Many anglers are familiar with Yellowstone’s native trout—the Yellowstone cutthroat. But fewer anglers are aware that Westslope cutthroat are native to the park, in addition to Arctic grayling.
Specifically, Westslope cutthroat are native to the Missouri River drainage (as are grayling). They were once the most widely distributed cutthroat subspecies, but they currently occupy less than 5% of their historical native range, according to the Park Service. But plenty of opportunity exists to help these fish thrive once more, even while their cousins fight lake trout in Yellowstone Lake.
In particular, a lot of traction has been gained in restoring westslope cutthroat to the upper reaches of the Gibbon River. Back in 2017, a fish restoration project started on the Gibbon above Virginia Cascades, and the Park Service says it encompasses 21 stream miles, and 232 lake acres. Roughly 75,000 cutthroat and 170,000 grayling have been planted in Wolf, Grebe, and Ice Lakes, in addition to the surrounding tributaries. These lakes form the headwaters of the Gibbon.
The results have been impressive lately, as Paul Weamer noted in a recent story. Weamer is an author and also runs the Yellowstone Fly Fishing Volunteer program, a group of anglers who give their time to catch fish each summer, aiding biologists in gaining information about fish populations throughout the park.
One of the volunteers caught a 19-inch westslope cutthroat from Grebe Lake in 2024, and in total, Weamer’s group caught 683 cutthroat and grayling from both Grebe and Wolf Lake over eight days of fishing. The best grayling caught during their time was 16 inches long—not a size to sneeze at for grayling.
Weamer also noted that a spawning population of grayling is now established in Grebe Lake, which is “exceedingly rare to find…in the Lower 48.”
The Upper Gibbon, above Virginia Cascades, also has a good population of fish. These trout and grayling tend towards the smaller side, however, which has led biologists to believe this section of the river acts as a nursery. Smaller fish eventually work their way below the Cascades, where they grow to much larger sizes.
As of Weamer’s writing, biologists had successfully restored westslope cutthroat to 21% of their historical native range, no small feat in today’s conservation world.
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