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Auteur (up) Colléter, M.; Gascuel, D.; Albouy, C.; Francour, P.; Tito de Morais, L.; Valls, A.; Le Loc'h, F. url  doi
openurl 
  Titre Fishing inside or outside? A case studies analysis of potential spillover effect from marine protected areas, using food web models Type Article scientifique
  Année 2014 Publication Revue Abrégée Journal of Marine Systems  
  Volume 139 Numéro Pages 383-395  
  Mots-Clés Biomass exports; Ecopath; EcoTroph; Fishing impact; food web model; Marine protected area (MPA)  
  Résumé Marine protected areas (MPAs) are implemented worldwide as an efficient tool to preserve biodiversity and protect ecosystems. We used food web models (Ecopath and EcoTroph) to assess the ability of MPAs to reduce fishing impacts on targeted resources and to provide biomass exports for adjacent fisheries. Three coastal MPAs: Bonifacio and Port-Cros (Mediterranean Sea), and Bamboung (Senegalese coast), were used as case studies. Pre-existing related Ecopath models were homogenized and ecosystem characteristics were compared based on network indices and trophic spectra analyses. Using the EcoTroph model, we simulated different fishing mortality scenarios and assessed fishing impacts on the three ecosystems. Lastly, the potential biomass that could be exported from each MPA was estimated. Despite structural and functional trophic differences, the three MPAs showed similar patterns of resistance to simulated fishing mortalities, with the Bonifacio case study exhibiting the highest potential catches and a slightly inferior resistance to fishing. We also show that the potential exports from our small size MPAs are limited and thus may only benefit local fishing activities. Based on simulations, their potential exports were estimated to be at the same order of magnitude as the amount of catch that could have been obtained inside the reserve. In Port Cros, the ban of fishing inside MPA could actually allow for improved catch yields outside the MPA due to biomass exports. This was not the case for the Bonifacio site, as its potential exports were too low to offset catch losses. This insight suggests the need for MPA networks and/or sufficiently large MPAs to effectively protect juveniles and adults and provide important exports. Finally, we discuss the effects of MPAs on fisheries that were not considered in food web models, and conclude by suggesting possible improvements in the analysis of MPA efficiency.  
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  ISSN 0924-7963 ISBN Médium  
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  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1197  
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Auteur (up) Corrales, X.; Coll, M.; Tecchio, S.; Bellido, J.M.; Fernández, Á.M.; Palomera, I. url  doi
openurl 
  Titre Ecosystem structure and fishing impacts in the northwestern Mediterranean Sea using a food web model within a comparative approach Type Article scientifique
  Année 2015 Publication Revue Abrégée Journal of Marine Systems  
  Volume 148 Numéro Pages 183-199  
  Mots-Clés comparative approach; Ecopath model; ecosystem approach to fisheries; fishing impacts; Mass-balance model; Northwestern Mediterranean Sea  
  Résumé We developed an ecological model to characterize the structure and functioning of the marine continental shelf and slope area of the northwestern Mediterranean Sea, from Toulon to Cape La Nao (NWM model), in the early 2000s. The model included previously modeled areas in the NW Mediterranean (the Gulf of Lions and the Southern Catalan Sea) and expanded their ranges, covering 45,547 km2, with depths from 0 to 1000 m. The study area was chosen to specifically account for the connectivity between the areas and shared fish stocks and fleets. Input data were based on local scientific surveys and fishing statistics, published data on stomach content analyses, and the application of empirical equations to estimate consumption and production rates. The model was composed of 54 functional groups, from primary producers to top predators, and Spanish and French fishing fleets were considered. Results were analyzed using ecological indicators and compared with outputs from ecosystem models developed in the Mediterranean Sea and the Gulf of Cadiz prior to this study. Results showed that the main trophic flows were associated with detritus, phytoplankton, zooplankton and benthic invertebrates. Several high trophic level organisms (such as dolphins, benthopelagic cephalopods, large demersal fishes from the continental shelf, and other large pelagic fishes), and the herbivorous salema fish, were identified as keystone groups within the ecosystem. Results confirmed that fishing impact was high and widespread throughout the food web. The comparative approach highlighted that, despite productivity differences, the ecosystems shared common features in structure and functioning traits such as the important role of detritus, the dominance of the pelagic fraction in terms of flows and the importance of benthic–pelagic coupling.  
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  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1327  
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Auteur (up) Gasche, L.; Gascuel, D.; Shannon, L.; Shin, Y.-J. url  doi
openurl 
  Titre Global assessment of the fishing impacts on the Southern Benguela ecosystem using an EcoTroph modelling approach Type Article scientifique
  Année 2012 Publication Revue Abrégée Journal of Marine Systems  
  Volume 90 Numéro 1 Pages 1-12  
  Mots-Clés Ecosystem indicators; EcoTroph; Fishing impact; Overfishing; southern Benguela; Trophic modelling  
  Résumé We show that the EcoTroph model based on trophic spectra is an efficient tool to build ecosystem diagnoses of the impact of fishing. Using the Southern Benguela case study as a pretext, we present the first thorough application of the model to a real ecosystem. We thus review the structure and functioning of EcoTroph and we introduce the user to the steps that should be followed, showing the various possibilities of the model while underlining the most critical points of the modelling process. We show that EcoTroph provides an overview of the current exploitation level and target factors at the ecosystem scale, using two distinct trophic spectra to quantify the fishing targets and the fishing impact per trophic level. Then, we simulate changes in the fishing mortality, facilitating differential responses of two groups of species within the Southern Benguela ecosystem to be distinguished. More generally, we highlight various trends in a number of indicators of the ecosystem's state when increasing fishing mortality and we show that this ecosystem is moderately exploited, although predatory species are at their MSY. Finally, trophic spectra of the fishing effort multipliers EMSY and E(0.1) are proposed as tools for monitoring the ecosystem effects of fishing.  
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  Numéro d'Appel LL @ pixluser @ collection 190  
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Auteur (up) Grüss, A.; Schirripa, M.J.; Chagaris, D.; Drexler, M.; Simons, J.; Verley, P.; Shin, Y.-J.; Karnauskas, M.; Oliveros-Ramos, R.; Ainsworth, C.H. url  doi
openurl 
  Titre Evaluation of the trophic structure of the West Florida Shelf in the 2000s using the ecosystem model OSMOSE Type Article scientifique
  Année 2015 Publication Revue Abrégée Journal of Marine Systems  
  Volume 144 Numéro Pages 30-47  
  Mots-Clés Gag grouper; Marine ecosystem modeling; Natural mortality; resource management; trophic structure; West Florida Shelf  
  Résumé We applied the individual-based, multi-species OSMOSE modeling approach to the West Florida Shelf, with the intent to inform ecosystem-based management (EBM) in this region. Our model, referred to as ‘OSMOSE-WFS’, explicitly considers both pelagic-demersal and benthic high trophic level (HTL) groups of fish and invertebrate species, and is forced by the biomass of low trophic level groups of species (plankton and benthos). We present a steady-state version of the OSMOSE-WFS model describing trophic interactions in the West Florida Shelf in the 2000s. OSMOSE-WFS was calibrated using a recently developed evolutionary algorithm that allowed simulated biomasses of HTL groups to match observed biomasses over the period 2005–2009. The validity of OSMOSE-WFS was then evaluated by comparing simulated diets to observed ones, and the simulated trophic levels to those in an Ecopath model of the West Florida Shelf (WFS Reef fish Ecopath). Finally, OSMOSE-WFS was used to explore the trophic structure of the West Florida Shelf in the 2000s and estimate size-specific natural mortality rates for a socio-economically important species, gag grouper (Mycteroperca microlepis). OSMOSE-WFS outputs were in full agreement with observations as to the body size and ecological niche of prey of the different HTL groups, and to a lesser extent in agreement with the observed species composition of the diet of HTL groups. OSMOSE-WFS and WFS Reef fish Ecopath concurred on the magnitude of the instantaneous natural mortality of the different life stages of gag grouper over the period 2005–2009, but not always on the main causes of natural mortality. The model evaluations conducted here provides a strong basis for ongoing work exploring fishing and environmental scenarios so as to inform EBM. From simple size-based predation rules, we were indeed able to capture the complexity of trophic interactions in the West Florida Shelf, and to identify the predators, prey and competitors of socio-economically important species as well as pivotal prey species of the ecosystem.  
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  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1253  
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Auteur (up) Grüss, A.; Schirripa, M.J.; Chagaris, D.; Velez, L.; Shin, Y.-J.; Verley, P.; Oliveros-Ramos, R.; Ainsworth, C.H. url  doi
openurl 
  Titre Estimating natural mortality rates and simulating fishing scenarios for Gulf of Mexico red grouper (Epinephelus morio) using the ecosystem model OSMOSE-WFS Type Article scientifique
  Année 2016 Publication Revue Abrégée Journal of Marine Systems  
  Volume 154, Part B Numéro Pages 264-279  
  Mots-Clés Fishing scenarios; Gulf of Mexico; Marine ecosystem modeling; Natural mortality; Red grouper; West Florida Shelf  
  Résumé The ecosystem model OSMOSE-WFS was employed to evaluate natural mortality rates and fishing scenarios for Gulf of Mexico (GOM) red grouper (Epinephelus morio). OSMOSE-WFS represents major high trophic level (HTL) groups of species of the West Florida Shelf, is forced by the biomass of plankton and benthos groups, and has a monthly time step. The present application of the model uses a recently developed ‘stochastic mortality algorithm’ to resolve the mortality processes of HTL groups. OSMOSE-WFS predictions suggest that the natural mortality rate of juveniles of GOM red grouper is high and essentially due to predation, while the bulk of the natural mortality of adult red grouper results from causes not represented in OSMOSE-WFS such as, presumably, red tides. These results were communicated to GOM red grouper stock assessments. Moreover, OSMOSE-WFS indicate that altering the fishing mortality of GOM red grouper may have no global impact on the biomass of the major prey of red grouper, due to the high complexity and high redundancy of the modeled system. By contrast, altering the fishing mortality of GOM red grouper may have a large impact on the biomass of its major competitors. Increasing the fishing mortality of red grouper would increase the biomass of major competitors, due to reduced competition for food. Conversely, decreasing the fishing mortality of red grouper would diminish the biomass of major competitors, due to increased predation pressure on the juveniles of the major competitors by red grouper. The fishing scenarios that we evaluated may have slightly different impacts in the real world, due to some discrepancies between the diets of red grouper and its major competitors predicted by OSMOSE-WFS and the observed ones. Modifications in OSMOSE-WFS are suggested to reduce these discrepancies.  
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  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1500  
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