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| Registros recuperados: 96 | |
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| Leleu, Kevin; Rochet, Marie-joelle; Frangoudes, Katia; Ciolek, Delphine. |
| Ce document présente les principaux résultats du programme CarRejet à travers la description du panorama des rejets en mer, la synthèse des causes de rejet identifiées à partir des cas étudiés, et la synthèse des stratégies d’adaptation envisageables à partir des causes de rejet observées. Des conclusions reprennent les principaux résultats et les limites qui sont apparues au cours du programme, accompagnées de recommandations en vue des futurs travaux à entreprendre pour aborder au mieux la prochaine OD. |
| Tipo: Text |
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| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00190/30133/28596.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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| 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... |
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| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00029/13988/11166.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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| De Lara, Michel; Doyen, Luc; Guilbaud, Therese; Rochet, Marie-joelle. |
| Fisheries management agencies have to drive resources on sustainable paths, i.e. within defined boundaries for an indefinite time. The viable-control approach is proposed as a relevant method to deal with sustainability. We analyse the ICES precautionary approach (PA) by means of the notion of viability domain, and provide a mathematical test for sustainability. It is found that the PA based on spawning-stock biomass (SSB) and fishing mortality (F) indicators is sustainable only when recruits make a significant contribution to SSB. In this case, advice based upon SSB, with an appropriate reference point, is sufficient to ensure sustainability. In all other cases, SSB is not a sufficient metric of stock productivity and must be complemented with other... |
| Tipo: Text |
Palavras-chave: Viability; Sustainable management; Indicators; ICES precautionary approach. |
| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/2007/publication-2821.pdf |
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| Cotter, John; Petitgas, Pierre; Abella, Alvaro; Apostolaki, Panayiota; Mesnil, Benoit; Politou, Chrissi-yianna; Rivoirard, Jacques; Rochet, Marie-joelle; Spedicato, Maria Teresa; Trenkel, Verena; Woillez, Mathieu. |
| Ideas and considerations are put forward for managing fisheries and marine populations using primarily trawl surveys to supply biological and spatial indicators of the state of stocks, and to permit catch per unit effort (CPUE)-based assessments. Trawl surveys seldom allow absolute estimates of fish population sizes but, if appropriately located, timed, and designed, can provide a broad range of information about catchable fish species and the ecosystem that supports them. This information may be more conducive to sustainable management of fisheries than the traditional focus on the abundances of selected stocks. The paper first briefly proposes how survey-based methods might supplement existing fishery-dependent stock assessments, as would be necessary... |
| Tipo: Text |
Palavras-chave: Fishing effort indicator; Fisheries independent assessment; Survey based stock assessment; Spatial indicator; State indicator; Trawl survey; Fisheries management. |
| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/2009/publication-6691.pdf |
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| Dube, Benoit; Dimeet, Joel; Rochet, Marie-joelle; Tetard, Alain; Gaudou, Olivier; Messannot, Cecile; Fauconnet, Laurence; Morizur, Yvon; Biseau, Alain; Salaun, Michele. |
| Ce document est une synthèse des informations collectées en 2011 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: 2012 |
URL: http://archimer.ifremer.fr/doc/00109/21976/19586.pdf |
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| De Lara, Michel; Doyen, Luc; Guilbaud, Therese; Rochet, Marie-joelle. |
| This paper deals with the control of nonlinear systems in the presence of state and control constraints for discrete-time dynamics in finite-dimensional spaces. The viability kernel is known to play a basic role for the analysis of such problems and the design of viable control feedbacks. Unfortunately, this kernel may display very nonregular geometry and its computation is not an easy task in general. In the present paper, we show how monotonicity properties of both dynamics and constraints allow for relevant analytical upper and lower approximations of the viability kernel through weakly and strongly invariant sets. An example on fish harvesting management illustrates some of the assertions. |
| Tipo: Text |
Palavras-chave: Monotonicity; Invariance; Viability; State constraints; Control. |
| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/2007/publication-2405.pdf |
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| Bundy, Alida; Shannon, Lynne J.; Rochet, Marie-joelle; Neira, Sergio; Shin, Yunne-jai; Hill, Louize; Aydin, Kerim. |
| Marine ecosystems have been exploited for a long time, growing increasingly vulnerable to collapse and irreversible change. How do we know when an ecosystem may be in danger? A measure of the status of individual stocks is only a partial gauge of its status, and does not include changes at the broader ecosystem level, to non-commercial species or to its structure or functioning. Six ecosystem indicators measuring trends over time were collated for 19 ecosystems, corresponding to four ecological attributes: resource potential, ecosystem structure and functioning, conservation of functional biodiversity, and ecosystem stability and resistance to perturbations. We explored the use of a decision-tree approach, a definition of initial ecosystem state (impacted... |
| Tipo: Text |
Palavras-chave: Comparative approach; Decision tree; Ecosystem classification; Ecosystem indicator; Exploited marine ecosystems. |
| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00002/11374/12047.pdf |
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| Rochet, Marie-joelle; Rice, Jake. |
| An evaluation framework developed to help select an appropriate suite of indicators to support an ecosystem approach to fisheries management was tested experimentally by asking independent experts to weight the selection criteria provided and to score indicators against those criteria in several ecological settings. The steps in selecting indicators proved to be prone to subjectivity and value judgement, and differences in scores between experts were the main factor contributing to variability in evaluation results. Having to justify scores in a written document did not improve consistency among the experts. The framework, however, did enhance transparency by explicitly stating each issue to be addressed in the selection process, and by giving experts or... |
| Tipo: Text |
Palavras-chave: Selection criteria; Indicators; Fisheries management; Ecosystems; Criteria weights. |
| Ano: 2005 |
URL: http://archimer.ifremer.fr/doc/2005/publication-483.pdf |
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| Rochet, Marie-joelle; Trenkel, Verena; Carpentier, Andre; Coppin, Franck; Gil De Sola, Luis; Leaute, Jean-pierre; Mahe, Jean-claude; Maiorano, Porzia; Mannini, Alessandro; Murenu, Matteo; Piet, Gerjan; Politou, Chrissi-yianna; Reale, Bruno; Spedicato, Maria-teresa; Tserpes, George; Bertrand, Jacques. |
| P>1. The development of ecosystem approaches to environmental management implies the need to account for multiple pressures on ecosystems. Trends in multiple metrics that respond differently to changes in major environmental pressures need to be combined to evaluate the impacts of fishing and environmental changes on fish communities. 2. An exploited fish community is viewed as a three-level food chain in which the two upper levels, or functional groups, are targeted by fishing fleets, while the lowest level is subject to environmental variation. Qualitative modelling is used to predict changes at the two upper levels, that is, top-down vs. bottom-up perturbations. Abundance and length metrics are calculated from survey data for 14 Mediterranean and... |
| Tipo: Text |
Palavras-chave: Bottom-up control; Community metrics; Compensation; Ecosystem approach to fisheries; Ecosystem assessment; Functional groups; Groundfish community; Mediterranean; North Atlantic; Top-down control. |
| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00008/11925/8637.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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| 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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| Depestele, Jochen; Rochet, Marie-joelle. |
| Discards generated from marine fisheries have significantly affected species populations and community composition of seabirds through mechanisms such as competition, predator–prey interactions and nutrient transfer. Our understanding of the fate of discards beyond seabird scavenging is fragmented, but it is likely that similar mechanisms come into play. This study contributes in resolving this knowledge gap by quantifying the amount and composition of discards that become available to scavengers other than seabirds. The key was nevertheless found in revealing seabird discard consumption, as seabirds are likely the first in taking profit of fishery discards due to their high mobility. Their selective consumption determines the composition and amount of... |
| Tipo: Text |
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| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00310/42146/41458.pdf |
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| Rochet, Marie-joelle; Trenkel, Verena; Peronnet, Isabelle. |
| Discards of the French trawler fleet operating in the Celtic Sea in 1997 were studied. Twenty-six trips, representing 0.8% of the total fishing effort, were sampled. This fleet consists of three métiers, benthic trawlers, demersal trawlers and Nephrops trawlers. The fleet discarded an estimated 30,000 tons of animals in 1997, while landing 63,000 tons. The total quantity discarded did not differ among métiers, but the species composition of discards did. Benthic trawlers discarded mainly by-catch species, whereas demersal and Nephrops trawlers discarded primarily their target species. Whiting, megrim, Nephrops and hake were discarded in larger numbers than landed. Hence discards should probably be taken into account in catch-based assessments. However,... |
| Tipo: Text |
Palavras-chave: Espèce non commerciale; Langoustine; Baudroie; Poisson plat; Gadidé; Mer celtique; Echantillonnage des rejets; Non commercial species; Nephrop; Anglerfish; Flatfish; Gadoid; Trawler; Celtic Sea; Discard sampling. |
| Ano: 2001 |
URL: https://archimer.ifremer.fr/doc/2001/rapport-1575.pdf |
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| Collie, Jeremy; Rochet, Marie-joelle. |
| The North Sea and Georges Bank fish communities have lost species and size diversity over the past several decades. Hypotheses that may explain these changes include climate change that may induce shifts in the food web, historical and contemporary fishing pressure and selective fishing of certain species or sizes. We use a comparative approach to examine the support for these different hypotheses. Using standardized trawl-survey data, we identify the useful indicators of species diversity, and functional diversity as measured by changes in size structure and changes in functional groups. The North Sea and Georges Bank fish communities have much in common, including shared species and congeneric species. However, the communities are subject to different... |
| Tipo: Text |
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| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00029/13992/11172.pdf |
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| Registros recuperados: 96 | |
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