Groups Move to Save the Westslope Cutthroat Trout

Fish discovered by Lewis and Clark threatened


Rob Ament, American Wildlands 406-586-8175


Abigail Dillen, 406-586-9699

“Goodrich had caught half a dozen very fine trout and a number of both species of the white fish. These trout are from sixteen to twenty-three inches in length, precisely resemble our mountain or speckled trout in the form and the position of their fins, but the specks on these are of a deep black instead of the red or gould colour of those common to the U’ States.” – Journal entry of Meriwether Lewis, June 13, 1805, Great Falls of the Missouri River (Mont.), on his discovery of the westslope cutthroat trout.

After nearly a decade of deflecting efforts to protect dwindling populations of the trout Lewis and Clark discovered in the northern Rockies 200 years ago, federal fisheries managers are facing legal action to save the fish species. A lawsuit demanding the U.S. Fish and Wildlife Service revisit its decision denying protecton to the westslope cutthroat trout under the Endangered Species Act was filed in U.S. District Court in Washington, D.C. today. The suit was filed by Earthjustice on behalf of American Wildlands, Clearwater Biodiversity Project, Montana Environmental Information Center, and fly-fishing legend Bud Lilly.

“Here we go again,” said Lilly, an iconic Montana fishing guide, “it looks like their final decision not to protect the state fish of Montana and Idaho doesn’t hold any more water than their earlier renditions.” He is referring to this fourth in a series of lawsuits brought by conservationists to force the government to abide by the Endangered Species Act’s requirements and base its decision on unbiased reviews of the best available scientific information.

Conservationists are concerned that the government has once again misconstrued and misrepresented published scientific papers on the greatest threat to the species’ existence: hybridization with other trout, primarily non-natives. Scientists researching westslope cutthroat trout have written two letters to the Fish and Wildlife Service, published several peer-reviewed scientific articles, and are preparing to publish additional commentary in a scientific journal on the threat of hybridization to westslope cutthroat trout. They believe the Fish and Wildlife Service has made a faulty decision not to protect the westslope ‘cutt under the Endangered Species Act — based on misuse of published data — and they want to set the record straight.

“The Fish and Wildlife Service has a long and lamentable history of not listing species, regardless of the science. This time it isn’t about my science versus your science,” said American Wildlands’ Executive Director Rob Ament. “It’s all the experts saying wrong, wrong, wrong.”

In an earlier lawsuit (the third) by conservationists, the Fish and Wildlife Service contended that westslope cutthroat, though heavily hybridized with rainbow trout and restricted to a fraction of its historic multi-state range, faced no significant danger of extinction. However, the native trout’s future brightened when a federal judge reprimanded the Fish and Wildlife Service and ordered the agency to reevaluate its methods — focusing on hybridization — for refusing to list westslope cutts as a threatened species. The Fish and Wildlife Service’s second refusal to list the species as threatened under the Endangered Species Act, in response to the judge’s order, is the basis for this lawsuit.

Earthjustice attorney Abby Dillen said, “The Fish and Wildlife Service’s interpretation of the science is a real head-scratcher, until you realize that the results of such a reading of the facts allows them to live in an illusory world where westslope cutthroat trout aren’t in danger of extinction.”


  • Lewis and Clark recorded their encounters with the westslope cutthroat trout in their journals and collected samples in 1805. The fish’s scientific name (Oncorhyncus clarki lewisi) is derived from the famous explorers’ names.
  • The main causes for the decline of westslope cutthroat trout (WCT) are degraded habitat, competition from non-native fish and hybridization.
  • To artificially bolster habitat size, the U.S. Fish and Wildlife Service counted an entire stream or river as WCT habitat, even if the fish was found in only a single spot in the stream or river.
  • As part of its decision, the U.S. Fish and Wildlife Service concluded that a WCT can be up as much as 20 percent hybridized and still be considered a pure-strain WCT.
  • Last year, U.S. District Judge Emmet G. Sullivan ordered the U.S. Fish and Wildlife Service to consider the threat of hybridization when he ordered the agency to reconsider its original decision not to list the westslope cutthroat trout.
  • WCT require cool, clean, oxygenated waters and are therefore sensitive to the sedimentation that occurs in streams close to disturbed areas.
  • Due to its stringent habitat needs, the westslope cutthroat trout is as an indicator species of overall ecosystem health.

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