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Auteur Zudaire, I.; Murua, H.; Grande, M.; Pernet, F.; Bodin, N.
Titre Accumulation and mobilization of lipids in relation to reproduction of yellowfin tuna (Thunnus albacares) in the Western Indian Ocean Type Article scientifique
Année 2014 Publication Revue Abrégée Fisheries Research
Volume Numéro Pages 50-59
Mots-Clés FADs; Fecundity; Income-capital breeder; Lipid class composition; Reproductive allocation strategy; Tropical tuna
Résumé Total lipid content and lipid class composition were analyzed in gonads, liver and white muscle of yellowfin tuna (Thunnus albacares) throughout ovary development to understand its reproductive allocation strategy and to assess the relation between female condition and reproduction. A total of 112 females were collected onboard purse-seiner in the Western Indian Ocean from January to March 2009, from June to July 2009, and from April to May 2010. Gonads were characterized by highly variable total lipid contents ranging from 5 to 27 μg mg−1 of wet weight (ww) with a predominance of neutral lipids, mainly triacylglycerols (TAG) and sterol- and wax-esters. The different lipid classes in gonads described an accumulative pattern through the maturity process from immature to hydration phase. Total lipid content in liver varied from 10 to 21 μg mg−1 ww, and serves as fuel for yellowfin tuna reproduction. TAG and phospholipid deposits became depleted as the ovary developed, suggesting a transfer of lipids directly from liver to the oocytes during vitellogenesis. In contrast, muscle total lipid content was low and constant throughout ovarian development (2.5–6 μg mg−1 ww). Hence, yellowfin tuna can be defined as an income-capital breeder species for which the cost of reproduction depends mainly on concurrent energy income from feeding and only little on stored lipids. Besides, no significant relationship between gonad lipid composition and fecundity was found in females able to spawn. Finally, the influence of yellowfin tuna aggregation behaviour on reproductive female condition has been investigated: gonad total lipid contents were higher in females caught in free-swimming schools than in females caught under fish aggregating devices (FADs). However, these results did not clarify whether the influence of FADs on associated yellowfin tuna affects their reproductive capacity.
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Auteur institutionnel Thèse
Editeur Lieu de Publication Éditeur
Langue Langue du Résumé Titre Original
Éditeur de collection Titre de collection Advances in Fisheries Research in Ibero-America Titre de collection Abrégé
Volume de collection (down) 160 Numéro de collection Edition
ISSN 0165-7836 ISBN Médium
Région Expédition Conférence
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1209
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Auteur Merino, G.; Barange, M.; Fernandes, J.A.; Mullon, C.; Cheung, W.; Trenkel, V.; Lam, V.
Titre Estimating the economic loss of recent North Atlantic fisheries management Type Article scientifique
Année 2014 Publication Revue Abrégée Progress in Oceanography
Volume Numéro Pages 314-323
Mots-Clés
Résumé It is accepted that world’s fisheries are not generally exploited at their biological or their economic optimum. Most fisheries assessments focus on the biological capacity of fish stocks to respond to harvesting and few have attempted to estimate the economic efficiency at which ecosystems are exploited. The latter is important as fisheries contribute considerably to the economic development of many coastal communities. Here we estimate the overall potential economic rent for the fishing industry in the North Atlantic to be B€ 12.85, compared to current estimated profits of B€ 0.63. The difference between the potential and the net profits obtained from North Atlantic fisheries is therefore B€ 12.22. In order to increase the profits of North Atlantic fisheries to a maximum, total fish biomass would have to be rebuilt to 108 Mt (2.4 times more than present) by reducing current total fishing effort by 53%. Stochastic simulations were undertaken to estimate the uncertainty associated with the aggregate bioeconomic model that we use and we estimate the economic loss NA fisheries in a range of 2.5 and 32 billion of euro. We provide economic justification for maintaining or restoring fish stocks to above their MSY biomass levels. Our conclusions are consistent with similar global scale studies.
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Auteur institutionnel Thèse
Editeur Lieu de Publication Éditeur
Langue Langue du Résumé Titre Original
Éditeur de collection Titre de collection North Atlantic Ecosystems, the role of climate and anthropogenic forcing on their structure and function Titre de collection Abrégé
Volume de collection (down) 129, Part B Numéro de collection Edition
ISSN 0079-6611 ISBN Médium
Région Expédition Conférence
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1200
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Auteur Sabarros, P.S.; Grémillet, D.; Demarcq, H.; Moseley, C.; Pichegru, L.; Mullers, R.H.E.; Stenseth, N.C.; Machu, E.
Titre Fine-scale recognition and use of mesoscale fronts by foraging Cape gannets in the Benguela upwelling region Type Article scientifique
Année 2014 Publication Revue Abrégée Deep Sea Research Part II: Topical Studies in Oceanography
Volume Numéro Pages 77-84
Mots-Clés Area-restricted search; Behavioral shift; Environmental cue; Feeding activity; Fractal landscape; Morus capensis; Oceanographic fronts; seabird; South Africa; southern Benguela
Résumé Oceanic structures such as mesoscale fronts may become hotspots of biological activity through concentration and enrichment processes. These fronts generally attract fish and may therefore be targeted by marine top-predators. In the southern Benguela upwelling system, such fronts might be used as environmental cues by foraging seabirds. In this study we analyzed high-frequency foraging tracks (GPS, 1 s sampling) of Cape gannets Morus capensis from two colonies located on the west and east coast of South Africa in relation to mesoscale fronts detected on daily high-resolution chlorophyll-a maps (MODIS, 1 km). We tested the association of (i) searching behavior and (ii) diving activity of foraging birds with mesoscale fronts. We found that Cape gannets shift from transiting to area-restricted search mode (ARS) at a distance from fronts ranging between 2 and 11 km (median is 6.7 km). This suggests that Cape gannets may be able to sense fronts (smell or vision) or other predators, and that such detection triggers an intensified investigation of their surroundings (i.e. ARS). Also we found that diving probability increases near fronts in 11 out of 20 tracks investigated (55%), suggesting that Cape gannets substantially use fronts for feeding; in the remaining cases (45%), birds may have used other cues for feeding including fishing vessels, particularly for gannets breeding on the west coast. We demonstrated in this study that oceanographic structures such as mesoscale fronts are important environmental cues used by a foraging seabird within the rich waters of an upwelling system. There is now need for further investigations on how Cape gannets actually detect these fronts.
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Auteur institutionnel Thèse
Editeur Lieu de Publication Éditeur
Langue Langue du Résumé Titre Original
Éditeur de collection Titre de collection Fronts, Fish and Top Predators Titre de collection Abrégé
Volume de collection (down) 107 Numéro de collection Edition
ISSN 0967-0645 ISBN Médium
Région Expédition Conférence
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1204
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Auteur Ternon, J.F.; Roberts, M.J.; Morris, T.; Hancke, L.; Backeberg, B.
Titre In situ measured current structures of the eddy field in the Mozambique Channel Type Article scientifique
Année 2014 Publication Revue Abrégée Deep Sea Research Part II: Topical Studies in Oceanography
Volume Numéro Pages 10-26
Mots-Clés Geostrophic currents; Mesoscale eddies; Mozambique Channel; S-ADCP measurements; Wind driven circulation
Résumé Circulation and the related biological production have been studied during five cruises conducted in the Mozambique Channel (MZC) between 2005 and 2010. The circulation in the MZC is known to be highly turbulent, favouring enhanced primary production as a result of mesoscale eddy dynamics, and connectivity throughout the Channel due to the variable currents associated with migrating eddies. This paper presents the results of in situ measurements that characterize the horizontal and vertical currents in the surface and subsurface layers (0–500 m). The in situ data were analysed together with the geostrophic eddy field observed from satellite altimeter measurements. Different circulation regimes were investigated, including the “classical” anticyclonic eddy generated at the Channel narrows (16°S), the enhancement of southward migrating eddies by merging with structures (both cyclonic and anticyclonic) formed in the east of the Channel, and the presence of a fully developed cyclonic eddy at the Channel narrows. Comparison between in situ measurements (S-ADCP and velocities derived from surface drifters) and the geostrophic current derived from sea surface height measurements indicated that the latter can provide a reliable, quantitative description of eddy driven circulation in the MZC, with the exception that these currents are weaker by as much 30%. It is also suggested from in situ observation (drifters) that the departure from geostrophy of the surface circulation might be linked to strong wind conditions. Finally, our observations highlight that a-geostrophic currents need to be considered in future research to facilitate a more comprehensive description of the circulation in this area.
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Auteur institutionnel Thèse
Editeur Lieu de Publication Éditeur
Langue Langue du Résumé Titre Original
Éditeur de collection Titre de collection The Mozambique Channel: Mesoscale Dynamics and Ecosystem Responses Titre de collection Abrégé
Volume de collection (down) 100 Numéro de collection Edition
ISSN 0967-0645 ISBN Médium
Région Expédition Conférence
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Numéro d'Appel LL @ pixluser @ collection 388
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Auteur Galletti, F.
Titre La protection juridique des réseaux écologiques marins. Compétences et implications du droit de la mer contemporain Type Chapitre de livre
Année 2014 Publication Revue Abrégée
Volume Numéro Pages 765-791
Mots-Clés Droit de l'environnement; Droit international de la mer; Droit public; Etat; Gouvernance; Réseaux écologiques marins
Résumé
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Auteur institutionnel Thèse
Editeur Editoriale Scientifica Lieu de Publication Napoli Éditeur
Langue Fre Langue du Résumé Titre Original
Éditeur de collection Titre de collection Titre de collection Abrégé La contribution de la Convention des Nations Unies sur le Droit de la Mer à la bonne gouvernance des
Volume de collection (down) Vol. 2 Numéro de collection 2 Edition
ISSN ISBN 978-88-6342-638-0 Médium
Région Expédition Conférence
Notes Approuvé pas de
Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1614
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