The purpose of this study was to observe growth, survival, and spatial distribution of the Florida largemouth bass (Micropterus salmoides floridanus) and of the northern subspecies (M. s. salmoides) in an Oklahoma reservoir thermally enriched by a heated effluent from an electrical generating plant. Hatchery-reared fingerlings of both subspecies were stocked in 1974 and 1975 after they were marked with either fluorescent pigments sprayed into the dennis, or, with magnetized metal injected into the nasal cartilage. Growth of the Florida subspecies was greater than that of the northern subspecies in both years of the study, but the difference was significant only in 1975. Overwinter survival of Florida bass was lower than that of northern bass in both years, and was especially low (1.6%) during the winter of 1974-75, when lake temperatures were lower than during the winter of 1975-76. Spatial distribution of Florida bass during the winter of 1974-75 was largely limited to the vicinity of the thermal plume.