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Auteur Dhurmeea, Z.; Zudaire, I.; Chassot, E.; Cedras, M.; Nikolic, N.; Bourjea, J.; West, W.; Appadoo, C.; Bodin, N. url  doi
openurl 
  Titre Reproductive Biology of Albacore Tuna (Thunnus alalunga) in the Western Indian Ocean Type Article scientifique
  Année 2016 Publication (down) Revue Abrégée Plos One  
  Volume 11 Numéro 12 Pages e0168605  
  Mots-Clés Fecundity; Histology; Indian Ocean; Latitude; Marine fish; Oocytes; Ovaries; Tuna  
  Résumé The reproductive biology of albacore tuna, Thunnus alalunga, in the western Indian Ocean was examined through analysis of the sex ratio, spawning season, length-at-maturity (L50), spawning frequency and fecundity. From 2013 to 2015, a total of 923 female and 867 male albacore were sampled. A bias in sex ratio was found in favor of females with fork length (LF) < 100 cm. Using histological analyses and gonadosomatic index, spawning was found to occur between 10°S and 30°S, mainly to the east of Madagascar from October to January. Large females contributed more to reproduction through their longer spawning period compared to small individuals. The L50 (mean ± standard error) of female albacore was estimated at 85.3 ± 0.7 cm LF. Albacore spawn on average every 2.2 days within the spawning region and spawning months, from November to January. Batch fecundity ranged between 0.26 and 2.09 million oocytes and the relative batch fecundity (mean ± standard deviation) was estimated at 53.4 ± 23.2 oocytes g-1 of somatic-gutted weight. The study provides new information on the reproductive development and classification of albacore in the western Indian Ocean. The reproductive parameters will reduce uncertainty in current stock assessment models which will eventually assist the fishery to be sustainable for future generations.  
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  Volume de collection Numéro de collection Edition  
  ISSN 1932-6203 ISBN Médium  
  Région Expédition Conférence  
  Notes Approuvé pas de  
  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1706  
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Auteur Villon, S.; Mouillot, D.; Chaumont, M.; Darling, E.S.; Subsol, G.; Claverie, T.; Villeger, S. doi  openurl
  Titre A Deep learning method for accurate and fast identification of coral reef fishes in underwater images Type Article scientifique
  Année 2018 Publication (down) Revue Abrégée Ecol. Inform.  
  Volume 48 Numéro Pages 238-244  
  Mots-Clés Automated identification; Convolutional neural network; density; Machine learning; Marine fishes; neural-networks; system; temperate; Underwater pictures; video stations; visual census; vulnerability  
  Résumé Identifying and counting fish individuals on photos and videos is a crucial task to cost-effectively monitor marine biodiversity, yet it remains difficult and time-consuming. In this paper, we present a method to assist the identification of fish species on underwater images, and we compare our model performances to human ability in terms of speed and accuracy. We first tested the performance of a convolutional neural network (CNN) trained with different photographic databases while accounting for different post-processing decision rules to identify 20 fish species. Finally, we compared the performance of species identification of our best CNN model with that of humans on a test database of 1197 fish images representing nine species. The best CNN was the one trained with 900,000 images including (i) whole fish bodies, (ii) partial fish bodies and (iii) the environment (e.g. reef bottom or water). The rate of correct identification was 94.9%, greater than the rate of correct identification by humans (89.3%). The CNN was also able to identify fish individuals partially hidden behind corals or behind other fish and was more effective than humans to identify fish on smallest or blurry images while humans were better to identify fish individuals in unusual positions (e.g. twisted body). On average, each identification by our best CNN using a common hardware took 0.06 s. Deep Learning methods can thus perform efficient fish identification on underwater images and offer promises to build-up new video-based protocols for monitoring fish biodiversity cheaply and effectively.  
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  Langue English Langue du Résumé Titre Original  
  Éditeur de collection Titre de collection Titre de collection Abrégé  
  Volume de collection Numéro de collection Edition  
  ISSN 1574-9541 ISBN Médium  
  Région Expédition Conférence  
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  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2475  
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Auteur 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 (down) 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  
  Région Expédition Conférence  
  Notes Approuvé pas de  
  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1197  
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Auteur Campbell, S.J.; Darling, E.S.; Pardede, S.; Ahmadia, G.; Mangubhai, S.; Amkieltiela; Estradivari; Maire, E. doi  openurl
  Titre Fishing restrictions and remoteness deliver conservation outcomes for Indonesia's coral reef fisheries Type Article scientifique
  Année 2020 Publication (down) Revue Abrégée Conserv. Lett.  
  Volume Numéro Pages e12698  
  Mots-Clés data-poor fisheries; dynamics; food webs; gear restrictions; management; marine protected areas; small-scale fisheries; South East Asia; targets  
  Résumé Coral reef fisheries depend on reef fish biomass to support ecosystem functioning and sustainable fisheries. Here, we evaluated coral reefs across 4,000 km of the Indonesian archipelago to reveal a large gradient of biomass, from 17,000 kg/ha. Trophic pyramids characterized by planktivore dominance emerged at high biomass, suggesting the importance of pelagic pathways for reef productivity. Total biomass and the biomass of most trophic groups were higher within gear restricted and no-take management, but the greatest biomass was found on unmanaged remote reefs. Within marine protected areas (MPAs), 41.6% and 43.6% of gear restricted and no-take zones, respectively, met a global biomass target of 500 kg/ha, compared with 71.8% of remote sites. To improve conservation outcomes for Indonesia's biodiverse and economically important coral reef fisheries, our results suggest to: (1) strengthen management within Indonesia's existing MPAs and (2) precautionarily manage remote reefs with high biomass.  
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  Langue English Langue du Résumé Titre Original  
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  ISSN 1755-263x ISBN Médium  
  Région Expédition Conférence  
  Notes WOS:000510789900001 Approuvé pas de  
  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2733  
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Auteur Kaplan, D.; Chassot, E.; Amande, J.M.; Dueri, S.; Demarcq, H.; Dagorn, L.; Fonteneau, A. url  doi
openurl 
  Titre Spatial management of Indian Ocean tropical tuna fisheries: potential and perspectives Type Article scientifique
  Année 2014 Publication (down) Revue Abrégée Ices Journal of Marine Science  
  Volume 71 Numéro 7 Pages 1728-1749  
  Mots-Clés Bycatch; conservation; Indian Ocean; Marine protected areas (MPAs); pelagic; spatial management of fisheries; tropical tuna fisheries  
  Résumé Effective use of spatial management in the pelagic realm presents special challenges due to high fish and fisher mobility, limited knowledge and significant governance challenges. The tropical Indian Ocean provides an ideal case study for testing our ability to apply existing data sources to assessing impacts of spatial management on tuna fisheries because of several recent controversial spatial closures. We review the scientific underpinnings of pelagic MPA effects, spatio-temporal patterns of Indian Ocean tuna catch, by catch and fish movements, and the consequences of these for the efficacy of spatial management for Indian Ocean tropical tuna fisheries. The tropical Indian Ocean is characterized by strong environmental fluctuations, regular seasonal variability in catch, large observed tuna displacement distances, relatively uniform catch-per-unit-effort and bycatch rates over space, and high fisher mobility, all of which suggest significant variability and movement in tropical tuna fisheries that are simply not well adapted to static spatial closures. One possible exception to this overall conclusion would be a large time/area closure east of Somalia. If closed for a significant fraction of the year it could reduce purse-seine bycatch and juvenile tuna catch. Dynamic closures following fish migratory patterns are possible, but more focused information on fish movements will be needed for effective implementation. Fortunately, several recent improvements in conventional fishery management and reporting will likely enhance our ability to evaluate spatial and non-spatial management options in the near future, particularly as pertaining to bycatch species.  
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  Éditeur de collection Titre de collection Titre de collection Abrégé  
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  ISSN 1054-3139 ISBN Médium  
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  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1199  
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