Chlorinated hydrocarbons in fish-eating birds wintering in the Gdańsk Bay, 1981–82 and 1982–83

Seventy-four samples of adipose fat of 10 species of fisheating birds commonly wintering in Gdańsk Bay and one of little auk, a rare species in this area, have been analysed for residues of HCB, ΣBHC, ΣDDT and PCBs. Auks (guillemot, black guillemot and razorbill), which probably stay a whole year in the Baltic area, contained in their fat twice the level of PCBs as mergansers, and 5–6 times as much as in divers and grebes—birds which stay in the sea mainly after the breeding season. ΣDDT levels were somewhat higher but comparable in auks and grebes, and lower in mergansers and divers. ΣBHC and HCB levels were 3–4 times and 5–10 times higher, respectively, in auks than in birds from other families studied. When comparing residue levels found in adipose fat of birds taken during the wintering seasons of 1981–1982 and 1982–1983 with those taken in 1975–1976 or 1980–1981, an initially rapid, but in recent years a rather slow decline in ΣDDT level is detectable for grebes, mergansers and divers, and in the case of PCBs the residue levels fell slightly. In auks, the ΣDDT residue level fell by half, but remains rather stable in recent years, while there are only minor fluctuations in the residue level of PCBs.