After a thorough review of all available scientific information, the U.S. Fish and Wildlife Service has determined that the westslope cutthroat trout does not warrant listing as a threatened species under the Endangered Species Act because abundant, stable, and reproducing populations remain well distributed throughout its historic range.
The Service based its finding on information contained in a 1999 status review as well as a 2003 status update report prepared by the fish and game departments of the States of Idaho, Montana, Oregon, and Washington, and the U.S. Forest Service. That report confirms that westslope cutthroat trout populations currently occupy 33,500 of its historic stream miles (59 percent) in the United States and genetically pure populations inhabit approximately 3,500 stream miles (57 percent of tested stream miles; 10 percent of occupied miles) and may inhabit as many as 12,600 miles of stream in which no potentially hybridizing fishes occur. Many of these genetically-pure populations of the fish are found in habitats protected by natural barriers preventing interbreeding with other trout subspecies.
While the Service acknowledges that only a small portion (about 18%) of existing westslope cutthroat trout populations have been genetically tested, the Service concluded that the sampling that has been accomplished clearly indicates that numerous, genetically pure westslope cutthroat trout remain today.
On April 14, 2000, the Service published a finding that the westslope cutthroat trout was not likely to become either a threatened or endangered species in the foreseeable future. Subsequently, American Wildlands and four other environmental groups filed a lawsuit arguing that the Service acknowledged hybridization as a threat to the species but included hybrids in the overall westslope cutthroat trout population without providing a justification.
The Court ruled in favor of the plaintiffs and ordered the Service to reconsider whether to list the westslope cutthroat as a threatened subspecies and to more thoroughly take into account the hybridization issue when making that decision. In addition, the Court directed the Service to present its" scientifically-based conclusion about the extent to which it is appropriate to include
