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Auteur (up) 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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  ISSN 1932-6203 ISBN Médium  
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  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1706  
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Auteur (up) Díez, G.; Moreno, G.; Galaz, T.; Dagorn, L.; Murua, J. url  doi
openurl 
  Titre Digestive activity and stomach temperature in farmed bluefin tuna Thunnus thynnus measured by acoustic tag Type Article scientifique
  Année 2017 Publication Revue Abrégée J Fish Biol  
  Volume 90 Numéro 6 Pages 2504-2511  
  Mots-Clés acoustic; Bluefin tuna; digestion; farm; tag; Temperature  
  Résumé Eight farmed Atlantic bluefin tuna Thunnus thynnus were tagged with temperature and depth transmitters inserted in chub mackerels Scomber colias to characterize their digestive activity, feeding physiology and behaviour in captivity. Results obtained in the experiment can be used to optimize daily T. thynnus feeding strategy in farms, reducing the early regurgitation of food and thus the environmental effects of inappropriate feeding practices.  
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  Langue en Langue du Résumé Titre Original  
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  Volume de collection Numéro de collection Edition  
  ISSN 1095-8649 ISBN Médium  
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  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2145  
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Auteur (up) DRUON, J.-N.; FROMENTIN, J.-M.; AULANIER, F.; HEIKKONEN, J. url  openurl
  Titre Potential feeding and spawning habitats of Atlantic bluefin tuna in the Mediterranean Sea Type Article scientifique
  Année 2011 Publication Marine Ecology-progress Series Revue Abrégée  
  Volume 439 Numéro Pages 223-240  
  Mots-Clés Habitat mapping; Bluefin tuna; Thunnus thynnus; Feeding; Spawning; Mediterranean Sea; Remote sensing; Satellite data  
  Résumé Atlantic bluefin tuna Thunnus thynnus (ABFT) is a fish of high market value which has recently become strongly overexploited, notably in the Mediterranean Sea. This area is an essential habitat for ABFT reproduction and growth. We present here an approach for deriving the daily mapping of potential ABFT feeding and spawning habitats based on satellite-derived sea surface temperature (SST) and chl a concentration. The feeding habitat was mainly derived from the simultaneous occurrence of oceanic fronts of temperature and chl a content while the spawning habitat was mostly inferred from the heating of surface waters. Generally, higher chl a contents were found to be preferred for the feeding habitat and a minimum SST value was found for the spawning habitat. Both habitats were defined by the presence of relevant oceanographic features and are therefore potential and functionally-linked habitats. This approach provides, for the first time, a synoptic view of the potential ABFT habitats in the Mediterranean Sea. The model performs well in areas where both satellite data and ABFT observations are available, as 80% of presence data are in the vicinity of potential habitats. The computed monthly, seasonal and annual maps of potential feeding and spawning habitat of ABFT from 2003 to 2009 are in good agreement with current knowledge on ABFT. Overall, the habitat size of ABFT is about 6% of the Mediterranean Sea surface. The results displayed a strong seasonality in habitat size and locations as well as high year-to-year variations (30 to 60%), particularly for the potential spawning habitat, which is key information for evaluating the utility of ABFT Marine Protected Areas in the Mediterranean Sea.  
  Adresse IFREMER, Ctr Rech Halieut Mediterraneen & Trop, F-34203 Sete, France.  
  Auteur institutionnel Thèse  
  Editeur Inter-research Lieu de Publication Éditeur  
  Langue Langue du Résumé Titre Original  
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  Volume de collection Numéro de collection Edition  
  ISSN 0171-8630 ISBN Médium  
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  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ 16053 collection 1003  
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Auteur (up) Dueri, S.; Bopp, L.; Maury, O. url  doi
openurl 
  Titre Projecting the impacts of climate change on skipjack tuna abundance and spatial distribution Type Article scientifique
  Année 2014 Publication Revue Abrégée Global Change Biology  
  Volume 20 Numéro 3 Pages 742-753  
  Mots-Clés Apecosm-E; Atlantic Ocean; global warming; Indian Ocean; Katsuwonus pelamis; Pacific Ocean; scenario; Tropical tuna  
  Résumé Climate-induced changes in the physical, chemical, and biological environment are expected to increasingly stress marine ecosystems, with important consequences for fisheries exploitation. Here, we use the APECOSM-E numerical model (Apex Predator ECOSystem Model – Estimation) to evaluate the future impacts of climate change on the physiology, spatial distribution, and abundance of skipjack tuna, the worldwide most fished species of tropical tuna. The main novelties of our approach lie in the mechanistic link between environmental factors, metabolic rates, and behavioral responses and in the fully three dimensional representation of habitat and population abundance. Physical and biogeochemical fields used to force the model are provided by the last generation of the IPSL-CM5 Earth System Model run from 1990 to 2100 under a &8216;business-as-usual&8217; scenario (RCP8.5). Our simulations show significant changes in the spatial distribution of skipjack tuna suitable habitat, as well as in their population abundance. The model projects deterioration of skipjack habitat in most tropical waters and an improvement of habitat at higher latitudes. The primary driver of habitat changes is ocean warming, followed by food density changes. Our projections show an increase of global skipjack biomass between 2010 and 2050 followed by a marked decrease between 2050 and 2095. Spawning rates are consistent with population trends, showing that spawning depends primarily on the adult biomass. On the other hand, growth rates display very smooth temporal changes, suggesting that the ability of skipjack to keep high metabolic rates in the changing environment is generally effective. Uncertainties related to our model spatial resolution, to the lack or simplification of key processes and to the climate forcings are discussed.  
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  ISSN 1354-1013 ISBN Médium  
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  Numéro d'Appel LL @ pixluser @ collection 327  
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Auteur (up) Dueri, S.; Guillotreau, P.; Jiménez-Toribio, R.; Oliveros-Ramos, R.; Bopp, L.; Maury, O. url  doi
openurl 
  Titre Food security or economic profitability? Projecting the effects of climate and socioeconomic changes on global skipjack tuna fisheries under three management strategies Type Article scientifique
  Année 2016 Publication Revue Abrégée Global Environmental Change  
  Volume 41 Numéro Pages 1-12  
  Mots-Clés Bioeconomic model; climate change; fishery management; Mey; Msy; Skipjack tuna  
  Résumé We investigate the interactions between anthropogenic climate change, socioeconomic developments and tuna fishery management strategies. For this purpose, we use the APECOSM-E model to map the effects of climate change and commercial fishing on the distribution of skipjack tuna biomass in the three oceans, combined with a new bioeconomic module representing the rent or profit of skipjack fisheries. For forcing, we use Representative Concentration Pathway (RCP) 8.5, the highest emission scenario for greenhouse gas concentrations presented in the IPCC’s Fifth Assessment Report (AR5), and the IPCC Socioeconomic Shared Pathway (SSP) 3, which is characterized by low economic development and a strong increase in the world population. We first investigate the impact of climate change on regional skipjack abundance, catches and profits in three oceans (Atlantic, Indian and Pacific) in 2010, 2050 and 2095. We then study the effects of three management strategies (maximum sustainable yield or MSY, maximum economic yield or MEY, and zero rent or ZR) on the future distribution of fishing fleets between oceans and on global economic rent. Our model projections for 2050 and 2095 show an increase in global skipjack biomass compared to 2010 and major changes in its distribution, impacting local and regional fishing efforts. The Pacific Ocean will continue to dominate the skipjack market. In our modeling of management strategies, the currently predominant MSY strategy would have been unprofitable in 2010, due to a decreased catch per unit effort (CPUE). In the future, however, technological developments should increase fishing efficiency and make MSY profitable. In all the scenarios, a MEY strategy is more profitable than MSY but leads to the lowest catches and the highest prices. This raises ethical questions in a world where food security may become a top priority. In the scenarios where MSY generates an economic loss (e.g. 2010), a ZR strategy allows global stocks to be exploited at high but still profitable levels. Conversely, in the scenarios where MSY is profitable, (e.g. 2095) ZR leads to overfishing and smaller global catches. We conclude that the most appropriate management strategy at any time is likely to change as environmental and socioeconomic conditions evolve. The decision to follow one or other strategy is a complex one that must be regularly reviewed and updated.  
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  ISSN 0959-3780 ISBN Médium  
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  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1601  
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