Histopathologic lesions in cutthroat trout (Salmo clarki) exposed chronically to the insecticide endrin.

Pathologic conditions associated with exposure to endrin were found in the gill, liver, pancreas, brain and gonad of cutthroat trout. Edema, hemorrhage and possibly intracapillary congestion characterized gill damage after exposure to the highest level of endrin in bath. Hepatic lesions in young trout were of a type frequently described as preceding the development of hepatomas in nutritionally deficient fish. The increased incidence and severity of hepatic degenerative changes observed in fish exposed to high levels of endrin suggested nutritional deficiency enhanced by exposure to endrin. Marked hyperplasia of pancreatic islets and irregular, atypical oocytes were observed after exposure to high endrin levels.