Fisher Translocation Project

Reintroduction of fishers to the northern Sierra Nevada and Southern Cascades

The fisher (Pekania pennanti) population in California is the largest in the Pacific States. Concern about its status resulted in a cooperative project between the California Department of Fish and Wildlife, U.S. Fish and Wildlife Service, Sierra Pacific Industries (SPI), and North Carolina State University to translocate fishers into a portion of their historical range in the northern Sierra Nevada and Southern Cascades. In addition to returning fishers to a portion of their former range, the project has provided a unique opportunity to study an isolated population of fishers in an area intensively managed for timber production.

From 2009-2011, 40 fishers (24 females, 16 males) were released on a large tract of SPI land near Stirling City (east of Chico). The translocated fishers were captured at diverse locations in Humboldt, Shasta, Siskiyou, and Trinity counties. Before clearance for translocation, each animal's health and condition was thoroughly screened.

Since their release, the translocated fishers and their progeny have been intensively monitored and studied. Focal monitoring topics have included fisher survival, home range establishment and characteristics, movements, and reproduction. Habitat use is also being studied. Dr. Roger Powell and Ph.D. candidate Aaron Facka of North Carolina State University have led the research effort, with extensive cooperation and support from other project partners.

CDFW volunteer and North Carolina State University graduate student Aaron Facka releases a fisher as part of the translocation project.

Monitoring through early 2016 suggests the new population is stable or growing. Female fishers have successfully raised young within the project area every spring since the initial release. In spring 2015, 13 of 18 monitored females denned, and a minimum of 21 fisher kits were documented by early summer. Capture and monitoring efforts in fall 2015 indicated a minimum population size of 50 (the actual size is almost certainly higher, as not all animals are captured). Fisher survival rates are high (0.80 annual rate for adults). Translocated fishers maintained, and usually increased their weights after release, and juvenile fishers born in the Stirling study area weighed more than similarly-aged juveniles captured from the translocation source populations. Furthermore, in recent years fishers have been regularly detected on U.S. Forest Service and other private lands well beyond the release sites on SPI land, suggesting that the progeny of the translocated fishers are now using and/or colonizing other portions of the Southern Cascades and northern Sierra.

To discern the impacts of removing fishers from the “donor populations”, cooperators also monitored a Siskiyou County fisher population that was the source of nine of the translocated fishers. All demographic variables monitored suggested the donor population remained stable despite the removal of the fishers.

For more information about the project, please contact CDFW Senior Environmental Scientists Richard Callas or Pete Figura.