ACCUMULATION OF PCBS BY LAKE TROUT (SALVELINUS-NAMAYCUSH) - AN INDIVIDUAL-BASED MODEL APPROACH

To explain the variation in growth and in concentration of polychlorin ated biphenyls (PCBs) among individual fish, an individual-based model (IBM) was applied to the lake trout (Salvelinus namaycush) population in Lake Michigan. The IBM accurately represented the variation in gro wth exhibited by the different age classes of lake trout. Uncertainty analysis of the IBM revealed that mean PCB concentration for the lake trout population was most sensitive to PCB concentration in their prey . The variability in PCB concentration among lake trout individuals wa s not adequately explained by the IBM, unless variation in prey fish P CBs was included in the model. To accomplish this, the simulated lake trout population was divided into subsets subjected to different level s of PCB concentration in the prey fish. Thus, model results indicated that variability in prey fish PCB concentration was an important comp onent of the variation in PCB concentration observed among individual lake trout comprising the Lake Michigan population.