Lahontan Cutthroat Trout
By: Austin Pearson
As you’ve driven along rivers and streams in your travels, you may have wondered what species of fish could be lurking beneath the surface, just out of view. You may have even taken your daydreaming a step further and wondered what our waterways and their fish populations were like before dams, irrigation, and European settlers began exploding across the landscape.
A Lahontan cutthroat trout from Pyramid Lake. Photo by: Austin Pearson
For instance, did you know that the Lahontan cutthroat trout (Oncorhynchus clarkii henshawi) (LCT) was the only species of trout that historically inhabited the Truckee River watershed, including Lake Tahoe, and that it would overrun the river each spring with huge fish during its spawning migration? The fish were so large and plentiful, in fact, that when John C. Fremont first “discovered” the Truckee River in 1844 he named it the Salmon Trout River (Richards 2004).
LCT are a spectacular fish to observe up close. Like all subspecies of cutthroat trout, they have a bright red to orange slash under the jaw, hence the name cutthroat. Like a lot of fish, coloration can vary somewhat depending on environmental factors, but overall, the LCT typically has a yellowish copper tint with rosy hues along the middle of the body. Compared to other trout species, they have relatively large, rounded spots, distributed along the sides of the body and sometimes on the head and belly.
LCT are the largest of all the cutthroat trout subspecies, with the largest recorded fish at 41 pounds, caught back in 1925 (Behnke 2002). There are unofficial observations of even bigger fish, approaching the 60-pound range. It hasn’t been an easy run for the LCT, however. Read on to learn about the plight of this trout and steps that are being taken to restore it to its historic waters.
History and Threats
LCT are native to northwestern Nevada, northeastern California, and a small piece of southeastern Oregon, an area that forms the Lahontan Basin, a subregion within the Great Basin. During the Pleistocene, a period of time that stretches from around 2.6 million to 11,700 years ago, precipitation rates were higher and temperatures were cooler, resulting in lower evaporation rates. These conditions allowed water to collect over millennia, forming prehistoric Lake Lahontan.
Towards the end of the Pleistocene, the climate began to warm, with precipitation decreasing and evaporation increasing. Lake Lahontan slowly dried down and splintered into the few lakes that remain today, Pyramid Lake being the largest. As the water dried down, the alkalinity and total dissolved solids concentration within these lakes increased to levels that would kill most other freshwater trout species. However, the LCT evolved to thrive in this hostile environment.
As obligatory cold water stream spawners, some LCT in this new, more arid landscape would migrate over 100 miles from Pyramid Lake up into Lake Tahoe and its tributaries to spawn in their pristine gravel beds (USFWS 2009). Then came the introduction of dams and diversions to support human development, which impacted LCT’s ability to migrate to their spawning grounds.
An image of the Derby Dam. Photo Courtesy of: Greg Chapel
In 1903, the Bureau of Reclamation authorized construction of Derby Dam on the Truckee River, approximately 30 miles upstream of Pyramid Lake, and it was completed in 1905. The dam was built to divert water into the Carson River watershed for crop irrigation. This stopped the LCT’s ability to spawn in tributaries upstream of Derby Dam. By 1938, the last successful spawning run from Pyramid Lake was observed by federal biologists as all flow in the Truckee River was diverted for irrigation use and trout below the dam were stranded (Behnke 2002). Soon after, a similar story played out at Walker Lake, another remnant of Lake Lahontan.
With the ability to spawn naturally removed from the Pyramid Lake and Walker Lake populations, LCT numbers in these drainages declined precipitously. LCT was further plagued throughout its range by over-harvesting, mining, logging, and pollution. Today, one of the primary obstacles to self-sustaining LCT populations is the presence of introduced non-native trout species. Nonnative trout compete with LCT for food resources and even feed on young LCT. Some species of nonnative trout can hybridize with LCT, which degrades the genetic pool and can eventually eliminate pure LCT from a stream or lake. Overall, LCT have been wiped out from most of the major drainages they occurred in and are largely restricted to isolated headwaters (LCTCC 2019).
Protection and Restoration
LCT was first listed as endangered under the federal Endangered Species Act in 1970. Its listing status was later revised to threatened in 1975. At the same time, a special rule under Section 4(d) of the Endangered Species Act was published that allows States to permit angling and harvest of LCT. It was also listed by the State of Oregon as threatened in 1987.
As it stands now, approximately 10.5 percent of historical LCT habitat supports self-sustaining populations of this species (LCTCC 2019) and other populations have been maintained through hatchery rearing, stocking programs, and restoration. While most of the existing populations are primarily supported by fish hatcheries, some self-sustaining populations persist, largely in the headwaters of watersheds, and sometimes in areas where LCT did not occur historically.
In fact, the Pyramid Lake population, the genetics of which were thought to be extinct, is being restored from an isolated population that was planted over a hundred years ago in the Pilot Peak Range in western Utah. After extensive research and DNA analysis, it was determined that this isolated population was in fact from the original Pyramid Lake population. In 2006, the U.S. Fish and Wildlife Service began transplanting fish from the Pilot Peak population into Pyramid Lake (Peacock 2017). Since then, LCT in Pyramid Lake have begun growing to sizes upwards of 30 pounds, reminiscent of the fish first observed by John C. Fremont in the 1800’s.
Several restoration projects have also been undertaken to help ensure we don’t lose any more populations of LCT and to expand their current distribution into more of their historic range. These efforts typically require removal of nonnative trout species, placement of barriers to ensure nonnatives will not simply move back in, and restocking with pure-strain LCT. Other efforts include habitat restoration, better water management policies, and construction of fish bypasses, and screens.
In 2004, construction of the upstream fish bypass around Derby Dam was completed. In 2020, construction of the Derby Dam Farmers Screen and downstream bypass was completed, the largest in the nation of its kind (Alexis Vaivoda, personal communication, Oct. 13, 2022). The upstream bypass allows fish to swim around Derby dam to access spawning grounds above the dam, and the screen allows out migrating fish to pass below the dam through the downstream bypass without getting caught in the Truckee Canal and being diverted into the Carson River Drainage. Since completion of these projects, LCT have been able to move upstream and downstream of Derby Dam during their spawning migration for the first time since Derby Dam was constructed in 1905, restoring access to a portion of their historic spawning grounds above the dam.
While a lot of work remains to be done to facilitate a self-sustaining population of LCT in Pyramid Lake, and tributaries and lakes upstream of it, this is a significant step and provides a glimmer of hope that daydreams of this prehistoric giant overrunning the Truckee River may one day, again, become a reality.
INTERESTING FACTS
A Lahontan cutthroat trout from Slinkard Creek. Photo by: Gregg Whitley
Derby Dam, on the Truckee River, was the first project completed by the brand-new U.S. Reclamation Service (today’s Bureau of Reclamation), organized under the Reclamation Act of 1902.
LCT is the state fish of Nevada.
It is estimated that LCT historically occupied 6,864 miles of stream and 314,502 acres of lake habitat (USFWS 2009).
LCT currently occupy 588 miles of stream and 147,113 acres of lake habitat within their historic range (USFWS 2009).
The Paiute and Washoe tribes relied on LCT as a food source and found that they could make a living by selling smoked LCT to miners in the 1860’s (Richards 2004).
Truckee River LCT were once a popular item sold in markets in Sacramento, San Francisco, Salt Lake City, Los Angeles, and Denver (Richards 2004).
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