SPATIAL AND TEMPORAL VARIATIONS IN CHEMICAL CONTAMINATION OF AMERICANEELS, ANGUILLA-ROSTRATA, CAPTURED IN THE ESTUARY OF THE ST-LAWRENCE-RIVER

Levels of polychlorinated biphenyls (PCBs), mirex, and pesticides were 10-100 times higher in migratory adult American eels, Anguilla rostra ta, sampled at Kamouraska, Quebec, in 1990 than in eels from an uncont aminated reference tributary; concentrations in eels within the estuar y varied little among sites. In contrast, mercury levels were the same at estuarine and reference sites, suggesting natural sources or atmos pheric deposition of mercury. Dioxins, furans, and polynuclear aromati c hydrocarbons were virtually absent at all sites. During the 7 wk of migration, levels of PCBs, mirex, and pesticides in eels increased, wh ile mercury did not. Since 1982, levels of PCBs and mirex have decline d by 68 and 56%, respectively, and the percentage of eels exceeding hu man health guidelines for PCBs and mirex was about twofold lower in 19 90 than in 1982. Levels of other pesticides have also declined, except that dieldrin is unchanged since 1982. While chemical concentrations are declining, levels of specific, highly toxic PCB congeners are suff iciently high that eel consumption by beluga whales (Delphinapterus le ucas) is still likely to be hazardous. The hazard to the eels themselv es is unknown due to a scarcity of toxicity data, but the highest conc entrations of chemicals were observed in gonads.