AB 8:137-144 (2010)  -  DOI: https://doi.org/10.3354/ab00220

ABSTRACT: Although being a widely introduced and successfully established species, the European catfish Silurus glanis L. (the world’s third largest freshwater fish) remains poorly studied in its introduced areas. Here we studied the trophic ecology of non-native European catfish in a large river system in south-western France using stomach content and stable isotope analyses (SIA). We used fin samples for SIA of catfish and hence tested the validity of using fin tissue as a proxy for muscle in SIA. The mean δ¹⁵N and δ¹³C values analysed from fin tissues did not differ from those analysed from muscle tissue and reflected strong and consistent relationships (r² = 0.95 for carbon and r² = 0.98 for nitrogen). The δ¹⁵N values varied almost 5‰ among the analysed catfish individuals, while δ¹³C values varied >5‰. Total length of these catfish ranged from 200 to 2240 mm and was correlated with δ¹⁵N and especially with δ¹³C values. Although catfish length and δ¹⁵N values were positively correlated, the mean trophic positions of catfish increased only slightly from smaller individuals to larger ones (4.3 to 4.7). However, larger catfish were considerably ¹³C-enriched in their δ¹³C values compared to smaller individuals and had up to 4‰ higher δ¹³C values than their expected aquatic prey. This might indicate frequent consumption of mammals and/or non-aquatic birds by the larger sized individuals, which were found in the catfish stomachs.

KEY WORDS: Stable isotopes · Introduced species · Top predator · River · Food web · Fin clips

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Cite this article as: Syväranta J, Cucherousset J, Kopp D, Crivelli A, Céréghino R, Santoul F (2010) Dietary breadth and trophic position of introduced European catfish Silurus glanis in the River Tarn (Garonne River basin), southwest France. Aquat Biol 8:137-144. https://doi.org/10.3354/ab00220 Export citation Share:    Facebook - - linkedIn