Coho Salmon (Oncorhynchus kisutch) and Herring Gulls (Larus argentatus) as Indicators of Organochlorine Contamination in Lake Ontario

Coho salmon (Oncorhynchus kisutch) and herring gulls (Larus argentatus) in the Great Lakes depend to a large extent on alewives (Alosa pseudoharengus) and smelt (Osmerus mordax) for their food. All of these species range widely in the lakes, and therefore provide an integrated measure of levels of organochlorine contaminants in the lakes. Organochlorine residues were determined in herring gull eggs from four eastern Lake Ontario colonies, coho salmon from western Lake Ontario, and pooled alewife and smelt from the stomach contents of the salmon. The mean apparent bioconcentration factor was 2.9 ± 0.7 for accumulation of PCBs, DDE, mirex, photomirex, HCB, dieldrin, and DDD in coho salmon muscle from alewives and smelt. The salmon had a mean weight of 2.4 kg and a mean lipid content of 8.2%. The bioconcentration factor was 50 ± 10 for accumulation of PCBs with more than five chlorines, DDE, mirex, and photomirex in herring gull eggs. PCBs with fewer than six chlorines, HCB, dieldrin, and DDD were concentrat...