| Arctic grayling | |
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Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Actinopterygii |
| Order: | Salmoniformes |
| Family: | Salmonidae |
| Genus: | Thymallus |
| Species: | T. arcticus |
| Binomial name | |
| Thymallus arcticus Pallas, 1776 | |
| Synonyms[2] | |
previous scientific names
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TheArctic grayling (Thymallus arcticus) is aspecies offreshwater fish in thesalmonfamilySalmonidae.T. arcticus is widespread throughout theArctic andPacific drainages inCanada,Alaska, andSiberia, as well as the upperMissouri River drainage inMontana. In the U.S. state ofArizona, an introduced population is found in theLee Valley and other lakes in theWhite Mountains. They were also stocked at Toppings Lake by theTeton Range and in lakes in the highUinta Mountains in Utah, as well as alpine lakes of theBoulder Mountains (Idaho) incentral Idaho.
The scientific name of the Arctic grayling isThymallus arcticus. It was named in 1776 by German zoologistPeter Simon Pallas from specimens collected in Russia. The name of the genusThymallus first given to grayling (T. thymallus) described in the1758 edition ofSystema Naturae by Swedish zoologistCarl Linnaeus originates from thefaint smell of the herbthyme, which emanates from the flesh.[3]
Arctic grayling grow to a maximum recorded length of 76 cm (30 in) and a maximum recorded weight of 3.8 kg (8.4 lb). Of typicalthymalline appearance, the Arctic grayling is distinguished from the similarEuropean grayling (T. thymallus) by the absence ofdorsal andanal 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 pinkiridescence.T. a. arcticus has been recorded as reaching an age of 18 years.
Arctic grayling are widespread in Arctic Ocean drainages fromHudson Bay, Canada toAlaska and in Arctic and Pacific drainages to centralAlberta andBritish Columbia in Canada. They do not occur naturally in theFraser andColumbia river basins.[5] There are remnant native populations of fluvial Arctic grayling in the upperMissouri River drainage in theBig Hole River andRed Rock basin ("Montana Arctic grayling"). Fluvial Arctic grayling have been reestablished in the upperRuby River, a tributary of theBeaverhead River. The native range formerly extended south into theGreat Lakes basin inMichigan, where the species was extirpated by 1936 due to habitat destruction, unregulated logging, and competition from non-native fish species.
The arctic grayling occurs naturally in the Arctic Ocean basin in Siberia from theOb toYenisei drainages and inEuropean Russia in some tributaries ofPechora river.[6] Lake dwelling forms of Arctic grayling have been introduced in suitable lake habitats throughout theRocky Mountains including lakes in theTeton Range in Wyoming,central Idaho and the highUinta Mountains in Utah,[7][8]Cascade Mountains andSierra Nevada Mountains as far south asArizona.
Several life history forms of Arctic grayling occur:fluvial populations that live and spawn in rivers;lacustrine populations that live and spawn in lakes; andpotamodromous populations that live in lakes and spawn in tributary streams.[9]
The Arctic grayling occurs primarily in cold waters of mid-sized to large rivers and lakes, returning to rocky streams to breed. The various subspecies are omnivorous.Crustaceans,insects and insectlarvae, and fish eggs form the most important food items. Larger specimens ofT. arcticus becomepiscivorous and the immature fish feed onzooplankton and insect larvae.
Spawning takes place in the spring. Adult fish seek shallow areas of rivers with fine, sand substrate and moderate current. Males are territorial and court females by flashing their colourful dorsal fins; the fins are also used to brace receptive females during the vibratory release ofmilt androe. The fish are nonguarders: the eggs are left to mix with the substrate. Although the Arctic grayling does not excavate a nest, the highly energetic courtship and mating tends to kick up fine material which covers thezygotes. The zygote is small (approximately 3 mm or 0.1 in in diameter) and the embryo will hatch after two to three weeks. The newly hatched embryo remains in the substrate until all theyolk has been absorbed. They emerge at a length of around 12 to 18 mm (0.5 to 0.7 in), at which time they formshoals at the river margins. The juveniles grow quickly during their first two years of life.
Arctic grayling are considered a secure species throughout their range.[10] Although some populations at the southern extent of its native range have been extirpated,[11] it remains widespread elsewhere and is not listed on theIUCN Red List of threatened species.
The fluvialpopulation in the upper Missouri river basin once merited a high priority for listing under theEndangered Species Act (ESA) by theUS Fish & Wildlife Service (FWS). This unique southernmost population is now extirpated from all areas of the basin with the exception of theBig Hole River watershed. In preparation for an ESA listing, the US FWS began implementing a "Candidate Conservation Agreement with Assurances" (CCAA). This agreement protects cooperating landowners from being prosecuted under the ESA "takings" clause so long as they fulfill specific obligations, spelled out in a contractual arrangement and intended to restore the dwindling population. Finally, in 2014 the FWS determined not to list the grayling under ESA, due to the effectiveness of the CCAA.[12]
In 2025, efforts to reintroduce Arctic grayling toMichigan streams began, with 400,000 eggs planted in coldwater streams as part of a collaborative restoration initiative.[13]
The Arctic grayling is economically important; it is a "key subsistence species"[14]: 43 for theIñupiat people of theAlaska North Slope, it is raised commercially forfood and it is one of the most important species forsport fishing in Alaska.[14]: 47
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