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Thymallus arcticus

What do they look like?

Arctic grayling have elongated and trout-like bodies. Like other salmon, they have short heads, large eyes, small, toothed mouths, and forked tails. Arctic grayling are 15 to 36 cm long, with an average weight of 1 to 2 kg. The largest individual on record was around 76 cm long and 3.8 kg. They have dark colors on their backs, from dark purple to blue grey. Their sides are gray or blue with patterns of v-shaped markings. Males are often more brightly colored than females. The fins can have bright pink and orange stripes on them. ("Arctic Grayling (Thymallus arcticus)", 2013; "Arctic Grayling Recovery", 2012)

  • Sexual Dimorphism
  • male more colorful
  • Range mass
    3.8 (high) kg
    8.37 (high) lb
  • Average mass
    1.5 kg
    3.30 lb
  • Range length
    76 (high) cm
    29.92 (high) in
  • Average length
    15-36 cm

Where do they live?

Arctic grayling are found throughout the much of the northern hemisphere, including northern Canada, Alaska, and Siberia. They were once found throughout the Arctic as far west as the Kara River in Russia, as far east as the western shores of the Hudson Bay in Canada, and as far south as Michigan. Though they no longer occur naturally in North America apart from Canada and Alaska. They have been introduced into high elevation lakes of the western mountain states, such as Arizona and California, and the upper Missouri River drainage in Montana. (Sepulveda, et al., 2013; Stamford and Taylor, 2004)

What kind of habitat do they need?

Arctic grayling live in high-elevation, mid to large, cold and clear freshwater lakes and rivers. In the early spring, they migrate from overwintering areas to rocky streams for spawning. They then move to summer feeding areas before finding a suitable wintering spot, where they spend 8 to 9 months under ice. (Baccante, 2011; Hughes and Reynolds, 1994)

  • These animals are found in the following types of habitat
  • polar
  • freshwater
  • Aquatic Biomes
  • lakes and ponds
  • rivers and streams

How do they grow?

Arctic grayling fry hatch 2 to 3 weeks after spawning, and they are approximately 1.3 cm long at hatching. The fry immediately move toward the calm and warm shoreline waters where they will become juveniles at 5 to 10 cm by the end of summer. They continue to grow quickly and reach maturity in 3 to 4 years. At this point, they begin to grow much more slowly as they dedicate more of their annual energy intake to spawning efforts. ("Arctic Grayling (Thymallus arcticus)", 2013; Wedekind, et al., 2013)

  • Development - Life Cycle
  • temperature sex determination

How do they reproduce?

Arctic grayling spawn in spring in shallow areas of rivers with moderate current as well as a gravel or rocky areas and fine sand sediments. Males court females by flashing their colorful dorsal fins. The eggs are dropped onto the river bottom and are left there to develop. (Kratt and Smith, 1980)

Arctic grayling lay eggs in the spring, when ice begins to break up. Depending on the size of the female, she may lay between 1,500 and 30,000 eggs. The eggs sink to the bottom and become lodged between pebbles and gravel. Only about 10% of the fry that hatch from the eggs will reach adulthood and be able to spawn. ("Arctic Grayling (Thymallus arcticus)", 2013; Kratt and Smith, 1980)

  • How often does reproduction occur?
    Arctic grayling breed once yearly in springtime spawning events.
  • Breeding season
    Breeding occurs in spring.
  • Range number of offspring
    1500 to 30000
  • Average time to hatching
    2.5 weeks
  • Average age at sexual or reproductive maturity (female)
    3.5 years
  • Average age at sexual or reproductive maturity (male)
    3.5 years

Arctic grayling parents generally do not invest much in the young apart from defending the spawning area. (Kratt and Smith, 1980; Miano, 2013)

  • Parental Investment
  • pre-fertilization
    • provisioning
    • protecting
      • male
      • female

How long do they live?

The lifespan of arctic grayling is usually around 18 years for both males and females. However, individuals in Alaska have been known to live up to 32 years. Most mortality occurs in eggs, larvae, and fingerlings or in areas where these fish are heavily fished. ("Arctic Grayling (Thymallus arcticus)", 2013; "Arctic Grayling Recovery", 2012)

  • Range lifespan
    Status: wild
    32 (high) years
  • Typical lifespan
    Status: wild
    18 (high) years

How do they behave?

Arctic grayling migrate between streams used for spawning, development, summer feeding, and overwintering in order to survive in their harsh arctic habitats. Some individuals, however, are sedentary. They are active during the day. (Davis, et al., 2010; Gingerich, et al., 2010)

Home Range

Arctic grayling may move tens of miles on a seasonal or annual basis between spawning, feeding, and sheltering habitats. Some arctic grayling have been known to travel more than 160 km (100 miles) in one year. (Davis, et al., 2010; Gingerich, et al., 2010)

How do they communicate with each other?

There is little information on arctic grayling communication and perception. But, like other freshwater fish, they probably use a lateral line system that detects pressure changes in the water and they are also likely to be able to detect chemical cues in the water. They are visual predators, reacting to visual cues to detect and attack prey. (Bleckmann and Zelick, 2009)

What do they eat?

During the brief northern summers, arctic grayling eat drifting aquatic insects, such as black flies, mayflies, stoneflies, and caddisflies. At times, they eat eggs of spawning salmon, smaller fish, or terrestrial insects that have fallen into the water. They may even eat an occasional vole, lemming, or shrew. Young arctic grayling feed on zooplankton and eventually transition to feeding on insect larvae. ("Arctic Grayling Recovery", 2012; Davis, et al., 2010)

What eats them and how do they avoid being eaten?

  • These animal colors help protect them
  • cryptic

What roles do they have in the ecosystem?

Arctic grayling are one of the top predators in their aquatic habitats. They prey on a wide variety of insects, fish and other small animals. They are also hosts to several parasite species. (Arai and Mudry, 1983; Davis, et al., 2010; Muzzall, 1990)

Commensal or parasitic species (or larger taxonomic groups) that use this species as a host
  • Cystidicoloides tenuissima
  • Pomphorhynchus bulbocoli

Do they cause problems?

There are no known adverse effects of arctic grayling on humans.

How do they interact with us?

Arctic grayling are raised commercially for food and fished for sport. ("Arctic Grayling (Thymallus arcticus)", 2013)

  • Ways that people benefit from these animals:
  • food

Are they endangered?

While arctic grayling are not currently considered endangered, they are sensitive to pollution in the areas they live. They are most vulnerable to overfishing, competition, road culverts, mining, agriculture, and destructive forestry practices. Recent findings suggest that arctic grayling populations may be in decline and need protection. ("Arctic Grayling (Thymallus arcticus)", 2013)


Michael Hsieh (author), The College of New Jersey, Keith Pecor (editor), The College of New Jersey.


Alaska Department of Fish and Game. Arctic Grayling (Thymallus arcticus). Anchorage, Alaska: Alaska Department of Fish and Game. 2013. Accessed October 15, 2013 at

US Fish & Wildlife Service. Arctic Grayling Recovery. Washington, DC: US Fish & Wildlife Service. 2012. Accessed October 15, 2013 at

Arai, H., D. Mudry. 1983. Protozoan and metzoan parasites of fishes from the headwaters of the Parsnip and McGregor Rivers, British Columbia: a study of possible parasite transfaunations. Canadian Journal of Fisheries and Aquatic Sciences, 40: 1676-1684.

Baccante, D. 2011. Further evidence of size gradients of arctic grayling (Thymallus arcticus) along stream length. Journal of Ecosystems and Management, 11: 13-17.

Bleckmann, H., R. Zelick. 2009. Lateral line system of fish. Integrative Zoology, 4: 13-25.

Davis, J., A. Rosemond, S. Eggert, W. Cross, J. Wallace. 2010. Long-term nutrient enrichment decouples predator and prey production. Proceedings of the National Academy of Sciences, 107: 1210126.

Gingerich, A., D. Philipp, C. Suski. 2010. Effects of nutritional status on metabolic rate, exercise and recovery in a freshwater fish. Journal of Comparative Physiology B, 180: 371-384.

Hughes, N., J. Reynolds. 1994. Why do arctic grayling (Thymallus arcticus) get bigger as you go upstream?. Canadian Journal of Fisheries and Aquatic Systems, 51: 2154-2163.

Kratt, L., R. Smith. 1980. The analysis of the spawning behaviour of the arctic grayling Thymallus arcticus (Pallas) with observations on mating success. Journal of Fish Biology, 17: 661-666.

Miano, A. 2013. Lake Trout (Salvelinus namaycush) and Arctic Grayling (Thymallus arcticus) Diet, Population and Migration Dynamics in Arctic Ecosystems. Biology Honors Paper at Connecticut College.

Muzzall, P. 1990. Parasites of arctic grayling, Thymallus arcticus (Pallas), stocked into Michigan lakes. Canadian Journal of Zoology, 68: 596-599.

Sepulveda, A., D. Rutz, S. Ivey, K. Dunker, J. Gross. 2013. Introduced northern pike predation on salmonids in southcentral Alaska. Ecology of Freshwater Fish, 22: 268-279.

Stamford, M., E. Taylor. 2004. Phylogeographical lineages of arctic grayling (Thymallus arcticus) in North America: divergence, origins and affinities with Eurasian Thymallus. Molecular Ecology, 13: 1533-1549.

Wedekind, C., G. Evanno, T. Szekely, M. Pompini, O. Darbellat, J. Guthruf. 2013. Persistent unequal sex ratio in a population of grayling (Salmonidae) and possible role of temperature increase. Conservation Biology, 27: 229-234.

University of Michigan Museum of ZoologyNational Science Foundation

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Hsieh, M. 2014. "Thymallus arcticus" (On-line), Animal Diversity Web. Accessed April 22, 2024 at

BioKIDS is sponsored in part by the Interagency Education Research Initiative. It is a partnership of the University of Michigan School of Education, University of Michigan Museum of Zoology, and the Detroit Public Schools. This material is based upon work supported by the National Science Foundation under Grant DRL-0628151.
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