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US Fish & Wildlife Service FieldNotes

LAHONTAN NFH: Lahontan Cutthroat Trout Program to Restore Potential Giant Fish to Native Habitat

Region 8, May 11, 2012
Evan Anderson removes excess milt from eggs after mixing in ziploc bag.
Evan Anderson removes excess milt from eggs after mixing in ziploc bag. - Photo Credit: n/a
Biologists collect milt from anesthetized males.
Biologists collect milt from anesthetized males. - Photo Credit: n/a
Lahontan cutthroat trout are raised in a raceway until adulthood.
Lahontan cutthroat trout are raised in a raceway until adulthood. - Photo Credit: n/a

By Cindy Sandoval, External Affairs

According to Lahontan National Fish Hatchery (NFH) Complex manager Lisa Heki, the U.S. Fish and Wildlife Service (Service)  program to reintroduce threatened Lahontan cutthroat trout (Oncorhynchus clarkii henshawi) to its historical region is a rare opportunity.

The story of the Lahontan cutthroat trout is not unlike many other native western fish. These fish played key historical roles in the culture and economy of the region. They were a major food source for local Native Americans in the Tahoe, Walker, and Pyramid basins. However, due to heavy timber harvests and a high demand for water for agriculture the Lahontan cutthroat trout was cut off from their spawning area. By the 1930s the large fish had disappeared in its native habits where the 114 mile migration in the Truckee River between Lake Tahoe and Pyramid Lake was cut off.

Forty years after the seeming demise of this large lake trout, Robert Benke, an inland trout taxonomist, discovered a population in the isolated area of Pilot Peak Utah said Heki. This discovery of a Lahontan cutthroat trout population thought lost was a rare opportunity in fish conversation. A genetic comparison with museum mounts revealed the Pilot Peak strain found in Utah are descendants of the original population of Lahontan cutthroat from the Truckee Basin.

With an interest in returning the long lived and often 40-50lbs fish to its native habit, the Service started a brood stock of Lahontan cutthroat at a hatchery in Gardnerville, NV. What started in a small garage like structure with PVC tubes has grown into a hatchery that houses nearly 3,000 brood stock cutthroat trout and releases their offspring into local waters each year. Throughout the process of raising and releasing the Lahontan cutthroat trout, the genetic diversity is carefully preserved and continues to be tracked during annual spawning activities. The diversity is maintained by placing a pit tag into each fish that contains its specific lineage along with age, and growth. When spawning season occurs a computer systems has already matched the best mate for each fish so that the threatened population can maintain diversity, health, and its wild stock lineage.

Once fish are ready to spawn team members at the Lahontan NFH complex carefully remove the milt and eggs from the mature fish and mix them in plastic bags. The eggs are then rinsed three times and placed in water for 1 hour to acclimate to local condition. After this the eggs are inspected and placed in trays to develop. Evidence that this process is successful in producing healthy fish can be seen with last week’s catch of a 17 pound Lahontan cutthroat in the Truckee Basin. The large size of the trout can be attributed to a historic trait were sexual maturity is reached late, so that the majority of the trout’s energy goes into growth. Biologist at the hatchery joke that, “Soon people won’t be able to fish for Lahontan from Kayaks” for fear of being pulled into the water by a large fish on their line.

The rapid growth of this species has many interested about its return to local waters. The trout has already been stocked in Pyramid Lake, Lake Tahoe, Marlett and the Truckee River. The Lahontan NFH complex also provides eggs to California Department of Fish and Game to raise at Moccassin Creek State hatchery for later stocking. When asked what outcome he would like for this project, hatchery supervisor Thomas Hogan said, “More fishing for native species, I want people to be excited about this.” With special rules under the Endangered Species Act the public is allowed a rare opportunity of recreational fishing for the threatened Lahontan cutthroat trout. With the continued collaboration of federal, state and tribal governments the Lahontan cutthroat is on the road to recovery in its native habitats.

Contact Info: Cynthia Sandoval, 916-978-6159, cynthia_d_sandoval@fws.gov