Westslope Cutthroat Trout

Westslope cutthroat trout laying on grass
Westslope cutthroat trout are one of 11 native species in Yellowstone National Park.

NPS/Todd Koel

 

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.

 
 
Barrier on East Fork Specimen Creek creates a waterfall along the creek
Barrier on East Fork Specimen Creek prevents nonnative fish from invading restoration area.

NPS

 

Restoration

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.

 

Resources

2009. Yellowstone cutthroat trout: Conserving a heritage population in Yellowstone Lake. Mammoth Hot Springs, WY: National Park Service.

Baril, L.M., D.W. Smith, T. Drummer, and T.M. Koel. 2013. Implications of cutthroat trout declines for breeding opsreys and bald eagles at Yellowstone Lake. Journal of Raptor Research 47(3): 234–245.

Bigelow, P.E., T.M. Koel, D. Mahony, B. Ertel, B. Rowdon, and S.T. Olliff. 2003. Protection of native Yellowstone cutthroat trout in Yellowstone Lake, Yellowstone National Park, Wyoming, Edited by US Department of the Interior, National Park Service. Fort Collins, CO: National Park Service, Water Resources Division.

Gresswell, R.E. and J.D. Varley. 1988. Effects of a century of human influence on the cutthroat trout of Yellowstone Lake. In R.E. Gresswell, ed., Status and management of interior stocks of cutthroat trout, 45–52. Vol. Symposium 4. American Fisheries Society.

Gresswell, R.E., W.J. Liss, and G.L. Larson. 1994. Lifehistory organization of Yellowstone cutthroat trout (Oncorhynchus clarkii bouvieri) in Yellowstone Lake. Canadian Journal of Fisheries and Aquatic Sciences 51(S1):298–309.

Gresswell, R.E. 1995. Yellowstone cutthroat trout. In M. K. Young, ed., Conservation assessment for inland cutthroat trout, 36–54. Fort Collins, CO: US Forest Service, Rocky Mountain Forest and Range Experiment Station.

Heckmann, R. 1994. Cutthroats and parasites: Yellowstone Lake’s complex community of fish and companion organisms. Yellowstone Science 2(3).

Kerkvliet, J., C. Nowell, and S. Lowe. The economic value of a predator: Yellowstone trout. In A. P. Curlee, A. Gillesberg and D. Casey, ed., Greater Yellowstone predators: Ecology and conservation in a changing landscape: Proceedings of the third biennial conference on the Greater Yellowstone Ecosystem, 143–150. Yellowstone National Park, WY: Northern Rockies Conservation Cooperative and Yellowstone National Park.

Koel, T.M., P.E. Bigelow, P.D. Doepke, B.D. Ertel, and D.L. Mahony. 2005. Nonnative lake trout result in Yellowstone cutthroat trout decline and impacts to bears and anglers. Fisheries 30(11):10–19.

Koel, T.M., P.E. Bigelow, P.D. Doepke, B.D. Ertel, and D.L. Mahoney. 2006. Conserving Yellowstone cutthroat trout for the future of the Greater Yellowstone Ecosystem: Yellowstone’s Aquatic Sciences Program. Yellowstone Science 14(2).

Koel, T.M., D.L. Mahony, K.L. Kinnan, C. Rasmussen, C.J. Hudson, S. Murcia, and B.L. Kerans. 2006. Myxobolus cerebralis in native cutthroat trout of the Yellowstone Lake ecosystem. Journal of Aquatic Animal Health 18(3):157–175.

May, B.E., W. Urie, and B.B. Shepard. 2003. Range-wide status of Yellowstone cutthroat trout (Oncorhynchus clarkii bouvieri): 2001, Edited by US Forest Service, Montana Fish, Wildlife and Parks, Montana Cooperative Fishery Research Unit. Bozeman, MT.

National Park Service, Yellowstone National Park. 2010. Native Fish Conservation Plan / Environmental Assessment, Edited by Department of the Interior. Yellowstone Center for Resources.

Reinhart, D.P., S.T. Olliff, and K.A. Gunther. Managing bears and developments on cutthroat spawning streams in Yellowstone National Park. In A.P. Curlee, A. Gillesberg and D. Casey, ed., Greater Yellowstone predators: Ecology and conservation in a changing landscape: Proceedings of the third biennial conference on the Greater Yellowstone Ecosystem, 161–169. Yellowstone National Park, WY: Northern Rockies Conservation Cooperative and Yellowstone National Park.

Varley, J.D. and P. Schullery. 1995. The Yellowstone Lake crisis: Confronting a lake trout invasion: a report to the director of the National Park Service. Yellowstone National Park, WY: National Park Service, Yellowstone Center for Resources.

 
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Last updated: November 4, 2019

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