Inconnu
Encyclopedia
Stenodus leucichthys is a species of freshwater whitefish
in the family Salmonidae
. It is also known variously by the common names sheefish, inconnu, connie, nelma and beloribitsa. There are two subspecies
, sometimes considered distinct species, one of which lives in Eurasian and North American rivers of the Arctic basin, the other in the landlocked Caspian Sea
basin. If only one species is recognised, Stenodus leucichthys is the only member of the monotypic
genus
Stenodus.
. 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 from 14 to 25 kg (30.9 to 55.1 lb).
The fish eat plankton
for their first year of life and then become predators of smaller fish. They live in lake
s and river
s and in the brackish water
at the outlets of rivers into the ocean, and may migrate
1500 kilometres (932.1 mi) to spawn.
, whereas other sources still make no distinction.
by the IUCN. The stock however survives in hatcheries and some populations are maintained by stocking.
Freshwater whitefish
The freshwater whitefish are fish of the subfamily Coregoninae in the salmon family Salmonidae. Along with the freshwater whitefish, the Salmonidae includes the freshwater and anadromous trout and salmon species as well as graylings...
in the family Salmonidae
Salmonidae
Salmonidae is a family of ray-finned fish, the only living family currently placed in the order Salmoniformes. It includes salmon, trout, chars, freshwater whitefishes and graylings...
. It is also known variously by the common names sheefish, inconnu, connie, nelma and beloribitsa. There are two subspecies
Subspecies
Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...
, sometimes considered distinct species, one of which lives in Eurasian and North American rivers of the Arctic basin, the other in the landlocked Caspian Sea
Caspian Sea
The Caspian Sea is the largest enclosed body of water on Earth by area, variously classed as the world's largest lake or a full-fledged sea. The sea has a surface area of and a volume of...
basin. If only one species is recognised, Stenodus leucichthys is the only member of the monotypic
Monotypic
In biology, a monotypic taxon is a taxonomic group with only one biological type. The term's usage differs slightly between botany and zoology. The term monotypic has a separate use in conservation biology, monotypic habitat, regarding species habitat conversion eliminating biodiversity and...
genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
Stenodus.
Description
The fish has a large mouth with a protruding lower jaw and a high and pointed dorsal finDorsal fin
A dorsal fin is a fin located on the backs of various unrelated marine and freshwater vertebrates, including most fishes, marine mammals , and the ichthyosaurs...
. 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 from 14 to 25 kg (30.9 to 55.1 lb).
The fish eat plankton
Plankton
Plankton are any drifting organisms that inhabit the pelagic zone of oceans, seas, or bodies of fresh water. That is, plankton are defined by their ecological niche rather than phylogenetic or taxonomic classification...
for their first year of life and then become predators of smaller fish. They live in lake
Lake
A lake is a body of relatively still fresh or salt water of considerable size, localized in a basin, that is surrounded by land. Lakes are inland and not part of the ocean and therefore are distinct from lagoons, and are larger and deeper than ponds. Lakes can be contrasted with rivers or streams,...
s and river
River
A river is a natural watercourse, usually freshwater, flowing towards an ocean, a lake, a sea, or another river. In a few cases, a river simply flows into the ground or dries up completely before reaching another body of water. Small rivers may also be called by several other names, including...
s and in the brackish water
Brackish water
Brackish water is water that has more salinity than fresh water, but not as much as seawater. It may result from mixing of seawater with fresh water, as in estuaries, or it may occur in brackish fossil aquifers. The word comes from the Middle Dutch root "brak," meaning "salty"...
at the outlets of rivers into the ocean, and may migrate
Fish migration
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 thousands of kilometres...
1500 kilometres (932.1 mi) to spawn.
Distribution and taxonomy
The species Stenodus leucichthys can be divided into two geographical subspecies. In recent literature these have also been considered as separate species, a treatment followed by the IUCN Red ListIUCN Red List
The IUCN Red List of Threatened Species , founded in 1963, is the world's most comprehensive inventory of the global conservation status of biological species. The International Union for Conservation of Nature is the world's main authority on the conservation status of species...
, whereas other sources still make no distinction.
- Stenodus leucichthys leucichthys (GüldenstädtJohann Anton GüldenstädtJohann Anton Güldenstädt was a Baltic German naturalist and explorer in Russian service....
, 1772), the nominate subspecies, is found only in rivers draining to the Caspian SeaCaspian SeaThe Caspian Sea is the largest enclosed body of water on Earth by area, variously classed as the world's largest lake or a full-fledged sea. The sea has a surface area of and a volume of...
, such as Volga and UralUral RiverThe Ural or Jayıq/Zhayyq , known as Yaik before 1775, is a river flowing through Russia and Kazakhstan. It arises in the southern Ural Mountains and ends at the Caspian Sea. Its total length is 1,511 mi making it the third longest river in Europe after the Volga and the Danube...
in particular. This subspecies, known as the beloribitsa, is now extinct in the wildExtinct in the WildExtinct in the Wild is a conservation status assigned to species or lower taxa, the only known living members of which are being kept in captivity or as a naturalized population outside its historic range.-Examples:...
. - Stenodus leucichthys nelma (PallasPeter Simon PallasPeter Simon Pallas was a German zoologist and botanist who worked in Russia.- Life and work :Pallas was born in Berlin, the son of Professor of Surgery Simon Pallas. He studied with private tutors and took an interest in natural history, later attending the University of Halle and the University...
, 1773), known as the nelma, is found in rivers draining to the Arctic basin in North-East Europe, northern Asia and North America.
Conservation
Fish of the nominate subspecies used to inhabit particularly the Volga, Ural and Terek rivers, and migrate up to 3000 kilometres (1,864.1 mi) upstream from the Caspian to their spawning grounds in the spring. Following the construction of dams and hydropower reservoirs, the migration and natural reproduction has been impeded, and the taxon is now considered as extinct in the wildExtinct in the Wild
Extinct in the Wild is a conservation status assigned to species or lower taxa, the only known living members of which are being kept in captivity or as a naturalized population outside its historic range.-Examples:...
by the IUCN. The stock however survives in hatcheries and some populations are maintained by stocking.
External links
- "Mackenzie River Ecosystem: A Dynamic Delta: Inconnu: The "Unknown" Fish" GreatCanadianRivers.com
- Stenodus leucichthys nelma Illustration by N.N. Kondrakov. NOAA Photo Library.