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Auteur |
Zhou, C.; He, P.; Xu, L.; Bach, P.; Wang, X.; Wan, R.; Tang, H.; Zhang, Y. |
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Titre |
The effects of mesoscale oceanographic structures and ambient conditions on the catch of albacore tuna in the South Pacific longline fishery |
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Article scientifique |
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Année  |
2020 |
Publication |
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Revue Abrégée |
Fisheries Oceanography |
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Numéro |
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Mots-Clés |
albacore tuna; environmental conditions; hook depth; longline; ocean eddy; ocean fronts; South Pacific Ocean |
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Résumé |
Albacore tuna (Thunnus alalunga) exhibit patchy concentrations associated with biological process at a wide range of spatial scales, resulting in variations in their catchability by fishing gears. Here, we investigated the association of catch variation for pelagic longlines in the South Pacific Ocean with oceanographic mesoscale structures (in horizontal dimension) and ambient conditions (in vertical dimension). The distribution of albacore tuna as indicated by catch per unit effort (CPUE) of longlines was significantly related to the presence of mesoscale structures, with higher CPUE found at locations closer to thermal fronts and with greater gradient magnitudes, as well as areas marked by peripheral contour line of the anticyclone indicated by Sea Surface Height Anomalies 0.05 m. Surface mesoscale current velocity had the negative effect on the catch, probably as a result of decreased catchability by shoaling the hook depth. Vertical distribution of albacore in the survey region of South Pacific Ocean was hardly restricted by ambient temperature and oxygen concentration, though effect of ambient temperature was relevant and showed a negatively linear correlation with CPUE at the range of 20–24°C. On the contrary, albacore distribution was evidently dominated by the water depth and showed strong preference on water depth of 200 m, which was likely a representative feeding layer. The presence of prey resources and their accessibility by albacore revealed by mesoscale structures in the biological and physical processes, and catchability determined by the location of the baited hooks comprehensively contribute to the variability of catch. |
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en |
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ISSN |
1365-2419 |
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MARBEC @ isabelle.vidal-ayouba @ |
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2732 |
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Auteur |
Rouyer, T.; Bonhommeau, S.; Giordano, N.; Giordano, F.; Ellul, S.; Ellul, G.; Deguara, S.; Wendling, B.; Bernard, S.; Kerzerho, V. |
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Titre |
Tagging Atlantic bluefin tuna from a Mediterranean spawning ground using a purse seiner |
Type |
Article scientifique |
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Année |
2020 |
Publication |
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Revue Abrégée |
Fish Res. |
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Volume |
226 |
Numéro |
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Pages |
105522 |
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Mots-Clés |
Eastern Atlantic and Mediterranean stock; Electronic tagging; Large Atlantic bluefin tuna; migration; Migrations; movements; population-structure; Purse seine; thermal biology; thunnus-thynnus |
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Résumé |
Atlantic bluefin tuna, Thunnus thynnus, is as an emblematic and commercially valuable large pelagic species. In the past ten years, the purse seine fishery in the Mediterranean represents more than 50 % of the catch. Nowadays, purse seines target large fish and operate during the spawning season in the spawning grounds. Electronic tagging has shed a considerable amount of light on the ecology and behaviour of bluefin tuna over the past twenty years. However, such technique has rarely been applied on large bluefin tunas caught by the Mediterranean purse seine fishery despite its major importance. The logistical constraints related to this specific fishery, combined with the timing of migration of the fish and the requirements related to the handling of big fish have made adequate tagging from purse seines complex. Here we detail such an operation, designed to bridge the knowledge gap on the migratory behaviour of tunas targeted by the purse seine fishery. Three large bluefin tunas from the same school were tagged during the fishing operation of a French purse seine, resulting in a different migration pattern than previous deployments. The fish were tagged onboard in less than 2 min and efficiently, avoiding any subsequent mortality. These results contrast with those from tagging operations carried out in the Northwest Mediterranean, which underlies the importance of tagging operations from purse seines to obtain unbiased description of the movements of the eastern Atlantic bluefin tuna stock in the context of its management. |
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English |
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ISSN |
0165-7836 |
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WOS:000525305200010 |
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Numéro d'Appel |
MARBEC @ isabelle.vidal-ayouba @ |
collection |
2771 |
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Auteur |
Travassos Tolotti, M.; Forget, F.; Capello, M.; Filmalter, J.D.; Hutchinson, M.; Itano, D.; Holland, K.; Dagorn, L. |
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Titre |
Association dynamics of tuna and purse seine bycatch species with drifting fish aggregating devices (FADs) in the tropical eastern Atlantic Ocean |
Type |
Article scientifique |
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Année |
2020 |
Publication |
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Revue Abrégée |
Fish Res. |
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Volume |
226 |
Numéro |
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Pages |
105521 |
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Mots-Clés |
Acoustic telemetry; behavior; Behavior; carcharhinus-falciformis; floating objects; Floating objects; obesus; pacific-ocean; patterns; Pelagic fish; Residence time; silky sharks; skipjack katsuwonus-pelamis; Tropical tuna; vertical movements; yellowfin thunnus-albacares |
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Résumé |
Several pelagic fish species are known to regularly associate with floating objects in the open ocean, including commercially valuable species. The tuna purse seine industry takes advantage of this associative behavior and has been increasingly deploying free-drifting man-made floating objects, also known as fish aggregating devices (FADs). Using passive acoustic telemetry, this study describes the associative dynamics of the main targeted tropical tuna species (Thunnus albacores, T. obelus and Katsuwonus pelamis), as well as three major bycatch species, silky shark (Carcharhinus falciformis), rainbow runner (Elagatis bipinmdata) and oceanic triggerfish (Canthidermis maculata). Short-term excursions away from the FADs were frequently performed by all tuna species as well by silky sharks. These excursions were characterized by a marked diel pattern, mainly occurring during nighttime. Rainbow runners and oceanic triggerfish were much more present at the FADs and rarely performed excursions. Average continuous residence times (CRTs) ranged from 6 days, for silky shark, up to 25 days for bigeye tuna. Similar to silky shark, average CRTs for skipjack tuna and oceanic triggerfish were less than 10 days. For yellowfin tuna and rainbow runner, CRTs averaged 19 and 16 days, respectively. Bigeye and yellowfin tuna remained associated to a single drifting FAD for a record of 55 days and 607 km traveled. |
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English |
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ISSN |
0165-7836 |
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Notes |
WOS:000525305200009 |
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pas de |
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Numéro d'Appel |
MARBEC @ isabelle.vidal-ayouba @ |
collection |
2772 |
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Auteur |
Escalle, L.; Gaertner, D.; Chavance, P.; Murua, H.; Simier, M.; Jose Pascual-Alayon, P.; Menard, F.; Ruiz, J.; Abascal, F.; Mérigot, B. |
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Titre |
Catch and bycatch captured by tropical tuna purse-seine fishery in whale and whale shark associated sets: comparison with free school and FAD sets |
Type |
Article scientifique |
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Année |
2019 |
Publication |
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Revue Abrégée |
Biodivers. Conserv. |
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Volume |
28 |
Numéro |
2 |
Pages |
467-499 |
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Mots-Clés |
diversity; mortality; atlantic; biology; Bycatch; strategies; Megafauna; behavior; dominance; yellowfin; Catch composition; Diversity; Ecosystem approach to fisheries management; swimming speeds; Tuna purse-seine fishery |
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Résumé |
In an ecosystem approach to fisheries management (EAFM) framework of the tuna purse-seine fishery, the assessment of target species, but also that of bycatch species, is essential. In the Atlantic and Indian oceans, purse-seine nets are sometimes set around tuna schools associated with whale sharks and baleen whales, although less frequently than around free-swimming tuna schools or those associated with fish aggregating devices (FAD). However, knowledge on the targeted catch and bycatch in these megafauna associated fishing sets is still relatively limited. Therefore, the aims of this study were to assess species and size composition of the target tuna species, as well as the diversity of bycatch species in whale and whale shark associated sets. Whale associated sets were found to be very similar to free school sets in terms of tuna catch (large yellowfin tuna), bycatch occurrence (presence in half the sets) and species assemblage (alpha and beta diversity). Whale shark associated sets were intermediate between FAD and free school sets, with tuna catch (skipjack and juvenile yellowfin) closer to FAD than to free school sets. However, the presence of large yellowfin, the bycatch composition (with almost no finfish, abundantly captured in FAD sets) and the species assemblage showed similarity with free school sets. This study highlights the need for an EAFM in the tuna purse-seine fishery by providing knowledge on pelagic multi-specific catches and bycatches. |
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English |
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ISSN |
0960-3115 |
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Numéro d'Appel |
MARBEC @ alain.herve @ |
collection |
2482 |
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| Lien permanent pour cet enregistrement |
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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. |
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Titre |
Seasonal habitat and length influence on the trophic niche of co-occurring tropical tunas in the eastern Atlantic Ocean |
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Article scientifique |
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Année |
2019 |
Publication |
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Revue Abrégée |
Can. J. Fish. Aquat. Sci. |
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Volume |
76 |
Numéro |
1 |
Pages |
69-80 |
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Mots-Clés |
lipids; top predators; pacific-ocean; thunnus-albacares; stable-isotope analyses; western; vertical movements; bigeye tuna; vinciguerria-nimbaria; yellowfin tuna |
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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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English |
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ISSN |
0706-652x |
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Numéro d'Appel |
MARBEC @ alain.herve @ |
collection |
2483 |
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| Lien permanent pour cet enregistrement |
