“We knew early on that if our partners could get Lahontan cutthroat trout back into their historic habitat and work to give them a fighting chance, they’d possibly be able to recover on their own.”
— STEPHANIE BYERS, BIOLOGIST,
LAHONTAN NATIONAL FISH HATCHERY
By Dan Hottle
February 22, 2018
With a little help from state and federal fisheries biologists, highly-revered Lahontan cutthroat trout that disappeared from a California alpine lake more than 80 years ago are making their way back home.
“Decades of over-fishing and habitat degradation in the Lake Tahoe Basin caused these unique native fish to vanish from the system all the way back in the 1930s, and now we’re working to bring them back where they belong,” said Stephanie Byers, a senior fisheries biologist for the Lahontan National Fish Hatchery Complex in Gardnerville, Nevada, which has been raising a broodstock of the famed species since 1995.
Operating under a new fisheries conservation agreement with the California Department of Fish and Wildlife that was signed last May, the hatchery complex and its partners have ramped up efforts to reintroduce threatened Lahontan cutthroat trout back into the Fallen Leaf Lake watershed that neighbors Lake Tahoe. Restoring the fish in the lake began in 2002 as one of several short-term conservation tasks outlined in the multi-agency Truckee River Short-Term Action Plan.
This year, the complex staff and partners are operating under a new, five-year action plan. According to biologists, returning the native trout species back into a high mountain lake has not been without challenges: The oligotrophic, or low nutrient production, characteristics of the crystal clear, 6,300-foot elevation lake means there’s less for newly-minted and stocked young Lahontan cutthroat trout to eat.
Additionally, the introduction of non-native species such as rainbow, brown and mackinaw, or lake trout, into the system nearly a century ago means there’s an increased risk of hybridization, along with an increased risk of the Lahontan cutthroat trout becoming food themselves.
“Lahontan cutthroat trout recovery in general is particularly challenging due to the large complex nature of the watersheds, especially in the Lake Tahoe Basin,” said Sarah Mussulman, the Department’s senior environmental scientist. “The number and diversity of non-native species present in the Lahontan cutthroat trout’s historic habitat and the ability for them to interbreed with other non-native trout species such as rainbow trout adds another layer of challenges.”
As part of the recent agreement, the California Department of Fish and Wildlife receives Lahontan cutthroat trout eggs from the hatchery and raises the species in its American River Hatchery in Gold River, California to help restore recreational fisheries in the eastern Sierra region.
“We knew early on that if our partners could get Lahontan cutthroat trout back into their historic habitat and work to give them a fighting chance, they’d possibly be able to recover on their own,” said Byers. “That meant suppressing non-native trout species and creating a niche for them in their native environment with improved stocking management.”
Several years of research showed that in order for young, reintroduced Lahontan to have a better chance at surviving, more strategic stocking methods needed to be incorporated.
“Rather than stocking large numbers of Lahontan cutthroat trout at a time in one portion of the lake, our crews now stock smaller batches more frequently throughout areas of the lake where there is more natural refugia — places for them to hide,” said Service fishery biologist Jason Smith. “In addition, we wait until the summertime so that we can stock larger Lahontan cutthroat trout into the warmer, upper thermocline layer of the lake at a time in the season when predatory lake trout are down deeper in colder waters.”
Smith said the changes in stocking locations and timing afforded fish a critical adjustment period to acclimatize to the lake and more quickly seek cover from predators, giving them a much-needed boost toward survival. The results paid off quickly. In 2012 after reintroduction approaches were refined, the lake’s population numbers began to slowly turn in favor of Lahontan cutthroat trout.
That same year, biologists saw that stocked and tagged Lahontan cutthroat trout were observed attempting to spawn into Glen Alpine Creek at the lake’s inlet once again.
“This summer within three days of stocking, we observed hundreds of cutthroat gathering at the mouth of Glen Alpine Creek,” said Smith. “It was the first time we’d observed that many stocked Lahontan cutthroat trout migrating all the way across the lake to instinctually seek out their historic stream habitat.”
Not only are biologists excited, local residents who support the conservation effort to restore Fallen Leaf’s native fish are monitoring the success as well.
“The agency partners have taken great steps to work with local homeowners and other interested groups for the success of this effort as well as for other Lahontan cutthroat trout recovery efforts in the Tahoe Basin,” said Sarah Muskopf, an aquatic biologist with the U.S. Forest Service’s Lake Tahoe Basin Management Unit. “The long-term outcome of returning these large, lake-dwelling cutthroats is something we’re all excited to see.”
“We’re thrilled to be a small part of the effort to bring back the lake’s native species,” said Dave Bunnett, director of Stanford University’s Sierra Camp, which incorporates information about the restoration project into naturalist programs it provides for more than 300 camp guests each year. The university owns lakefront property including portions of Glen Alpine Creek where the hatchery complex installs and monitors a fish barrier, called a weir, every season to block the spawning of non-native trout.
“It’s always fun when we get to observe (U.S.) Fish and Wildlife Service biologists stocking fish from our sailing dock, knowing that we’re helping to bring back a native fish that can only be found in this part of the world,” Bunnett added.
Lake residents and other visitors who come from afar for the iconic species also have the chance to help the recovery effort by submitting fish measurements and other critical data on Lahontan cutthroat trout they catch to Service biologists.
Anglers can call a hotline to report Lahontan cutthroat trout catch in the lake at (775) 861-6355.
Returning Lahontan cutthroat trout to Fallen Leaf Lake revives a historic fishery, improves shoreline angling opportunities, and provides the chance to reinvigorate the watershed’s ecosystem as a whole.
“The return of spawning Lahontan cutthroat trout is not only historic for the lake, it also means that nesting bald eagles and black bears may also return in greater historic numbers to Glen Alpine Creek one day,” Muskopf said.
Lahontan cutthroat trout recovery partners include the Washoe Tribe, Tahoe Regional Planning Agency, California Tahoe Conservancy, Lahontan National Fish Hatchery Complex, California Department of Fish and Wildlife, Nevada Department of Wildlife and U.S. Forest Service Lake Tahoe Basin Management Unit.