| Abstract
| - The Great Lakes Strategy 2002 establishes the long-termgoal that all Great Lakes fish should be safe to eat withoutrestriction. As an indicator of progress toward that goal,the Strategy specifies that lake trout PCBs will decline 25%from 2000 to 2007. We estimated the plausibility ofachieving this near-term goal by examining a time−seriesof Lake Michigan lake trout PCB concentrations from1972 to 2000. We used two different Bayesian approaches,Bayesian model averaging (BMA) and dynamic linearmodels (DLM), to model the trajectory of these historicaldata and forecast concentrations through 2007. Bothapproaches indicate that the probability of a 25% reductionfrom 2000 to 2007 is negligible. The most likely lake troutPCB declines predicted by the BMA and DLM over this timeperiod are 6.8% and 8.9%, respectively. Our resultssuggest that declines in lake trout PCBs will be in therange of 5−10% assuming conditions similar to recent years.This rate of decline will be difficult to discern withoutadequate data collection. If sufficient data are not gatheredto document further declines, then the relaxation of laketrout consumption advisories is indeed a long-term prospect.
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