TWENTY-FOURTH ANNUAL EASTERN FISH HEALTH WORKSHOP Royal Pavilion Resort, Atlantic Beach, NC MARCH 9-11, 1999 Reproductive Problems In Yellow Perch From Lake Michigan Vicki S. Blazer1, C. Densmore1, and C.S. Schrank2 1National Fish Health Research Laboratory, USGS/BRD, 1700 Leetown Road, Kearneysville, WV 25430; 2Bureau of Fisheries Management and Habitat Protection, Wisconsin Department of Natural Resources, Madison, WI 53707 Yellow perch indices from the Green Can Reef, Lake Michigan, suggest declines in the yellow perch population since the late 1980's with potential year class failures. Wisconsin DNR initiated a study to obtain information on the quality of gonads and exposure of these fish to pollutants. Reproductive and toxicological endpoints were examined in yellow perch collected from Lake Michigan and a reference site, Lake Mendota, WI, in Winter 1996, Spring 1997 and Fall 1997. These included gonadosomatic and hepatosomatic indices; staging of gonads; histopathology of gonads; plasma estrogen, testosterone and vitellogenin; liver mixed function oxidase activity; and selected chemical concentrations. Analyses suggest that yellow perch from Lake Michigan are exposed to higher levels of p,p' DDE and PCBs and have higher EROD activity when compared to yellow perch from Lake Mendota. Most interesting was the high prevalence (approximately 30%) of male gonads containing testicular tumors. A low incidence of leiomyomas was observed, however, most of the tumors appear to be germ cell tumors (seminomas). Tumor descriptions and other histologic findings will be presented. Return to 24th Annual Eastern Fish Health Workshop Return to Leetown Science Center Home Page