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| Brosset, Pablo; Le Bourg, Baptiste; Costalago, David; Banaru, Daniela; Van Beveren, Elisabeth; Bourdeix, Jean-herve; Fromentin, Jean-marc; Menard, Frederic; Saraux, Claire. |
| Since 2008, a severe decrease in size and body condition together with a demographic truncation has been observed in the sardine (secondarily in anchovy) population of the Gulf of Lions (NW Mediterranean Sea). In parallel, sprat biomass, which was negligible before, has increased tenfold. All of these changes have strongly affected the regional fisheries. Using trophic and isotopic data from contrasting periods of low versus high growth and condition, we investigated potential changes in diet and interspecific feeding interactions through time. Evidence of resource partitioning was found between sprat and both anchovy and sardine in 2004 and 2005. Since 2010, the isotopic niches of the 3 species have tended to overlap, suggesting higher risk of competition... |
| Tipo: Text |
Palavras-chave: Trophic ecology; Anchovy; Sardine; Sprat; Dietary overlap; NW Mediterranean. |
| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00347/45822/45540.pdf |
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| Van Beveren, Elisabeth; Bonhommeau, Sylvain; Fromentin, Jean-marc; Bigot, Jean-louis; Bourdeix, Jean-herve; Brosset, Pablo; Roos, David; Saraux, Claire. |
| Since 2007, the ecosystem of the Gulf of Lions has shifted to a different regime, characterised by a low anchovy (Engraulis encrasicolus) and sardine (Sardina pilchardus) biomass and a remarkably high sprat (Sprattus sprattus) biomass. Surprisingly, the abundance and recruitment of anchovy and sardine remained high. To understand which processes (bottom-up or top-down control, etc.) could have caused this shift, we studied the changes in body condition, growth and size and age of anchovy, sardine and sprat over 1984–1985 and 1992–2012, using data from scientific surveys. The annual age structure of anchovy and sardine was estimated using Bayesian mixture models based on size frequency data with priors on the age–length relationship derived from independent... |
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| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00192/30335/29917.pdf |
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| Brosset, Pablo; Fromentin, Jean-marc; Menard, Frederic; Pernet, Fabrice; Bourdeix, Jean-herve; Bigot, Jean-louis; Van Beveren, Elisabeth; Perez Rodia, Maria A.; Choy, Sandrine; Saraux, Claire. |
| As condition is a key variable in population dynamics (especially for survival, growth and reproduction), the use of well-defined and accurate fish condition indices is capital. In particular, condition indices (morphometric, bioenergetic and biochemical) have never been compared and validated for the European anchovy Engraulis encrasicolus, the European pilchard Sardina pilchardus and the European sprat Sprattus sprattus. The accuracy of two indirect methods, the morphometric relative condition index Kn and the bioenergetics index determined with the Distell Fish Fatmeter was investigated by comparing with a direct measure of relative lipid content carried out with a thin layer chromatography-flame ionization detector. Estimations from the fatmeter... |
| Tipo: Text |
Palavras-chave: Anchovy; Fatmeter; Lipids; Mediterranean Sea; Sardine; Sprat. |
| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00226/33741/32304.pdf |
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| Giannoulaki, Marianna; Pyrounaki, Maria M.; Bourdeix, Jean-herve; Ben Abdallah, Lotfi; Bonanno, Angelo; Basilone, Gualtiero; Iglesias, Magdalena; Ventero, Ana; De Felice, Andrea; Leonori, Iole; Valavanis, Vasilis D.; Machias, Athanassios; Saraux, Claire. |
| Our knowledge for the distribution of Atlantic mackerel (Scomber scombrus) in the Mediterranean Sea is limited and fragmented. In the current work habitat suitability modeling was applied to summer acoustic surveys data of Atlantic mackerel juveniles derived from the north part of the Mediterranean (i.e., acoustic data from the Gulf of Lions, pelagic trawls held during acoustic surveys in Spanish Mediterranean waters, south Adriatic Sea, Strait of Sicily, and North Aegean Sea) using generalized additive models (GAMs) along with satellite environmental and bathymetry data. Bathymetry along with sea surface temperature and circulation patterns, expressed through sea level anomaly and the zonal component of the absolute geostrophic velocity, were the... |
| Tipo: Text |
Palavras-chave: Habitat suitability modeling; Atlantic mackerel; Nursery grounds; Mediterranean Sea; Generalized additive models; Acoustic surveys. |
| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00395/50657/51347.pdf |
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| Pethybridge, H.; Bodin, Nathalie; Arsenault-pernet, E. -j.; Bourdeix, Jean-herve; Brisset, Blandine; Bigot, Jean-louis; Roos, David; Peter, M.. |
| We describe the total lipid content, lipid class composition and fatty acid profiles of adult forage fishes (anchovy, sardine and sprat) sampled in the NW Mediterranean Sea in 2010 and 2011. Inter-and intra-species differences were mostly related to sampling period with limited effect of gender or total length. As an assemblage, total lipid content and relative levels of triacylglycerols and fatty acids 16:1n7, 20:5n3 and 14:0 in forage fish were highest in summer and autumn, indicating better feeding conditions and a more pronounced diatom-supported food web. In contrast, total lipid content was lowest at the end of winter and spring, and coincided with high levels of 22:6n3, indicating a more herbivorous diet based on dinoflagellates. Resource... |
| Tipo: Text |
Palavras-chave: Trophic markers; Environmental variations; Clupeiformes; Nutritional condition; Prey quality; Ecosystem health. |
| Ano: 2014 |
URL: https://archimer.ifremer.fr/doc/00239/34997/33530.pdf |
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| Brosset, Pablo; Menard, Frederic; Fromentin, Jean-marc; Bonhommeau, Sylvain; Ulses, Caroline; Bourdeix, Jean-herve; Bigot, Jean-louis; Van Beveren, Elisabeth; Roos, David; Saraux, Claire. |
| Endogenous and environmental variables are fundamental in explaining variations in fish condition. Based on more than 20 yr of fish weight and length data, relative condition indices were computed for anchovy and sardine caught in the Gulf of Lions. Classification and regression trees (CART) were used to identify endogenous factors affecting fish condition, and to group years of similar condition. Both species showed a similar annual cycle with condition being minimal in February and maximal in July. CART identified 3 groups of years where the fish populations generally showed poor, average and good condition and within which condition differed between age classes but not according to sex. In particular, during the period of poor condition (mostly recent... |
| Tipo: Text |
Palavras-chave: Anchovy; Sardine; Relative condition factor; NW Mediterranean Sea; Endogenous effect; Environmental effect. |
| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00272/38334/36575.pdf |
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| Saraux, Claire; Fromentin, Jean-marc; Bigot, Jean-louis; Bourdeix, Jean-herve; Morfin, Marie; Roos, David; Van Beveren, Elisabeth; Bez, Nicolas. |
| Understanding the ecological and anthropogenic drivers of population dynamics requires detailed studies on habitat selection and spatial distribution. Although small pelagic fish aggregate in large shoals and usually exhibit important spatial structure, their dynamics in time and space remain unpredictable and challenging. In the Gulf of Lions (north-western Mediterranean), sardine and anchovy biomasses have declined over the past 5 years causing an important fishery crisis while sprat abundance rose. Applying geostatistical tools on scientific acoustic surveys conducted in the Gulf of Lions, we investigated anchovy, sardine and sprat spatial distributions and structures over 10 years. Our results show that sardines and sprats were more coastal than... |
| Tipo: Text |
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| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00226/33739/32151.pdf |
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| Saraux, Claire; Van Beveren, Elisabeth; Brosset, Pablo; Queiros, Quentin; Bourdeix, Jean-herve; Dutto, Gilbert; Gasset, Eric; Jac, Cyrielle; Bonhommeau, Sylvain; Fromentin, Jean-marc. |
| Around 2008, an ecosystem shift occurred in the Gulf of Lions, highlighted by considerable changes in biomass and fish mean weight of its two main small pelagic fish stocks (European anchovy, Engraulis encrasicolus; European sardine, Sardina pilchardus). Surprisingly these changes did not appear to be mediated by a decrease in fish recruitment rates (which remained high) or by a high fishing pressure (exploitation rates being extremely low). Here, we review the current knowledge on the population's dynamics and its potential causes. We used an integrative ecosystem approach exploring alternative hypotheses, ranging from bottom-up to top-down control, not forgetting epizootic diseases. First, the study of multiple population characteristics highlighted a... |
| Tipo: Text |
Palavras-chave: Population dynamics; Top-down; Disease; Zooplankton; Exploited species; Bottom-up. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00427/53861/54903.pdf |
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