ЛИНЕЙНЫЙ РОСТ ОКУНЯ PERCA FLUVIATILIS L., 1758 (PERCIDAE) В БАССЕЙНАХ РЕК НУРА И САРЫСУ

Abstract

The article presents the data on linear growth of perch from 35 water bodies in the Nura and Sarysu river basin in Central Kazakhstan obtained using the inverse calculation method. The obtained annual values of linear growth, increments and their variability have been analyzed. The increments were defined as a contribution of annual growth to the obtained length, but not as the initial length increase. At that, in the analysis the maximum age was limited to the most common 6 years. As a result, it has been stated that some populations from small depressive rivers have lower growth rates. Perches from southern parts of the Sarysu River grow more slowly, compared to the populations from the Nura River which is located northward. Studying the scheme of the body length advancing has reviled the distinctive features of samplings from the Ashchisu River, 
 a tributary of the Nura River. Samplings from the Kurgaldzhin lakes are characterized by greater variability of annual growth values against the general background over a long time. Besides, they have a high correlation of the values in subsequent years. Samples from the Ashisuy, on the contrary, have the least correlation. The Kurgaldzhin groups are open for migrants, which evidently explains the discovered features. The populations from the Ashchisu River watershed have been isolated from the indigenous basin for more than 35 years, which may have determined the features 
 of growth. The influence of hydrological and hydroclimatic factors on perch growth has been stated. But the influence of the structure of ichthyocenosis and on the population size has not been found, probably, due to the relatively identical living conditions of the studied samples.