The paiute cutthroat trout PCT is one of the rarest species of fish found in california and is listed as a threatened species under the u. S. Endangered species act

This $453,646.00 Project Grant, awarded by the U.S. Department of the Interior Fish and Wildlife Service under the Cooperative Endangered Species Conservation Fund (CFDA 15.615) program, supports efforts to remove non-native rainbow trout and hybrids from Silver King Creek in California. The goal is to maintain the genetic integrity of the threatened Paiute cutthroat trout, one of the rarest fish species in California. The project will utilize environmental DNA (eDNA) sampling to locate areas with high densities of rainbow trout, and then employ electrofishing techniques to selectively remove the non-native fish while returning the native Paiute cutthroat trout unharmed. This approach aims to diminish the rainbow trout gene pool in the creek, driving it toward elimination and supporting recovery of the threatened Paiute cutthroat trout population. The grant award period runs from April 1, 2025 through March 31, 2028.

Its native range is restricted to about 20 KM of habitat in silver king creek, a remote headwater tributary to the east fork carson river in the carsoniceberg wilderness in alpine county. Currently, the single greatest threat to PCT in their native range is hybridization with rainbow trout. The purpose of this proposal is to continue efforts to remove rainbow trout and their hybrids from silver king creek. Maintaining the genetic integrity of PCT is a critical part of recovering the species and ultimately removing IT from the endangered species list. The proposed work has two main components. The first is utilizing recent advances in detecting the presence of species by sampling their DNA in the environment. This tool is called environmental DNA, or edna, and involves filtering water and then extracting DNA from the filter and analyzing IT to detect particular species in this case, rainbow trout. We propose to use edna to inform US where we should focus our efforts to capture and remove rainbow trout from within the native range of PCT in silver king creek. The second component of the proposed work involves using controlled pulses of electricity in the water to temporarily stun the fish, net them, and then inspect them to make species identifications. This tool is commonly used in freshwater fishery management and is called electrofishing. The results of the edna survey will tell US where the greatest densities of rainbow trout and hybrids occur in silver king creek and where we should focus the electrofishing to capture and remove them. This tool allows US to selectively remove the nonnative trout and return the PCT to the stream unharmed. This approach of selectively removing individuals provides a means for diminishing the rainbow trout gene pool in silver king creek, driving IT toward elimination, while also allowing the pure PCT gene pool to flourish. The expected outcome of this work by the end of the 3YEAR grant period would be to reduce the introgressive hybridization rate to less than 5% at the population level for PCT, an outcome which would represent a major step toward recovery of the species. This work requires a crew of about 24 biologists and a large amount of equipment. The funding being sought in this proposal would provide logistical support from a packer which is needed to be able to conduct the rainbow trout removal work in a remote backcountry setting. Because of the remote location, the gear for this many workers and the equipment needed for conducting edna sampling and electrofishing must be transported by mule train. Additionally, analysis of edna samples and tissue samples from the fish requires specialized genetics services. This grant will provide the funding for both support services. Project deliverables will include databases, analyses, progress updates, and annual reports, the final of which will assess progress made toward achieving the target outcome.