'Extinct' Trout Run Spawns For First Time In 76 Years

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Fisheries biologist Corene Luton measures a Lahontan cutthroat trout as it moves through the fish passage facility at Marble Bluff Dam, Nevada | Photo: USFWS/Flickr/Creative Commons License

Great news from the Truckee River: Pyramid Lake's population of Lahontan cutthroat trout has been seen spawning in the river for the for the first time since 1938. And it's only due to a lucky break that the Pyramid Lake population of cutthroats hasn't been extinct since then.

The Lahontan cutthroat trout, Oncorhynchus clarki henshawi, is named for the patch of bright red that appears under its chin during spawning season. It once swam in lakes and streams all up and down the east side of the Sierra Nevada. Pyramid Lake's population, which provided early 20th-century anglers with record-breaking catches weighing up to 41 pounds, ranged from that brackish desert lake north of Reno all the way up the 121-mile-long Truckee River to Lake Tahoe.

But overfishing and introduced competitors like the Mackinaw eliminated the Lahontan cutthroat from Tahoe by the mid-1930s, and dam-building on the river's lower reaches above the point where it flows into Pyramid Lake took away too much spawning habitat for the fish to survive without help. By 1944, Pyramid Lake Lahontan cutthroat were gone from Pyramid Lake.

But as it happens, someone planted a few Pyramid Lake cutthroats in a stream in the Pilot Mountains 400 miles away near the Utah border. They did well there, and after genetic testing done by the U.S. Fish and Wildlife Service proved the Pilot Peak cutthroats definitely descended from the Pyramid Lake population, USFWS planted some of them in Pyramid Lake in 2006.

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This April, biologists from the Pyramid Lake Paiute Tribe, on whose reservation the 188 square mile lake sits, noticed spawning nests being dug in the gravel of the Truckee River below Marble Bluff Dam. Tests showed the trout digging those nests were indeed Pyramid Lake Lahontan cutthroat, making this spring the run's first spawn since 1938. Since April, as many as 89 fish have spawned in the short stretch of river below the dam.

Across its range, the Lahontan cutthroat is listed as Threatened under the federal Endangered Species Act. In other streams across its range, the Lahontan cutthroat is vulnerable to low flows and too-warm water due to water diversions for agriculture and residential use. It's also threatened by non-native trout species planted for anglers' enjoyment: lake trout eat the fish or their eggs, while rainbow trout interbreed with cutthroats, giving rise to hybrids called "cutbows."

A couple of miles of spawning habitat is admittedly meager compared to the 121 miles of the historic Truckee. In the 1970s a bypass channel, the "Pyramid Lake Fishway," was built to provide access to the river above Marble Bluff Dam for cutthroats and the lake's other listed fish, the cui-ui. Declining lake levels stranded the outlet of the Fishway, making it unusable by fish. A 2000 feasibility study for reconfiguring the Pyramid Lake Fishway so that it might actually be accessible to Pyramid Lake fish would seem to have had little effect, if Google Maps satellite views of the fishway are any indication. The outlet remains bone dry and unconnected to the lake.

Still, it's cause for celebration. Three generations of trout fans have grown up knowing that Pyramid Lake's original cutthroat trout were gone forever. Now that turns out to have been temporary. Hooray!

For ongoing environmental coverage in March 2017 and afterward, please visit our show Earth Focus, or browse Redefine for historic material.
KCET's award-winning environment news project Redefine ran from July 2012 through February 2017.

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