The Arctic Grayling is a species native to northern North America. The only populations native to the lower 48 states were in Michigan and Montana, and the Michigan population is now extinct. Consequently, the fluvial or river-dwelling population in the upper Big Hole River are the last remnants of this native Fish of Special Concern. Originally, the fluvial Arctic Grayling was widespread throughout the upper Missouri river drainage as far downstream as Great Falls. Lewis and Clark made note of these "new kind of white or silvery trout" in 1805. The lake-dwelling form is fairly common in 30 or more lakes across the western half of the state. These lake fish are genetically, but not visibly, different from our native fluvial Arctic Grayling. Grayling are gullible to the angler's lures and also seem to be easily out-competed by other salmonid species. This probably explains much of their demise from their native range. They are spring spawners and broadcast their eggs over a gravel bottom in moving streams. Grayling can overpopulate, producing severely stunted populations in some mountain lakes. Grayling are truly a unique Montana species. The iridescent hues of a spawning grayling's dorsal fin are brilliant. Exceptional individuals can weigh up to 3 pounds and reach 20 inches in length. They are generalists, eating a variety of aquatic invertebrates (Montana Fish, Wildlife, and Parks).
Western Hemisphere Range
Very mobile; up to 60 mile seasonal movements between habitats in Big Hole. Utilizes various habitats in multiple places over life history.
Today in Montana Arctic Grayling are found primarily small, cold, clear lakes with tributaries suitable for spawning. They do not coexist well with other fishes except cutthroat trout and others with which they evolved.
Although fluvial Arctic Grayling inhabit the entire Big Hole River, highest densities occur in the vicinity of Wisdom. The majority of spawning occurs near Wisdom in the main stem and several tributaries (Liknes and Gould 1987, Shepard and Oswald 1989, Byorth 1994). Fluvial Arctic Grayling are reared in the vicinity of where they hatch; thus, the Wisdom area provides the majority of rearing habitat as well (Montana AFS Species Status Account
Arctic Grayling rarely live beyond 5 years in the Big Hole River. Fast growth rates and short life spans result in domination of spawning by fish aged 3 and 4 years. Thus, poor recruitment in a given year may substantially affect recruitment to the population for several years (Montana AFS Species Status Account
Arctic Grayling grow quickly in the Big Hole River, reaching full sexual maturity and nearly maximal size by age 3 (Montana AFS Species Status Account
On 20 August 2014, the U.S. Fish and Wildlife Service published a notice in the Federal Register indicating that, "after review of the best available scientific and commercial information, we find that listing the Upper Missouri River DPS of Arctic Grayling is not warranted at this time. The best available scientific and
commercial information indicates that habitat-related threats previously identified, including habitat fragmentation, dewatering, thermal stress, entrainment, riparian habitat loss, and effects from climate change, for the Upper Missouri River DPS of Arctic Grayling have been sufficiently ameliorated and that 19 of 20 populations of Arctic Grayling are either stable or increasing. This action removes the Upper Missouri River DPS of the Arctic Grayling from our candidate list". Additional information on the species' management can be found on the U.S. Fish and Wildlife Service's Species Account