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Auteur Gaertner, D.; Hallier, J.-P. url  doi
openurl 
  Titre Tag shedding by tropical tunas in the Indian Ocean and other factors affecting the shedding rate Type Article scientifique
  Année 2015 Publication Fisheries Research Revue Abrégée  
  Volume 163 Numéro Si Pages 98-105  
  Mots-Clés averaging; Bayesian model; Beta-binomial model; Indian Ocean; Shedding rate; Tagging data; Tropical tunas  
  Résumé A key objective of the Regional Tuna Tagging Project Indian Ocean was to estimate tag-shedding rates, Type-I (immediate tag shedding) and Type-II (long-term tag shedding). To assess this, a series of double-tagging experiments (26,899 double tags released with 4555 recoveries) were conducted as part of the broader tagging program. After omitting data from tags placed by less experienced taggers, the results of our analyses did not show any evidence that individual differences between taggers (i.e., a tagger effect) impacted estimates of tag-shedding rates. However, it was shown that the probability of retaining the second tag (inserted in the left side of the fish) was larger than retaining the first tag (inserted in the right side, i.e., the side typically tagged in single-tagging experiments). We used a Bayesian model averaging approach to account for model uncertainty in the estimates of the parameters a and L used to calculate the probability of tag retention Q(t)= alpha e-((L t)) for the right tag. The parameter estimates were alpha = 0.993 and L (per year) = 0.030 (skipjack); alpha = 0.972 and L (per year) = 0.040 (yellowfin); and alpha = 0.990 and L (per year) = 0.021 (bigeye). These results agree with estimates obtained by other large-scale tropical tuna tagging projects. We showed that tag loss has a moderate impact on the underestimation of the exploitation rate (bias = 2-6% depending on the tuna species). However, non-reporting leads to a bias of around 7% when using the high reporting rate estimate of purse seiners. Finally, tag shedding (specifically Type-II shedding) modified the individual weights of the samples of recaptures. Consequently, the total instantaneous mortality estimates (Z; calculated from mean times-at-large) were reduced by a range of 1-3%.  
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  Editeur Lieu de Publication Éditeur Murua, H.; Marsac, F.; Eveson, J.P.  
  Langue Langue du Résumé Titre Original  
  Éditeur de collection Titre de collection Titre de collection Abrégé  
  Volume de collection Numéro de collection Edition (up)  
  ISSN 0165-7836 ISBN Médium  
  Région Expédition Conférence  
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  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1104  
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Auteur Keller, S.; Quetglas, A.; Puerta, P.; Bitetto, I.; Casciaro, L.; Cuccu, D.; Esteban, A.; Garcia, C.; Garofalo, G.; Guijarro, B.; Josephides, M.; Jadaud, A.; Lefkaditou, E.; Maiorano, P.; Manfredi, C.; Marceta, B.; Micallef, R.; Peristeraki, P.; Relini, G.; Sartor, P.; Spedicato, M.T.; Tserpes, G.; Hidalgo, M. doi  openurl
  Titre Environmentally driven synchronies of Mediterranean cephalopod populations Type Article scientifique
  Année 2017 Publication Revue Abrégée Prog. Oceanogr.  
  Volume 152 Numéro Pages 1-14  
  Mots-Clés atlantic bluefin tuna; balearic sea; Cephalopods; Dynamic factor analysis; ecological niche approach; fisheries; fluctuations; hake merluccius-merluccius; Illex coindetii; life-history; Mediterranean; medits; octopus; Octopus vulgaris; squid; Synchrony; time-series  
  Résumé The Mediterranean Sea is characterized by large scale gradients of temperature, productivity and salinity, in addition to pronounced mesoscale differences. Such a heterogeneous system is expected to shape the population dynamics of marine species. On the other hand, prevailing environmental and climatic conditions at whole basin scale may force spatially distant populations to fluctuate in synchrony. Cephalopods are excellent case studies to test these hypotheses owing to their high sensitivity to environmental conditions. Data of two cephalopod species with contrasting life histories (benthic octopus vs nectobenthic squid), obtained from scientific surveys carried out throughout the Mediterranean during the last 20 years were analyzed. The objectives of this study and the methods used to achieve them (in parentheses) were: (i) to investigate synchronies in spatially separated populations (decorrelation analysis); (ii) detect underlying common abundance trends over distant regions (dynamic factor analysis, DFA); and (iii) analyse putative influences of key environmental drivers such as productivity and sea surface temperature on the population dynamics at regional scale (general linear models, GLM). In accordance with their contrasting spatial mobility, the distance from where synchrony could no longer be detected (decorrelation scale) was higher in squid than in octopus (349 vs 217 km); for comparison, the maximum distance between locations was 2620 km. The DFA revealed a general increasing trend in the abundance of both species in most areas, which agrees with the already reported worldwide proliferation of cephalopods. DFA results also showed that population dynamics are more similar in the eastern than in the western Mediterranean basin. According to the GLM models, cephalopod populations were negatively affected by productivity, which would be explained by an increase of competition and predation by fishes. While warmer years coincided with declining octopus numbers, areas of high sea surface temperature showed higher densities of squid. Our results are relevant for regional fisheries management and demonstrate that the regionalisation objectives envisaged under the new Common Fishery Policy may not be adequate for Mediterranean cephalopod stocks. (C) 2017 Elsevier Ltd. All rights reserved.  
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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 (up)  
  ISSN 0079-6611 ISBN Médium  
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  Numéro d'Appel MARBEC @ alain.herve @ collection 2132  
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Auteur Dalongeville, A.; Andrello, M.; Mouillot, D.; Albouy, C.; Manel, S. doi  openurl
  Titre Ecological traits shape genetic diversity patterns across the Mediterranean Sea: a quantitative review on fishes Type Article scientifique
  Année 2016 Publication Revue Abrégée J. Biogeogr.  
  Volume 43 Numéro 4 Pages 845-857  
  Mots-Clés atlantic bluefin tuna; bass dicentrarchus-labrax; climate-change; cod gadus-morhua; ecological traits; effective population-size; genetic diversity; gilthead sea; life-history traits; marine fishes; marine populations; Mediterranean Sea; microsatellite markers; microsatellites; mitochondrial; mitochondrial DNA; molecular markers; population genetics  
  Résumé AimWe set out to identify the determinants of the variation in genetic diversity among fish species and test whether multi-species genetic diversity is randomly distributed in space. LocationMediterranean Sea. MethodsWe collected genetic diversity data from 39 published studies on Mediterranean fishes (31 species) along with the spatial coordinates of the sampling sites. We focused on microsatellite heterozygosity (151 data points) and mitochondrial haplotype diversity (201 data points). We used linear regressions to link genetic diversity and 11 ecological traits. We also tested for spatial autocorrelation and trends in the residuals. ResultsAmong-species variation in microsatellite heterozygosity was explained by three ecological traits: vertical distribution, migration type and body length. Variation in mitochondrial haplotype diversity was also explained by vertical distribution and migration type, and by reproductive strategy (semelparity). However, vertical distribution and migration type showed opposite effects on microsatellites and mitochondrial diversity. After accounting for the effects of ecological traits, no spatial pattern was detected, except for one of the species considered. Main conclusionsEcological factors explain an important proportion of the among-species genetic diversity. These results suggest that life history strategies of the species influence the variation of microsatellite diversity indirectly through their effect on effective population size, while the spatial variations of genetic diversity seem to be too complex to be identified in our analysis. We found very different effects of traits on mitochondrial and nuclear DNA diversity, which can be explained by the specificities of mitochondrial DNA (absence of recombination, maternal inheritance and non-neutrality).  
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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 (up)  
  ISSN 0305-0270 ISBN Médium  
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  Numéro d'Appel MARBEC @ alain.herve @ collection 1627  
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Auteur Walker, E.; Rivoirard, J.; Gaspar, P.; Bez, N. url  doi
openurl 
  Titre From forager tracks to prey distributions: an application to tuna vessel monitoring systems (VMS) Type Article scientifique
  Année 2015 Publication Ecological Applications Revue Abrégée  
  Volume 25 Numéro 3 Pages 826-833  
  Mots-Clés Gps; multivariate geostatistics; presence index; spatiotemporal distribution; trajectometry; Tropical tuna; vessel monitoring system (VMS)  
  Résumé In the open ocean, movements of migratory fish populations are typically surveyed using tagging methods that are subject to low sample sizes for archive tags, except for a few notable examples, and poor temporal resolution for conventional tags. Alternatively, one can infer patterns of movement of migratory fish by tracking movements of their predators, i.e., fishing vessels, whose navigational systems (e.g., GPS) provide accurate and frequent VMS (vessel monitoring system) records of movement in pursuit of prey. In this paper, we develop a state-space model that infers the foraging activities of fishing vessels from their tracks. Second, we link foraging activities to probabilities of tuna presence. Finally, using multivariate geostatistical interpolation (cokriging) we map the probability of tuna presence together with their estimation variances and produce a time series of indices of abundance. While the segmentation of the trajectories is validated by observers' data, the present VMS-index is compared to catch rate and proved to be useful for management perspectives. The approach reported in this manuscript extends beyond the case study considered. It can be applied to any foragers that engage in an attempt of capture when they see prey and for whom this attempt is linked to a tractable change in behavior.  
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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 (up)  
  ISSN 1051-0761 ISBN Médium  
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  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1116  
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Auteur Filmalter, J.D.; Cowley, P.D.; Potier, M.; Menard, F.; Smale, M.J.; Cherel, Y.; Dagorn, L. doi  openurl
  Titre Feeding ecology of silky sharks Carcharhinus falciformis associated with floating objects in the western Indian Ocean Type Article scientifique
  Année 2017 Publication Revue Abrégée J. Fish Biol.  
  Volume 90 Numéro 4 Pages 1321-1337  
  Mots-Clés atlantic; By-catch; diet; ecosystem; fad; fish aggregating devices; fish aggregation device; food-consumption; isurus-oxyrinchus; pacific-ocean; pelagic fishes; Pelagic shark; Purse-seine fishery; shortfin mako; Yellowfin tuna  
  Résumé The silky shark Carcharhinus falciformis is commonly associated with floating objects, including fish aggregating devices (FADs), in the Indian Ocean. While the motives for this associative behaviour are unclear, it does make them vulnerable to capture in the tuna purse seine fishery that makes extensive use of FADs. Here, the diet of 323 C. falciformis, caught at FADs in the Indian Ocean, was investigated to test the hypothesis that trophic benefits explain the associative behaviour. A high proportion of stomachs with fresh contents (57%) suggested that extensive feeding activity occurred while associated with FADs. Multiple dietary indices showed that typical non-associative prey types dominated, but were supplemented with fishes typically found at FADs. While the trophic benefits of FAD association may be substantial, our results suggest that associative behaviour is not driven solely by feeding. (C) 2016 The Fisheries Society of the British Isles  
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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 (up)  
  ISSN 0022-1112 ISBN Médium  
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  Numéro d'Appel MARBEC @ alain.herve @ collection 2142  
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