Historically the most abundant and widely distributed subspecies of cutthroat trout, the westslope cutthroat trout (Onchorhynchus clarkii lewisi, WCT) occupies less than 5% of its former range in the upper Missouri River drainage. It evolved from a common ancestor of the Yellowstone subspecies, and shares their food and habitat requirements. By the 1930s, WCT were nearly eliminated from park streams because of the stocking of competing trout (nonnative brook and brown trout) and interbreeding with nonnative rainbow and Yellowstone cutthroat trout. In most of its remaining habitat (an estimated 64% of the approximately 641 stream miles it once occupied in the park), it exists only in hybridized form.
Native species restoration depends on secure brood sources. A brood should be accessible, safe from contamination, self-sustaining, genetically diverse, abundant, of traceable origin, and pose no risk to existing wild populations.
Genetically pure WCT only persisted in one tributary in the Madison River drainage (now called Last Chance Creek), and in the Oxbow/Geode Creek complex where they were introduced in the 1920s. In 2006, Yellowstone began efforts to restore WCT in East Fork Specimen Creek and High Lake by constructing a fish barrier, removing nonnative fish, and stocking genetically pure WCT. In 2016 and 2018, surveys conducted throughout East Fork Specimen Creek indicated a naturally reproducing population of westslope cutthroat trout, with all fish appearing healthy. Unfortunately research in 2019 revealed that hybridized fish have moved upstream of the constructed barrier, threatening the restored portion of the creek. The long-term goal for this watershed is to integrate East Fork Specimen Creek into a larger westslope cutthroat trout restoration project that includes the North Fork to improve the resilience of this isolated population to natural threats.
A range expansion project is being conducted in Goose Lake and two other small, historically fishless lakes in the Firehole drainage. Nonnative fish removal was conducted in 2011 and staff stocked fry from 2013 to 2015. The long-term project goal is to one day use this pure westslope population as a brood source, providing offspring for restoration projects elsewhere within the upper Missouri River system.
Another range expansion project is the upper Gibbon River. In 2017, native fish restoration began on the upper portion of Gibbon River, above Virginia Cascades. This project encompasses more than 18 stream miles and 232 lake acres (Wolf, Grebe, and Ice lakes).Since fall of 2017, park biologists have introduced approximately 59,000 westslope cutthroat and 140,000 arctic grayling to Wolf, Grebe, and Ice lakes and surrounding tributaries. Fish removal continued on the upper Gibbon River in 2018 and 2019 between Virginia Cascades and Little Gibbon Falls. Complete removal of non-native fish in this section of river will take several years.Future restoration projects for westslope cutthroat trout and Arctic grayling will take place in will be in North Fork Specimen and Cougar creeks. Once completed, native fish will be restored to an additional 61 km of stream waters.
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Yellowstone Cutthroat Trout
Yellowstone cutthroat trout are the most widespread native fish in the park.
Mottled sculpin live in shallow, cold water throughout Yellowstone except the Yellowstone River above Lower Falls and in Yellowstone Lake.
Yellowstone’s minnows are small fish living in a variety of habitats and eating a variety of foods.
Last updated: January 28, 2020