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Auteur Dortel, E.; Sardenne, F.; Bousquet, N.; Rivot, E.; Million, J.; Le Croizier, G.; Chassot, E.
Titre An integrated Bayesian modeling approach for the growth of Indian Ocean yellowfin tuna Type Article scientifique
Année 2015 Publication Fisheries Research Revue Abrégée
Volume 163 Numéro Si Pages 69-84
Mots-Clés fisheries; Hierarchical Bayesian model; Indian Ocean yellowfin; Tagging
Résumé The Indian Ocean Tuna Tagging Program provided a unique opportunity to collect demographic data on the key commercially targeted tropical tuna species in the Indian Ocean. In this paper, we focused on estimating growth rates for one of these species, yellowfin (Thunnus albacares). Whilst most growth studies only draw on one data source, in this study we use a range of data sources: individual growth rates derived from yellowfin that were tagged and recaptured, direct age estimates obtained through otolith readings, and length-frequency data collected from the purse seine fishery between 2000 and 2010. To combine these data sources, we used an integrated Bayesian model that allowed us to account for the process and measurement errors associated with each data set. Our results indicate that the gradual addition of each data type improved the model's parameter estimations. The Bayesian framework was useful, as it allowed us to account for uncertainties associated with age estimates and to provide additional information on some parameters (e.g., asymptotic length). Our results support the existence of a complex growth pattern for Indian Ocean yellowfin, with two distinct growth phases between the immature and mature life stages. Such complex growth patterns, however, require additional information on absolute age of fish and transition rates between growth stanzas. This type of information is not available from the data. We suggest that bioenergetic models may address this current data gap. This modeling approach explicitly considers the allocation of metabolic energy in tuna and may offer a way to understand the underlying mechanisms that drive the observed growth patterns.
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Editeur Lieu de Publication Éditeur Murua, H.; Marsac, F.; Eveson, J.P.
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Volume de collection Numéro de collection Edition
ISSN 0165-7836 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1103
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Auteur Hattab, T.; Albouy, C.; Lasram, F.B.R.; Somot, S.; Le Loc'h, F.; Leprieur, F.
Titre Towards a better understanding of potential impacts of climate change on marine species distribution: a multiscale modelling approach Type Article scientifique
Année 2014 Publication Revue Abrégée Global Ecology and Biogeography
Volume 23 Numéro 12 Pages 1417-1429
Mots-Clés climate change; exploited species; habitat loss; hierarchical filtering; Mediterranean Sea; spatial scale; species distribution modelling
Résumé Aim In this paper, we applied the concept of ‘hierarchical filters’ in community ecology to model marine species distribution at nested spatial scales. Location Global, Mediterranean Sea and the Gulf of Gabes (Tunisia). Methods We combined the predictions of bioclimatic envelope models (BEMs) and habitat models to assess the current distribution of 20 exploited marine species in the Gulf of Gabes. BEMs were first built at a global extent to account for the full range of climatic conditions encountered by a given species. Habitat models were then built using fine-grained habitat variables at the scale of the Gulf of Gabes. We also used this hierarchical filtering approach to project the future distribution of these species under both climate change (the A2 scenario implemented with the Mediterranean climatic model NEMOMED8) and habitat loss (the loss of Posidonia oceanica meadows) scenarios. Results The hierarchical filtering approach predicted current species geographical ranges to be on average 56% smaller than those predicted using the BEMs alone. This pattern was also observed under the climate change scenario. Combining the habitat loss and climate change scenarios indicated that the magnitude of range shifts due to climate change was larger than from the loss of P. oceanica meadows. Main conclusions Our findings emphasize that BEMs may overestimate current and future ranges of marine species if species–habitat relationships are not also considered. A hierarchical filtering approach that accounts for fine-grained habitat variables limits the uncertainty associated with model-based recommendations, thus ensuring their outputs remain applicable within the context of marine resource management.
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ISSN 1466-8238 ISBN Médium
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Numéro d'Appel LL @ pixluser @ collection 391
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Auteur Le Marchand, M.; Hattab, T.; Niquil, N.; Albouy, C.; Le Loc'h, F.; Lasram, F.B.R.
Titre Climate change in the Bay of Biscay: Changes in spatial biodiversity patterns could be driven by the arrivals of southern species Type Article scientifique
Année 2020 Publication Revue Abrégée Marine Ecology Progress Series
Volume 647 Numéro Pages 17-31
Mots-Clés Climate change; Ecological niche model; Habitat model; Hierarchical filters; Species distribution; Species turnover
Résumé Under climate change, future species assemblages will be driven by the movements and poleward shift of local species and the arrival of more thermophilic species from lower latitudes. To evaluate the impacts of climate change on marine communities in the Bay of Biscay, we used the hierarchical filters modelling approach. Models integrated 3 vertical depth layers and considered 2 Intergovernmental Panel on Climate Change (IPCC) scenarios (Representative Concentration Pathway, RCP2.6 and RCP8.5) and 2 periods (2041-2050 and 2091-2100) to simulate potential future species distributions. Results predicted potentially suitable future ranges for 163 species as well as future arrivals of non-indigenous southern species. We aggregated these results to map changes in species assemblages. Results revealed that coastal areas would undergo the highest species loss among the Bay of Biscay species, depending on their vertical habitat (benthic, demersal, benthopelagic or pelagic). Benthic and demersal species were projected to experience a westward shift, which would induce a deepening of those species. In contrast, pelagic species were projected to shift northward. The potential ecological niche for half of the studied species, mostly benthic and demersal, was projected to decrease under climate change. In addition, a high rate of southern species arrivals is expected (+28%). Assessment of community composition showed high species replacement within the 0-50 m isobath, driven by the replacement of native species by southern ones. This could lead to a major reorganization of trophic networks and have socio-economic impacts.
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Volume de collection Numéro de collection Edition
ISSN 0171-8630, 1616-1599 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2814
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Auteur Robert, M.; Faraj, A.; McAllister, M.K.; Rivot, E.
Titre Bayesian state-space modelling of the De Lury depletion model : strengths and limitations of the method, and application to the Moroccan octopus fishery Type Article scientifique
Année 2010 Publication Revue Abrégée Ices Journal of Marine Science
Volume 67 Numéro Pages 1272-1290
Mots-Clés Bayesian; De; depletion; hierarchical; Lury; Mcmc; model; modelling; octopus; recruitment; state-space
Résumé The strengths and limitations of a Bayesian state-space modelling framework are investigated for a De Lury depletion model that accommodates two recruitment pulses per year. The framework was applied to the Moroccan fishery for common octopus ( Octopus vulgaris) between 1982 and 2002. To allow identifiability, natural mortality ( M) and the recruitment rhythm were fixed, and the variance of both process and observation errors were assumed to be equal. A simulation-estimation ( SE) approach was derived to test the performance of the method. If the data showed responses to harvest, the estimates of the most important figures, i.e. the initial abundance and the second recruitment pulse, were accurate, with relatively small bias. Results confirm that greater depletion yields smaller bias and uncertainty and that inferences are sensitive to the mis-specification of M. The 21 depletion series in the Moroccan dataset were jointly treated in a hierarchical model including random walk to capture the systematic fluctuations in estimates of catchability and initial abundance. The model provides estimates of the annual recruitment and monthly octopus population size. The recruitment estimates could be used to investigate the link between recruitment variability and the coastal North African upwelling regime to improve understanding of the dynamics and management of octopus stocks.
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ISSN 1054-3139 ISBN Médium
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Numéro d'Appel LL @ pixluser @ collection 99
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