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.