Comparative morphological characteristics of populations of the common walleye Sander lucioperca (Linnaeus, 1758) of the Kuban River and the Sea of Azov

The paper analyzes the counting and linear values of morphological features of pikeperch in the upper and lower reaches of the Kuban River with those from literary sources of pikeperch populations in the Sea of Azov. It was found that they do not go beyond the species values. The average values of counting features of pikeperch in the Kuban River were calculated and determined. The analysis of the variation of pikeperch features within the populations of the middle and lower reaches of the Kuban River was carried out using the variation coefficient (Cv). It showed that the features do not go beyond the permissible values, and the populations are suitable for pairwise comparison. Comparisons of populations with each other were carried out using the Student t-test. The reliable level of significance was taken into account from 95 to 99%. It was revealed that the ratios of variable features between all the studied populations, of the total number, exceed or equal 50% therefore, the diverse living conditions of the pike-perch of the compared populations have a significant effect on its counting and linear features. In addition, a comparison of river and sea form populations of pikeperch of Kuban and Don Populations was conducted using cluster analysis. Kuban populations of river form, by Euclidean distance, strongly diverge from sea Kuban and Don Populations both by counting and linear features. It was revealed that river lifestyle has a strong effect on linear features responsible for resistance to currents, and sea lifestyle increases average body values, but reduces quantitative indicators of all counting features.