7634

• UCREFRP Catalog Number: 7634
• Author: U.S. Fish and Wildlife Service.
• Title: Threatened Wildlife of the United States.
• USFW Year: 1973.
• USFW - Doc Type: Washington, D.C.
• Copyright Material: NO

ARCTIC GRAYLING Thymallus arcticus (Pallas, 1776)
Order: SALMONIFORMES Family: SALMONIDAE
The grayling, now considered one species, was formerly in a separate family, the
THYMALLIDAE, and contained three species:
Thymallus si nifer Richardson, 1823, Arctic grayling
Thymallus tricolor Cope, 1865, Michigan grayling (extinct)
Thymallus montanus Milner, 1874, Montana grayling
The Arctic grayling is neither rare nor endangered in Alaska
The paper is primarily concerned with the Montana form of the grayling and the following
remarks apply to the Montana form .
Distinguishing characteristics: Huge dorsal fin, particularly in the spawning male,
which is bluish-green with bright pink or red spots. The back is olive, shading into
a light purple on the sides and abluish-white on the belly. Sides of body above pectorals
with irregular black spots . With adipose fin and large scales . Usual weight in Montana
is less than a pound.
Present distribution: Relict and transplanted populations exist in 20 lakes and 25 streams
in Montana, however substantial populations occur in only a few of these; 20 lakes in Utah;
3 lakes in Wyoming; 2 lakes in Washington, 1 lake in Colorado; and in Glacier and
Yellowstone National Parks .
Former distribution: The Arctic grayling was common in the Missouri River drainage
above Great Falls , mostly in Montana . The Michigan form was found in the upper part
of the Lower Peninsula of Michigan and the Otter River drainage in the Upper Peninsula.
Status: Very uncommon.
Estimated numbers: No data.
Fecundity: Grebe Lake, Yellowstone National Park--average 1,650 eggs per adult female;
Rogers Lake, Montana--range 1,000 to 15,000 eggs per female; averages 5,828 eggs per
female, 750-840 eggs per ounce and 2,737 eggs per female, 627 eggs per ounce.
Reasons for decline: Change of habitat resulting from timber removal; surface mining
and overgrazing; streams became warmer, gravel spawning areas became covered with silt
and sand. Beaver dams block spawning migrations. Water of some streams is used for
irrigation. Competition from other species, including brook trout, rainbow trout, and
suckers.
Protective measures already taken: Limited fishing permitted in grayling habitat on
Red Rock Lakes National Wildlife Refuge . A counting weir was installed on Red Rock
Creek . Length of fishing season was reduced in other Montana waters . Hatchery
production varies considerably at State and National fish hatcheries . About a million fry,
10,000-20,000 fingerlings and 10,000-30,000 six-inch fish are reared annually.
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