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| Registros recuperados: 51 | |
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| Bonhommeau, Sylvain; Blanke, Bruno; Treguier, Anne-marie; Grima, Nicolas; Rivot, Etienne; Vermard, Youen; Greiner, Eric; Le Pape, Olivier. |
| The migration duration of European eel (Anguilla anguilla) larvae (leptocephali) from the spawning areas in the Sargasso Sea to the European continental shelf remains highly controversial, with estimates varying from 6 months to more than 2 yr. We estimated the fastest migration period and the shortest distance travelled by eel larvae by simulating Lagrangian particles released in the Sargasso Sea and by simulating a range of larval behaviours (fixed-depth drift, vertical diurnal migration and active-depth selection to maximize current velocity). This enabled us to compute (i) a passive drift speed, and (ii) a hypothetic swimming speed needed for European eel larvae to cross the Atlantic in 6 months (i.e., the migration duration estimated from otolith... |
| Tipo: Text |
Palavras-chave: Sargasso Sea; Migration duration; Leptocephali; Lagrangian modelling; Gulf Stream; Fractals; Anguilla. |
| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/2009/publication-6865.pdf |
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| Vigneau, Joel; Biseau, Alain; Cochard, Marie-laure; Vermard, Youen. |
| Expression de la demande : La demande d’avis de la part de la Direction Interrégionale de la mer Manche Est – mer du Nord (DIRM-MMN) datant du 25 février 2015 et référencée 25/2015 est présentée en annexe. La demande fait référence à un arrêté d’interdiction faite à une liste d’engins traînants de fond dans les zones de nourricerie en Baie de Seine afin de favoriser la reconstitution des stocks de sole. La liste des engins prohibés (annexe III de l’arrêté) inclut les dragues remorquées par bateau, code DRB selon la nomenclature FAO. Le comité régional des pêches de Basse-Normandie (CRPBN) s’inquiète de cette interdiction, arguant du fait que la zone protégée en baie de Seine occidentale englobe une partie des gisements mouliers de Grandcamp et Ravenoville,... |
| Tipo: Text |
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| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00255/36625/79503.pdf |
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| Nielsen, J. Rasmus; Thunberg, Eric; Holland, Daniel S.; Schmidt, Jorn O.; Fulton, Elizabeth A.; Bastardie, Francois; Punt, Andre E.; Allen, Icarus; Bartelings, Heleen; Bertignac, Michel; Bethke, Eckhard; Bossier, Sieme; Buckworth, Rik; Carpenter, Griffin; Christensen, Asbjorn; Christensen, Villy; Da-rocha, Jose M.; Deng, Roy; Dichmont, Catherine; Doering, Ralf; Esteban, Aniol; Fernandes, Jose A.; Frost, Hans; Garcia, Dorleta; Gasche, Loic; Gascuel, Didier; Gourguet, Sophie; Groeneveld, Rolf A.; Guillen, Jordi; Guyader, Olivier; Hamon, Katell; Hoff, Ayoe; Horbowy, Jan; Hutton, Trevor; Lehuta, Sigrid; Little, L. Richard; Lleonart, Jordi; Macher, Claire; Mackinson, Steven; Mahevas, Stephanie; Marchal, Paul; Mato-amboage, Rosa; Mapstone, Bruce; Maynou, Francesc; Merzereaud, Mathieu; Palacz, Artur; Pascoe, Sean; Paulrud, Anton; Plaganyi, Eva; Prellezo, Raul; Van Putten, Elizabeth I.; Quaas, Martin; Ravn-jonsen, Lars; Sanchez, Sonia; Simons, Sarah; Thebaud, Olivier; Tomczak, Maciej T.; Ulrich, Clara; Van Dijk, Diana; Vermard, Youen; Voss, Rudi; Waldo, Staffan. |
| Marine ecosystems evolve under many interconnected and area-specific pressures. To fulfil society's intensifying and diversifying needs while ensuring ecologically sustainable development, more effective marine spatial planning and broader-scope management of marine resources is necessary. Integrated ecological–economic fisheries models (IEEFMs) of marine systems are needed to evaluate impacts and sustainability of potential management actions and understand, and anticipate ecological, economic and social dynamics at a range of scales from local to national and regional. To make these models most effective, it is important to determine how model characteristics and methods of communicating results influence the model implementation, the nature of the... |
| Tipo: Text |
Palavras-chave: Bio-economic models; Comparative model evaluation; Fisheries management advice; Integrated ecological-economic fisheries models; Marine spatial planning and cross-sector management; Performance criteria and scales and risks; Use and acceptance and implementation and communication and flexibility and complexity. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00391/50269/50898.pdf |
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| Bonhommeau, Sylvain; Le Pape, O.; Gascuel, D.; Blanke, Bruno; Treguier, Anne-marie; Grima, Nicolas; Vermard, Youen; Castonguay, M.; Rivot, E.. |
| Using Lagrangian simulations, based on circulation models over three different hydroclimatic periods in the last 45 years in the North Atlantic Ocean, the trans-Atlantic migration of the European eel Anguilla anguilla leptocephali was simulated via the passive drift of particles released in the spawning area. Three different behaviours were modelled: drifting at fixed depth, undergoing a vertical migration or choosing the fastest currents. Simulations included mortality hypotheses to estimate a realistic mean migration duration and relative survival of A. anguilla larvae. The mean migration duration was estimated as 21 months and the mortality rate as 3 center dot 8 per year, i.e. < 0 center dot 2% of A. anguilla larvae may typically survive the... |
| Tipo: Text |
Palavras-chave: Migration duration; Leptocephalus mortality; Lagrangian modelling. |
| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/2009/publication-6614.pdf |
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| Biseau, Alain; Le Mao, Patrick; Sartoretto, Stephane; Tourolle, Julie; Menot, Lenaick; Fabri, Marie-claire; Larnaud, Pascal; Drogou, Mickael; Morandeau, Fabien; Vacherot, Jean-philippe; Vermard, Youen. |
| Tipo: Text |
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| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00300/41147/41077.pdf |
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| Pelletier, Dominique; Mahevas, Stephanie; Drouineau, Hilaire; Vermard, Youen; Thebaud, Olivier; Guyader, Olivier; Poussind, Benjamin. |
| In order to provide reliable scientific advice and support for fisheries management, it is necessary to evaluate the biological and economic sustainability of complex fisheries, such as multi-species multi-fleet fisheries. Existing policy-screening modelling tools are not fully suitable in this purpose due to either an over-simplified description of population dynamics, or due to the lack of consideration of economic aspects. In this paper, we present a package that enables quantitative bioeconomic assessment of management scenarios. Population dynamics is described through spatially- and seasonally-explicit models. Exploitation dynamics is characterized by several fishing activities with specific spatial and seasonal features, and practiced by several... |
| Tipo: Text |
Palavras-chave: Policy screening; Natural resource management; Fisheries dynamics; Bioeconomic model; Population dynamics; Complex systems; Simulation tool. |
| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/2009/publication-6782.pdf |
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| Queiros, Ana M.; Huebert, Klaus B.; Keyl, Friedemann; Fernandes, Jose A.; Stolte, Willem; Maar, Marie; Kay, Susan; Jones, Miranda C.; Hamon, Katell; Hendriksen, Gerrit; Vermard, Youen; Marchal, Paul; Teal, Lorna R.; Somerfield, Paul J.; Austen, Melanie C.; Barange, Manuel; Sell, Anne F.; Allen, Icarus; Peck, Myron A.. |
| The Paris Conference of Parties (COP21) agreement renewed momentum for action against climate change, creating the space for solutions for conservation of the ocean addressing two of its largest threats: climate change and ocean acidification (CCOA). Recent arguments that ocean policies disregard a mature conservation research field and that protected areas cannot address climate change may be oversimplistic at this time when dynamic solutions for the management of changing oceans are needed. We propose a novel approach, based on spatial meta-analysis of climate impact models, to improve the positioning of marine protected areas to limit CCOA impacts. We do this by estimating the vulnerability of ocean ecosystems to CCOA in a spatially explicit manner and... |
| Tipo: Text |
Palavras-chave: Climate change; Conservation; COP21; Ecosystem model; Habitat; Marine spatial planning; Ocean; Ocean acidification; Species distribution; Warming. |
| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00360/47089/48566.pdf |
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| Du Pontavice, Hubert; Randon, Marine; Lehuta, Sigrid; Vermard, Youen; Savina-rolland, Marie. |
| In fisheries science, a mismatch between the delineation of a fish stock and the underlying biological population can lead to inaccurate assessment and management. Previous results suggested a potential spatial structuration of the Eastern English Channel (EEC) stock of common sole, Solea solea, in three sub-populations. In this article, we propose to investigate the spatial population structure of common sole in the EEC using the von Bertalanffy Growth Function parameters as indicators of population segregation. In order to test the sub-population hypothesis and evaluate its robustness to data sources, we developed three models, all including an area effect on growth parameters. The first model was aimed at testing a potential data source effect (in... |
| Tipo: Text |
Palavras-chave: Key-words; Von Bertalanffy growth function; Stock structuration; Solea solea; Flatfish; Life-history traits; Metapopulation. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00445/55625/57301.pdf |
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| Gloaguen, Pierre; Mahevas, Stephanie; Rivot, Etienne; Woillez, Mathieu; Guitton, Jerome; Vermard, Youen; Etienne, Marie-pierre. |
| The understanding of the dynamics of fishing vessels is of great interest to characterize the spatial distribution of the fishing effort and to define sustainable fishing strategies. It is also a prerequisite for anticipating changes in fishermen's activity in reaction to management rules, economic context, or evolution of exploited resources. Analyzing the trajectories of individual vessels offers promising perspectives to describe the activity during fishing trips. A hidden Markov model with two behavioral states (steaming and fishing) is developed to infer the sequence of non-observed fishing vessel behavior along the vessel trajectory based on Global Positioning System (GPS) records. Conditionally to the behavior, vessel velocity is modeled with an... |
| Tipo: Text |
Palavras-chave: Hidden Markov model; Vessels dynamics; RECOPESCA; Autoregressive process; Baum-Welch algorithm. |
| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00179/29049/27485.pdf |
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| Vermard, Youen; Marchal, Paul; Mahevas, Stephanie; Thebaud, Olivier. |
| The scope of this paper is to describe, evaluate, and forecast fishing trip choices of the Bay of Biscay pelagic fleet using random utility modeling (RUM). First, alternative fishing trip choices of this fleet were identified using multivariate statistical methods based on species landings weighted by value and defined as distinct fishing activity or fisheries (termed metiers). A RUM was specified, which included trip components as attributes during the period 20012004 ( a lagged percentage of the value per unit of effort of the main species caught, total value per unit of effort, and inertia in terms of changes from one metier to another). For the main metiers, the proportion of correct effort allocation is 90% during the calibration period of 2001-2004.... |
| Tipo: Text |
Palavras-chave: Management; Métier; Fishing effort; Fisher's behavior; RUM. |
| Ano: 2008 |
URL: http://archimer.ifremer.fr/doc/2008/publication-6096.pdf |
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| Tidd, Alex N.; Vermard, Youen; Marchal, Paul; Pinnegar, John; Blanchard, Julia L.; Milner-gulland, E. J.. |
| The European Union and other states are moving towards Ecosystem Based Fisheries Management to balance food production and security with wider ecosystem concerns. Fishing is only one of several sectors operating within the ocean environment, competing for renewable and non-renewable resources that overlap in a limited space. Other sectors include marine mining, energy generation, recreation, transport and conservation. Trade-offs of these competing sectors are already part of the process but attempts to detail how the seas are being utilised have been primarily based on compilations of data on human activity at large spatial scales. Advances including satellite and shipping automatic tracking enable investigation of factors influencing fishers' choice of... |
| Tipo: Text |
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| Ano: 2015 |
URL: http://archimer.ifremer.fr/doc/00254/36518/35064.pdf |
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| Bourdaud, Pierre; Travers-trolet, Morgane; Vermard, Youen; Marchal, Paul. |
| Managing mixed fisheries requires understanding fishers’ behaviour to allow predicting future fisheries distribution and impact on marine ecosystems. A new approach was developed to compare fine scale fishing effort distribution of Eastern English Channel (EEC) bottom trawlers, to the monthly- and spatially-resolved abundance distributions of commercial species. First, the added-value of using species-specific spatial overlap metric to quantify effective fishing effort and improve the relationship between fishing effort and fishing mortality was assessed. Second, based on the Ideal Free Distribution (IFD) theory, the species-specific weights given by fishers to different species were estimated by maximizing the overlap between target species assemblage and... |
| Tipo: Text |
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| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00446/55747/57402.pdf |
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| Lehuta, Sigrid; Petitgas, Pierre; Mahevas, Stephanie; Huret, Martin; Vermard, Youen; Uriarte, Andres; Record, Nicholas R.. |
| Assessing the validity of a model is essential for its credibility especially when the model is used as decision making tool. Complex dynamic fishery models are recommended to investigate the functioning of fisheries and to assess the impact of management strategies, particularly spatial fishing regulations. However, their use is limited due to the difficulty and computational cost of parameterizing and gaining confidence, particularly for parameter rich models. These difficulties are compounded by uncertainty regarding parameter values, many of which are often taken from literature or estimated indirectly. Here we propose a methodology to improve confidence and understanding in the model, easily transferable to any complex model. The approach combines... |
| Tipo: Text |
Palavras-chave: Bay of Biscay anchovy; Dynamic fishery model; Model selection; Uncertainty; Validation. |
| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00148/25965/24150.pdf |
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| Cormon, Xochitl; Ernande, Bruno; Kempf, Alexander; Vermard, Youen; Marchal, Paul. |
| North Sea saithe Pollachius virens, a major top predator in the area, supports the fishery economy of several European countries. However, recent stock assessments suggested a decrease in spawning stock biomass along with a decline in saithe mean weight-at-ages. In this context, we investigated North Sea saithe growth characteristics at the population level. First, saithe annual weight increments and age-length relationships were studied. Modelling of saithe age-length relationships was carried out using (1) the traditional von Bertalanffy growth function model, (2) the Verhulst logistic model and (3) an empirical linear model. Second, the effects of environmental factors on saithe growth were investigated. Explanatory environmental factors included food... |
| Tipo: Text |
Palavras-chave: Bottom-up processes; Von Bertalanffy growth function; Logistic growth; Norway pout; Prey availability effects; Density-dependence; Predator-prey interactions; Resource limitation; Competition. |
| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00314/42499/41875.pdf |
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| Vermard, Youen; Rivot, Etienne; Mahevas, Stephanie; Marchal, Paul; Gascuel, Didier. |
| Recent advances in technologies have lead to a vast influx of data on movements, based on discrete recorded position of animals or fishing boats, opening new horizons for future analyses. However, most of the potential interest of tracking data depends on the ability to develop suitable modelling strategies to analyze trajectories from discrete recorded positions. A serious modelling challenge is to infer the evolution of the true position and the associated spatio-temporal distribution of behavioural states using discrete, error-prone and incomplete observations. In this paper, a Bayesian Hierarchical Model (HBM) using Hidden Markov Process (HMP) is proposed as a template for analyzing fishing boats trajectories based on data available from... |
| Tipo: Text |
Palavras-chave: Bayesian Hierarchical Models; Hidden Markov Model; State-space model; VMS; Fleet behaviour; Fishing effort. |
| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00009/11993/9342.pdf |
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| Registros recuperados: 51 | |
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