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Auteur (up) Capello, M.; Deneubourg, J.L.; Robert, M.; Holland, K.N.; Schaefer, K.M.; Dagorn, L.
Titre Population assessment of tropical tuna based on their associative behavior around floating objects Type Article scientifique
Année 2016 Publication Revue Abrégée Sci Rep
Volume 6 Numéro Pages 36415
Mots-Clés abundance; aerial surveys; archival tag data; bluefin tuna; continental-shelf; fish aggregating devices; katsuwonus-pelamis; pacific-ocean; tagging data; thunnus-albacares
Résumé Estimating the abundance of pelagic fish species is a challenging task, due to their vast and remote habitat. Despite the development of satellite, archival and acoustic tagging techniques that allow the tracking of marine animals in their natural environments, these technologies have so far been underutilized in developing abundance estimations. We developed a new method for estimating the abundance of tropical tuna that employs these technologies and exploits the aggregative behavior of tuna around floating objects (FADs). We provided estimates of abundance indices based on a simulated set of tagged fish and studied the sensitivity of our method to different association dynamics, FAD numbers, population sizes and heterogeneities of the FAD-array. Taking the case study of yellowfin tuna (Thunnus albacares) acoustically-tagged in Hawaii, we implemented our approach on field data and derived for the first time the ratio between the associated and the total population. With more extensive and long-term monitoring of FAD-associated tunas and good estimates of the numbers of fish at FADs, our method could provide fisheries-independent estimates of populations of tropical tuna. The same approach can be applied to obtain population assessments for any marine and terrestrial species that display associative behavior and from which behavioral data have been acquired using acoustic, archival or satellite tags.
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Langue English Langue du Résumé Titre Original
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Volume de collection Numéro de collection Edition
ISSN 2045-2322 ISBN Médium
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Numéro d'Appel MARBEC @ alain.herve @ collection 1682
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Auteur (up) 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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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 1354-1013 ISBN Médium
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Numéro d'Appel MARBEC @ alain.herve @ collection 2169
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Auteur (up) Sardenne, F.; Chassot, E.; Fouche, E.; Menard, F.; Lucas, V.; Bodin, N.
Titre Are condition factors powerful proxies of energy content in wild tropical tunas? Type Article scientifique
Année 2016 Publication Revue Abrégée Ecol. Indic.
Volume 71 Numéro Pages 467-476
Mots-Clés body condition; cod gadus-morhua; condition indexes; ecosystem; Energy variability; fish; Fish health; katsuwonus-pelamis; Large pelagic species; Proximate composition; thunnus-albacares; western indian-ocean; Yellowfin tuna
Résumé The “condition” is used as an indicator of fish health and is generally equated with the quantity of energy reserves. Biometric condition factors have been widely used and preferred over costly and time-consuming biochemical condition. Here, we investigated the relevance of four common condition factors based on biometric measurements (Le Cren's index, girth -length index, gonado-somatic index and hepato-somatic index) and of size- and weight -based empirical models to describe the physiological condition of tropical tunas. Biometric condition factors of bigeye (Thunnus obesus), skipjack (Katsuwonus pelamis) and yellowfin (Thunnus albacares) tunas sampled throughout 2013 in the western Indian Ocean region were assessed against benchmark biochemical indices (lipid content, protein content, triacylglycerol:sterol ratio and energy density) estimated in tissues with different physiological functions, i.e. red muscle, white muscle, liver, and gonads. Our findings suggest that tropical tunas do not store lipids in white muscle and that protein content is less variable than lipid content, which largely varies with ontogeny and the seasons according to tissue and species. This variability induced inconsistency between biometric factors, including the empirically adjusted ones, and biochemical indices, with the exception of the gonado-somatic index that fitted well to the composition of the gonads in the three species, and especially in females. (C) 2016 Elsevier Ltd. All rights reserved.
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Langue English Langue du Résumé Titre Original
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Volume de collection Numéro de collection Edition
ISSN 1470-160x ISBN Médium
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Notes Approuvé pas de
Numéro d'Appel MARBEC @ alain.herve @ collection 1697
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Auteur (up) Travassos Tolotti, M.; Forget, F.; Capello, M.; Filmalter, J.D.; Hutchinson, M.; Itano, D.; Holland, K.; Dagorn, L.
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
Année 2020 Publication Revue Abrégée Fish Res.
Volume 226 Numéro Pages 105521
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
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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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 0165-7836 ISBN Médium
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Notes WOS:000525305200009 Approuvé pas de
Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2772
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Auteur (up) Veras, L.Q.; Capello, M.; Forget, F.; Tolotti, M.T.; Veras, D.P.; Dagorn, L.; Hazin, F.H.
Titre Aggregative capacity of experimental anchored Fish Aggregating Devices (aFADs) in Northeastern Brazil revealed through electronic tagging data Type Article scientifique
Année 2020 Publication Revue Abrégée Ocean Coast. Res.
Volume 68 Numéro Pages e20284
Mots-Clés Acoustic tagging; Artisanal fishing; associative behavior; Associative behavior; dolphinfish coryphaena-hippurus; fads; fisheries; food security; Moored FADs; Pelagic fish; small-pelagic fish; southeast coast; tuna katsuwonus-pelamis; vertical movements; yellowfin thunnus-albacares
Résumé Catches of pelagic fish associated to anchored Fish Aggregating Devices have been responsible for increases in income, fish consumption, and even cultural identity of artisanal fishing communities in many developing countries worldwide. Nonetheless, in Brazil, aFAD fishing is still poorly developed and studied. In this experiment, FADs were anchored offshore the city of Recife (Northeastern Brazil) to investigate the potential of moored buoys in the aggregation of commercially important pelagic species near the coast, as an alternative fishing site for artisanal fishers. The behavior of acoustically tagged fish was investigated to assess whether they were attracted to the FADs and how long they remained associated to them. The results indicated that, although economically important species were found near the FADs, they did not remain associated for long periods. From the four species tagged, Acanthocybium solandri, Coryphaena hippurus, Thunnus atlanticus, and Caranx crysos, only the two latter were detected at the FADs. Both species presented a preference for a specific FAD, with stronger site fidelity being recorded for C. crysos. This species presented Total Resident Times (TRTs) of more than a month and continuous residence times of more than 14 consecutive days. T atlanticus, on the other hand, remained around the buoys for short time intervals, with a maximum TRT of only two days. Short diurnal excursions far from the FADs and few longer excursions during nighttime were recorded for C. crysos. These results do not support the possible use of moored FADs near the coast of Recife as an alternative fishing site for artisanal fisheries. It is possible that the geomorphological characteristics of the experimental area did not favor the aggregative behavior of large pelagic fish species, such as tunas, around FADs.
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Langue English Langue du Résumé Titre Original
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Volume de collection Numéro de collection Edition
ISSN ISBN Médium
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Notes WOS:000600345300001 Approuvé pas de
Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2971
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