TEMPORAL AND AGE-RELATED TRENDS IN LEVELS OF POLYCHLORINATED BIPHENYLCONGENERS AND ORGANOCHLORINE CONTAMINANTS IN LAKE ONTARIO LAKE TROUT (SALVELINUS-NAMAYCUSH)

Concentrations of 21 organochlorine contaminants (OCs) and 61 polychlo rinated biphenyl (PCB) congeners were determined in archived samples o f whole lake trout (Salvelinus namaycush), age 4 fears, collected year ly from eastern Lake Ontario between 1977 and 1993. Temporal trend dat a show decreases in all parameters analyzed in samples collected from 1977 to 1993. OC levels declined between 60 and 90% from 1977 to 1993. Trends of total PCB and PCB congeners concentrations were variable, b ut overall levels declined 80% between 1977 and 1993, from 9.060 ng/g in 1.977 to 1.720 ng/g in 1993. Reanalyzed total PCB levels vary rando mly from the historical total PCB levels, but overall exhibit a much s moother trend. The means of the two sample sets were not significantly different at a probability of 0.05. Lake trout aged from 3 to 9 years old, collected in 1988, were analyzed to determine changes in contami nant concentrations with age. OC levels on average increased three-fol d from 3-year-old lake trout up to 9-year-old lake trout. Total PCB le vels increased from 2.760 ng/g in 3-year-old lake trout to 8.000 ng/g in 9-year-old lake trout, and PCB congener concentrations showed simil ar increases over the same age range. Lipid content declined 30% betwe en 1977 and 1993, but lipid normalizing the data did not change the ob served trends.