Arctic Grayling

A submerged view of a fish in shallow water
Of the 11 native fish in Yellowstone, Arctic grayling is one of three considered a sport fish.

©Jay Fleming


Arctic grayling (Thymallus arcticus montanus) were indigenous to the park in the headwaters of the Madison and Gallatin rivers and to the Gibbon and Firehole rivers below their first falls. Fluvial grayling were eliminated from their entire native range within the park by the introduction of competing nonnative fishes such as brown trout and brook trout, and the fragmentation of migration pathways by the construction of the Hebgen Dam outside the park. Grayling within the upper Gallatin River drainage disappeared around 1900, while grayling in the upper Madison River drainage disappeared by 1935. The only known populations left in the park are adfluvial (primarily lake-dwelling) descendants of fish that were stocked in Cascade and Grebe lakes.

When Grebe and Wolf lakes were treated with Rotenone in 2017 to remove rainbow trout, all Arctic Grayling in the system were lost as well. The NPS is now working to restore these Arctic grayling populations along with WCT.



One of the goals of the park’s 2010 Native Fish Conservation Plan is to restore fluvial grayling to approximately 20% of their historical distribution. The upper reaches of Grayling Creek are considered the best site for immediate fluvial grayling restoration. Near the park boundary, a small waterfall exists in the creek (which flowed directly into the Madison River prior to the construction of Hebgen Dam in 1914).

The Grayling Creek restoration project aims to establish Arctic grayling and westslope cutthroat trout to 95 kilometers (59 miles) of connected stream habitat in one of the most remote drainages in the species historic range within Yellowstone.

During summer 2013, the waterfall was modified to prevent upstream movement of fish into the system. During August 2013, a crew of 27 biologists from Yellowstone National Park, Montana Fish, Wildlife and Parks, Gallatin National Forest, Turner Enterprises, and US Fish and Wildlife Service treated the stream segment with piscicide to remove all fish. A second treatment took place in 2014. Restocking the Grayling Creek watershed with native fluvial Arctic grayling and WCT began in 2015 and continued through 2017. The effort included moving approximately 950 juvenile and adult WCT to the lower reaches of Grayling Creek, above the project barrier. In addition, 54,200 WCT eggs and 210,000 fluvial grayling eggs were placed in remote-site incubators throughout the upper watershed. In 2018, park biologists and Montana State University researchers began to evaluate the success of reintroduction efforts on upper Grayling Creek. Preliminary results suggest that WCT are slowly repopulating the system, but grayling are struggling to establish a self-sustaining population.

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1 minute, 32 seconds

To maintain the natural biodiversity of the Yellowstone ecosystem, sometimes you have to start small. Fish biologist Todd Koel discusses efforts to restore native fish in Grayling Creek, a cup of eggs at a time.



Kaya, C. 2000. Arctic grayling in Yellowstone: Status, management, and recent restoration efforts. Yellowstone Science 8(3).

Steed, A.C., A.V. Zale, T.M. Koel, and S.T. Kalinowski. 2011. Population viability of Arctic grayling in the Gibbon River, Yellowstone National Park. North American Journal of Fisheries Management 30:1582-1590

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Young cutthroat trout swimming in shallow water
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Last updated: May 8, 2023

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