Effect of sublethal pentachlorophenol on early oogenesis in maturing female rainbow trout (Salmo gairdneri)

Female rainbow trout (Salmo gairdneri) were exposed to sublethal levels of purified pentachlorophenol (99 + % PCP) and the effects upon ovarian development were assessed. A significant increase in atresia among Stage 2 oocytes (Balbiani stage), was recorded in females exposed for 18 days to 22 and 49 g/L during July 1984. The number of viable Stage 2 oocytes, relative to controls, were reduced to 52% and 19% at 22 and 49 g/L, respectively, significantly reducing the number of viable oocytes available to complete oogenesis. A similar response under identical conditions was not observed in December 1983. This is the first report demonstrating a significant effect on oogenesis following sublethal PCP exposure during early summer.