Westslope Cutthroat Trout

The westslope cutthroat trout (Onchorhynchus clarkii lewisii, WCT) currently occupies less than 5% of its previous range in the upper Missouri River drainage, including Yellowstone National Park. Historically, it was the most abundant and widely distributed subspecies of cutthroat trout. During the first half of the 20th century, the stocking of non-native competing brown trout and interbreeding rainbow trout and Yellowstone cutthroat trout reduced genetically pure WCT populations. In 2004, the Montana Natural Heritage Program designated the WCT a Species of Concern because it is considered vulnerable to extinction. The U.S. Fish and Wildlife Service has designated WCT a Species of Special Management Concern, but determined that listing the WCT as threatened under the Endangered Species Act was not warranted. The issue is being considered by the U.S. District Court for the District of Columbia.