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| Registros recuperados: 51 | |
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| Marchal, Paul; Bartelings, Heleen; Bastardie, François; Batsleer, Jurgen; Delaney, Alyne; Girardin, Raphael; Gloaguen, Pierre; Hamon, Katell; Hoefnagel, Ellen; Jouanneau, Charlène; Mahevas, Stephanie; Nielsen, Rasmus; Piwowarczyk, Joanna; Poos, Jan-jaap; Schulze, Torsten; Rivot, Etienne; Simons, Sarah; Tidd, Alex; Vermard, Youen; Woillez, Mathieu. |
| The scope of this report is to present the science developed within the VECTORS project to improve the understanding of the key processes driving the behaviour of human agents utilising a variety of EU maritime domains. While particular attention has been paid to the spatial interactions between fishing activities and other human uses (e.g., maritime traffic, offshore wind parks, aggregate extractions), the behaviour of non-fishing sectors of activity has also been considered. Various quantitative and semi-qualitative approaches have been pursued to gain better insight into behavioural drivers based on past data, and also forecast how human agents would react if access was constrained by either management (e.g. Marine Protected Areas – MPA), or the... |
| Tipo: Text |
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| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00223/33377/31802.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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| 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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| Girardin, Raphael; Fulton, Elizabeth A.; Lehuta, Sigrid; Rolland, Marie; Thebaud, Olivier; Travers-trolet, Morgane; Vermard, Youen; Marchal, Paul. |
| The ecosystem model Atlantis was used to investigate the key dynamics and processes that structure the Eastern English Channel ecosystem, with a particular focus on two commercial flatfish species, sole (Solea solea) and plaice (Pleuronectes platessa). This complex model was parameterized with data collected from diverse sources (a literature review, survey data, as well as landings and stock assessment information) and tuned so both simulated biomass and catch fit 2002–2011 observations. Here, the outputs are mainly presented for the two focus species and for some other vertebrates found to be important in the trophic network. The calibration process revealed the importance of coastal areas in the Eastern English Channel and of nutrient inputs from... |
| Tipo: Text |
Palavras-chave: Ecosystem modelling; Flatfish fisheries; Trophic relationships; Calibration; Atlantis; Eastern English Channel. |
| Ano: 2018 |
URL: http://archimer.ifremer.fr/doc/00354/46524/46289.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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| Vermard, Youen; Lehuta, Sigrid; Savina-rolland, Marie; Biseau, Alain. |
| La DPMA sollicite l’Ifremer pour déterminer la réduction de la mortalité par pêche nécessaire pour l’atteinte de l’objectif du Rendement Maximum Durable (RMD) entre 2015 et 2020, avec l’estimation des Totaux Admissibles de Capture (TAC) pour chaque année. La DPMA souhaite également faire appel à l’expertise de votre Institut pour évaluer les mesures de gestion proposées ci-après par une estimation de la réduction de la mortalité par pêche, ou par une estimation des impacts potentiels, en cas de données insuffisantes : - Limitation de l’effort de pêche par flottille par une réduction du nombre de jour de pêche. Une répartition par flottille et par mois de la mortalité par pêche est nécessaire pour déterminer s’il existe une saisonnalité sur cette pêcherie,... |
| Tipo: Text |
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| Ano: 2014 |
URL: https://archimer.ifremer.fr/doc/00228/33960/32299.pdf |
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| Biseau, Alain; Bellail, Robert; Bertignac, Michel; Biais, Gerard; Bigot, Jean-louis; Bouche, Ludovic; Bourjea, Jerome; Caro, Anthony; De Casamajor, Marie-noelle; Caill-milly, Nathalie; Drogou, Mickael; Duhamel, Erwan; Fifas, Spyros; Foucher, Eric; Fromentin, Jean-marc; Jadaud, Angelique; Lampert, Luis; Laurans, Martial; Lissardy, Muriel; Lorance, Pascal; Mahe, Jean-claude; Mahe, Kelig; Masse, Jacques; Morandeau, Gilles; Pawlowski, Lionel; Poisson, Francois; Reynal, Lionel; Roos, David; Verin, Yves; Vermard, Youen; Vigneau, Joel. |
| Ce document présente l'état des principaux stocks exploités par les flottes françaises en termes de mortalité par pêche et de biomasse de reproducteurs. La situation fin 2010 (début 2011) par rapport aux points de référence (de précaution et Fmsy) est indiqué lorsque les indicateurs sont estimés et que les références sont définies. Les grandes tendances en matière d'évolution des mortalités et biomasses sont également indiquées. |
| Tipo: Text |
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| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00035/14656/11956.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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| Lecomte, Jean-baptiste; Le Pape, Olivier; Baillif, Hélène; Nevoux, Marie; Vermard, Youen; Savina-rolland, Marie; Veron, Matthieu; Lehuta, Sigrid; Hunter, Ewan; Rivot, Etienne. |
| Quantifying connectivity within fish metapopulations is an important component in understanding population dynamics and providing an evidence base for assessment and management. We investigate meta-population connectivity of the common sole (Solea solea L.) in the Eastern English Channel (EEC). The EEC common sole stock is currently assessed as a single and spatially homogeneous population but connectivity induced through adult movements within this stock and with nearby stocks remains unknown. To fill this knowledge gap, we developed a state-space mark-recovery model, designed to estimate adult connectivity, using mark-recapture data from multiple release experiments from 1970 to 2018 across the EEC and adjacent management areas. The model estimates... |
| Tipo: Text |
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| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00515/62634/67003.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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| Cormon, Xochitl; Kempf, Alexander; Vermard, Youen; Vinther, Morten; Marchal, Paul. |
| During the last 15 years, northern European hake (Merluccius merluccius) has increased in abundance, and its spatial distribution has expanded in the North Sea region in correlation with temperature. In a context of global warming, this spatial shift could impact local trophic interactions: direct impacts may affect forage fish through modified predator–prey interactions, and indirect impacts may materialize through competition with other resident predators. For instance, North Sea saithe (Pollachius virens) spatial overlap with hake has increased while saithe spawning-stock biomass has decreased recently notwithstanding a sustainable exploitation. In this context, we investigated the range of potential impacts resulting from most recent hake emergence in... |
| Tipo: Text |
Palavras-chave: Hake; Interspecific competition; Maximum sustainable yield; Multispecies stock assessment; Norway pout; Predator-prey interactions; Saithe; Simple foodweb; SMS. |
| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00327/43794/45917.pdf |
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| Ulrich, Clara; Reeves, Stuart A.; Vermard, Youen; Holmes, Steven J.; Vanhee, Willy. |
| Single-species management is a cause of discarding in mixed fisheries, because individual management objectives may not be consistent with each other and the species are caught simultaneously in relatively unselective fishing operations. As such, the total allowable catch (TAC) of one species may be exhausted before the TAC of another, leading to catches of valuable fish that cannot be landed legally. This important issue is, however, usually not quantified and not accounted for in traditional management advice. A simple approach using traditional catch and effort information was developed, estimating catch potentials for distinct fleets (groups of vessels) and metiers (type of activity), and hence quantifying the risks of over-and underquota utilization... |
| Tipo: Text |
Palavras-chave: Advice; Demersal; Effort; Fcube; Mixed fisheries; North Sea; TACs. |
| Ano: 2011 |
URL: https://archimer.ifremer.fr/doc/00044/15491/12970.pdf |
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| Girardin, Raphael; Hamon, Katell; Pinnegar, John; Poos, Jan Jaap; Thebaud, Olivier; Tidd, Alex; Vermard, Youen; Marchal, Paul. |
| Anticipating fisher behaviour is necessary for successful fisheries management. Of the different concepts that have been developed to understand individual fisher behaviour, random utility models (RUMs) have attracted considerable attention in the past three decades, and more particularly so since the 2000s. This study aimed at summarizing and analysing the information gathered from RUMs used during the last three decades around the globe. A methodology has been developed to standardize information across different studies and compare RUM results. The studies selected focused on fishing effort allocation. Six types of fisher behaviour drivers were considered: the presence of other vessels in the same fishing area, tradition, expected revenue, species... |
| Tipo: Text |
Palavras-chave: Fisher behaviour; Meta-analysis; Random utility model. |
| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00357/46834/47127.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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| Registros recuperados: 51 | |
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