Paiute cutthroat trout recovery effort continues despite the Slink Fire

a man kneeling on a bank  holding a bucket with small fish in water

California Department of Fish and Wildlife fisheries biologist John Hanson releasing Paiute cutthroat trout into Silver King Creek. Photo courtesy of Rachel Van Horne/USDA Forest Service

By Erica Hupp
Courtesy of the USDA Forest Service
December 9, 2020

The Paiute cutthroat trout made national headlines last year when the Humboldt-Toiyabe National Forest, California Department of Fish and Wildlife, U.S. Fish and Wildlife Service and other partners returned this California native fish to its home waters in Alpine County for the first time in more than 100 years. The Paiute cutthroat trout was one of the first species in the nation listed under the federal Endangered Species Act in the 1960s.

two small fish in a creek

Newly released Paiute cutthroat trout swimming in Silver King Creek, the fish’s historic home. Photo courtesy of Rachel Van Horne/USDA Forest Service

Recovery efforts continued this October when fisheries biologists relocated 44 Paiute cutthroat trout by pack animals from the nearby Corral Valley Creek into Silver King Creek, the fish’s historic home. Both creeks are in the Carson-Iceberg Wilderness on the Humboldt-Toiyabe National Forest.

“In 2019, the first translocation effort was completed when 30 Paiute cutthroat trout were moved from Coyote Valley Creek to Silver King Creek,” said Rachel Van Horne, Humboldt-Toiyabe National Forest fisheries biologist. “It was a momentous occasion, but the translocation efforts into the mainstem of Silver King Creek will need to continue yearly until a self-sustaining population has been established.”

A genetically pure population of Paiute cutthroat trout was established in Corral Valley Creek and other suitable waters decades ago to ensure survival of the species while restoration work took place within Silver King Creek to remove introduced nonnative trout that displaced and hybridized with the native Paiute cutthroat trout.

a charred forrest with snow on the ground

The aftermath of the Slink Fire on the Humboldt-Toiyabe National Forest. Credit: Chad Mellison/USFWS

The Slink Fire, which occurred in September 2020, added urgency to the effort. The 26,759-acre fire burned about half of the Corral Valley Creek watershed, potentially threatening the pure Paiute cutthroat trout population. “I would like to recognize the great job the three incident management teams, Sierra Front Team #3, Great Basin Team #6, and Nevada Team #3, did to protect the Paiute cutthroat trout habitat during the Slink Fire,” said Bill Dunkelberger, Humboldt-Toiyabe National forest supervisor.

Five people in a green field looking into a narrow stream

California Department of Fish and Wildlife biologists performed population assessments of the Paiute cutthroat trout in the Corral Valley Creek the week before the lightning-caused Slink Fire ignited. Photo courtesy of California Department of Fish and Wildlife

“Without everyone’s hard work, the Paiute cutthroat trout population in Corral Valley Creek may have been decimated, and this would have been a huge loss for the recovery effort,” added Dunkelberger.

According to Chad Mellison, Service fish and wildlife biologist and Slink Fire wildland fire resource advisor, the issue with wildfires is that their severity can influence fish populations and their habitat. As vegetation burns, increased sediment erodes into nearby bodies of water.

“This material fills in spaces where fish would lay eggs and can, in some cases, damage their gills,” explained Mellison.“ Migration routes can also be blocked or altered.” As a resource advisor, Mellison provides guidance to agency administrators and incident management teams to help them develop suppression strategies that best avoid, minimize, or mitigate impacts to critical natural resources.

Another significant issue is temperature change. Fish which have precise habitat requirements, like the Paiute cutthroat trout, are most at risk. When plants which shade cold-water streams are destroyed, the overall water temperature rises. Even just a few degrees change can have an impact on metabolic and reproductive rates of the fish living there.

a dry landscape with scarce vegetation and an orange sky

The Slink Fire creates an orange haze in the sky. Credit: Chad Mellison/USFWS

Once the area was deemed safe, Van Horne, who was also a member of the Slink Fire burned area emergency response team, went out to Corral Valley to see the effects of the fire. The team is made up of scientists and specialists with expertise in soils, hydrology, natural and cultural resources, engineering, and recreation. They conduct assessments of the burned area to determine treatments needed to minimize threats to human life and mitigate unacceptable degradation to natural and cultural resources in an area burned by a fire.

“I was nicely surprised with the mosaic burn, which includes patches of burned and unburned areas, that occurred in the Corral Valley,” said Van Horne.

Van Horne explained that this type of burning is known to support biodiversity outcomes, but until the area recovers, the Corral Valley Creek will need to be continuously monitored to ensure the Paiute cutthroat trout habitat is not negatively affected by the fire. Since this portion of the fire was within wilderness and because of the overall positive effects of the fire to the landscape, there were no on-the-ground landscape treatments recommended for Corral Valley.

aerial shot of a partially burned forest

Aerial photo of the upper part of Corral Valley after the Slink Fire burned through. Photo courtesy of USDA Forest Service

To ensure that the population of Paiute cutthroat trout in Corral Valley is protected until recovery occurs, the Humboldt-Toiyabe National Forest worked with partners to come up with the best plan moving forward. The California Department of Fish and Wildlife decided to concentrate their relocation efforts from to Corral Valley Creek to Silver King Creek in the event that post-fire sediment impacts occurred.

two hands hold a small fish on a measuring device

All the Paiute cutthroat trout that were collected in Corral Valley Creek were measured, weighed and genetic samples were taken. After the fish were examined, they were put in fish cans that were placed on mules for transportation to Silver King Creek. Credit: Joanna Gilkeson/USFWS

“Recovering this iconic trout has been a top priority for the Department for many years,” said Department fisheries biologist Sarah Mussulman. “Continuing to move fish into their historic range is critical for long-term success of the project and for genetics management. I’m very pleased that despite many additional challenges due to COVID and wildfires, we were able to successfully move another 44 fish this year. This is worth celebrating!”

The translocation from Corral Valley Creek also served a dual purpose of continuing to build the population in the mainstem of Silver King Creek, while protecting the genetics of the fish in Corral Valley Creek should post-fire effects impact the population as the area moves into the winter.

Genetic samples were taken from all fish that were moved from Corral Valley Creek, so biologists will be able to track their reproductive success in the mainstem of Silver King Creek as a self-sustaining population is established. “When we walked up to the Silver King Creek to release the fish from Corral Valley Creek, there was one of the fish we released last year swimming in the pool,” added Van Horne. “Seeing that fish thriving in its historic range is what this project is all about!”

Each year that Paiute are moved into Silver King Creek is one step closer to a self-sustaining population,” said Van Horne. “Hopefully next year when we walk to the stream’s edge, we will see baby fish! Natural reproduction within the Silver King Creek would be momentous milestone for this recovery effort, so stay tuned.”