On October 6, 2014 the U.S. Fish and Wildlife Service announced its proposal to list the west coast fisher population as a threatened species under the Federal Endangered Species Act.
Fishers have been part of the forests in on the west coast for thousands of years, but now their numbers are diminishing and have virtually disappeared from forests across Washington, Oregon, and parts of the Sierra Nevada in California. Their range was dramatically reduced in the 1800’s because of trapping, pest control, and the conversion of historically multi-aged, closed forests to single-age, open forests through logging, fire, and farming. Current threats include small population sizes, habitat loss and fragmentation associated with logging, severe wildfires, and rodenticides which have become a recent and troubling threat to fisher populations.
The announcement of the proposal initiated a 90-day comment period. The process allows the U.S. Fish and Wildlife Service to conduct a scientific review of the proposal and receive public comment. The final determination on listing the fisher will be informed by all scientific and public comments and is expected by September 2015. More information can be found on this U.S. Fish and Wildlife Service page.
Researchers are currently investigating the direct and indirect effects of each of the identified threats to fishers. Rodenticides have been found in fishers in Olympic National Park, Klamath and Siskiyou Mountains, and Southern Sierra Nevada. Rodenticide use has been documented at illegal marijuana sites on public, private, and tribal lands in California. According to published data (see Gabriel et al. 2012 and Thompson et al. 2013), 58 carcasses were tested for the specific toxin found in rodenticides. Seventy-nine percent tested positive in California, and 75 percent tested positive in Washington indicating an emerging threat to fishers and other wildlife.
In California, there are estimated to be less than 500 fishers in the Southern Sierra Nevada Mountains. In the Klamath Mountains of Northern California and Southern Oregon the population is estimated to be less than 5,000 individuals. Although fishers are found throughout North America, their range on the West Coast has been reduced dramatically, which spurred our current reintroduction to the northern Sierra Nevada.