''Stenodus nelma'', known alternatively as the nelma, sheefish, siifish, inconnu or connie, is a commercial species of

freshwater whitefish The freshwater whitefish are fishes of the subfamily Coregoninae, which contains whitefishes (both freshwater and anadromous) and ciscoes, and is one of three subfamilies in the salmon family Salmonidae. Apart from the subfamily Coregoninae, ...

in the family

Salmonidae Salmonidae (, ) is a family (biology), family of ray-finned fish, the only extant member of the suborder Salmonoidei, consisting of 11 extant genera and over 200 species collectively known as "salmonids" or "salmonoids". The family includes salmo ...

. It is widespread in the Arctic rivers from the

Kola Peninsula The Kola Peninsula (; ) is a peninsula in the extreme northwest of Russia, and one of the largest peninsulas of Europe. Constituting the bulk of the territory of Murmansk Oblast, it lies almost completely inside the Arctic Circle and is border ...

(

White Sea The White Sea (; Karelian language, Karelian and ; ) is a southern inlet of the Barents Sea located on the northwest coast of Russia. It is surrounded by Karelia to the west, the Kola Peninsula to the north, and the Kanin Peninsula to the nort ...

basin) eastward across Siberia to the

Anadyr River The Anadyr (; Yukaghir: Онандырь; ) is a river in the far northeast of Siberia which flows into the Gulf of Anadyr of the Bering Sea and drains much of the interior of Chukotka Autonomous Okrug. Its basin corresponds to the Anadyrsky ...

and also in the North American basins of the

Yukon River The Yukon River is a major watercourse of northwestern North America. From its source in British Columbia, it flows through Canada's territory of Yukon (itself named after the river). The lower half of the river continues westward through the U.S ...

and

Mackenzie River The Mackenzie River (French: ; Slavey language, Slavey: ' èh tʃʰò literally ''big river''; Inuvialuktun: ' uːkpɑk literally ''great river'') is a river in the Canadian Canadian boreal forest, boreal forest and tundra. It forms, ...

Appearance and lifestyle

''Stenodus nelma'' is an

anadromous Fish migration is mass relocation by fish from one area or body of water to another. Many types of fish migrate on a regular basis, on time scales ranging from daily to annually or longer, and over distances ranging from a few metres to thousa ...

fish, up to in length. The fish has a large mouth with a protruding lower jaw and a high and pointed

dorsal fin A dorsal fin is a fin on the back of most marine and freshwater vertebrates. Dorsal fins have evolved independently several times through convergent evolution adapting to marine environments, so the fins are not all homologous. They are found ...

. It is generally silver in color with a green, blue or brown back. The meat is white, flaky and somewhat oily. An adult fish weighs up to . The fish eat

plankton Plankton are the diverse collection of organisms that drift in Hydrosphere, water (or atmosphere, air) but are unable to actively propel themselves against ocean current, currents (or wind). The individual organisms constituting plankton are ca ...

for their first year of life and then become

predator Predation is a biological interaction in which one organism, the predator, kills and eats another organism, its prey. It is one of a family of common List of feeding behaviours, feeding behaviours that includes parasitism and micropredation ...

s of smaller fish. They live in

lake A lake is often a naturally occurring, relatively large and fixed body of water on or near the Earth's surface. It is localized in a basin or interconnected basins surrounded by dry land. Lakes lie completely on land and are separate from ...

s and

river A river is a natural stream of fresh water that flows on land or inside Subterranean river, caves towards another body of water at a lower elevation, such as an ocean, lake, or another river. A river may run dry before reaching the end of ...

s and in the

brackish water Brackish water, sometimes termed brack water, is water occurring in a natural environment that has more salinity than freshwater, but not as much as seawater. It may result from mixing seawater (salt water) and fresh water together, as in estuary ...

at the outlets of rivers into the ocean. They may

migrate Migration, migratory, or migrate may refer to: Human migration * Human migration, physical movement by humans from one region to another ** International migration, when peoples cross state boundaries and stay in the host state for some minimum le ...

more than to their upriver spawning grounds, but some populations spend their entire life in fresh water and do not migrate.

Systematics

''Stenodus nelma'' has previously been considered a subspecies of ''

Stenodus leucichthys ''Stenodus leucichthys'', also known as the inconnu, sheefish, ''ak balyk'', or ''beloribitsa'', is a species of large, anadromous, freshwater whitefish in the family Salmonidae. In the strict sense its natural distribution is restricted to the ...

'' (''S. leucichthys nelma''). The typical ''Stenodus leucichthys'' (beloribitsa) is a landlocked Eurasian species restricted to the

Caspian Sea The Caspian Sea is the world's largest inland body of water, described as the List of lakes by area, world's largest lake and usually referred to as a full-fledged sea. An endorheic basin, it lies between Europe and Asia: east of the Caucasus, ...

basin, and now

extinct in the wild A species that is extinct in the wild (EW) is one that has been categorized by the International Union for Conservation of Nature as only consisting of living members kept in captivity or as a naturalized population outside its historic range ...

Inuit fishing for sheefish at Selawik NWR

References

External links

"Mackenzie River Ecosystem: A Dynamic Delta: Inconnu: The "Unknown" Fish"
GreatCanadianRivers.com

Illustration by N.N. Kondrakov. NOAA Photo Library. Stenodus Freshwater fish of the Arctic Fish of the Arctic Ocean Fish described in 1773 Fish of Russia Fish of the United States {{Salmonidae-stub