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PACIFIC SOUTHWEST REGION: Paiute Cutthroat Trout, Among the Rarest in the World, Returning to Native Habitat
California-Nevada Offices , September 11, 2013
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CDFW Environmental Scientist Ben Ewing works the neutralization station at Silver King Creek for the Paiute Cutthroat Trout Restoration Project, Aug. 2013.
CDFW Environmental Scientist Ben Ewing works the neutralization station at Silver King Creek for the Paiute Cutthroat Trout Restoration Project, Aug. 2013. - Photo Credit: Carol Oz/CDFW photo
Paiute cutthroat trout have a purple hue and the black lack body spots of similar species.
Paiute cutthroat trout have a purple hue and the black lack body spots of similar species. - Photo Credit: Michael Graybrook
In 1912, Basque sheep herders moved Paiute cutthroat trout above Llewellyn Falls and isolated the species before nonnative trout reached their historic habitat in Silver King Creek.
In 1912, Basque sheep herders moved Paiute cutthroat trout above Llewellyn Falls and isolated the species before nonnative trout reached their historic habitat in Silver King Creek. - Photo Credit: Photo Courtsey of California Department of Fish and Wildlife

By Cindy Sandoval

The Paiute cutthroat trout is one the rarest trout in the world and is federally listed as a threatened species. The small native trout had a home range of 11.1 miles in a single creek located in Alpine County, California. It is believed the trout was isolated in Silver King Creek eight to ten thousand years ago when receding water and a series of waterfalls disconnected the fish from other similar species. Currently the trout is found in only a few isolated populations and has disappeared from their ancestral reach of Silver King Creek.

During the week of August 26, 2013, the California Department of Fish and Wildlife (CDFW), U.S. Forest Service and U.S. Fish and Wildlife Service started restoration of 11 miles of Silver King Creek. When complete, the restoration will return the rare trout to its historical home and it can be removed from protection under the Endangered Species Act.

The historic habitat of the Paiute cutthroat trout was the 11.1 miles of Silver King Creek from Llewellyn Falls downstream to Silver King Gorge. This habitat also granted the trout access to three tributary creeks: Tamarack Creek, Tamarack Lake Creek and Coyote Valley Creek. However, today the remaining populations of Paiute cutthroat trout in the Silver King Creek basin now exist upstream of their native range, above Llewellyn Falls.

The Paiute cutthroat or PCT is distinguished from other trout by a slender body, relatively small scales, purple hue and absence of body spots. Similar cutthroat trout species will possess 50 to 100 body spots and Paiute cutthroat rarely have more than five spots on the entire body. “Around the early 1900s, Basque sheep herders in the area caught and transported Paiute cutthroat trout over Llewellyn Falls into the fishless upper reaches of Silver King Creek. This early transport outside the native range would end up being the salvation for the trout” said fisheries biologist Kathy Hill with CDFW.

Soon after the Paiute’s transport upstream, rainbow trout were stocked in the area and these introduced fish had a tragic effect on the Paiute trout. Early settlers in the area began to notice a change in the once pristine population below the falls. By 1933, the Paiute trout below Llewellyn Falls began to show body spots, the first visible signs that the Paiute trout below the falls was no longer genetically pure. Along with competing for resources, the rainbow trout had begun to hybridize with the native fish.

Concerned with saving the Paiute cutthroat trout, the then California Department of Fish and Game made several attempts to transplant Paiute cutthroat trout into other creeks. The first introduction was made in 1937 into upper and lower Leland Lakes. That transplant failed, but other Paiutes were moved to the North Fork of Cottonwood Creek in 1946 and offspring of these founder fish still survive to this day. Thanks to these efforts the species has four self-sustaining, pure populations left but all reside outside the original native range of Silver King Creek.

With only four small populations remaining the trout was listed as endangered in 1967 and reclassified as threatened in 1975. Since then multiple agencies and non-profits have been working to return the trout home and August’s restoration was a monumental step forward.

The partner agencies chemically treated 11 stream miles of Silver King Creek and three tributaries located below Llewellyn Falls to remove all non-native fish present. In an effort to reduce the number of non-native fish and provide an increased recreational opportunity for local fisherman, CDFW changed the fishing regulations in Silver King Creek. “Before the treatment, fishing regulations were changed so those fishing in the area could keep 10 fish per day,” said CDFW Wildlife Officer Eric Elliot.

Once chemically treated water reached Snodgrass Creek it was neutralized to bind the fish toxin and stop it from having fatal effects on fish downstream. “Chemical treatment of Silver King Creek is the only way to remove nonnative fish from a creek this large and complex” said Hill. “We have to ensure there are no fish present before we can return Paiute cutthroat trout to their native range.”

With the first restoration compete there is still more work to be done. To confirm no fish survived the treatment there will be electrofishing done over the 11 mile stretch to search for any nonnative trout remaining. There will also be another chemical treatment scheduled for next summer. Signs are now posted to educate the public about the rare fish and efforts to save it. Local law enforcement will continue patrols in the area to discourage illegal activity such as moving nonnative fish into the treatment area. However, the odds of nonnative trout again entering Silver King Creek are low as the basin is very rugged terrain. The first nonnative fish stocking occurred with the aid of horse and mule pack-trains according to CDFW.

Once the treatment area of Silver King Creek is found to be free of fish, reintroduction can take place. Paiute cutthroat trout from the four self-sustaining populations in existence today will be released in the creek. Restocking will only be done with pure Paiute cutthroat that have been identified by genetic tests at UC Davis.

While it will still be a few years before the rare trout is swimming in its ancestral waters, this summer’s restoration is an important milestone in the decades of work that federal, state and non-profit groups have dedicated to protecting and recovering one of the rarest trout in the world.

Cindy Sandoval is a Pathways intern in external affairs at the Pacific Southwest Regional Office in Sacramento, Calif.


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



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