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Auteur Moreno, G.; Dagorn, L.; Capello, M.; Lopez, J.; Filmalter, T.; Forget, F.; Sancristobal, I.; Holland, K.
Titre Fish aggregating devices (FADs) as scientific platforms Type Article scientifique
Année 2016 Publication Revue Abrégée Fish Res.
Volume 178 Numéro Pages 122-129
Mots-Clés abundance; Acoustic tags; association; behavior; Echo-sounder buoy; fad; Fishing technology; indian-ocean; pacific-ocean; Pelagic ecosystem; pelagic fish; purse-seine fisheries; thunnus-albacares; Tropical tuna; Tuna; western; yellowfin
Résumé Fish aggregating devices (FADs) are floating objects used by fishers to aggregate pelagic fish such as tunas, and enhance the catch of these species. Because this is so important for tuna fisheries, nearly 100,000 FADs are deployed by fishers every year in the world's tropical oceans. Fishers use geo-locating buoys to track and maintain these FADs by visiting them regularly, reinforcing them if they are weak or replacing them. Many of these buoys are now equipped with echo-sounders in order to provide remote information on the aggregated biomass. FADs are currently only used for fishing purposes but they can also serve scientific objectives. In this paper, we investigate the potential of these data for improving our knowledge on the ecology of tunas and other pelagic animals as well as to obtain fishery-independent indices of distribution and abundance. These FADs also represent platforms for scientists to deploy scientific instruments, such as electronic tag receivers, cameras and hydrophones. Because FADs naturally aggregate several pelagic species other than tuna, these instrumented FADs can be a unique opportunity to observe pelagic ecosystem dynamics that are not possible from conventional research vessels. The amount of cost-effective data that they can provide would make a significant contribution to the scientific understanding of pelagic ecosystems. This information is vital for improved conservation and management of pelagic fisheries. (C) 2015 Elsevier B.V. All rights reserved.
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ISSN 0165-7836 ISBN Médium
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Numéro d'Appel MARBEC @ alain.herve @ collection 1650
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Auteur Lefevre, S.; Mckenzie, D.J.; Nilsson, G.E.
Titre Models projecting the fate of fish populations under climate change need to be based on valid physiological mechanisms Type Article scientifique
Année 2017 Publication Revue Abrégée Glob. Change Biol.
Volume 23 Numéro 9 Pages 3449-3459
Mots-Clés aerobic scope; coryphaena-hippurus; energy-demand teleosts; gadus-morhua l; gill surface area; growth; makaira-nigricans; marlin tetrapturus-albidus; metabolism; metabolism-size relationship; oxygen consumption; oxygen-consumption; ram ventilation; Respiration; scaling; swimming performance; tuna katsuwonus-pelamis
Résumé Some recent modelling papers projecting smaller fish sizes and catches in a warmer future are based on erroneous assumptions regarding (i) the scaling of gills with body mass and (ii) the energetic cost of 'maintenance'. Assumption (i) posits that insurmountable geometric constraints prevent respiratory surface areas from growing as fast as body volume. It is argued that these constraints explain allometric scaling of energy metabolism, whereby larger fishes have relatively lower mass-specific metabolic rates. Assumption (ii) concludes that when fishes reach a certain size, basal oxygen demands will not be met, because of assumption (i). We here demonstrate unequivocally, by applying accepted physiological principles with reference to the existing literature, that these assumptions are not valid. Gills are folded surfaces, where the scaling of surface area to volume is not constrained by spherical geometry. The gill surface area can, in fact, increase linearly in proportion to gill volume and body mass. We cite the large body of evidence demonstrating that respiratory surface areas in fishes reflect metabolic needs, not vice versa, which explains the large interspecific variation in scaling of gill surface areas. Finally, we point out that future studies basing their predictions on models should incorporate factors for scaling of metabolic rate and for temperature effects on metabolism, which agree with measured values, and should account for interspecific variation in scaling and temperature effects. It is possible that some fishes will become smaller in the future, but to make reliable predictions the underlying mechanisms need to be identified and sought elsewhere than in geometric constraints on gill surface area. Furthermore, to ensure that useful information is conveyed to the public and policymakers about the possible effects of climate change, it is necessary to improve communication and congruity between fish physiologists and fisheries scientists.
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ISSN 1354-1013 ISBN Médium
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Numéro d'Appel MARBEC @ alain.herve @ collection 2169
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Auteur Nikolic, N.; Lauretta, M.; Patucca, A.; Morandeau, G.
Titre Characterization and standardization of the Atlantic albacore French pelagic trawl fishery Type Article scientifique
Année 2018 Publication Revue Abrégée Aquat. Living Resour.
Volume 31 Numéro Pages 31
Mots-Clés Albacore; Atlantic; behavior; catch; catch rates; fisheries; habitat; migration; north pacific albacore; ocean; stock; thunnus-alalunga; trawl; tuna
Résumé We compiled and analysed logbook data from the French trawl albacore fishery covering the period 1991-2015. The dataset comprised catch and effort data for the French fleet operating in the Bay of Biscay and Celtic Sea, as well as spatiotemporal and gear characteristics. Generalized linear modelling was used to model spatial, seasonal, environmental, and gear covariates of fleet CPUE rates. A long-term index of relative abundance is provided that can be integrated into the stock assessment of North Atlantic albacore. The analysis revealed higher albacore CPUE associated with relatively low sea surface temperature and distinct seasonal effects. The derived abundance trend for the French trawl fishery agreed with the estimated time series of stock abundance from recent assessments.
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ISSN 0990-7440 ISBN Médium
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Numéro d'Appel MARBEC @ alain.herve @ collection 2426
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Auteur Navarro, J.; Saez-Liante, R.; Albo-Puigserver, M.; Coll, M.; Palomera, I.
Titre Feeding strategies and ecological roles of three predatory pelagic fish in the western Mediterranean Sea Type Article scientifique
Année 2017 Publication Revue Abrégée Deep-Sea Res. Part II-Top. Stud. Oceanogr.
Volume 140 Numéro Pages 9-17
Mots-Clés diet; ecosystem structure; iberian peninsula; indian-ocean; isotope ratios; Marine predators; Pelagic ecosystem; Stable isotopes; stable-isotopes; Stomach contents; swordfish; top predators; Trophic ecology; trophic level; xiphias-gladius; Yellowfin tuna
Résumé Knowing the feeding ecology of marine predators is pivotal to developing an understanding of their ecological role in the ecosystem and determining the trophic relationships between them. Despite the ecological importance of predatory pelagic fish species, research on these species in the Mediterranean Sea is limited. Here, by combining analyses of stomach contents and stable isotope values, we examined the feeding strategies of swordfish, Xiphias gladius, little tunny, Euthynnus alletteratus and Atlantic bonito, Sarda sarda, in the western Mediterranean Sea. We also compared the trophic niche and trophic level of these species with published information of other sympatric pelagic predators present in the ecosystem. Results indicated that, although the diet of the three species was composed mainly by fin-fish species, a clear segregation in their main feeding strategies was found. Swordfish showed a generalist diet including demersal species such as blue whiting, Micromesistius poutassou, and European hake, Merluccius merluccius, and pelagic fin-fish such as barracudina species (Arctozenus risso and Lestidiops jayakari) or small pelagic fish species. Little tunny and Atlantic bonito were segregated isotopically between them and showed a diet basically composed of anchovy, Engraulis encrasicolus, and round sardinella, Sardinella aurita, and sardines, Sardina pilchardus, respectively. This trophic segregation, in addition to potential segregation by depth, is likely a mechanism that allows their potential coexistence within the same pelagic habitat. When the trophic position of these three predatory pelagic fish species is compared with other pelagic predators such as bluefin tuna, Thunnus thynnus, and dolphinfish, Coryphaena hippurus, present in the western Mediterranean Sea, we found that they show similar intermediate trophic position in the ecosystem. In conclusion, the combined stomach and isotopic results highlight, especially for little tunny and Atlantic bonito, the trophic importance of Clupeoid species in their diet. In addition, the importance of demersal resources for swordfish provides evidence for the pelagic-demersal coupling of the ecosystem and the need to manage marine resources in an integrated way. (C) 2016 Elsevier Ltd. All rights reserved.
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ISSN 0967-0645 ISBN Médium
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Numéro d'Appel MARBEC @ alain.herve @ collection 2175
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Auteur Lopez, J.; Moreno, G.; Lennert-Cody, C.; Maunder, M.; Sancristobal, I.; Caballero, A.; Dagorn, L.
Titre Environmental preferences of tuna and non-tuna species associated with drifting fish aggregating devices (DFADs) in the Atlantic Ocean, ascertained through fishers' echo-sounder buoys Type Article scientifique
Année 2017 Publication Revue Abrégée Deep-Sea Res. Part II-Top. Stud. Oceanogr.
Volume 140 Numéro Pages 127-138
Mots-Clés behavior; catch rates; Echo-sounder buoy; Environmental preferences; equatorial atlantic; fad; floating objects; french-polynesia; gamm; habitat; pacific-ocean; Pelagic fish; Purse seine; thunnus-albacares; Tropical tuna; Tuna; western indian-ocean
Résumé Understanding the relationship between environmental variables and pelagic species concentrations and dynamics is helpful to improve fishery management, especially in a changing environment. Drifting fish aggregating device (DFAD)-associated tuna and non-tuna biomass data from the fishers' echo-sounder buoys operating in the Atlantic Ocean have been modelled as functions of oceanographic (Sea Surface Temperature, Chlorophyll-a, Salinity, Sea Level Anomaly, Thermocline depth and gradient, Geostrophic current, Total Current, Depth) and DFAD variables (DFAD speed, bearing and soak time) using Generalized Additive Mixed Models (GAMMs). Biological interaction (presence of non-tuna species at DFADs) was also included in the tuna model, and found to be significant at this time scale. All variables were included in the analyses but only some of them were highly significant, and variable significance differed among fish groups. In general, most of the fish biomass distribution was explained by the ocean productivity and DFAD-variables. Indeed, this study revealed different environmental preferences for tunas and non-tuna species and suggested the existence of active habitat selection. This improved assessment of environmental and DFAD effects on tuna and non-tuna catchability in the purse seine tuna fishery will contribute to transfer of better scientific advice to regional tuna commissions for the management and conservation of exploited resources.
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Éditeur de collection Titre de collection Titre de collection Abrégé
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ISSN 0967-0645 ISBN Médium
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Numéro d'Appel MARBEC @ alain.herve @ collection 2177
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