundances. The simplest model has four distinct cases with different asymptotic stable states. The model allows for fishing mortality on both predator and prey. If fishing mortality on either the predator, the prey or both are varied, the system might move to new stable states. The threshold values act as reference points for fishing exploitation, as they indicate a structural change in the predator-prey... |
| Tipo: Text |
Palavras-chave: Predator-prey model; Reference points; Differential equations. |
| Ano: 2004 |
URL: http://archimer.ifremer.fr/doc/00453/56511/58207.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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| 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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| 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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| Dimeet, Joel; Rochet, Marie-joelle; Badts, Vincent; Dintheer, Christian; Dube, Benoit; Fauconnet, Laurence; Gaudou, Olivier; Messannot, Cecile; Morizur, Yvon; Tetard, Alain. |
| En 2011 le programme d’observation a continué à mobiliser des ressources substantielles, et à perfectionner ses outils et produits : évolution et suivi du plan d’échantillonnage, numérisation des bordereaux de terrain, analyse des refus d’embarquements par les professionnels, et édition d’un document de restitution des observations à l’intention des professionnels. L’équipe a également poursuivi ses efforts d’accompagnement du développement de la base de données halieutique et des logiciels qui l’environnent. Il est regrettable que ces efforts ne soient pas terminés et que de nouvelles difficultés viennent toujours compliquer et retarder la livraison d’une base de données enfin opérationnelle. Les progrès dans l’utilisation des données d’observation à la... |
| Tipo: Text |
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| Ano: 2012 |
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| Rochet, Marie-joelle; Catchpole, Tom; Cadrin, Steve. |
| Discarding is considered by many as an important problem in world fisheries. In many regions, data collection onboard commercial vessels has intensified, and the understanding of both human and ecological drivers of discards is improving quickly. Discarding patterns vary widely across regions, fisheries, gears, and species. Fishers' responses to regulations and markets explain these complex patterns, on top of resource availability partly driven by environmental fluctuations. This expanded knowledge base provides an appropriate basis for discussing the discard mitigation measures proposed in various settings. In September 2012, a theme session was convened at the ICES Annual Science Conference in Bergen, Norway, to discuss these issues. This themed set of... |
| Tipo: Text |
Palavras-chave: Bycatch and discards; Catch quotas; Compliance; Landing obligation; Landing quotas; Market incentives; Minimum landing sizes; Onboard observer programmes; Selectivity. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00202/31353/29911.pdf |
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| Rochet, Marie-joelle; Daures, Fabienne; Trenkel, Verena. |
| This paper introduces a semiqualitative approach to analyse the joint dynamics of fleets and stocks in a multispecies, multifleet fishery. We ask whether changes in fleets affect resource dynamics and whether trends in resource influence fleet dynamics more than external drivers do. External drivers include vessel buyback, fuel price, and fish prices, as well as environmental fluctuations. Resource status is measured by abundance and length metrics; fleet capacity is measured by total horse power, and economic metrics such as profitability and earnings are examined as well. A maximum likelihood approach is used to identify the combined metric trends with the largest support in the data. The approach is applied to the French Bay of Biscay fisheries in... |
| Tipo: Text |
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| Ano: 2012 |
URL: http://archimer.ifremer.fr/doc/00076/18730/16336.pdf |
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| Cornou, Anne-sophie; Dimeet, Joel; Goascoz, Nicolas; Scavinner, Marion; Rochet, Marie-joelle. |
| Ce document est une synthèse des informations collectées en 2015 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. Ce travail s'inscrit dans le cadre d'un partenariat entre le Comite National des Pêches Maritimes et des Élevages Marins (CNPMEM), la Direction des Pêches Maritimes et de l'Aquaculture (DPMA) du Ministère de l’Écologie, du Développement Durable et de l’Énergie, et l'Ifremer. |
| Tipo: Text |
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| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00353/46441/46185.pdf |
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| Cornou, Anne-sophie; Goascoz, Nicolas; Scavinner, Marion; Chassanite, Aurore; Dubroca, Laurent; Rochet, Marie-joelle. |
| Ce document est une synthèse des informations collectées en 2016 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. Ce travail s'inscrit dans le cadre d'un partenariat entre le Comite National des Pêches Maritimes et des Élevages Marins (CNPMEM), la Direction des Pêches Maritimes et de l'Aquaculture (DPMA) du Ministère de l’Agriculture et de l'alimentation, et l'Ifremer. |
| Tipo: Text |
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| Ano: 2017 |
URL: http://archimer.ifremer.fr/doc/00418/52945/53885.pdf |
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| Cornou, Anne Sophie; Goascoz, Nicolas; Scavinner, Marion; Prioul, Francois; Sabbio, Andrea; Dubroca, Laurent; Renaud, Florent; Rochet, Marie-joelle. |
| Ce document est une synthèse des informations collectées en 2017 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. Ce travail s'inscrit dans le cadre d'un partenariat entre le Comite National des Pêches Maritimes et des Élevages Marins (CNPMEM), la Direction des Pêches Maritimes et de l'Aquaculture (DPMA) du Ministère de l’Agriculture et de l'Alimentation, et l'Ifremer. |
| Tipo: Text |
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| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00461/57314/59410.pdf |
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| Fauconnet, Laurence; Trenkel, Verena M.; Morandeau, Gilles; Caill-milly, Nathalie; Rochet, Marie-joelle. |
| To implement an ecosystem approach to fisheries management, there is a need to characterize the total pressure exerted by fisheries at the community level. French onboard observer data were used to derive catch metrics and compare fishing distribution across community components between two sites in the Southern Bay of Biscay. Sample-based rarefaction curves were used to standardize metrics across different active and passive gears, and correct for sample size differences. Six metrics for species, length and functional catch composition were tested. Length and functional metrics were found the most relevant metrics to highlight differences in catches between gears, sites, and gear-site interactions. Significant differences were found between gears, mainly... |
| Tipo: Text |
Palavras-chave: Catch diversity; Gear comparison; Multivariate analyses; Southern Bay of Biscay. |
| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00248/35882/34468.pdf |
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| Registros recuperados: 96 | |
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