When Crater Lake National Park was established in 1902, native Bull Trout (Salvelinus confluentus) occupied many streams and rivers of southern Oregon's Upper Klamath Basin. Within Crater Lake National Park, Bull Trout occurred naturally in Sun Creek and lower Annie Creek.
Fish Stocking Introduced Brook Trout
Very early in the twentieth century, people began to stock nonnative trout in southern Oregon streams to improve sport fishing. The introduction of nonnative trout, particularly Brook Trout (S. fontinalis), caused a dramatic decline in the distribution and abundance of Bull Trout. Brook Trout compete for resources with Bull Trout and also hybridize with the native species to produce sterile offspring.
Early Bull Trout Conservation
During the late 1980s, surveys by National Park Service scientists determined that Bull Trout no longer occurred in Annie Creek and were limited to a small area near the headwaters of Sun Creek. Brook Trout were found throughout both streams. This finding was typical of the Upper Klamath Basin where at least 40% of historical Bull Trout populations have disappeared. Bull Trout were listed as a threatened species under the federal Endangered Species Act in 1999.