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2 species of lenok or trout for fly fishing in Mongolia.

Lenoks, also known as Siberian trout, Asian trout, or Manchurian trout, and by some Mongolians as Zeveg, are found in various regions of Asia, including Russia, Mongolia, China, and Korea. There are 4 species, and two of them inhabit Mongolia. This fish genus, Brachymystax, features a dark red body and vibrant-colored fins. Females reach sizes of 60 cm and males 70 cm. During spawning, the body turns dark red, and the dorsal and pectoral fins change to a rainbow of colors. For the sports fisherman, they are of great interest, as these native trout aggressively feed on the surface. They are long-lived fish that, unlike other salmonids, grow very slowly. They are cold-water fish whose habitat may be threatened by climate change. Recent studies show how the change in river temperatures in summer is causing gastrointestinal problems and a direct decrease in their populations. As mentioned, they inhabit rivers and lakes with very cold water and coexist with ice for some months of the year. They are not anadromous species that descend to the ocean. They feed on insects, fish, frogs, mice, and taimen spawning. The 4 species belonging to this genus of the salmonid family are:

Fly Fishing Mongolia

Distribution of the two species of blunt-nosed and sharp-nosed in Mongolia: Selenge, Orkhon, Eroo, Tuul, Delger Moron, Eg, Chuluut, Suman, and Ider rivers, and Hövsgöl, Terkhiin Tsagaan, Ugii lakes, and lakes of Darkhad Depression (Arctic drainage); Kherlen, Onon, and Khalkhin rivers, and Buir Lake (Amur drainage).

Species of Lenok

1 - Sharp-nosed Lenok: Brachymystax lenok (Species existing in Mongolia)

Throughout Siberia, evidence supports the existence of two different evolutionary lines of lenoks, characterized by sharp and blunt noses, currently considered two distinct species out of the four existing ones. Phenologically, they are distinguished by the shape of their noses. It is important to note that, although they inhabit different geographical areas, they sometimes coexist in the same river, leading to the presence of hybrid lenoks. The sharp-nosed Brachymystax lenok has an extensive distribution in central and eastern Russia, as well as northern Mongolia, and locally in northeastern Kazakhstan (Irtysh Basin) and northeastern China (Amur Basin). In contrast, the two species share territory in the Selenge River basin (a tributary of the Yenisei) and in the Amur Basin. This phenomenon is also observed in some rivers of Kazakhstan.

2 - Blunt-nosed Lenok: Brachymystax tumensis (Species existing in Mongolia)

Brachymystax tumensis, the blunt-nosed lenok, is mainly found in southeastern Russia and more locally in the northeast and center of the country, as well as in northeastern Mongolia (Amur Basin), northern China, and Korea. One of the rivers in Mongolia with better populations of this species is the Khalkhin River, where the blunt-nosed lenok is more abundant although both species coexist.

3 - Brachymystax tsinlingensis

Brachymystax tsinlingensis is not found in Mongolia; it is distributed in streams of the Yellow and Yangtze River basins in the Qinling Mountains of China.

4 - Brachymystax savinovi

Brachymystax savinovi is found in Lake Markakol and adjacent rivers in eastern Kazakhstan.

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