The cutthroat trout (Oncorhynchus clarki) is a species of salmonid native to cold-water tributaries of the Pacific Ocean, Rocky Mountains and Great Basin in North America. As a member of the genus Oncorhynchus, it is one of the Pacific trout, a group that includes the widely distributed rainbow trout. Cutthroat trout are popular gamefish, especially among anglers who enjoy fly fishing. The common name "cutthroat" refers to the distinctive red coloration on the underside of the lower jaw. The specific name clarki was given to honor explorer William Clark, coleader of the Lewis and Clark Expedition. Cutthroat trout usually inhabit and spawn in small to moderately large, clear, well-oxygenated, shallow rivers with gravel bottoms and clear, cold, moderately deep lakes. They are native to the alluvial or freestone streams that are typical tributaries of the Pacific basin, Great Basin and Rocky Mountains. They are spring spawners and naturally hybridize with rainbow trout to produce fertile cutbows. Some populations of the coastal cutthroat trout (O. c. clarki) are semianadromous. Several subspecies of cutthroat are currently listed as threatened in their native ranges due to habitat loss and introduction of non-native species. Two subspecies, O. c. alvordensis and O. c. macdonaldi, are considered extinct. Cutthroat trout are raised in hatcheries to restore native populations, as well as stock non-native lake environments to support angling. The cutthroat trout type species and several subspecies are the state fish in seven western U.S. states. Subspecies in Oregon include the Alvord cutthroat trout, Whitehorse Basin cutthroat trout, and the Humboldt cutthroat trout.