Polychlorinated biphenyls and organochlorines in by-caught harbour porpoises phorpoises Phocoena phocoena and common dolphins Delphinus delphis from irish coastal waters

Concentrations of eleven organochlorine (OC) pesticides and ten individual polychlorinated biphenyls (PCB) in blubber and liver from twelve harbour porpoises Phocoena phocoena and eight common dolphins Delphinus delphis incidentally caught in fishing nets in Irish waters are presented. All animals sampled contained persistent pollutants. Female harbour porpoises had highest concentrations of OC pesticides in blubber and male common dolphins in liver. Harbour porpoises had higher mean concentrations of lindane (121-154ng g^-1 extractable lipid), dieldrin (116-121ng g^-1) and α-BHC (54-128ng g^-1) but common dolphins had greater overall concentrations of DDT (9444-3998ng g^-1). The predominant DDT metabolite was pp-DDE and for the chlordanes was t-nonachlor. Concentrations of ICES 7 PCB (liver-blubber) were similar in both species (4075-7999ng g^-1 in harbour porpoise and 4076-8945ng g^-1 in common dolphins). The sum of ICES 7 PCB in porpoises ranged from 3041ng g^-1 to 12,270ng g^-1 extractable lipid in the blubber of females and from 2911ng g^-1 to 10,429ng g^-1 in males; in common dolphins it ranged from 798ng g^-1 to 11,074ng g^-1 in the blubber of females and from 1555ng g^-1 to 15,883ng g^-1 in males. Contaminant levels were generally similar to those reported from Scotland but lower than reported from Scandinavia. Ratios of DDT to DDE suggest that there are limited new sources of DDT in the Irish marine environment.