Fisher (Pekania pennanti)

This article was originally published by the Washington Department of Fish and Wildlife as part of its annual report Threatened and Endangered Wildlife in Washington.

Fisher released on the Olympic Peninsula. Photo by Jessica Hoffman.
Fisher released on the Olympic Peninsula. Photo by Jessica Hoffman.

State Status: Endangered, 1998
Federal Status: Candidate, 2004
Recovery Plans: State, 2006

The fisher is a large, dark brown member of the weasel family, about the size of a large house cat (Figure 1).  Fishers generally eat small mammals (mice, voles, shrews, mountain beavers, and squirrels), snowshoe hares, ungulate carrion, birds, and insects. They also occasionally prey on beavers, muskrat, and porcupines.

The fisher was listed as endangered in Washington in 1998 (Lewis and Stinson 1998), and as a federal candidate species in its west coast range in 2004 (USFWS 2004).  Historically, fishers occurred throughout the forested habitats of western Washington, northeastern Washington and the Blue Mountains of southeastern Washington (Lewis et al. 2012).  Fishers were extirpated from Washington by the mid-1900s as the result of historical overharvest, incidental capture, predator control campaigns, and loss and fragmentation of mature low and mid-elevation coniferous forests.  Despite 70 years of protection, fishers did not recover in Washington.  No fishers were detected during extensive carnivore surveys in the 1990s, and the fisher was listed as a state endangered species in Washington.  Following the listing, WDFW developed a fisher reintroduction feasibility assessment (Lewis and Hayes 2004), a fisher recovery plan (Hayes and Lewis 2006), and an implementation plan for a fisher reintroduction in Olympic National Park (Lewis 2006). The reestablishment of self-sustaining fisher populations in three recovery areas, (Olympic Peninsula and the North and South Cascades) are essential goals of the fisher recovery plan.

Figure 2. Release locations for fishers (n=90) in Olympic National Park in 2008 (yellow stars), 2009 (blue stars), and 2010 (purple stars).

Olympic fisher reintroduction project. To restore fishers to Washington, WDFW, Olympic National Park, Conservation Northwest, British Columbia Ministry of the Environment, and other partners, initiated a reintroduction effort to capture and translocate fishers from central British Columbia to Olympic National Park over three years.

A total of 90 fishers (50 females, 40 males) were released at 21 locations in Olympic National Park from 2008 to 2010 (Figure 2). Each fisher was equipped with a radio-transmitter to allow project biologists to track their movements, assess survival, detect where and when a fisher established a home range, and to determine if females gave birth to kits. Fishers were tracked primarily from the air because of the limited access and rugged nature of Olympic National Park and surrounding area, and the limited power of the radio- transmitters. Ground telemetry and remote cameras were used to confirm that a female was occupying a den and caring for kits (Figure 3). Ground telemetry was also used to recover collars that were transmitting a mortality signal, which indicated that a fisher had died or that its collar had come off.

Automated camera photo of a female moving a kit from its natal den in Olympic National Forest, April 2011.

While monitoring released fishers for four years, biologists located the dens of seven females; litter sizes ranged from 1-4 kits. First year survival varied by release-year cohort; those released in year 1 had the highest survival rates (85-94%) as compared to those released in year 2 (33-65%) and in year 3 (52-78%). Male survival rates were greater than those of females.  Of the 35 fishers recovered, 14 (40%) were killed by a predator, seven (20%) were killed by a vehicle strike, 7 (20%) died of unknown causes, 4 (11%) died of an unknown cause but possibly by a predator, 2 (6%) drowned, and 1 (3%) died after it was caught and escaped from a trap.  Initial findings from survival analyses indicated that release-year (whether it was released in year 1, 2, or 3), sex, age, and the duration of time spent in captivity prior to release, were factors that influenced the survival of released fishers.

Arrows illustrating straight-line distances from release sites to the center of home ranges of 27 females (left) and 21 males (right) on the Olympic Peninsula, 2008-2011.

Fishers moved extensively after being released but most fishers established a home range by the end of their first summer (Figure 4; Lewis et al. 2012). Males moved greater distances from a release site to a home range than females, and females initiated home ranges over a longer period of time compared to males.  Fishers established home ranges in a variety of managed (e.g., Washington DNR lands, private timber company lands, tribal lands, Olympic National Forest) and unmanaged landscapes (Olympic National Park, wilderness areas in Olympic National Forest) (Figure 5). Initial findings of home range analyses indicate that fishers released on the Olympic Peninsula used home ranges that were the largest (females; mean: 63.5 + 39.2[SE] km2) or among the largest (males; mean: 128.3 + 66.9[SE] km2) reported for the species (Lewis et al 2012).

Home ranges (95% fixed-kernel contours) of 8 male (white) and 10 female (black) fishers on the Olympic Peninsula from 2008–2012 (not all home ranges are shown).

Monitoring has been successful in tracking the reintroduced population.  A photograph of a fisher at remote camera station in the Duckabush River watershed (Figure 6; March 2013), recoveries of 2 individuals killed by cars on State Highway 101 near Port Angeles (April and May 2013), and numerous other unconfirmed sightings indicate that fishers are persisting within the Olympic Recovery Area. The success of the reintroduction project at reestablishing a self-sustaining population will be determined by long-term monitoring to assess fisher occupancy and population growth throughout the Olympic Recovery Area.  Continued monitoring through 2015 by Olympic National park and partners, will use hair-snare and camera stations placed throughout the Olympic Peninsula to detect fishers. Detection data collected at these stations will be used to determine the location, size, persistence and genetic characteristics of fisher populations that now occur on the Olympic Peninsula, and will indicate if the reintroduction was successful.

Automated camera photo of fisher in the Duckabush River watershed, March 2013.

Cascades fisher reintroduction project. Recovery criteria require that fisher populations be established in the Cascade Recovery Area, as well as the Olympic Recovery Area for the fisher to be down-listed from endangered to threatened or sensitive (Hayes and Lewis 2006).  WDFW, National Park Service (NPS), and the US Forest Service are now planning for a reintroduction effort in the Cascade Recovery Area.  Information from the Olympic fisher reintroduction is being used to shape the reintroduction process for the Cascades to increase the likelihood of success. WDFW will be working with the NPS in 2013-2014 to conduct a NEPA analysis for the proposed fisher reintroduction in the Cascades and WDFW is developing an implementation plan for the reintroduction.  WDFW biologists are also coordinating with the British Columbia Ministry of Environmental to continue our cooperative  efforts to translocate fishers from central B.C. to the Washington Cascades as well as seeking funding and support to initiate a Cascades reintroduction project in fall 2014.

Partners and cooperators:  Olympic, North Cascades, and Mt. Rainier National Parks and the National Park Service; U.S. Geological Survey; U.S. Fish and Wildlife Service; Conservation Northwest; U.S. Forest Service; British Columbia Ministry of Environment; British Columbia Trappers Association; Doris Duke Foundation; Makah Tribe, Lower-Elwha Klallam Tribe; Quinault Tribe; Washington Department of Natural Resources; Washington’s National Park Fund; Seattle City Light; University of Washington; Wildlife Conservation Society.

Literature Cited

Lewis, J. C. 2006. Implementation plan for reintroducing fishers (Martes pennanti) to Olympic National Park. Washington Department of Fish and Wildlife, Olympia, Washington.

Lewis, J. C., P. J. Happe, K. J. Jenkins, and D. J. Manson. 2011. Olympic fisher reintroduction project: 2010 progress report. Washington Department of Fish and Wildlife, Olympia, Washington. (available at:

Lewis, J. C., P. J. Happe, K. J. Jenkins, and D. J. Manson. 2012. Olympic fisher reintroduction project: progress report 2008-2011. Washington Department of Fish and Wildlife, Olympia, Washington. (available at: )

Lewis, J. C. and G. E. Hayes. 2004. Feasibility assessment for reintroducing fishers to Washington. Washington Department of Fish and Wildlife, Olympia, Washington.

Lewis, J. C. and D. W. Stinson. 1998. Washington state status report for the fisher. Washington Department of Fish and Wildlife, Olympia, Washington.

Lewis J C., R. A. Powell, W. J. Zielinski. 2012. Carnivore Translocations and Conservation: Insights from Population Models and Field Data for Fishers (Martes pennanti). PLoS ONE 7(3): e32726. doi:10.1371/journal.pone.0032726

Hayes, G. E., and J. C. Lewis. 2006. Washington state recovery plan for the fisher. Washington Department of Fish and Wildlife, Olympia, Washington. 62 pp.

National Park Service. 2007. Fisher reintroduction plan/environmental assessment. Olympic National Park, Port Angeles, Washington.

U.S. Fish and Wildlife Service. 2004. Endangered and threatened wildlife and plants; 12-month finding for a petition to list the west coast distinct population segment of the fisher (Martes pennanti). Federal Register 69(68):18770-18792.


Source: Washington Department of Fish and Wildlife. 2013. Threatened and Endangered Wildlife in Washington: 2012 Annual Report. Listing and Recovery Section, Wildlife Program, Washington Department of Fish and Wildlife, Olympia. 251 pp.

About the Author: 
Species accounts were compiled by Derek Stinson, Gary Wiles, Gerald Hayes, Jeff Lewis, Lisa Hallock, Steve Desimone, and Joe Buchanan. Many other individuals took time from busy schedules to review species accounts or provide information or documents for this report, including WDFW district and assistant district wildlife biologists, research scientists, and people from other agencies. They include Harriet Allen, David Anderson, Hannah Anderson, Keith Aubry, Lynne Barre, Dana Base, Penny Becker, Scott Becker, Gary Bell, Gretchen Blatz, Joe Buchanan, Steve Desimone, Joe Engler, Greg Falxa, Howard Ferguson, Rich Finger, Scott Fitkin, John Fleckenstein, Eric Gardner, Joe Gaydos, Dawn Gedenberg, Gary Ivey, Lisa Hallock, Molly Hallock, Jeff Heinlen, Eric Holman, Steve Jeffries, Mary Linders, Mike Livingston, Russ Mullins, Travis Nelson, Heidi Newsome, Don Noviello, Brent Norberg, Gail Olson, Ann Potter, Scott Pearson, Leslie Robb, Elizabeth Rodrick, Ella Rowan, Lori Salzer, Chris Sato, Tammy Schmidt, Larry Schwitters, Michelle Tirhi, Laura Todd, Matt Vander Haegen, Jim Watson, and Kristin Wilkinson. Joe Higbee and Rod Gilbert allowed use of many photographs. David Speiser kindly allowed the use of his yellow-billed cuckoo photo..