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Auteur (up) Dambrine, C.; Huret, M.; Woillez, M.; Pecquerie, L.; Allal, F.; Servili, A.; de Pontual, H.
Titre Contribution of a bioenergetics model to investigate the growth and survival of European seabass in the Bay of Biscay – English Channel area Type Article scientifique
Année 2020 Publication Revue Abrégée Ecological Modelling
Volume 423 Numéro Pages 109007
Mots-Clés Dynamic Energy Budget theory; Early-life stages; Growth, Starvation; Northeast Atlantic
Résumé The European seabass (Dicentrarchus labrax) is a species of particular ecological and economic importance. Stock assessments have recently revealed the worrying state of the “Northern stock”, probably due to overfishing and a series of poor recruitments. The extent to which these poor recruitments are due to environmental variability is difficult to assess, as the processes driving the seabass life cycle are poorly known. Here we investigate how food availability and temperature may affect the growth and survival of wild seabass at the individual scale. To this end, we developed a bioenergetics model based on the Dynamic Energy Budget (DEB) theory. We applied it to seabass population of the Northeast Atlantic region (Bay of Biscay – English Channel area) throughout their entire life cycle. We calibrated the model using a combination of age-related length and weight datasets: two were from aquaculture experiments (larvae and juveniles raised at 15 and 20°C) and one from a wild population (juveniles and adults collected during surveys or fish market sampling). By calibrating the scaled functional response that rules the ingestion of food and using average temperature conditions experienced by wild seabass (obtained from tagged individuals), the model was able to reproduce the duration of the different stages, the growth of the individuals, the number of batches and their survival to starvation. We also captured one of the major differences encountered in the life traits of the species: farmed fish mature earlier than wild fish (3 to 4 years old vs. 6 years old on average for females, respectively) probably due to better feeding conditions and higher temperature. We explored the growth and survival of larvae and juveniles by exposing the individuals to varying temperatures and food levels (including total starvation). We show that early life stages of seabass have a strong capacity to deal with food deprivation: the model estimated that first feeding larvae could survive 17 days at 15°C. We also tested individual variability by adjusting the specific maximum assimilation rate and found that larvae and juveniles with higher assimilation capacity better survived low food levels at a higher temperature. We discuss our results in the context of the recent years of poor recruitment faced by European seabass.
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ISSN 0304-3800 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2724
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Auteur (up) Eduardo Nole, L.; Frédou, T.; Souza Lira, A.; Padovani Ferreira, B.; Bertrand, A.; Ménard, F.; Lucena Frédou, F.
Titre Identifying key habitat and spatial patterns of fish biodiversity in the tropical Brazilian continental shelf Type Article scientifique
Année 2018 Publication Revue Abrégée Continental Shelf Research
Volume 166 Numéro Pages 108-118
Mots-Clés Demersal fish assemblage; Fish assemblage structure; Habitat composition; Marine Protected Areas; Northeast Brazilian coast; Underwater footages
Résumé Knowledge of the spatial distribution of fish assemblages biodiversity and structure is essential for prioritizing areas of conservation. Here we describe the biodiversity and community structure of demersal fish assemblages and their habitat along the northeast Brazilian coast by combining bottom trawl data and underwater footage. Species composition was estimated by number and weight, while patterns of dominance were obtained based on frequency of occurrence and relative abundance. A total of 7235 individuals (830 kg), distributed in 24 orders, 49 families and 120 species were collected. Community structure was investigated through clustering analysis and by a non-metric multidimensional scaling technique. Finally, diversity was assessed based on six indices. Four major assemblages were identified, mainly associated with habitat type and depth range. The higher values of richness were found in sand substrate with rocks, coralline formations and sponges (SWCR) habitats, while higher values of diversity were found in habitats located on shallow waters (10–30 m). Further, assemblages associated with sponge-reef formations presented the highest values of richness and diversity. In management strategies of conservation, we thus recommend giving special attention on SWCR habitats, mainly those located on depths between 30 and 60 m. This can be achieved by an offshore expansion of existing MPAs and/or by the creation of new MPAs encompassing those environments.
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Volume de collection Numéro de collection Edition
ISSN 0278-4343 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2384
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Auteur (up) ROUYER, T.; FROMENTIN, J.-M.; HIDALGO, M.; STENSETH, N.C.
Titre Combined effects of exploitation and temperature on fish stocks in the Northeast Atlantic Type Article scientifique
Année 2014 Publication Ices Journal Of Marine Science Revue Abrégée
Volume 71 Numéro 7 Pages 1554-1562
Mots-Clés combined climate/exploitation effect; exploitation; fish stocks; Northeast Atlantic; response to climate; time-series
Résumé Fish stock fluctuations are affected by two potentially confounding forces: the removal of individuals by fisheries and climatic variations affecting the productivity of fish populations. Disentangling the relative importance of these forces has thus been a question of primary importance for fisheries management and conservation. Through the analysis of long-term time-series for 27 fish stocks from the Northeast Atlantic, the present study shows that the sign and intensity of the effect of temperature on biomass are dependent on the geographical location: the stocks located at the southernmost and northernmost latitudes of our study displayed stronger associations with temperature than the stocks located in the middle range of latitudes. As a consequence, the investigation of the combined effects of exploitation and the environment revealed that the stocks at the northern/southern boundaries of the spatial extent of the species were more prone to combined effects. The interplay between geographic location, climate and exploitation thus plays a significant role in fish stock productivity, which is generally ignored during assessment, thus affecting management procedures.
Adresse Inst Marine Res, Dept Coastal Zone Studies, Flodevigen Res Stn, N-4817 His, Norway.
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Editeur Oxford Univ Press Lieu de Publication Éditeur
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ISSN 1054-3139 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ 34107 collection 983
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Auteur (up) Rouyer, T.; Ottersen, G.; Durant, J.M.; Hidalgo, M.; Hjermann, D.Ø.; Persson, J.; Stige, L.C.; Stenseth, N.C.
Titre Shifting dynamic forces in fish stock fluctuations triggered by age truncation? Type Article scientifique
Année 2011 Publication Revue Abrégée Global Change Biology
Volume 17 Numéro 10 Pages 3046-3057
Mots-Clés age truncation; effects of exploitation; Northeast Arctic cod; Norwegian spring spawning herring; response to climate
Résumé Accumulating evidence shows that environmental fluctuations and exploitation jointly affect marine fish populations, and understanding their interaction is a key issue for fisheries ecology. In particular, it has been proposed that age truncation induced by fisheries exploitation may increase the population's sensitivity to climate. In this study, we use unique long-term abundance data for the Northeast Arctic stock of cod (Gadus morhua) and the Norwegian Spring-Spawning stock of herring (Clupea harengus), which we analyze using techniques based on age-structured population matrices. After identifying time periods with different age distributions in the spawning stock, we use linear models to quantify the relative effect of exploitation and temperature on the population growth rates. For the two populations, age truncation was found to be associated with an increasing importance of temperature and a relatively decreasing importance of exploitation, while the population growth rate became increasingly sensitive to recruitment variations. The results suggested that the removal of older age classes reduced the buffering capacity of the population, thereby making the population growth rate more dependent on recruitment than adult survival and increasing the effect of environmental fluctuations. Age structure appeared as a key characteristic that can affect the response of fish stocks to climate variations and its consequences may be of key importance for conservation and management.
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ISSN 1365-2486 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1668
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