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Auteur Díez, G.; Moreno, G.; Galaz, T.; Dagorn, L.; Murua, J. url  doi
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  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 (down) 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  
  Éditeur de collection Titre de collection Titre de collection Abrégé  
  Volume de collection Numéro de collection Edition  
  ISSN 1095-8649 ISBN Médium  
  Région Expédition Conférence  
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  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2145  
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Auteur Grande, M.; Murua, H.; Zudaire, I.; Arsenault-Pernet, E.J.; Pernet, F.; Bodin, N. doi  openurl
  Titre Energy allocation strategy of skipjack tuna Katsuwonus pelamis during their reproductive cycle Type Article scientifique
  Année 2016 Publication Revue Abrégée J. Fish Biol.  
  Volume (down) 89 Numéro 5 Pages 2434-2448  
  Mots-Clés bonito euthynnus-pelamis; cod gadus-morhua; fatty-acid-composition; highly migratory fish; Income breeder; Indian Ocean; lipid classes; oocyte growth; reproduction; sarda-sarda; teleost fish; thunnus-albacares; Tropical tuna; western indian-ocean  
  Résumé The lipid composition of somatic and reproductive tissues was determined for female skipjack tuna Katsuwonus pelamis caught in the western Indian Ocean between latitude 10 degrees N and 20 degrees S and longitude 40 degrees and 70 degrees E. The highest total lipid (TL) contents were in the liver and gonads, with white muscle levels approximately three-fold lower. Three lipid classes dominated: triacylglycerols (TAG), sterol esters and wax esters (SE-WE) and phospholipids (PL). Collectively, these accounted for between 70 and 80% of TLs. Changes in lipid concentrations were evaluated over the maturation cycle. Immature fish had the lowest gonad and liver TL levels; concentrations of TL, TAG, SE-WE and PL accumulated from immature to mature (spawning-capable) phase, reflecting sustained vitellogenic activity of the liver and a transfer of lipids to developing oocytes from the onset of vitellogenesis. Gonado-somatic and hepato-somatic indices were positively correlated with each other and positively related to TL in the gonads and liver. Fulton's condition index and lipid concentrations in muscle did not vary significantly over the maturation cycle; fat content in the main storage tissues was undepleted as the ovary developed. Hence, K. pelamis apparently supports reproduction directly from food intake over the breeding season. In the gonads, reserve lipids (SE-WE and TAG) and sterols were related to batch fecundity but this was not the case for somatic and hepatic tissues. These results suggest that K. pelamis utilizes an income breeding strategy.  
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  Volume de collection Numéro de collection Edition  
  ISSN 0022-1112 ISBN Médium  
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  Numéro d'Appel MARBEC @ alain.herve @ collection 1685  
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Auteur Sardenne, F.; Diaha, N.'G.C.; Amande, M.J.; Zudaire, I.; Couturier, L.I.E.; Metral, L.; Le Grand, F.; Bodin, N. doi  openurl
  Titre Seasonal habitat and length influence on the trophic niche of co-occurring tropical tunas in the eastern Atlantic Ocean Type Article scientifique
  Année 2019 Publication Revue Abrégée Can. J. Fish. Aquat. Sci.  
  Volume (down) 76 Numéro 1 Pages 69-80  
  Mots-Clés lipids; top predators; pacific-ocean; thunnus-albacares; stable-isotope analyses; western; vertical movements; bigeye tuna; vinciguerria-nimbaria; yellowfin tuna  
  Résumé In the Gulf of Guinea, bigeye tuna (Thunnus obesus; BET) and yellowfin tuna (Thunnus albacares; YFT) are an important part of commercial fisheries and play a prominent ecological role as top predators. Using fatty acid profiles and carbon and nitrogen stable isotopes, we examined their trophic niche partitioning in this understudied region. Trophic niche overlap was high (> 70%), similar to percentages in other ocean basins. BET occupied a higher trophic position than YFT and fed on deeper prey (high delta N-15 values and high proportions of monounsaturated fatty acids). The trophic position of YFT decreased slightly in the last 15 years (delta N-15 values decreased by similar to 0.5 parts per thousand), suggesting a change in epipelagic communities, as observed in the eastern Pacific Ocean. Ontogenic changes were limited to BET. For both species, the dietary proportion of the diatom marker 20:5(n-3) increased in the seasonal upwelling area, highlighting the influence of seasonal habitat on the diet of tuna. The relatively lipid-rich muscle (similar to 6% dry mass) of Atlantic tropical tuna suggests a richer diet in this region than that of Indian Ocean tropical tuna and (or) differences in energy allocation strategies.  
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  Langue English Langue du Résumé Titre Original  
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  Volume de collection Numéro de collection Edition  
  ISSN 0706-652x ISBN Médium  
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  Numéro d'Appel MARBEC @ alain.herve @ collection 2483  
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Auteur Escalle, L.; Gaertner, D.; Chavance, P.; Delgado de Molina, A.; Ariz, J.; Mérigot, B. doi  openurl
  Titre Forecasted consequences of simulated FAD moratoria in the Atlantic and Indian Oceans on catches and bycatches Type Article scientifique
  Année 2017 Publication Revue Abrégée ICES J. Mar. Sci.  
  Volume (down) 74 Numéro 3 Pages 780-792  
  Mots-Clés area; Bycatch; ecosystem approach to fisheries; fish aggregation device; management; Megafauna; Monte Carlo simulations; Purse-seine fishery; time; time-area restriction; tropical tuna purse-seine fishery; Tuna  
  Résumé Given the increasingly extensive use of drifting fish aggregation devices (FADs) by the purse-seine fisheries targeting tropical tunas, fishing effort restrictions have been introduced to manage tropical tuna stocks. However, these measures are focused on the protection of juvenile tunas and do not take account of the potential impact on bycatch or associated megafauna (whales and whale sharks). An iterative “fishing-day” Monte Carlo simulation model was developed to investigate the consequences on tropical tunas and bycatch of introducing extensive area 6-month moratoria on FAD activities. The model allowed for variability in a range of plausible values of the parameters characterizing the fishing operations conducted by European purse-seiners in the eastern tropical Atlantic and western Indian Oceans for the period 2005-2014. Monte Carlo simulations, using probabilities based on these fishery data, were carried out for the French and Spanish fishing fleets separately to account for differences in fishing strategies. The models predicted a decrease in FAD sets and an increase in free school sets. As a consequence, the catch of small tuna (<10 kg) decreased while the catch of large tuna (>= 10 kg) increased, leading to an overall increase in tuna catch of 100-200 tons/year/vessel in the Atlantic Ocean, and a decrease of 400-1500 tons/year/vessel in the Indian Ocean. The bycatch decreased in the Indian Ocean, while in the Atlantic Ocean billfishes, turtles and chondrichthyans bycatch increased slightly and other bony fishes decreased. Because fishing practices were modified, whale and whale shark associated sets increased slightly in the Indian Ocean.  
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  Langue English Langue du Résumé Titre Original  
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  Volume de collection Numéro de collection Edition  
  ISSN 1054-3139 ISBN Médium  
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  Numéro d'Appel MARBEC @ alain.herve @ collection 2105  
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Auteur Van Beveren, E.; Fromentin, J.-M.; Bonhommeau, S.; Nieblas, A.-E.; Metral, L.; Brisset, B.; Jusup, M.; Bauer, R.K.; Brosset, P.; Saraux, C. doi  openurl
  Titre Predator-prey interactions in the face of management regulations: changes in Mediterranean small pelagic species are not due to increased tuna predation Type Article scientifique
  Année 2017 Publication Revue Abrégée Can. J. Fish. Aquat. Sci.  
  Volume (down) 74 Numéro 9 Pages 1422-1430  
  Mots-Clés anchovy engraulis-encrasicolus; atlantic bluefin tuna; Energy density; fish condition; fisheries; food-consumption; Proximate composition; sea; thunnus-thynnus; Yellowfin tuna  
  Résumé Recently, the abundance of young Atlantic bluefin tuna (Thunnus thynnus) tripled in the northwestern Mediterranean following effective management measures. We investigated whether its predation on sardine (Sardina pilchardus) and anchovy (Engraulis encrasicolus) could explain their concurrent size and biomass decline, which caused a fishery crisis. Combining the observed diet composition of bluefin tuna, their modelled daily energy requirements, their population size, and the abundance of prey species in the area, we calculated the proportion of the prey populations that were consumed by bluefin tuna annually over 2011-2013. To assess whether tuna could alter the size structure of the three small pelagic fish populations (anchovy, sardine, and sprat (Sprattus sprattus)), the size distributions of the consumed prey species were compared with those of the wild populations. We estimated that the annual consumption of small pelagic fish by bluefin tuna is less than 2% of the abundance of these populations. Furthermore, size selectivity patterns were not observed. We thus concluded that tuna predation is unlikely to be the main cause of major changes in the small pelagic fish populations from this area.  
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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 0706-652x ISBN Médium  
  Région Expédition Conférence  
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  Numéro d'Appel MARBEC @ alain.herve @ collection 2195  
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