Contribution of anadromous fish to the diet of European catfish in a large river system |
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Authors: | Jari Syväranta Julien Cucherousset Dorothée Kopp Aurélia Martino Régis Céréghino Frédéric Santoul |
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Institution: | (1) EcoLab, UMR 5245 (CNRS-UPS-INPT), Université Paul Sabatier, bat 4R3, 118, route de Narbonne, 31062 Toulouse Cedex 9, France;(2) Present address: Centre for Conservation Ecology and Environmental Change, School of Conservation Sciences, Bournemouth University, Poole, Dorset, BH12 5BB, UK |
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Abstract: | Many anadromous fish species, when migrating from the sea to spawn in fresh waters, can potentially be a valuable prey for
larger predatory fish, thereby efficiently linking these two ecosystems. Here, we assess the contribution of anadromous fish
to the diet of European catfish (Silurus glanis) in a large river system (Garonne, southwestern France) using stable isotope analysis and allis shad (Alosa alosa) as an example of anadromous fish. Allis shad caught in the Garonne had a very distinct marine δ13C value, over 8‰ higher after lipid extraction compared to the mean δ13C value of all other potential freshwater prey fish. The δ13C values of European catfish varied considerably between these two extremes and some individuals were clearly specializing
on freshwater prey, whereas others specialized on anadromous fish. The mean contribution of anadromous fish to the entire
European catfish population was estimated to be between 53% and 65%, depending on the fractionation factor used for δ13C. |
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Keywords: | Alosa alosa Anadromous fish Migration Mixing model Silurus glanis Stable isotopes |
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