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USFWS Says Northern Rockies Fisher A Distinct Population Segment, Does Not Warrant ESA Protection
Posted on Friday, July 08, 2011 (PST)

The U.S. Fish and Wildlife Service has completed a status review of the fisher in the northern Rocky Mountains, and concluded it does not warrant protection under the Endangered Species Act in Idaho, Montana or Wyoming.


The fisher is a brown to dark blackish-brown medium-sized mammal found only in North America. Fishers occur in conifer forests and avoid areas with little or no cover. They prey on small mammals and birds. The fisher’s range extends across forested areas in Canada and extends south to the United States in the Great Lakes area and the Atlantic states as far south as West Virginia. Fishers are also found in southwest Oregon, northwest California, and the southern Sierra Nevada Mountains of California, in addition to the northern Rocky Mountains.


On March 6, 2009, the USFWS received a petition from the Defenders of Wildlife, Center for Biological Diversity, Friends of the Bitterroot, and Friends of the Clearwater requesting that the fisher in the northern Rocky Mountains (Idaho, Montana and Wyoming) be considered a “istinct population segment” and listed as endangered or threatened under the ESA, and critical habitat be designated.


The petitioners cited several reasons why the fisher in the northern Rockies should be protected under the ESA, including habitat loss and modification, trapping, inadequate regulatory mechanisms and small population size.


The USFWS published the results of its review of the petition, also called a 90-day finding, on April 15, 2010, indicating that the petition presented substantial information that listing of the fisher in the northern Rocky Mountains may be warranted.


It commenced a status review of the species at that time. No region-wide population trends or numbers are known for the northern Rocky Mountain population of fisher, but the contemporary fisher distribution is similar to that described historically for northern and north-central Idaho and is more expansive in northwestern and west-central Montana than what was known historically. Wyoming was excluded from this analysis based on a lack of recent verified records of fisher presence or historical evidence of a breeding population.


Based on a review of the available information, the federal agency determined that fishers in the northern Rocky Mountains meet the definition of a DPS because they are geographically separated from other fisher populations, and because the loss of this population would result in a significant gap in the range of the species and the loss of a unique genetic identity found nowhere else within the range of the species.


The USFWS analyzed potential factors that may affect the habitat and range of the fisher in the U.S. northern Rocky Mountains including timber harvest and management, climate change, fire, forest disease, furbearer trapping, disease and predator relationships, inadequacy of existing regulatory mechanisms, and the effects of small population size.


The agency concluded that the available information does not indicate that fishers in the northern Rockies are impacted by habitat loss or by current or foreseeable management of forest habitats because the species continues to occupy its known historic range and has expanded in some areas despite habitat alterations that have occurred within that range. Additionally, it found that the available information does not indicate that potential threats such as stochastic events, climate change, disease, predation, or the inadequacies of existing regulatory mechanisms significantly impact the species.


Trapping for fisher has been illegal in Idaho for over 60 years, but fishers are occasionally captured and killed accidentally in traps set for other species. Montana instituted a regulated and monitored trapping program that has demonstrated a sustained harvest of fishers over the past 30 years. Though fishers are easily trapped and populations may be sensitive to over-trapping, existing data indicate that the current level of intentional or incidental harvest does not cause a population-level effect to fishers in the northern Rockies region.


In issuing its determination, the USFWS said, “Therefore, based on a thorough review of the best available scientific information, we have determined that the northern Rocky Mountain population of fisher is not in danger of extinction or likely to become endangered within the foreseeable future. Despite not being warranted for listing as endangered or threatened, in making this finding we recognize that the fisher in the borthern Rockies may benefit from increased management emphasis due to its need for forest cover and its susceptibility to capture and mortality from furbearer harvest. We recommend and encourage additional research to improve the understanding of the species and precautionary measures to protect the species.


A copy of the 12-month finding and other information about the fisher is available at

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