PERSISTENT ORGANOCHLORINES IN BELUGA WHALES (DELPHINAPTERUS-LEUCAS) FROM THE ST-LAWRENCE-RIVER ESTUARY .2. TEMPORAL TRENDS, 1982-1994

Blubber samples from 16 dead beluga whales (Delphinapterus leucas) col lected during 1993-1994 in the St Lawrence River estuary were analysed for PCB congeners and other persistent organochlorines (DDT-group, ch lorinated bornanes (toxaphene, CHB), chlordane (Sigma CHL), hexachloro -cyclohexanes (Sigma HCH), chlorobenzenes (Sigma CBz), tris(p-chloroph enyl methane (TPMe) and mirex). Concentrations and relative proportion s of major individual organochlorine components were within the same r ange as previous results for this population. Temporal trends were stu died by combining the results with data from the analysis of 44 sample s (1986-1990) and (for DDT and Aroclor PCBs only) with 20 samples (198 2-1985) reported by Martineau et al., 1987. Results were lipid normali zed and then age-adjusted by an ANCOVA model. Significant relationship s between age and concentrations of most organochlorine groups were fo und for females but not for males. Significant declines were observed in Sigma DDT, and Aroclor PCBs (1.5- and 1.9-fold, respectively) in ma les between the 1982-1985 and 1993-1994 collection periods. Significan t declines were also observed for Sigma HCH and Sigma CBz in males bet ween 1986-1988 and 1993-1994. Mean concentrations of CHBs were signifi cantly higher in 1993-1994 than in earlier years while dieldrin, Sigma CHL, mirex, and TPMe showed no trend. Declines in concentrations of m ajor organochlorine groups were not observed in females possibly becau se of higher year to year, and within year, variation. The temporal tr end in DDT and PCB concentrations in male beluga blubber paralleled tr ends in seals, eels, and seabirds in the St Lawrence estuary observed during the 1980s. Copyright (C) 1996 Elsevier Science Ltd