Organochlorine compounds in trout from lakes over a 1600 meter elevation gradient in the Canadian Rocky Mountains

The effect of altitude on the concentration and composition of organochlorine compounds (OC) in trout was investigated along an elevation gradient of 1600 m in the Canadian Rocky Mountains. The eight lakes sampled were within or adjacent to national parks in sparsely settled parts of Alberta and British Columbia, thus contaminants were assumed to have derived from long-range atmospheric transport. Concentrations of several OCs in trout increased significantly with lake elevation. In general, these increases were most pronounced for the higher K-ow pesticides (i.e., dieldrin and DDTs), and less pronounced for lower K-ow pesticides (e.g., HCHs and HCB) and PCBs. Most OC concentrations in trout were inversely correlated with fish growth rate. Growth rate explained more of the variation for some OCs (particularly PCBs) than lake elevation. Differences in trophic position (indicated by delta N-15) explained little of the variation in OC concentration in comparison to other factors such as lake elevation and the growth rate and age of trout. Using principal component analysis (PCA), we identified the importance of lake elevation and octanol/water partition coefficient (K-ow) to the OC composition of trout.