Fish
Arctic Grayling
Thymallus arcticus · also called Arctic graylings
In a cold, clear northern river, a male Arctic grayling raises his enormous, sail-like dorsal fin in a courtship display, a fin so disproportionately large that it makes the species instantly recognisable among the region’s freshwater fish.
Overview
The Arctic grayling, Thymallus arcticus, is a distinctive freshwater fish native to cold rivers and lakes across Alaska, northern Canada, and a few isolated, relict populations in the northern contiguous United States. Its exceptionally large sail-like dorsal fin, strong dependence on cold, clear water, and dramatic contraction within the contiguous United States make it one of the more visually striking and conservation-relevant native fish of the far north.
A fin built for the far north, but fading in the south
While the Arctic grayling remains common and secure across the vast cold rivers of Alaska and northern Canada, its remaining populations within the contiguous United States now cling on in only a fraction of their former range.
Status
Least Concern overall, remaining widespread across Alaska and northern Canada, though contiguous United States populations have declined significantly and now survive mainly as isolated relict populations.
Arctic Grayling: common questions
Why does the Arctic grayling have such a large dorsal fin?
This species has an exceptionally large, sail-like dorsal fin, considerably larger relative to body size than in most other freshwater fish, and a male prominently displays this fin during courtship, likely as a visual signal to attract a female or assert dominance over rival males.
Is the Arctic grayling the same as the grayling found in Europe?
No, this species is a distinct species from the grayling found across Europe and parts of Asia. The two look broadly similar and are close relatives within the same family, but they occur on entirely different continents and are recognised as separate species.
Why has the Arctic grayling declined in the contiguous United States?
This species depends on cold, clear, well-oxygenated water, and within the contiguous United States, factors including habitat degradation, competition from introduced trout species, and barriers to migration have caused some historical populations, such as in Michigan, to disappear entirely, while others, including in Montana, now survive only within a greatly restricted range.
Where can you still find Arctic grayling in the United States?
Within the contiguous United States, this species survives today mainly as isolated, relict populations, with one of the most significant remaining populations found within a restricted range in Montana, a considerable contraction from a once broader historical distribution, while the species remains widespread and secure across Alaska and northern Canada.