Levels and patterns of PCBs and OC pesticides in harbour and grey seals from the St Lawrence Estuary, Canada

Blubber samples from harbour (Phoca vitulina) and grey seals (Halichoerus g rypus) captured in the St Lawrence Estuary were analysed for PCBs and OC pe sticides. Concentrations of Sigma PCB, Sigma DDT, Sigma CHLOR and mirex wer e higher in harbour than in grey seals, while Sigma HCH and HCB were simila r in the two species. Age vs. concentration plots showed that Sigma PCB, Si gma DDT and Sigma CHLOR concentrations increased with age in males, but pla teaued at sexual maturity in females. Concentrations of Sigma HCH decreased and mirex increased with age for post-weaning animals, regardless of gende r. HCB did not show age-related trends. PCB congener and OC pesticide patte rns varied within harbour seals (based on gender and maturity) and between harbour and grey seals. PCB and OC concentrations in harbour seals were low er than those seen in a sample of significantly older beluga whales. Both s pecies remain in the Estuary year-round. PCB and OC pesticide concentration s were higher in resident harbour seals than in either grey or harp seals t hat visit the Estuary seasonally. PCB and OC pesticide concentrations in ha rbour seals from the Estuary were generally higher than in harbour seals fr om other regions of North America. They were comparable to, or higher than those from the NE Atlantic Ocean and the North Sea, and lower than those fr om the Wadden and Baltic Seas. (C) 1999 Elsevier Science B.V. All rights re served.