The U.S. Fish and Wildlife Service announced today that its review of the status of mountain whitefish (Prosopium williamsoni) in Idaho’s Big Lost River concludes that protection under the federal Endangered Species Act (ESA) is not warranted.

The status review finds that the mountain whitefish in the Big Lost River is not a listable entity as defined by the ESA. The ESA defines a vertebrate animal as a “species” if the Service determines it is a separate species, subspecies or Distinct Population Segment (DPS). According to the statute, a population cannot be considered for the protections of the ESA unless it qualifies as a listable entity. Based on the best available scientific information and genetic data, as well as information presented for Service review, the mountain whitefish in the Big Lost River is not a separate species, subspecies or DPS compared to other mountain whitefish found in the West and therefore cannot be considered for the protections of the ESA.

Genetic data provided to the Service demonstrated that many populations of mountain whitefish show a high degree of genetic structuring, which indicates they are geographically isolated. Although the Service considered this information to be indicative of relative reproductive isolation of various populations, it was not sufficient to identify the mountain whitefish in the Big Lost River as a new species or subspecies, and they do not have other characteristics that suggest they may be a different species. Although the mountain whitefish in the Big Lost River do not qualify for listing under the ESA, the Service notes the mountain whitefish in the Big Lost River are an important component of the native diversity of that natural system, and emphasizes that its finding should not be construed to mean the fish are not worthy of preservation on a local level.

“The Service strongly supports continued cooperative conservation of mountain whitefish and its habitat in the Big Lost River basin,” Gary Burton, acting Idaho State Supervisor for the Service, said.

Western Watersheds Project first petitioned the Service to list the Big Lost River mountain whitefish in 2006. After reviewing the petition in 2007, the Service determined that the petitioned action was not warranted, based on a lack of substantial information indicating the mountain whitefish in the Big Lost River may be a separate species, subspecies, or DPS. The Western Watersheds Project then filed a complaint in 2008 challenging the Service’s finding. In response to that lawsuit, the United States District Court in Boise, Idaho, directed the Service to conduct a status review of mountain whitefish in the Big Lost River and, within one year, issue a finding on whether the population should be protected as a threatened or endangered species. The court ordered the Service to make a final listing determination by March 31, 2010.

Mountain whitefish, sometimes known as mountain herring, are members of the Salmonidae family. The species is found throughout mountainous areas of northwestern North America in both the United States and Canada. It is known to occur in the States of Washington, Oregon, Idaho, Wyoming, Montana, Colorado, Utah, Nevada and California. The preferred habitat for mountain whitefish is cold water streams and lakes, and some populations are restricted to lakes or isolated sink basins.

Mountain whitefish in the Big Lost River reside in a closed basin (sink) in southeast Idaho. The Big Lost River valley is the only one of five sink drainages in Idaho that contains mountain whitefish. Additional populations of mountain whitefish occur in other sink drainages, such as the Lahontan Basin in California and Nevada, and the Bonneville Basin in Utah.

For further information, please contact Steve Duke, U.S. Fish and Wildlife Service, Idaho Fish and Wildlife Office, by mail at 1387 S. Vinnell Way, Room 368, Boise, ID 83709; by telephone at 208-378-5345; by facsimile at 208-378-5262; or by electronic mail at: Persons who use a telecommunications device for the deaf (TDD) may call the Federal Information Relay Service (FIRS) at 800-877-8339.