Bull Trout (Salvelinus confluentus) belong to a genus of fish collectively known as char. The group includes Arctic Char (S. alpinus), White-Spotted Char (S. leucomaenis), Dolly Varden (S. malma), Lake Trout (S. namaycush), and Brook Trout (S. fontinalis).
Bull trout are native to western North America from northern California and Nevada through areas of Canada. Brook Trout are native to eastern North America, but have been stocked in rivers and streams throughout the western United States, including many within the range of Bull Trout.
Bull - Brook Trout Hybrids
Bull Trout and Brook Trout are two distinct species, but when they co-occur, they often spawn together and produce hybrid offspring. Genetic evidence from hybrid populations suggests that hybrids are almost always sterile. In other words, hybrids cannot produce offspring of their own. Therefore, when Bull Trout spawn with introduced Brook Trout, their genes are not passed on to future generations. Hybridization with Brook Trout has caused dramatic declines of Bull Trout in many streams including Sun Creek.