DESCRIPTION: The Lahontan cutthroat trout is a member of the Salmonidae (trout and salmon) family. Dark olive backs and reddish to yellowish sides frequently characterize the Lahontans found in stream. The sides of lake-dwelling Lahontans are often silvery. A broad, pinkish stripe may be present.
Body spots are the diagnostic character that distinguishes the Lahontan cutthroat subspecies from the Paiute cutthroat. Paiute cutthroat trout rarely have more than five body spots. Lahontans typically have 50 to 100 or more large, roundish-black spots that cover their bodies evenly and extend onto the head and often to the ventral surface (underside). A secondary distinguishing character is body color. Lahontans typically have a coppery to purplish-pink body color, whereas Paiutes from comparable streams are normally yellowish to light green.
Lahontans bodies are typically elongated, but not greatly flattened. Like other cutthroat trout, they have basibranchial teeth (on the base of the tongue), red slashes under the jaw (hence the name "cutthroat"), and smaller scales than rainbow trout. Lahontans have the highest number of gill rakers (small bony projections on the gills) found in any trout of the genus Oncorhynchus--21 to 28.
Spawning occurs from April through July, depending on stream flow, elevation, and water temperature. Females mature at 3 to 4 years of age, males at 2 to 3 years of age. Consecutive-year spawning by individuals is uncommon. Spawning behavior is similar to other stream-spawning trout. They pair up, display courtship, lay eggs in redds (nests) dug by females and chase intruders away from the nest. Lahontans generally spawn in riffle areas over gravel substrate. Lahontan spawning migrations have been observed in water temperature ranging from 41 to 61°F. Eggs generally hatch in 4 to 6 weeks, depending on water temperature, and fry emerge 13 to 23 days later.
Lahontans living in streams are opportunistic feeders, with diets consisting of drift organisms, typically terrestrial and aquatic insects. In lakes, small Lahontans feed largely on insects and zooplankton and larger Lahontans feed on other fish.
DISTRIBUTION: Lahontan cutthroat trout are native to the Lahontan basin of central Nevada and mid-eastern California. The present distribution is restricted to a few lakes and streams within and outside the historic range. In California, Lahontans occupy less than 5 percent of their historic habitats. The surviving California populations contain about 2000 to 3000 adult fish each. They are found in the following river systems:
- Truckee River Basin: Independence Lake (Sierra and Nevada counties) Independence Creek (Nevada County) Pole Creek (Placer County)
- Carson River Basin: Golden Canyon Creek (Alpine County) East Fork Carson River (Alpine County) Murray Canyon Creek (Alpine County) Poison Flat Creek (Alpine County)
- Walker River Basin: By-Day Creek (Mono County) Murphy Creek (Mono County)
- Yuba River System: Macklin Creek (Sierra County) East Fork Creek (Nevada County) Unnamed tributary to East Fork Creek (Nevada County)
- Stanislaus River System: Disaster Creek (Alpine County) Marshall Canyon Creek (Alpine County)
- San Joaquin River: System: Portuguese Creek (Madera County) Cow Creek (Fresno County)
- Owens River System: O'Harrel Canyon Creek (Mono County)
CLASSIFICATION: Federal Threatened Species (Federal Register 35:16047; October 13, 1970 and 40:29864; July 16, 1975) Note: In 1975, the species was changed form endangered to threatened.
CRITICAL HABITAT: None designated.
Prepared by Endangered Species Divison, Sacramento Fish and Wildlife Office, US Fish and Wildlife Service.