Lahontan Cutthroat Trout swims back from extinction; population in the hundreds of thousands
More than 150 years ago, the waters of Lake Tahoe, the Truckee River and Pyramid Lake were dominated by a single apex predator.
Due to dams, overfishing, introduction of nonnative fishes, and degraded habitat, the Lahontan Cutthroat Trout had disappeared from those native waters by the early 1940s.
Then in the 1970s, the Lahontan Cutthroat Trout, with their distinguishing red to orange slash mark at the throat, was identified by fish biologist Robert Behnke in a small, remote stream in the Pilot Peak area near the Nevada-Utah border.
“We don’t have any specific information about how they might of ended up in that really isolated small stream. The population in Pyramid Lake, before it disappeared, the state of Nevada had moved them everywhere into the waters in Northern Nevada, but none of those stockings persisted and so the genetics don’t show up in any other populations,” said Lisa Heki, project leader at the Lahontan National Fish Hatchery Complex. “We’ve done extensive genetic analysis in comparison of all populations of LCT, and the Pilot Peak (fish) — through genetic analysis of museum mounts — are the only ones historically related to that original, large size LCT that was found in Tahoe and Pyramid.”
A ‘CONSERVATION STORY’
In the early 2000s, Mary Peacock, a conservation geneticist from the University of Nevada, Reno, confirmed the fish population from Pilot Peak was the Lahontan Cutthroat Trout, according to the U.S. Fish & Wildlife Service, by extracting DNA samples from museum mounts of the original lake population, which later confirmed a match.
Due to conservation efforts and work done by the Lahontan National Fish Hatchery Complex and other groups, the Lahontan Cutthroat Trout now exist in the hundreds of thousands in Pyramid Lake, the Truckee River, and Fallen Leaf Lake.
“It’s a pretty significant conservation story that everyone has been a key player in, from our program, to fishermen, to researchers and other partners — the Pyramid Lake Paiute Tribe,” said Heki.
The Lahontan National Fish Hatchery Complex has been stocking the Lahontan Cutthroat Trout in Fallen Leaf Lake since 2002 and in Pyramid Lake since 2006. The historic population of Lahontan Cutthroat Trout was known to be long lived, and large in size, reportedly reaching up to 40 pounds and possibly larger. Today, Heki said trout of nearly 30 pounds have been caught.
There are now roughly 900,000 of the fish in Pyramid Lake and the Truckee River. The hatchery stocks 30,000 to 35,000 of the fish annually in Fallen Leaf Lake, and about 225,000 in Pyramid Lake, which now has roughly 900,000 fish in it.
The amount of trout that have been migrating from Pyramid Lake up the Truckee River have also increased, going from a few dozen in 2013 to a record set this year of 775 migrating fish. If next year is a good water year, Heki said she expects to see more than 1,000 migrating Pilot Peak Lahontan Cutthroat Trout and possibly up to 2,000 of the fish.
As of now, one of the major obstacles in keeping the fish from their historic migration route from Pyramid up the Truckee River and its tributaries and toward Lake Tahoe is the Derby Dam, located roughly 20 miles east of Reno.
Ground is set to break on the Derby Dam Fish Screen Project next Wednesday, according to the U.S. Bureau of Reclamation, and will likely be completed the fall of 2020, allowing the Lahontan Cutthroat Trout to begin migrating farther upstream to the California-Nevada border. There are several other structures that are fish barriers, according to Heki, between the border and the Lake Tahoe dam.
“The goal in the next five or so years is to have passage all the way from Pyramid to Tahoe,” said Heki.
REESTABLISHING THE ECOYSTEM
“We don’t know a lot about how they historically used these systems, but they would migrate up to where you have perennial cold water for spawning, incubation, and rearing, into those tributaries.”
Currently there are no plans to enable the fish to move beyond Lake Tahoe Dam, something Heki said isn’t a priority for conservationists at this point.
“I don’t think it would be a high priority in the next decade, because you can have populations supported in Fallen Leaf Lake and Lake Tahoe, which the genetics show historically there were these little subgroups,” she said. “From a conservation standpoint, I don’t think it’s an immediate goal … there’s always hope that you can tweak a system a little bit and make room for a native species, but that’s longer term.”
Among the obstacles facing a naturally reproducing population at Fallen Leaf Lake are nonnative species of rainbow trout, which can hybridize with Lahontan Cutthroat Trout, leading to a loss in population. Recently, a new weir has been installed which will allow for the Lahontan National Fish Hatchery Complex to better manage and protect the trout that are migrating from the lake into Glen Alpine Creek.
“That will hopefully refine our methods for supporting a naturally reproducing population of LCT,” said Heki.
The weirs control access to spawning areas, and act to barricade downstream movement of rainbow trout.
Moving forward, plans are to continue to work with local agencies and fishermen to expand the habitat and grow the population of a fish that once ruled the lakes and streams of the region.
“For Tahoe, for Fallen Leaf Lake, for Pyramid, their historic lake waters, they are the top predator in these systems,” said Heki. “That’s another important component for these ecosystems and reestablishing the health of these ecosystems is putting back the native top predator.”
Justin Scacco is a reporter for the Sierra Sun. Contact him at firstname.lastname@example.org.