Historically the most abundant and widely distributed subspecies of cutthroat trout throughout the West, 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 have only persisted in one tributary of 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 hybridized and 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. 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.
Another restoration 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. A population survey in 2018 yielded 18 fish that ranged from 15-20 inches in length. 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.
The largest WCT restoration effort in Yellowstone is the Grayling Creek project, which will restore WCT to over 20 stream miles of native habitat. Another large restoration 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). In fall 2017 and spring 2018, park biologists introduced westslope cutthroat trout and Arctic grayling to Wolf and Grebe lakes. Fish removal continued on the upper Gibbon River in 2018 between Virginia Cascades and Little Gibbon Falls. Complete removal of non-native fish in this section of river will take 1–2 years. Future restoration projects will be in North Fork Specimen and Cougar creeks. Once these projects are completed, an additional 61 kilometers (38 miles) of stream will be restored fish native to Yellowstone.
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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.
Suckers are bottom-dwelling fish that use ridges on their jaws to scrape flora and fauna from rocks.
Last updated: November 4, 2019