(Oncorhynchus clarkii lewisi)
Physical Characteristics: Small trout with a rosy underside and dark speckled tail, averaging 8-12 inches long. These fish have teeth under the tongue, on the roof of the mouth, and in the front of the mouth. They can be distinguished from rainbow trout by the red, pink, or orange marking underneath the jaw, hence the name “cutthroat.”
Diet: Aquatic invertebrates and insects.
Habitat: Prefers cold, clear streams for spawning with deep, sheltered pools in which to winter.
Range: Westslope are native to north-central Idaho’s and British Columbia’s upper Columbia River system and northern tributaries of the Snake River. In Clearwater Country, several streams have established catch-and-release regulations that have helped enhance and protect the population, such as Cayuse Creek, Kelly Creek and their tributaries, along with White Sand Creek, Weir-Post Office Creek, and others.
Reproduction: Cutthroat require flowing water to spawn successfully in optimal temperatures of 40 to 49 degrees F. Peak spawning activity can occur as late as mid-October, with spawning completed by early November. Most spawn annually after reaching maturity. They can successfully spawn over a variety of river bottoms.
Threats: Pure Westslope-cutthroat have been extirpated throughout most of their historic range and existing populations are in danger of habit destruction from logging, road-building, grazing, mining, urban development, agriculture and dams, and introduction of and hybridization with non-native hatchery species. Fortunately, conservation campaigns have encompassed a range of support from scientists, conservationists, historians, sport fishing communities, and representatives of both Native American and ranching communities. The fish is officially classified as a species of “special concern.”
Miscellaneous: The Westslope-cutthroat trout is an indicator species of the health of the entire ecosystem. It requires pure, cold water for survival, secure connected habitat (tributaries and main stems), and protection from introduced nonnative fish. When these requirements are not met, the number of individuals plummets. The subspecies is also in danger of hybridization and may in fact disappear from the Northern Rockies without a region wide, long-term effective protection and recovery effort. The fish has the trinomial name Oncorhynchus clarkii lewisi, in honor of Lewis and Clark, who discovered the subspecies at “Great Falls of the Missouri”, in what is now Montana during their 1805-06 expedition.