ORGANOCHLORINE RESIDUES IN HARBOR PORPOISE AND BOTTLE-NOSED DOLPHINS STRANDED ON THE COAST OF SCOTLAND, 1988-1991

The organochlorine (OC) residues, chlorobiphenyls (CBs), DDT and its m etabolites, dieldrin, hexachlorobenzene and technical chlordane mixtur es have been determined in the blubber of harbour porpoise and bottlen ose dolphins from around the north and east coasts of Scotland as a re sult of strandings and bycatches between 1988 and 1991. The concentrat ions of OCs range from some of the lowest values reported at 280 mu-g kg-1 for t-CBs, 145 mu-g kg-1 for t-DDT and 71 mu-g kg-1 for dieldrin to some of the highest values, 23000 mu-g kg-1 for t-CBs, and 10200, m u-g kg-1 for t-DDT. OC levels were correlated with the age and sex of the sample of harbour porpoise and bottlenose dolphins from the Moray Firth area. The study confirms that the concentration of these compoun ds is highly dependent on co-factors of age and sex, and that data fro m single or small numbers of animals may be of limited value in compar ing information on organochlorine residues in mammals within or betwee n regions.