Sevan trout
Encyclopedia
The Sevan trout ( išxan) is an endemic fish species of Lake Sevan
in Armenia
. It is a salmonid fish related to the brown trout
.
The fish is endangered, because various competitors were introduced into the lake during the Soviet
period, including common whitefish
(Coregonus lavaretus) from Lake Ladoga
, goldfish
(Carasius auratus) and narrow-clawed crayfish
(Astacus leptodactylus), and of lake level change. On ther hand, the Sevan trout itself has been successfully introduced to the Issyk Kul
lake in Kyrgyzstan
.
A resolution by Armenia's Council of Ministers in 1976 stopped the commercial fishing of Sevan trout and organized National Park "Sevan". The fish are nowadays also reared in hatcheries.
The Sevan trout has four (or two) distinct strains differing in their breeding time and place, and growth rate:
The winter bakhtak is the largest form and can grow to considerable size, up to 90 cm and 15 kg. It breeds within the lake. The summer bakhtak is smaller (<50 cm), and breeds naturally both in rivers and within lake near river mouths. Gegharkuni is a migratory form that naturally breeds exclusively in rivers; it also feeds on plankton in addition to benthos
. Bojak in turn is a dwarfed form that breeds within the lake in the winter, and does not exceed 33 cm and 0.25 kg.
Water level regulation has been destructive for sevan trout reproduction. Currently, the summer bakhtak and gegharkuni are mainly propagated by hatcheries. The winter bakhtak and bojak may be extinct within the lake.
Lake Sevan
Lake Sevan is the largest lake in Armenia and the Caucasus region. It is one of the largest high-altitude lakes in the world.Lake Sevan is situated in the central part of the Republic of Armenia, inside the Gegharkunik Province, at the altitude of 1,900m above sea level...
in Armenia
Armenia
Armenia , officially the Republic of Armenia , is a landlocked mountainous country in the Caucasus region of Eurasia...
. It is a salmonid fish related to the brown trout
Brown trout
The brown trout and the sea trout are fish of the same species....
.
The fish is endangered, because various competitors were introduced into the lake during the Soviet
Soviet Union
The Soviet Union , officially the Union of Soviet Socialist Republics , was a constitutionally socialist state that existed in Eurasia between 1922 and 1991....
period, including common whitefish
Common whitefish
Coregonus lavaretus is a species of freshwater whitefish, in the family Salmonidae. It is the type species of its genus Coregonus.There are widely different concepts about the number of species in the genus Coregonus and the delimitation of the species Coregonus lavaretus.-Lavaret:In a narrow...
(Coregonus lavaretus) from Lake Ladoga
Lake Ladoga
Lake Ladoga is a freshwater lake located in the Republic of Karelia and Leningrad Oblast in northwestern Russia, not far from Saint Petersburg. It is the largest lake in Europe, and the 14th largest lake by area in the world.-Geography:...
, goldfish
Goldfish
The goldfish is a freshwater fish in the family Cyprinidae of order Cypriniformes. It was one of the earliest fish to be domesticated, and is one of the most commonly kept aquarium fish....
(Carasius auratus) and narrow-clawed crayfish
Astacus leptodactylus
Astacus leptodactylus, the Danube crayfish, Galician crayfish, Turkish crayfish or narrow-clawed crayfish is a species of crayfish imported and introduced to Central Europe in 19th century from the Caspian Sea region.-Description:...
(Astacus leptodactylus), and of lake level change. On ther hand, the Sevan trout itself has been successfully introduced to the Issyk Kul
Issyk Kul
Issyk Kul is an endorheic lake in the northern Tian Shan mountains in eastern Kyrgyzstan. It is the tenth largest lake in the world by volume and the second largest saline lake after the Caspian Sea. Although it is surrounded by snow-capped peaks, it never freezes; hence its name, which means "hot...
lake in Kyrgyzstan
Kyrgyzstan
Kyrgyzstan , officially the Kyrgyz Republic is one of the world's six independent Turkic states . Located in Central Asia, landlocked and mountainous, Kyrgyzstan is bordered by Kazakhstan to the north, Uzbekistan to the west, Tajikistan to the southwest and China to the east...
.
A resolution by Armenia's Council of Ministers in 1976 stopped the commercial fishing of Sevan trout and organized National Park "Sevan". The fish are nowadays also reared in hatcheries.
The Sevan trout has four (or two) distinct strains differing in their breeding time and place, and growth rate:
- winter bakhtak (Salmo ischchan ischchan)
- summer bakhtak (Salmo ischchan aestivalis)
- gegharkuni (Salmo ischchan gegarkuni)
- bojak (Salmo ischchan danilewskii).
The winter bakhtak is the largest form and can grow to considerable size, up to 90 cm and 15 kg. It breeds within the lake. The summer bakhtak is smaller (<50 cm), and breeds naturally both in rivers and within lake near river mouths. Gegharkuni is a migratory form that naturally breeds exclusively in rivers; it also feeds on plankton in addition to benthos
Benthos
Benthos is the community of organisms which live on, in, or near the seabed, also known as the benthic zone. This community lives in or near marine sedimentary environments, from tidal pools along the foreshore, out to the continental shelf, and then down to the abyssal depths.Many organisms...
. Bojak in turn is a dwarfed form that breeds within the lake in the winter, and does not exceed 33 cm and 0.25 kg.
Water level regulation has been destructive for sevan trout reproduction. Currently, the summer bakhtak and gegharkuni are mainly propagated by hatcheries. The winter bakhtak and bojak may be extinct within the lake.