Arctic grayling (Thymallus)
Arctic grayling have compressed, elongate bodies. Coloration is bluish-black to purple on the back, silver blue to gray on the sides, and gray on the belly. Coloration generally fades to a dull gray when arctic grayling are taken from the water. Sides have a scattering of dark spots. The head and mouth are small, and small teeth fill both jaws.
The arctic grayling have a distinctive long, sail-like dorsal fin with 17 to 25 rays covered with large iridescent red or purple spots. This dorsal fin is largest on adult males. The caudal (tail) fin is deeply forked, with the lower lobe often longer than the top lobe. The pelvic fins are often marked with pink to orange stripes.
Arctic grayling feed mostly on the surface but will occasionally feed at lower depths. Their main diet consists of insects and insect larvae, but they will also eat mollusks, prey fish, and fish eggs, especially when sharing the same rivers with spawning salmon. At these times, arctic grayling will feed avidly upon the salmon eggs and the young salmon smelts. They continue to eat voraciously all summer to prepare for the mostly foodless months of winter, where they will often live under a thick layer of ice.
Arctic grayling are native throughout the Arctic, from western Siberia in Russia to the shores of Hudson Bay in Canada. In North America, arctic grayling inhabit the colder climates from the Hudson Bay west to Alaska. The southernmost part of their native range in North America is northern Montana. Arctic grayling have been introduced with moderate success to other areas that have similar environments, such as high mountain lakes in the western U.S.
Arctic grayling are found most often in medium to large rivers with clear, cold water. They also occupy lakes with similar water quality. In lakes, they are most often found at river mouths or along rocky shorelines and are seldom found in deep water. They prefer unpolluted waters, but can thrive in water that has low levels of dissolved oxygen. This fact helps them survive in the deep pools that remain unfrozen under as much as six feet of ice during the winter. The ideal temperature range for arctic grayling is 42 to 50 F.
Arctic grayling can either have a highly migratory life, utilizing different streams for spawning, juvenile rearing, summer feeding and wintering, or spend their entire lifecycle in one section of a river or lake.
Arctic grayling are members of the Salmonidae family and are closely related to salmon, whitefish, and trout.
The range of arctic grayling used to include the Great Lakes region, but due to over fishing, competition from introduced species, and habitat degradation, they are no longer present in these locales.
The Arctic grayling has been an important food source in remote areas for native Alaskans.