Red Rock Lakes National Wildlife Refuge
Mountain-Prairie Region

Arctic Grayling Restoration Project attempts to recover the native population at Red Rock Lakes National Wildlife Refuge.

Over the last several years, fisheries scientists have designed a plan to protect the dwindling native population of the Arctic Grayling at the Red Rock Lakes National Wildlife Refuge. Upper Red Rock Lake is the southern-most portion of their North American Range and the goal is to increase the chances of survival of this species of fish in this watershed. Due to the dwindling numbers of fish in the Upper Missouri River area, this fish is officially a candidate for listing on the USFWS Endangered or Threatened Species List.

Arctic Grayling Recovery Project

Click image for slideshow story of an event in 2012.

Several steps have been taken for the protection and restoration of the Arctic Grayling population at our Refuge:

  • studies on the Arctic Grayling's life cycle and food sources
  • environmental studies and testing to determine actual and ideal living and spawning conditions
  • structural changes at the Refuge to encourage breeding
  • artificial breeding assistance (egg incubation and placement)
  • seasonal inventory of fish sex, size, weight and health
  • catch and release creek policy and no-fishing in lakes

Click HERE for more information.

Photo Gallery of the Arctic Grayling
click photo below for more images:
Click for Arctic Grayling Physical Characteristics.

Arctic Grayling Characteristics


Arctic grayling (Thymallus arcticus)are in the same family (Salmonidae) as salmon, trout, and whitefish. Physically they have elongate, laterally compressed, trout-like bodies with deeply forked tails, and adults typically average 12-15 inches in length (the record in Alaska was 21 inches). Coloration can be striking, and varies from silvery or iridescent blue and lavender, to dark blue. The sides are marked with a varying number of V-shaped or diamond-shaped spots. During the spawning period, the colors darken and the males become more brilliantly colored than the females. A prominent morphological feature of Arctic grayling is the sail-like dorsal fin, which is large and vividly colored with rows of orange to bright green spots, and often has an orange border. The Arctic Grayling grows to a maximum recorded length of 30 inches and a maximum recorded weight of 8.4 pounds. Of typical thymalline appearance, the Arctic grayling is distinguished from the similar grayling like the European/Asian Grayling ( T. thymallus) by the missing dorsal and anal spines and by the presence of a larger number of soft rays in these fins. There is a dark midlateral band between the pectoral and pelvic fins, and the flanks may possess a pink iridescence. The Arctic Grayling in Alaska is known to live up to 18 years but in Montana is only expected to live between 7 and 11 years.

Click for Frequently Asked Questions.

Arctic Grayling Frequently Asked Questions

1) Are Arctic Grayling native to this area? [Answer: Arctic grayling in Montana represent a glacial relict population from the Wisconsinan Ice Age. The population in Upper Red Rock Lake represents the last endemic population of adfluvial Arctic grayling in the contiguous United States, although populations have been established in approximately 60 lakes throughout western Montana. Early accounts by homesteaders show that Arctic grayling were common throughout the lakes and streams of the upper Centennial Valley. The population began to decline in the 1930s, likely due to a combination of factors such as introduction of nonnative fish (such as brook, rainbow and cutthroat trout), water diversion, and heavy grazing of riparian corridors. Upper Red Rock Lake Arctic grayling currently only spawn in Red Rock and Odell creeks, although historically they spawned in other Upper Lake tributaries.]

2) How do Arctic Grayling survive in the Lake in the winter when it is frozen? [Answer: Generally, Arctic Grayling are well adapted to cold water. The lake doesn't freeze completely to the bottom, but there are problems due to the reduced lack of oxygen in a shallow and partially frozen lake. Scientists are trying to understand more about exactly where they reside in winter. It's possible that they swim up into the moving water of the creeks in winter to get more oxygen.]

3) Why do Arctic Grayling swim up a creek and spawn so far from where they live in the lake? [Answer: They are part of the salmon family and like those, they swim to the general area of their birth, usually a rocky or gravel stream bed far from where they live normally. At Red Rock Lakes, better quality spawning habitat exists farther up these streams than nearer to the lake.]

4) What is the difference between adfluvial and fluvial Grayling? [Answer: Adfluvial Arctic grayling spend the majority of their lives inhabiting lakes and use inlet or outlet streams for spawning, whereas fluvial grayling spend their lives in rivers and streams. It is thought that the majority of the fish in Upper Red Rock Lake spawn in Red Rock Creek. Grayling from both large Refuge lakes historically had used Elk Springs, Odell, Tom Creek plus several other smaller streams to spawn.]

5) Where are adfluvial Grayling found? [In Montana, These grayling have been introduced into many locations and are distributed throughout Montana in mountain lakes. Native adfluvial populations in Montana were limited to the Red Rock Lakes, and a few lakes in the Big Hole Drainage. Historically, the Red Rock population spawned in numerous tributaries to Upper and Lower Red Rock lakes. Currently, only Red Rock and Odell Creeks appear to support spawning by endemic adfluvial Arctic grayling (Boltz 2006). Declines in this population are attributed to habitat alteration, drought conditions, reduced stream flows, siltation, and predation or competition from non-native fish species

6) What do Arctic Grayling Eat? [Answer: They are generalists, eating a variety of aquatic invertebrates. They mainly consume small immature aquatic insects, including dipteran larvae and pupae, mayfly larvae, and caddis fly larvae. They will eat fish eggs, small fish and small mammals as well.]

7) What causes Arctic Grayling to spawn? [ A combination of water temperature (between 36 and 50F but closer to 50F), stream flow rate (2 to 5 feet per second), an acceptable gravel bottom, and minimum distraction from other fish allow them to spawn once per year.

8) How do they spawn in nature? [Answer: Male fish are territorial, staking a claim to a short length of stream bed and only allowing competitors to pass on the opposite side of the bank. They are also promiscuous, mating several times with several females. Females are also known to mate more than once with several males. They approach one another, the male hovers over the female, and if the male is acceptable, they quiver in increasing frequency depositing eggs and milt over a small depression of gravel (made by their quivering). The eggs stick to the small gravel.

9) Why is the native Arctic Grayling population dwindling in Montana? [Answer: The majority of the historical range of the Upper Missouri River of Arctic grayling has been altered by the construction of dams and reservoirs that created barriers obstructing migrations to spawning, wintering, or feeding areas and inundated grayling habitat. These modifications to the rivers have impacted the historical hydrology of river systems. These and other land use practices such as stream sedimentation, dewatering and entrainment, along with non-native fish species introductions have worked collectively or separately in reducing grayling numbers in their native range.]

Images were photographed by James N Perdue 2012.Permission to reuse is granted. Please give credit to photographer.

RETURN to Red Rock Lakes National Wildlife Home Page
Joint Project of US Fish & Wildlife Service and Montana Fish, Wildlife & Parks
Last updated: July 24, 2012