The Nonindigenous Occurrences section of the NAS species profiles has a new structure. The section is now dynamically updated from the NAS database to ensure that it contains the most current and accurate information. Occurrences are summarized in Table 1, alphabetically by state, with years of earliest and most recent observations, and the tally and names of drainages where the species was observed. The table contains hyperlinks to collections tables of specimens based on the states, years, and drainages selected. References to specimens that were not obtained through sighting reports and personal communications are found through the hyperlink in the Table 1 caption or through the individual specimens linked in the collections tables.

Thymallus arcticus
Thymallus arcticus
(Arctic Grayling)
Native Transplant

Copyright Info
Thymallus arcticus (Pallas, 1776)

Common name: Arctic Grayling

Taxonomy: available through www.itis.govITIS logo

Identification: Scott and Crossman (1973); Morrow (1980); Page and Burr (1991). Grayling can be distinguished from all other salmonids by the presence of a large, sail-like dorsal fin. At one time T. arcticus was divided into four separate species: T. signifer, T. montanus, T. tricolor, and T. ontariensis. Thymallus signifer is now treated as synonymous with T. arcticus, and the others are considered subspecies of T. arcticus (Lee et al. 1980 et seq.).

Size: 76 cm (Page and Burr 1991)

Native Range: Widespread in Arctic drainages from Hudson Bay to Alaska and in Arctic and Pacific drainages to central Alberta and British Columbia; upper Missouri River drainage, Montana. Formerly in Great Lakes basin, Michigan. Also in Asia (Page and Burr 1991).

The only remaining natural, native remnant population in the continental United States is in Big Hole River, Montana (Wydoski and Whitney 2003). All other populations are the result of introductions or re-introductions.

Native range data for this species provided in part by NatureServe NS logo
Hydrologic Unit Codes (HUCs) Explained
Interactive maps: Point Distribution Maps

Nonindigenous Occurrences:

Table 1. States with nonindigenous occurrences, the earliest and latest observations in each state, and the tally and names of HUCs with observations†. Names and dates are hyperlinked to their relevant specimen records. The list of references for all nonindigenous occurrences of Thymallus arcticus are found here.

StateFirst ObservedLast ObservedTotal HUCs with observations†HUCs with observations†
AK198019802South Central Alaska; Yakutat Bay-Gulf of Alaska
AZ194320047Black; Carrizo; Little Colorado Headwaters; Lower Colorado Region; Lower Verde; Middle Little Colorado; Tonto
CA1904198717California; California Region; Cottonwood-Tijuana; Lake Tahoe; Lower Klamath; Lower Sacramento; Lower Sacramento; North Fork American; Northern Mojave-Mono Lake; San Joaquin; Shasta; Upper Carson; Upper Merced; Upper Mokelumne; Upper Sacramento; Upper Yuba; West Walker
CO1899202115Arkansas Headwaters; Cache La Poudre; Colorado Headwaters; Eagle; North Platte Headwaters; Roaring Fork; San Luis; South Platte; South Platte Headwaters; St. Vrain; Upper Arkansas; Upper Arkansas-Lake Meredith; Upper North Platte; Upper South Platte; Upper Yampa
ID1900201137Beaver-Camas; Big Lost; Big Wood; Kootenai; Lemhi; Little Lost; Little Salmon; Lochsa; Lower Clark Fork; Lower Kootenai; Lower Middle Fork Salmon; Lower North Fork Clearwater; Medicine Lodge; Middle Kootenai; Middle Salmon-Chamberlain; Middle Salmon-Panther; North and Middle Forks Boise; North Fork Payette; Pacific Northwest Region; Payette; Pend Oreille Lake; Raft; Salmon; South Fork Boise; South Fork Coeur d'Alene; South Fork Payette; South Fork Salmon; Spokane; St. Joe; Upper Bear; Upper Henrys; Upper Middle Fork Salmon; Upper North Fork Clearwater; Upper Salmon; Upper Selway; Upper Snake; Upper Snake-Rock
IA190019002Coon-Yellow; Maquoketa
ME191419141New England Region
MI188020003Lake Superior; St. Joseph; Tittabawassee
MN197419822Baptism-Brule; Rainy Headwaters
MT190920239Belly; Clarks Fork Yellowstone; Flathead Lake; Flint-Rock; Middle Clark Fork; North Fork Flathead; South Fork Flathead; Upper Clark Fork; Upper Missouri-Dearborn
NE193919391Missouri Region
NV194119842Long-Ruby Valleys; West Walker
NH190719642Ammonoosuc River-Connecticut River; Black River-Connecticut River
NM195719901Rio Chama
OR190019802Umatilla; Upper Deschutes
SD193719371Missouri Region
UT1899202019Beaver Bottoms-Upper Beaver; Blacks Fork; Duchesne; East Fork Sevier; Escalante; Escalante Desert; Fremont; Jordan; Lower Bear; Lower Green; Lower Green-Diamond; Muddy; Provo; Upper Bear; Upper Colorado; Upper Green-Flaming Gorge Reservoir; Upper Sevier; Upper Weber; Utah Lake
VT190019801Lamoille River
VA197219721Upper Dan
WA194619781Upper Skagit
WI190019383Beartrap-Nemadji; Namekagon; Wolf
WY1937200112Big Horn Lake; Big Sandy; Clarks Fork Yellowstone; Clear; Crazy Woman; Medicine Bow; New Fork; Popo Agie; Snake Headwaters; Upper North Platte; Upper Tongue; Upper Wind

Table last updated 7/17/2024

† Populations may not be currently present.

* HUCs are not listed for states where the observation(s) cannot be approximated to a HUC (e.g. state centroids or Canadian provinces).

Ecology: Grayling generally inhabit clear, cold, high-altitude lakes and rivers (Behnke 2002; Wydoski and Whitney 2003). Spawning occurs in the spring, when water temperatures reach 45-50° F. Unlike most salmonids, grayling do not construct any sort of nest but spawn directly over gravel or rocky areas of smaller streams and tributaries (Behnke 2002). Diet primarily consists of aquatic and terrestrial invertebrates, zooplankton, small fishes, and occasionally fish eggs (Behnke 2002; Wydoski and Whitney 2003).

Means of Introduction: Authorized stocking for sportfishing. First stocked in Arizona in 1943 (Rinne 1995). First stocked in Connecticut in the 1870s (Whitworth 1996). Stocked in Nebraska in 1939 (Jones 1963). First stocked in southern Michigan in 1877 (Fukano et al. 1964).

Status: Established in several states, including Arizona (Rinne 1995). Reported from Colorado, Montana, Nevada, Oregon, and Vermont. Failed in Connecticut, Maine, Missouri, Nebraska, New Mexico, and Virginia. Extirpated from Pennsylvania.  Although largely extirpated from its native range within the Great Lakes basin, it is found in some inland lakes in the region that were not part of its original range.

Impact of Introduction: The impacts of this species are currently unknown, as no studies have been done to determine how it has affected ecosystems in the invaded range. The absence of data does not equate to lack of effects. It does, however, mean that research is required to evaluate effects before conclusions can be made.

Remarks: Native populations are considered extinct in Montana (Holton 1990) except for a remnant population in the Big Hole River (Wydoski and Whitney 2003).  The species has be re-stocked in the Red Rock, Madison, Gallatin and Sun drainages, as well as other locations. A relict population was present in the Great Lakes up until the 1930s, when it was extirpated due to competition with other introduced salmonids, habitat degradation, and fishing pressure (Hubbs and Lagler 1958). The Upper Missouri River population has been proposed to be classified as threatened or endangered under the Endangered Species Act (USFWS 2010).

References: (click for full references)

Baxter, G.T., and J.R. Simon. 1970. Wyoming fishes. Wyoming Game and Fish Department Bulletin 4, Cheyenne, WY.

Bean, T.H. 1892. The fishes of Pennsylvania, with descriptions of the species and notes on their common names, distribution, habits, reproduction, rate of growth and mode of capture. Report of the State Commissioners of Fisheries for the years 1889-90-91. Edwin K. Meyers, State Printer, Harrisburg, PA.

Beckman, W.C. 1952. Guide to the fishes of Colorado. University of Colorado Museum, Boulder, CO.

Becker, G.C. 1983. Fishes of Wisconsin. University of Madison Press, Madison, WI.

Behnke, R.J. 2002. Trout and salmon of North America. The Free Press, New York, NY.

Bickford, W.M. 1914. Notes on the Montana grayling. Transactions of the American Fisheries Society 43:153-155.

Bowers, G. M. 1901. Report of the commissioner of fish and fisheries for the year ending June 30, 1900. Part XXVI. U.S. Commission of Fish and Fisheries, Washington, D.C.

Cross, F.B., R.L. Mayden, and J.D. Stewart. 1986. Fishes in the western Mississippi basin (Missouri, Arkansas, and Red Rivers). 363-412 in C.H. Hocutt and E.O. Wiley, eds. The zoogeography of North American freshwater fishes. John Wiley and Sons, New York, NY.

Deacon, J.E., and J.E. Williams. 1984. Annotated list of the fishes of Nevada. Proceedings of the Biological Society of Washington 97(1):103-118.

DeLorme Mapping. 1992. Wyoming Atlas and Gazetteer. DeLorme Mapping, Freeport, ME.

Dill, W.A., and A.J. Cordone. 1997. History and status of introduced fishes in California, 1871-1996. California Department of Fish and Game Fish Bulletin, volume 178.

Eddy, S., and J.C. Underhill. 1974. Northern fishes, with special reference to the Upper Mississippi Valley, 3rd edition. University of Minnesota Press, Minneapolis, MN.

Ellis, M.M. 1974. Fishes of Colorado. University of Colorado Studies, Boulder, CO 11(1):1-136.

Everhart, W.H., and W.R. Seaman. 1971. Fishes of Colorado. Colorado Game, Fish and Parks Division, Denver, CO.

Fukano, K.G., H. Gowing, M.J. Hansen, and L.N. Allison. 1964. Introduction of exotic fish into Michigan. Michigan Department of Conservation, Institute of Fisheries Research, Ann Arbor, MI.

Gorges, M. 1994. Resident fish habitat management strategy for Wyoming. Bureau of Land Management, Wyoming State Office.

Holton, G.D. 1990. A field guide to Montana fishes. Montana Department of Fish, Wildlife and Parks, Helena, MT.

Hoover, E.E. 1936. Preliminary biological survey of some New Hampshire lakes. New Hampshire Fish and Game Department. Survey Report No. 1. Concord, NH.

Hubbs, C.L., and K.F. Lagler. 1958. Fishes of the Great Lakes region. University of Michigan Press, Ann Arbor, MI.

Hubert, W. 1994. Exotic fish. 158-174 in T.L. Parrish, and S.H. Anderson, eds. Exotic species manual. Wyoming Game and Fish Department, Laramie, WY.

Idaho Department of Fish and Game. 1990. Fisheries Management Plan 1991-1995. Appendix I - A list of Idaho fishes and their distribution by drainage. Idaho Department of Fish and Game.

Idaho Department of Fish and Game. 1996. Fisheries Management Plan 1996-2000. Idaho Department of Fish and Game.

Idaho Department of Fish and Game. 2012. Fish stocking information. http://fishandgame.idaho.gov/public/fish/stocking/

Jenkins, R.E., and N.M. Burkhead. 1994. Freshwater fishes of Virginia. American Fisheries Society, Bethesda, MD.

Johnson, H.E. 1937. Feeding Montana grayling fry. Progressive Fish Culturist 30:35-36.

Jones, D.J. 1963. A history of Nebraska's fisheries resources. Dingell-Johnson Federal Aid in Fish Restoration Project F-4-R Publication. Nebraska Game, Forestation and Parks Commission.

Kendall, W.C. 1914. An annotated catalogue of the fishes of Maine. Proceedings of the Portland Society of Natural History 3:1-198.

Koster, W.J. 1957. Guide to the fishes of New Mexico. University of New Mexico Press, Albuquerque, NM.

La Rivers, I. 1962. Fishes and fisheries of Nevada. Nevada State Print Office, Carson City, NV.

Lee, D.S., C.R. Gilbert, C.H. Hocutt, R.E. Jenkins, D.E. McAllister, and J.R. Stauffer, Jr. 1980. Atlas of North American freshwater fishes. North Carolina State Museum of Natural History, Raleigh, NC.

Linder, A.D. 1963. Idaho's alien fishes. Tebiwa 6(2):12-15.

Miller, R.R., and J.R. Alcorn. 1946. The introduced fishes of Nevada, with a history of their introduction. Transactions of the American Fisheries Society 73:173-193.

Miller, R.R., and C.H. Lowe. 1967. Fishes of Arizona. 133-151 in C.H. Lowe, ed. The vertebrates of Arizona, part 2. University of Arizona Press, Tucson, AZ.

Minckley, W.L. 1973. Fishes of Arizona. Arizona Fish and Game Department. Sims Printing Company, Inc., Phoenix, AZ.

Morris, J., L. Morris, and L. Witt. 1974. The fishes of Nebraska. Nebraska Game and Parks Commission, Lincoln, NE.

Morrow, J.E. 1980. The freshwater fishes of Alaska. Alaska Northwest Publishing Company, Anchorage, AK.

Moyle, P.B. 2002. Inland fishes of California. 2nd edition. University of California Press, Berkeley, CA.

Page, L.M. and B.M. Burr. 1991. A field guide to freshwater fishes of North America north of Mexico. The Peterson Guide Series, vol. 42. Houghton Mifflin Company, Boston, MA.

Pflieger, W.L. 1971. A distributional study of Missouri fishes. University of Kansas Museum of Natural History 20(3):225-570.

Phillips, G.L., W.D. Schmid, and J.C. Underhill. 1982. Fishes of the Minnesota region. University of Minnesota Press, Minneapolis, MN.

Rasmussen, J.L. 1998. Aquatic nuisance species of the Mississippi River basin. 60th Midwest Fish and Wildlife Conference, Aquatic Nuisance Species Symposium. December 7, 1998. Cincinnati, OH.

Rinne, J.N. 1995. The effects of introduced fishes on native fishes: Arizona, Southwestern United States. 149-159 in D.P. Philipp, J.M. Epifano, J.E. Marsden, J.E. Claassen, and R.J. Wolotina, Jr., eds. Protection of aquatic diversity. Proceedings of the World Fisheries Congress, Theme 3. Oxford & IBH Publishing Company, New Delhi.

Scott, W.B., and E.J. Crossman. 1973. Freshwater Fishes of Canada. Fisheries Research Board of Canada, Bulletin 184. Ottawa.

Shebley, W. H. 1917. History of the introduction of food and game fishes into the waters of California. California Fish and Game 3(1):3-10.

Sigler, W.F., and R.R. Miller. 1963. Fishes of Utah. Utah Department of Fish and Game, Salt Lake City, UT.

Sigler, W.F., and J.W. Sigler. 1987. Fishes of the Great Basin: a natural history. University of Nevada Press, Reno, NV.

Sigler, W.F., and J.W. Sigler. 1996. Fishes of Utah. University of Utah Press, Salt Lake City, UT.

Simpson, J., and R. Wallace. 1978. Fishes of Idaho. University of Idaho Press, Moscow, ID.

Sublette, J.E., M.D. Hatch, and M. Sublette. 1990. The fishes of New Mexico. University of New Mexico Press, Albuquerque, NM.

Tilmant, J.T. 1999. Management of nonindigenous aquatic fish in the U.S. National Park System. National Park Service.

U.S. Fish and Wildlife Service. 2010. Endangered and threatened wildlife and plants; revised 12-month finding to list the upper Missouri River distinct population segment of Arctic Grayling as endangered or threatened; proposed rule. Federal Register 50 CFR Part 17:54708-54753.

Whitworth, W.R. 1996. Freshwater fishes of Connecticut. State Geological and Natural History Survey of Connecticut, Bulletin 114.

Wiltzius, W.J. 1985. Fish culture and stocking in Colorado, 1872-1978. Division Report 12. Colorado Division of Wildlife.

Wydoski, R.S. and R.R. Whitney. 2003. Inland fishes of Washington. Second edition. University of Washington Press, Seattle, Washington.

Zuckerman, L.D., and R.J. Behnke. 1986. Introduced fishes in the San Luis Valley, Colorado. 435-452 in R.H. Stroud, ed. Fish culture in fisheries management. Proceedings of a symposium on the role of fish culture in fisheries management at Lake Ozark, MO, March 31-April 3, 1985. American Fisheries Society, Bethesda, MD.

FishBase Summary

Author: Pam Fuller, Matt Cannister, and Matt Neilson

Revision Date: 8/28/2019

Peer Review Date: 11/5/2012

Citation Information:
Pam Fuller, Matt Cannister, and Matt Neilson, 2024, Thymallus arcticus (Pallas, 1776): U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, https://nas.er.usgs.gov/queries/FactSheet.aspx?SpeciesID=943, Revision Date: 8/28/2019, Peer Review Date: 11/5/2012, Access Date: 7/17/2024

This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.


The data represented on this site vary in accuracy, scale, completeness, extent of coverage and origin. It is the user's responsibility to use these data consistent with their intended purpose and within stated limitations. We highly recommend reviewing metadata files prior to interpreting these data.

Citation information: U.S. Geological Survey. [2024]. Nonindigenous Aquatic Species Database. Gainesville, Florida. Accessed [7/17/2024].

Contact us if you are using data from this site for a publication to make sure the data are being used appropriately and for potential co-authorship if warranted.

For general information and questions about the database, contact Wesley Daniel. For problems and technical issues, contact Matthew Neilson.