The Yellowstone cutthroat trout (Oncorhynchus clarkii bouvieri) is a subspecies of the cutthroat trout (Oncorhynchus clarkii). It is a freshwater fish in the salmon family (family Salmonidae). Native only to a few U.S. states, their original range was upstream of Shoshone Falls on the Snake River and tributaries in Wyoming, also across the Continental Divide inYellowstone Lake and in the Yellowstone River as well as its tributaries downstream to the Tongue River in Montana. The species is also found in Idaho, Utah and Nevada.

The Yellowstone cutthroat trout is a prized game fish. Fly fishing is the most popular angling method because the subspecies feeds primarily on insects as adults, unlike introduced brown trout which are more piscivorous. Most varieties of cutthroat trout are less wary and selective than other trout species, thus angler success rates are higher.

Ref: Yellowstone Cutthroat Trout