DEPURATION OF TOXAPHENE IN LAKE TROUT AND WHITE SUCKERS IN A NATURAL ECOSYSTEM FOLLOWING A SINGLE IP DOSE

Subsamples of lake trout (Salvelinus namaycush) and white suckers (Catastomus commersoni) populations from a small lake (30 ha. surface area) located in the Experimental Lakes Area (ELA) in northwestern Ontario were treated with toxaphene. A total of 31 lake trout and 73 white suckers were given a single I.P. injection of 7 mug.g-1 of toxaphene between May 1988 and September 1988. A further 20 lake trout were injected with 3.5 mug.g-1 of toxaphene between May 1989 and September 1989. Fish were tagged with individually coded tags, weighed, measured and released back into the lake. Fish were recaptured during spring (white sucker) and fall (lake trout) spawning runs in 1989, 1990, 1991 and 1992. Meristic data were taken and a subsample was sacrificed for residue analyses. Depuration of toxaphene from both species was observed with half lives for total toxaphene of 524, 232 and 322 days for white suckers and the two doses in lake trout respectively. Half-lives in lake trout and white suckers for total toxaphene and for two of the more persistent components, octachlorobonane, T2, and nonachlorbornane T12, indicate that significant differences in species ability to eliminate toxaphene. The data also indicate that differences may exist in the half-lives of these components of toxaphene within a species.