Concentrations of organochlorines in lake trout (Salvelinus namaycush), burbot (Lota lota), and northern pike (Esox lucius) from subarctic lakes in Yukon Territory varied significantly among populations, and these differences could not be ascribed to size or age of the fishes. For each species, lipid content and trophic positioning (measured by stable nitrogen isotope ratios; d15 N) were significantly different across populations, and the latter differences could not be attributed to variable d15 N at the base of the food webs. Across lakes, concentrations of åPCB, åDDT, chlorinated bornanes (CHB), chlordane ( åCHL), chlorobenzenes ( åCBZ), and hexachlorocyclohexane ( åHCH) in lake trout and northern pike muscle and burbot liver were significantly related to their d15 N. The slopes of these log organochlorine Œ d15 N relations were greatest for more lipophilic contaminants ( åPCB, åDDT, CHB), indicating that they bioaccumulate to a greater degree than lesslipophilic contaminants. Lipid significantly predicted organochlorine concentrations both within and among populations oflake trout, and the slopes did not vary significantly with contaminant lipophilicity. Among-lake differences in åHCH in trout muscle were removed by adjusting concentrations by the covariate lipid. Lipid-adjusted concentrations of CHB, åPCB, åDDT, åCHL, and åCBZ in lake trout remained significantly different between lakes, and these differences were attributed to variable food chain lengths.
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