Stable isotope analysis of marine feeding signatures of Atlantic salmon in the North Atlantic

Abstract

Abstract Dempson, J. B., Braithwaite, V. A., Doherty, D., and Power, M. 2010. Stable isotope analysis of marine feeding signatures of Atlantic salmon in the North Atlantic. – ICES Journal of Marine Science, 67: 52–61. Differences in the marine feeding of three geographically distinct populations of Atlantic salmon (Salmo salar) in the North Atlantic (Conne River, Newfoundland; Koksoak River, Ungava Bay, Québec; River Erne, northwest Ireland) were examined using analyses of stable isotopes of carbon and nitrogen (δ13C and δ15N) and contrasted with isotope signatures obtained from a sample of salmon of unknown origin captured in the Labrador Sea. Although the overall range of δ13C and δ15N values (δ13C: from −22.42 to −19.37; δ15N: from 10.70 to 13.38) was similar to that reported by others, significant differences were found among populations and between different sea-age life-history groups. Reported differences in marine feeding between populations from the Northeast and Northwest Atlantic corroborated the stable isotope results. A surrogate measure of lipid content, the C:N ratio, was also compared among 1-sea-winter salmon. The highest levels were associated with the Koksoak River, suggesting that Subarctic populations may require higher energy reserves to contend with their longer migrations and more-severe environmental conditions.