SAT-732 Historical Occurrence of Intersex in Largemouth Bass (Micropterus Salmoides) and Smallmouth Bass (Micropterus Dolomieu)

Abstract The widespread occurrence of gonadal intersex (presence of testicular oocytes) has been recently reported in populations of Largemouth Bass (Micropterus salmoides) and Smallmouth Bass Micropterus dolomieu) from populations across North America. To evaluate the historical occurrence of intersex in bass species, gonads were examined visually and histologically from Largemouth Bass and Smallmouth Bass from museum specimens collected from 16 States. These fishes were collected between 1823-1965, before the widespread discharge of estrogenic chemicals to surface waters via wastewater effluents. All females examined had normal ovaries. Intersex gonads were identified in 17.8 % of male Largemouth Bass, and in 14.2% of male Smallmouth Bass. The intensity of testicular oocytes in some males was as great as observed since 2000. These results indicate that the occurrence of this form of intersex in these bass species is not a recent phenomenon.