THE EFFECTS OF THE BRAER OIL-SPILL, SHETLAND ISLES, SCOTLAND, ON P4501A IN FARMED ATLANTIC SALMON (SALMO-SALAR) AND THE COMMON DAB (LIMANDA-LIMANDA)

This paper describes the response of two fish species, the Atlantic sa lmon (Salmo salar) and the common dab (Limanda limanda) to the oil spi lled from the Braer tanker which grounded on the southern tip of Shetl and, Scotland, on 5 January 1993. Both the immediate sublethal effects and the long-term response to the oil which accumulated in sediments around the Shetland Isles, Scotland, are examined. The primary, respon se measured was the induction of detoxification enzymes and the relati onship of the levels or activities of these enzymes to the concentrati on and distribution of aromatic hydrocarbons measured in sediments, wa ter and fish. The results show that, immediately following the spill, there was a marked induction of Cytochrome P4501A enzymes in salmon, i ndicative of exposure to bioavailable aromatics. In dab there was evid ence of induction at some sites in January 1993 immediately following the spill brit, subsequently,, no induction has been observed in fish caught in the vicinity of Shetland despite the very high concentration s of oil measured in sediments at some locations. This would indicate that the polyaromatic hydrocarbons in these sediments are unlikely to be directly, bioavailable to fish. The effect of the oil spill on hepa tic pathology in dab was investigated and shells that pathology, predi ctive of neoplasia, such as basophilic foci and vacuolation, were obse rved in fish from the most contaminated sites in 1994 but not in 1993. The incidence of this pathology appeared to correlate with the degree of contamination at the sites, but additional studies are required to establish whether this was a consequence of the initial impact and ex posure from waterborne oil at the time of the spill or whether it was die to the continued exposure to oil from the sediments. (C) 1998 Else vier Science Ltd. All rights reserved.