Retrospective determination of primary feeding areas of Atlantic salmon (Salmo salar) using fingerprinting of chlorinated organic contaminants

Abstract

Abstract Svendsen, T. C., Vorkamp, K., Rønsholdt, B., and Frier, J-O. 2008. Retrospective determination of primary feeding areas of Atlantic salmon (Salmo salar) using fingerprinting of chlorinated organic contaminants. – ICES Journal of Marine Science, 65: 921–929. Atlantic salmon (Salmo salar) undertake extensive marine migrations. In the marine environment, the Atlantic salmon appears to suffer from heavy mortality, indicating the need for increased knowledge of its movements and habitat use at sea. Persistent organochlorine compounds (OCs) are found in measurable concentrations in all marine ecosystems. Geographically varying sources of OCs, transport, and transformation processes lead to different OC concentrations and compositions in the various ecosystems. As the principal source of organochlorine uptake in salmon is diet, populations utilizing different feeding areas may accumulate pollutant loads corresponding to their primary feeding areas. This hypothesis was tested by comparing the OC composition in Atlantic salmon from four locations: Lake Vättern (Sweden), Lake Vänern (Sweden), the Baltic Sea (off Denmark), and the River Imsa (Norway). Muscle and liver samples from each fish were analysed for 30 organochlorines (polychlorinated biphenyls, dichlorodiphenyltrichloroethanes, HCHs, hexachlorobenzene, and trans-nonachlor). Principal component analysis on normalized OC concentrations (OC pattern) showed separation of the salmon populations according to location; contaminant patterns were similar for liver and muscle tissue. It is therefore suggested that OC fingerprinting may be a valuable tool in identifying primary foraging areas of salmonids.