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Auteur Escalle, L.; Murua, H.; Amande, J.M.; Arregui, I.; Chavance, P.; Delgado de Molina, A.; Gaertner, D.; Fraile, I.; Filmalter, J.D.; Santiago, J.; Forget, F.; Arrizabalaga, H.; Dagorn, L.; Mérigot, B. url  doi
openurl 
  Titre Post-capture survival of whale sharks encircled in tuna purse-seine nets: tagging and safe release methods Type Article scientifique
  Année 2016 Publication Revue Abrégée Aquatic Conserv: Mar. Freshw. Ecosyst.  
  Volume 25 Numéro 4 Pages 433-447  
  Mots-Clés mega fauna; post-release mortality; Psat; Rhincodon typus; tropical tuna purse-seine  
  Résumé 1. Whale shark, the world's largest fish, is believed to be particularly vulnerable owing to its biological characteristics (slow growth, late maturation, great longevity) and is listed as Vulnerable by IUCN and included in Appendix II of CITES. 2. Whale sharks are occasionally encircled in tropical tuna purse-seine nets, throughout this global fishery. Although apparent immediate survival rates following encirclement and release have recently been assessed through scientific onboard observer programmes, a more rigorous methodology is still required for studying post-released survival. 3. This work provides a method for applying pop-up satellite tags and reports an enhanced release procedure for whale sharks. The first assessment of survival after release from purse-seine nets involved six whale sharks tagged between May and September 2014 in the eastern tropical Atlantic Ocean. Five tags transmitted data: three popped up as programmed (after 30 days), while two surfaced prematurely (one after 21 and the other after 71 days (programmed to pop off after 30 and 90 days, respectively)) but showed no sign of unusual behaviour. 4. Overall, whale sharks survived at least 21 days (one at least 71 days) after release from purse-seine nets. These observations based on five large individuals (total length > 8 m), suggest that whale sharks have a good chance of survival when released with the proposed method. 5. Additional tagging in this and other oceans, especially of juveniles which may be more sensitive to encirclement and release operations, is essential to further assess whale shark post-release survival rates in tuna purse-seine fisheries. Copyright © 2016 John Wiley & Sons, Ltd.  
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  Volume de collection Numéro de collection Edition  
  ISSN 1099-0755 ISBN Médium  
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  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1547  
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Auteur Mariani, P.; Křivan, V.; MacKenzie, B.R.; Mullon, C. url  doi
openurl 
  Titre The migration game in habitat network: the case of tuna Type Article scientifique
  Année 2016 Publication Revue Abrégée Theor Ecol  
  Volume 9 Numéro 2 Pages 219-232  
  Mots-Clés Bluefin tuna; Game theory; Habitat selection; Ideal free distribution; Plant Sciences; Structured population; Theoretical Ecology/Statistics; Zoology  
  Résumé Long-distance migration is a widespread process evolved independently in several animal groups in terrestrial and marine ecosystems. Many factors contribute to the migration process and of primary importance are intra-specific competition and seasonality in the resource distribution. Adaptive migration in direction of increasing fitness should lead to the ideal free distribution (IFD) which is the evolutionary stable strategy of the habitat selection game. We introduce a migration game which focuses on migrating dynamics leading to the IFD for age-structured populations and in time varying habitats, where dispersal is costly. The model predicts migration dynamics between these habitats and the corresponding population distribution. When applied to Atlantic bluefin tunas, it predicts their migration routes and their seasonal distribution. The largest biomass is located in the spawning areas which have also the largest diversity in the age-structure. Distant feeding areas are occupied on a seasonal base and often by larger individuals, in agreement with empirical observations. Moreover, we show that only a selected number of migratory routes emerge as those effectively used by tunas.  
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  ISSN 1874-1738, 1874-1746 ISBN Médium  
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  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1465  
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Auteur Nikolic, N.; Morandeau, G.; Hoarau, L.; West, W.; Arrizabalaga, H.; Hoyle, S.; Nicol, S.J.; Bourjea, J.; Puech, A.; Farley, J.H.; Williams, A.J.; Fonteneau, A. url  doi
openurl 
  Titre Review of albacore tuna, Thunnus alalunga, biology, fisheries and management Type Article scientifique
  Année 2016 Publication Revue Abrégée Rev Fish Biol Fisheries  
  Volume Numéro Pages 1-36  
  Mots-Clés Albacore; Tuna; Thunnus alalunga; Biology; Fishery  
  Résumé Albacore is one of the most important commercially harvested species in the world’s oceans. Despite a long history of scientific research, there is no global review or synthesis of knowledge about the species across all oceanic regions. We analysed 613 published studies that report on albacore and summarize the current state of knowledge on biology, stock structure, fisheries and management. To describe the trends in albacore fisheries, we examined the catch and effort databases of Regional Fisheries Management Organisations. The stocks of albacore are generally largest in the Pacific Ocean and smallest in the Mediterranean Sea. The biology of Atlantic and Pacific Ocean stocks are well documented, while the Indian Ocean and the Mediterranean Sea stocks are more data deficient. These two latter areas should be considered as priorities for future research and data collection in order to better understand the state of global stocks of albacore tuna. Improved information would also assist with delineating stock boundaries needed for sustainable management of this species.  
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  ISSN 0960-3166, 1573-5184 ISBN Médium  
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  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1707  
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Auteur Young, J.W.; Olson, R.J.; Ménard, F.; Kuhnert, P.M.; Duffy, L.M.; Allain, V.; Logan, J.M.; Lorrain, A.; Somes, C.J.; Graham, B.; Goñi, N.; Pethybridge, H.; Simier, M.; Potier, M.; Romanov, E.; Pagendam, D.; Hannides, C.; Choy, C.A. url  doi
openurl 
  Titre Setting the stage for a global-scale trophic analysis of marine top predators: a multi-workshop review Type Article scientifique
  Année 2015 Publication Revue Abrégée Rev Fish Biol Fisheries  
  Volume 25 Numéro 1 Pages 261-272  
  Mots-Clés climate change; Freshwater & Marine Ecology; Global diet data; Global nitrogen model; Global stable isotope data; Predictive analyses; top predators; Tuna trophic ecology; Zoology  
  Résumé Global-scale studies of marine food webs are rare, despite their necessity for examining and understanding ecosystem level effects of climate variability. Here we review the progress of an international collaboration that compiled regional diet datasets of multiple top predator fishes from the Indian, Pacific and Atlantic Oceans and developed new statistical methods that can be used to obtain a comprehensive ocean-scale understanding of food webs and climate impacts on marine top predators. We loosely define top predators not as species at the apex of the food web, but rather a guild of large predators near the top of the food web. Specifically, we present a framework for world-wide compilation and analysis of global stomach-contents and stable-isotope data of tunas and other large pelagic predatory fishes. To illustrate the utility of the statistical methods, we show an example using yellowfin tuna in a “test” area in the Pacific Ocean. Stomach-contents data were analyzed using a modified (bagged) classification tree approach, which is being prepared as an R statistical software package. Bulk δ15N values of yellowfin tuna muscle tissue were examined using a Generalized Additive Model, after adjusting for spatial differences in the δ15N values of the baseline primary producers predicted by a global coupled ocean circulation-biogeochemical-isotope model. Both techniques in tandem demonstrated the capacity of this approach to elucidate spatial patterns of variations in both forage species and predator trophic positions and have the potential to predict responses to climate change. We believe this methodology could be extended to all marine top predators. Our results emphasize the necessity for quantitative investigations of global-scale datasets when evaluating changes to the food webs underpinning top ocean predators under long-term climatic variability.  
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  ISSN 0960-3166, 1573-5184 ISBN Médium  
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  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1263  
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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 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  
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  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1706  
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