Thymallus arcticus
Arctic grayling

Key Characteristics

The artic grayling is an iridescent fish distinguished by its greatly enlarged dorsal fin and its small mouth. They have large, smooth scales and a lateral line that stretches the length of their body.

Status and Rank

  • State Status: X
  • State Rank: SX
  • Global Rank: G5


No known occurrences in Michigan

Updated 5/15/2018. Information is summarized from MNFI's database of rare species and community occurrences. Data may not reflect true distribution since much of the state has not been thoroughly surveyed.


Artic grayling occur in open waters of clear, cold medium to large rivers and lakes. They mainly occur in shallow water with rocky substrates.

Natural Community Types


For each species, lists of natural communities were derived from review of the nearly 6,500 element occurrences in the MNFI database, in addition to herbarium label data for some taxa. In most cases, at least one specimen record exists for each listed natural community. For certain taxa, especially poorly collected or extirpated species of prairie and savanna habitats, natural community lists were derived from inferences from collection sites and habitat preferences in immediately adjacent states (particularly Indiana and Illinois). Natural communities are not listed for those species documented only from altered or ruderal habitats in Michigan, especially for taxa that occur in a variety of habitats outside of the state.

Natural communities are not listed in order of frequency of occurrence, but are rather derived from the full set of natural communities, organized by Ecological Group. In many cases, the general habitat descriptions should provide greater clarity and direction to the surveyor. In future versions of the Rare Species Explorer, we hope to incorporate natural community fidelity ranks for each taxon.


Causes of the disappearance of the arctic grayling are unknown. Overfishing has been repeatedly mentioned as well as pollution. Additionally deforestation caused streams to warm and become silty. This habitat degradation, coupled with river log drives, severely depleted suitable spawning areas. The addition of brown and rainbow trout may have also been responsible for the extinction of the population.

Active Period

Spawning from fourth week of April to fourth week of May

Survey Methods

Page Citation

Michigan Natural Features Inventory. 2007. Rare Species Explorer (Web Application). Available online at [Accessed Sep 23, 2018]


Survey References

Technical References

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