Spatial patterns in PCB concentrations of Lake Michigan lake trout

Most of the PCB body burden in lake trout (Salvelinus namaycush) of the Gre at Lakes is from their food. PCB concentrations were determined in lake tro ut from three different locations in Lake Michigan during 1994-1995, and la ke trout diets were analyzed at all three locations. The PCB concentrations were also determined in alewife (Alosa pseudoharengus), rainbow smelt (Osm erus mordax), bloater (Coregonus hoyi), slimy sculpin (Cottus cognatus), an d deepwater sculpin (Myoxocephalus thompsoni), five species of prey fish ea ten by lake trout in Lake Michigan, at three nearshore sites in the lake. D espite the lack of significant differences in the PCB concentrations of ale wife, rainbow smelt, bloater, slimy sculpin, and deepwater sculpin from the southeastern nearshore site near Saugatuck (Michigan) compared with the co rresponding PCB concentrations from the northwestern nearshore site near St urgeon Bay (Wisconsin), PCB concentrations in lake trout at Saugatuck were significantly higher than those at Sturgeon Bay. The difference in the lake trout PCB concentrations between Saugatuck and Sturgeon Bay could be expla ined by diet differences. The diet of lake trout at Saugatuck was more conc entrated in PCBs than the diet of Sturgeon Bay lake trout, and therefore la ke trout at Saugatuck were more contaminated in PCBs than Sturgeon Bay lake trout. These findings were useful in interpreting the long-term monitoring series for contaminants in lake trout at both Saugatuck and the Wisconsin side of the lake.