In the News

Scientists See Progress in Reintroduction of
date posted: December 5 2005

Lake Tahoe Report #122
June 21, 2005
By John Cobourn and Heather Segale

Though the native Lahontan cutthroat trout went extinct in Lake Tahoe in 1939, the U.S. Fish and Wildlife Service, along with researchers and local partners, began experimenting with reintroduction of these fish in Fallen Leaf Lake in 2002. These native trout were eliminated from the waters of Tahoe due in part to overfishing, competition with nonnative species, and development of dams along watercourses that connected populations.

Since Lake Tahoe has been stocked with the nonnative lake trout, which is now the top predator and has dramatically changed the food chain in the lake, scientists do not know if the native fish can survive and reproduce there. Compared to Tahoe, Fallen Leaf Lake is a much smaller ecosystem. Scientists are using it for a test-study to learn what conditions are necessary for successful restoration of the native fish.

Brant Allen, of University of California, Davis Tahoe Environmental Research Center, and Sudeep Chandra, a professor at University of Nevada, Reno, began studying Fallen Leaf Lake’s ecosystem before the introduction of cutthroat and continue their studies today. Their research has used an ecological approach, looking at how the cutthroat interacts with other species in the lake.

Specific research has focused on each critical stage in the life cycle of the cutthroat. This includes the survival of young fish in the lake, the growth of adult fish, and the spawning of mature fish in Glen Alpine Creek. To determine if reintroduced cutthroats were spawning, Allen started snorkeling in Glen Alpine Creek this April. Four-foot snowbanks lined the creek, but his efforts were rewarded later in the spring.

“This spring we have seen cutthroat that were planted two and three years ago spawning in the creek,” reports Allen. Researchers are excited about the prospect of natural reproduction enhancing the stocked lake population. The fish that are using Glen Alpine Creek represent a segment of the population that has found a way to survive and grow in the lake environment. “It is great to see these fish spawning. The genetics that they pass along to their offspring are what we want to see fostered in the lake population.”

With this year’s ample snow pack and plentiful water, creek conditions should be ideal for the small cutthroat. While the numbers of LCT in Glen Alpine Creek are low, researchers hope to see larger spawning runs in the future with more and more cutthroat reaching maturity. The long-term goal is to create both a sustainable population and a recreational fishery of the native in Fallen Leaf Lake.

The Lahontan cutthroat trout, named for the distinctive red streak under its chin, once topped Lake Tahoe’s food chain and weighed as much as 40 pounds. It is now among the most endangered western salmonids. Some related strains of the species survive in lakes and streams outside the Tahoe Basin, such as parts of the Carson River’s upper watershed. The U.S. Fish and Wildlife Services Lahontan National Fish Hatchery provides the cutthroat for stocking Fallen Leaf Lake and for reintroduction in its native home range. This effort is part of a recovery plan for the Lahontan cutthroat, which was listed as a “threatened species” in the early 1980s under the Federal Endangered Species Act of 1966.

At Fallen Leaf Lake, the U.S. Fish and Wildlife Service (USFWS) is cooperating with the USDA Forest Service; the California Department of Fish and Game; University of California Davis’ Tahoe Environmental Research Center; University of Nevada, Reno; and the local community. Since the project began, over 62,000 Lahontan cutthroat trout of catchable size have been stocked in Fallen Leaf Lake. These fish have revitalized a shoreline recreational fishery that had been lacking since the 1970s. Surveys with anglers over the past two summers indicate they are pleased with the cutthroat and the fishing opportunity they provide. Researchers are likewise pleased, as they expect more cutthroat to be seen spawning in the years to come.

For now, much research remains to be done. Allen says it may take 20 years before the native fish can become self-sustaining in Fallen Leaf Lake. Like many of the efforts to restore the ecosystem of the Lake Tahoe watershed, the success of our efforts will be measured over decades rather than years.

Watch for the “Lake Tahoe Report” in the Tahoe Daily Tribune each Wednesday, and tune in to KOLO-TV News Channel 8 Tuesdays at 5 p.m. to learn more. The “Lake Tahoe Report” is a collaborative effort of the Lake Tahoe Environmental Education Coalition, University of Nevada Cooperative Extension, UC Davis Tahoe Environmental Research Center and the California State Water Resource Control Board. For more information, contact Heather Segale, UC Davis Tahoe Environmental Research Center, (530) 583-3279, or logon to www.lteec.org or www.tahoe.unr.edu.