NPSpecies

Fluvial form may be extinct.. Currently extinct from their former range in the Grayling Creek and Gallatin, Firehole, Madison, and Gibbon Rivers (although scattered individuals are sometimes found in the latter two, likely as emigrants from nearby lakes). Currently the only viable populations are in three lakes: Cascade Lake, Grebe Lake, and Wolf Lake (Varley and Schullery 1998).; Data Source: Todd Koel - YELL Supervisory Fishery Biologist, Doug Keinath-Lead Zoologist-Wyoming Natural Diversity Database

Fluvial form is native to the upper Missouri River drainage, adfluvial form introduced to upper Gibbon River lakes and to Cascade Lake which lies within the Yellowstone River drainage in the park.; Data Source: Todd Koel - YELL Supervisory Fishery Biologist

Adfluvial (lake dwelling) form is abundant in headwater lakes of the Gibbon River drainage where they were introduced, the species is occasionally found in the Gibbon and Madison Rivers; Data Source: Todd Koel - YELL Supervisory Fishery Biologist

Park Species Detail: no fluvial populations; 3 lake populations April 2006, Doug Keinath-Lead Zoologist-Wyoming Natural Diversity Database reports: The grayling in YNP are the subspecies called Montana grayling (T. a. montanus)., Park Species Data Source: NPFauna, D. Mahony