Cutthroat Trout are the indigenous trout of the tributaries that drain western Rocky Mtns and the Eastern Sierras. Sea run Cutthroats are also found in some tributaries of the Pacific Ocean from northern California to Washington State. They are closely related to the Coastal Rainbow Trout and sometimes hybridize with them. They are a popular gamefish, particularly with fly fishermen. Cutthroat trout usually inhabit and spawn in small to moderately large, clear, well-oxygenated, shallow rivers with gravel bottoms. In free flowing streams they are commonly found in the 10-15 inch range, but in lakes they can reach lengths of over 30 inches.