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Auteur DRUON, J.-N.; FROMENTIN, J.-M.; AULANIER, F.; HEIKKONEN, J.
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.
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Editeur Inter-research Lieu de Publication Éditeur (up)
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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 Nikolic, N.; Jérôme, M.; Fonteneau, A.; Evano, H.; Verrez-Bagnis, V.
Titre Identification of skipjack tuna juveniles based on DNA control region sequences and potential spawning area around reunion island Type Article scientifique
Année 2016 Publication Revue Abrégée Environmental Biology of Fishes
Volume 99 Numéro 2 Pages 171-178
Mots-Clés Age; dna; juvenile; Reunion island; skipjack tuna
Résumé In this study, we confirmed that DNA control region can be used to identify potential spawning area from pelagic juveniles species. We used the mitochondrial DNA control region to identify tuna juveniles predated by common dolphinfish and sampled in surface waters around Reunion Island. These were skipjack juveniles at an early stage (small length and young age). The biological results confirmed the species identification based on DNA analysis. Catch data by longline reveal a higher number of skipjack from October to December around Reunion Island corresponding to the period of our skipjack juvenile sampling
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Langue Langue du Résumé Titre Original
Éditeur de collection Titre de collection Titre de collection Abrégé
Volume de collection Numéro de collection Edition
ISSN 0378-1909 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1518
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Auteur Robert, M.; Dagorn, L.; Lopez, J.; Moreno, G.; Deneubourg, J.L.
Titre Does social behavior influence the dynamics of aggregations formed by tropical tunas around floating objects ? An experimental approach Type Article scientifique
Année 2013 Publication Revue Abrégée Journal of Experimental Marine Biology and Ecology
Volume 440 Numéro Pages 238-243
Mots-Clés Aggregation; Binary choice; FADs; Social behavior; tuna
Résumé Tropical tunas associate with objects floating at the surface of the ocean, a behavior widely exploited by fishers. However, the respective roles played by environmental variables and behavioral processes (e.g., social behavior) in the formation of these aggregations remain elusive. To investigate the role of social behavior in the dynamics of such aggregations, we used the binary choice approach. The experimental design comprised two close and identical anchored fish aggregating devices (FADS) equipped with an echo sounder buoy to monitor the aggregated biomass of tuna under each device. Analysis of the results entailed characterizing whether the aggregated biomass is distributed asymmetrically (indicative of social behavior playing a role in the dynamics) or symmetrically between the two close and identical FADs, and comparing the results with theoretical distributions based on different definitions of basic units (individual fish or small schools). The results suggest that social interactions underlie aggregation processes, which represents a major advance in our understanding of these aggregations, a priority for science-based fishery management. While recognizing the logistical and technical constraints, we encourage the development of experimental studies (e.g., in which animals are presented with controlled situations) to enhance our understanding of the behavior of large pelagic fish.
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ISSN 0022-0981 ISBN Médium
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Numéro d'Appel LL @ pixluser @ collection 249
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Auteur Poisson, F.; Abascal Crespo, F.; Ellis, J.R.; Chavance, P.; Pascal, B.; Santos, M.N.; Seret, B.; Korta, M.; Coelho, R.; Ariz, J.; Murua, H.
Titre Technical mitigation measures for sharks and rays in fisheries for tuna and tuna-like species: turning possibility into reality Type Article scientifique
Année 2016 Publication Revue Abrégée Aquat. Living Resour.
Volume 29 Numéro 4 Pages 402
Mots-Clés at-vessel mortality; Bycatch; california recreational fishery; circle hooks; eastern pacific-ocean; Elasmobranch; great-barrier-reef; j-hook performance; Mitigation; mortality; pelagic; pelagic longline fishery; postrelease survival; Purse seine fishery; rare-earth-metal; tuna regional fishery management organizations
Résumé Tuna fisheries have been identified as one of the major threats to populations of other marine vertebrates, including sea turtles, sharks, seabirds and marine mammals. The development of technical mitigation measures (MM) in fisheries is part of the code of conduct for responsible fisheries. An in-depth analysis of the available literature regarding bycatch mitigation in tuna fisheries with special reference to elasmobranchs was undertaken. Studies highlighting promising MMs were reviewed for four tuna fisheries (longline, purse seine, driftnets and gillnet, and rod and line – including recreational fisheries). The advantages and disadvantages of different MMs are discussed and assessed based on current scientific knowledge. Current management measures for sharks and rays in tuna Regional Fishery Management Organizations (t-RFMOs) are presented. A review of relevant studies examining at-vessel and postrelease mortality of elasmobranch bycatch is provided. This review aims to help fisheries managers identify pragmatic solutions to reduce mortality on pelagic elasmobranchs (and other higher vertebrates) whilst minimizing impacts on catches of target tuna species. Recent research efforts have identified several effective MMs that, if endorsed by t-RFMOs, could reduce elasmobranchs mortality rate in international tropical purse seine tuna fisheries. In the case of longline fisheries, the number of operational effective MMs is very limited. Fisheries deploying driftnets in pelagic ecosystems are suspected to have a high elasmobranchs bycatch and their discard survival is uncertain, but no effective MMs have been field validated for these fisheries. The precautionary bans of such gear by the EU and by some t-RFMOs seem therefore appropriate. Recreational tuna fisheries should be accompanied by science-based support to reduce potential negative impacts on shark populations. Priorities for research and management are identified and discussed.
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Langue English Langue du Résumé Titre Original
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Volume de collection Numéro de collection Edition
ISSN 0990-7440 ISBN Médium
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Numéro d'Appel MARBEC @ alain.herve @ collection 2056
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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.
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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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 1099-0755 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1547
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