On the nature of fish distribution in Gorny Altai

The information in this article about the characteristics of ichthyofauna composition in a number of lakes and rivers of Gorny Altay shows an adaptive nature of fish distribution in ponds of this mountain country. In rivers and lakes located at relatively high altitudes above sea level, ichthyocenoses are poor according to the number of their constituent species, and the number of fishe is low. The main reason for this is a relatively small value of radiation balance and the part of the solar energy that is absorbed by high mountain reservoirs. A significant limiting role in the formation of species diversity of ichthyocenoses is played by small sizes and the modules of rivers, their high velocity and strong bias, the mobility of bottom substrate, the lack of floodplain system, localized icings freezing, a short period of open water and low temperatures as well as forage supply of fish. A significant role in limiting the spread of fish upstream is played by waterfalls and areas with great steepness of the stream. The presence of insurmountable physical barriers to fish is the main cause of total absence offish in a large number of lakes and river systems in Gorny Altay. In alpine lakes, the taxonomic diversity of ichthyofauna composition is also limited by large depths, a short vegetation period, low water temperatures, a low quantity of nutrients in the water, a low degree of diversity and productive efficiency of biocenoses plankton and benthos. The factor that significantly restricts species diversity of ichthyocenoses in some rivers and lakes in Altai is a great number of mineral suspensions in water as a result of snowfields and glaciers melting. The adaptive nature of fish distribution in the conditions of Gorny Altay is manifested not only in a particular lake-river system as a whole, but within a lake or a short length of a river. We often meet Thymallus arcticus Pallas, 1776, Barbatulus toni Dybowski, 1869 or Сottus altaicus Kaschenko, 1899 and С. sibiricus Warpachowski, 1889 in a rough river stretch in the shade of large boulders or in pits. In lakes, fish, during summer feeding, as a rule, prefer the most productive area of littoral zone on a forage basis, and during winter - the deepest parts of a water body. In general, the adaptive nature of fish distribution in the waters of Gorny Altay should be taken into account while developing a strategy for protection and sport fishing in the region of Western Siberia.

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