CURRENT STATUS AND TEMPORAL TRENDS IN CONCENTRATIONS OF PERSISTENT TOXIC-SUBSTANCES IN SPORT FISH AND JUVENILE FORAGE FISH IN THE CANADIAN WATERS OF THE GREAT-LAKES

This paper presents a summary of the current status and temporal trend s over the past 15 - 20 years in contaminant levels in sport fish and juvenile forage fish in the Canadian waters of the Great Lakes. Fish c onsumption advisories summarized from the 1995 Guide to Eating Ontario Sport Fish showed that 67% of the 1736 consumption advisories in the Canadian waters of the Great Lakes had no restrictions. In the remaini ng 33% of the advisories, consumption of sport fish was restricted to 4 meals per month or less. Lake Erie had the fewest consumption restri ctions (19%) and Lake Ontario the most (45%). PCBs were the principal contaminants of concern responsible for 47% of the consumption restric tions in the Canadian waters of the Great Lakes and caused the most co nsumption restrictions in each of the Great Lakes except Lake Superior where toxaphene caused 69% of the consumption restrictions. Concentra tions of PCBs in sport fish declined in Lake Huron and Lake Ontario ov er the period 1976-1994. A decline in mirex concentrations in sport fi sh from Lake Ontario was also observed over the same time period. Conc entrations of Hg in sport fish from Lake St. Clair declined over the p eriod 1970-1994, but mercury in sport fish showed no trend over time i n Lake Huron or Lake Ontario over the period 1981-1994. Contaminant le vels in juvenile forage fish collected in 1993 and 1994 at 44 location s in the lower Great Lakes were assessed against wildlife protection g uidelines. Concentrations that exceeded the Forage Fish Contaminant In dex were observed at 17 locations with PCBs being the principal contam inant of concern. PCB concentrations in spottail shiners declined at 1 2 of 16 locations monitored in the lower Great Lakes over the period 1 975-1994.