Lahontan cutthroat trout
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Order: Salmoniformes
Family: Salmonidae
Species: Oncorhynchus clarki (Cutthroat Trout)

[Photo] Lahontan Cutthroat Trout (Oncorhynchus clarki henshawi) at Pyramid Lake, Nevada in April 2007. Size: 6.5 lb./26 in. Photo by Rhalden. License: public domain.

Lahontan cutthroat trout (Oncorhynchus clarki henshawi) is the largest cutthroat trout subspecies, and the state fish of Nevada. It is native to the drainages of the Truckee River, Humboldt River, Carson River, Walker River, Quinn River and several smaller rivers in the Great Basin of North America. These were tributaries of ancient Lake Lahontan during the ice ages until the lake shrank to remnants such as Pyramid Lake and Walker Lake about 9,000 years ago, although Lake Tahoe -- from which the Truckee flows to Pyramid Lake -- is still a large mountain lake.

Lahontan cutthroats evolved into a large (up to 1 meter) and moderately long-lived predator of chub, suckers and other fish growing as long as 30 or 40 cm. The trout was able to continue its predacious life history in the larger remnant lakes where prey fish continued to flourish, but upstream populations were forced to adapt to eating smaller fish and insects. Some experts consider O. c. henshawi in upper Humboldt River and tributaries to be a separate subspecies, adapted to living in small streams rather than large lakes.

The Lahontan cutthroats of Pyramid Lake were of considerable importance to the Paiute tribe at Pyramid and Walker Lakes. They and Cui-ui -- a sucker found only in Pyramid Lake -- were dietary mainstays and were used by other tribes in the area. During the 19th century and early 20th centuries, Lahontans were caught in tremendous numbers and shipped to towns and mining camps throughout the West; estimates have ranged as high as 1,000,000 pounds annually between 1860 and 1920.

American settlement in the Great Basin nearly extirpated these remarkable fish. A dam in Mason Valley blocked spawning runs from Walker Lake. By 1905 Derby Dam on the Truckee River below Reno interfered with Pyramid Lake's spawning runs. A poorly designed fish ladder washed away in 1907, then badly-timed water diversions to farms in the Fallon, Nevada area stranded spawning fish and desiccated eggs below the dam. By 1943 Pyramid Lake's population was extinct. Lake Tahoe's population was extinct by 1930 from competition and inbreeding with introduced Rainbow Trout, predation by introduced Lake trout, and diseases introduced along with these exotic species.

Pyramid and Walker Lakes have been re-stocked with fish captured in Summit Lake (Nevada), and those populations are maintained by fish hatcheries. Unfortunately the Summit Lake strain does not live as long or grow as large as the original strain of fish. However fish believed to have been stocked almost a century ago from the Pyramid Lake strain were discovered in a small stream along the Nevada-Utah border, and may eventually be used to restore the original strain.

Upstream populations have been isolated and decimated by poorly-managed grazing and excessive water withdrawals for Irrigation, as well as by hybridization and competition. They were classified as an endangered species between 1970 and 1975, then the classification was relaxed to threatened species.

Because it tolerates water too alkaline for other trout, Lahontan cutthroats are stocked in alkaline lakes outside its native range, including Lake Lenore (alternately Lenore Lake) in central Washington and Lake Mann in Oregon's Alvord Desert east of Steens Mountain.

The record size cutthroat trout was a 41-pound Lahontan caught in Pyramid Lake, however there is anecdotal and photographic evidence of even larger fish from this lake.

http://en.wikipedia.org/wiki/Lahontan_cutthroat_trout

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