Endocrine disruption and altered gonadal development in wild white perch (Morone americana) from the lower Great Lakes region

High prevalences of gonadal intersex have been observed in wild fish populations in areas impacted by domestic and industrial effluents. In this study, fish were collected in 1998 in the Cootes Paradise region of Hamilton Harbour in western Lake Ontario to determine whether gonadal abnormalities, including intersex, were present in young of the year (YOY) fish. The gonads of seven different species of fish were examined histologically and no abnormalities were observed in six of these species. However, intersex (i.e. testis-ova) gonads were observed in 8 of 16 male white perch (Morone americana ) collected in this survey. Subsequently in 1999 and 2000, white perch estimated to be YOY to approximately two years of age were collected from Cootes Paradise and from two other sites in the lower Great Lakes region. The cause of gonadal intersex in white perch is not known. However, since intersex was not observed in hatchery-reared white perch or in white perch from Deal Lake, New Jersey, the induction of intersex may take place through exposure to endocrine disrupting substances (EDSs) in contaminated regions of the lower Great Lakes. (Abstract shortened by UMI.)...