We investigated the organochlorine accumulation (p,p′-DDE and ∑PCB) and stable isotope ratios (N and C) in a migrating salmon (Salmo salar) population in the Baltic Sea. ∂15N in the entire population ranged from 11.7 to 13.7‰ and ∂13C ranged from −22.0 to −19.6‰. In the entire population, ∂15N were weakly related to p,p′-DDE and ∑PCB concentrations (r2=0.20 and 0.14, respectively). However, lipid content was a better predictor of organochlorine (OC) concentrations (r2=0.48 and 0.50, respectively). Lipid adjusted ∑PCB concentrations were not related to ∂15N, and lipid adjusted p,p′-DDE concentrations were only weakly related (r2=0.12). We divided the salmon population into three groups representing reproductive strategies: small males <5 kg (SM); large males >5 kg (LM); and females (F). ∂15N varied between the three reproductive strategies. The mean ∂15N for SM was 12.7±0.3‰, for F was 12.9±0.3‰, and for LM equalled 13.2±0.3‰. Lipid adjusted OC concentrations differed between the three reproductive strategies, with the females having the highest concentrations. We conclude that the ∂15N varied between reproductive strategies indicating differences in prey choice, but the lipid content was better able to predict OC concentrations than the trophic position of the salmon.
Subject classification (UKÄ)
- Environmental Sciences