The Pyramid Lake Trout

Of all American wild trout, few have suffered a worse decline than the wild trout of Pyramid Lake. Set in the desert regions of western Nevada, Pyramid Lake is one of a series of lakes, including Walker Lake on the Walker River, Cascade, Fallen Leaf and Summit Lakes, and Lake Tahoe on the California-Nevada border, that hold or used to hold stocks of the cutthroat subspecies Salmo clarki henshawi.

In Ice Age times, all of these lakes together with their river systems were part of a massive lake called Lake Lahontan: hence the name Lahontan cutthroat is given to the form of trout native to this region. It has been estimated that, at its maximum size some 25,000 years ago, Lake Lahontan covered about 8500 square miles with depths of up to 875 feet. As the climate warmed the lake shrank to leave the present smaller remnants and feeder streams surrounded by desert.

Some authorities consider that the cutthroats inhabiting the streams that drain into the eastern side of the ancient Lake Lahontan basin constitute a separate variety (the subspecies name Salmo clarki humboltensis has been suggested for these); but the differences between the varieties are fairly trivial.

Until the early years of this century, the Pyramid Lake cutthroats were famous for their size. The record is for a 41lb fish taken from the lake by John Skimmerhorn in July 1925; and some evidence exists that Indians and commercial netsmen formerly caught much bigger fish, possibly as large as 60lbs. In the last natural spawning run of the original Pyramid Lake stock, in 1938, the average size of trout was reported as 20lbs.

Apart from Lake Tahoe, none of the other lakes of the Lahontan basin ever produced fish of such size. This has been explained by the fact that Pyramid Lake trout are piscivorous, and had an abundant fish-food source in the form of tui chub; at the same time they had the genetic constitution that enabled them to grow to large size. Other lakes, with the Lahontan cutthroat but without tui chub, have been stocked with small fish; the trout have fed on them but never attained the size of the original Pyramid Lake trout.

The stocks of large trout attracted commercial netsmen. Between October 1888 and April 1889 almost 100 tons of Lahontan trout were taken from the Pyramid and Tahoe Lake systems and shipped for export. It is not clear just how badly this exploitation damaged the native trout of Pyramid Lake; but overfishing certainly caused the demise of the Tahoe and Walker Lake stocks. However, the Pyramid Lake trout were doomed later by the construction of the Derby Dam on the Truckee River: a major feeder stream of Pyramid Lake and the main. spawning stream for the Pyramid Lake cutthroat.

The dam was completed in 1905. It diverted most of the Truckee River flow to the Carson River, with the consequence that the Truckee virtually dried up: the last spawning run was in 1938. The shallow Lake Winnemucca, that shared the Truckee River with Pyramid Lake, soon disappeared. And the level of Pyramid Lake fell by 70 feet in 50 years.

The cutthroats of the other Lahontan lakes and river systems disappeared when the waters were artificially stocked with other forms of trout, notably rainbow. The wild varieties were lost either through failure to compete with the foreign trout, or through interbreeding.

Though the pure Lahontan cutthroat was once thought extinct, remnant populations have been discovered. These have been propagated artificially and are being used to restock waters that held this variety of trout, after the non-native fish have been removed. However, Pyramid Lake and Lake Tahoe are unlikely ever to produce trout of the size they once did; and they will never again produce spawning runs where the trout average 20 lbs.