Long‐term effects of toxaphene and depuration in lake trout and white sucker in a natural ecosystem

Abstract

AbstractIndividuals from lake trout (Salvelinus namaycush) and white sucker (Catastomus commersoni) populations in a small lake located in the Experimental Lakes Area in northwestern Ontario, Canada, were treated with single intraperitoneal injections of toxaphene (7 μg/g or 3.5 μg/g) to better understand its potential effects on fish in their natural environment. Wild fish were captured, tagged, weighed, measured, injected with toxaphene, and released back into the lake. They were subsequently recaptured during spring (white sucker) and fall (lake trout) for the next 5 years. In years 2 and 3 following treatment, fish were spawned to assess reproductive success and survival of their offspring. Survival of adult lake trout and white sucker treated with toxaphene was decreased compared with controls. No changes in growth were evident in either species due to toxaphene treatment. No differences occurred in fertilization rate, total survival, or incidence of deformities in eggs and fry from female lake trout treated with toxaphene. Fertilization rates and survival to swim‐up of white sucker eggs and fry from females treated with toxaphene decreased relative to controls in both years. Maternal transfer of toxaphene from female to eggs was observed in both white sucker and lake trout; levels in eggs were much lower than in treated females but were still significantly higher than in controls. Residue analyses showed that depuration of toxaphene was slower than expected, with estimated half‐lives of 314 and 793 d in lake trout and white sucker, respectively.