ECOLOGICAL AND CITO-GENETIC CHARACTERISTICS OF THE POPULATION STRUCTURE OF CRUCIAN CARP (CARASSIUS AURATUS GIBELIO, BLOCH, 1782) FROM SEVAN LAKE (ARMENIA)

The article studies the morphological characteristics, age, sex structure, fecundity and cytomorphological parameters of erythrocytes of Crucian carp ( Carassius auratus gibelio , Bloch, 1782) from both subwatersheds (Big and Small) of Lake Sevan. The analysis of cyto-morphological characteristics of nuclei and erythrocytes showed that the population of the Crucian carp from the lake is heterogeneous as a whole, and consists of individuals with small (diploid) and large nuclei and erythrocytes (subgroups I and II). In sampling taken from both subwatersheds of Lake Sevan occurrence of individuals with the smallest nuclei (diploid individuals) made 38.8%. Crucian carps with the largest nuclei of red blood cells (subgroup II) are noted among females more than among males, with a low percentage of occurrences - 17.5%. The ratios of the volumes of the nuclei of erythrocytes and the number of nucleoli in the nuclei of erythrocytes of Crucian carps can be indicating the existence of triploid individuals in Lake Sevan. The number of Crucian carps with the largest nuclei of red blood cells (subgroup II, possibly triploids) is 17.5% in both subwatersheds of Lake Sevan. During the spawning period males prevailed to females in Small Sevan (1.5 ♂:1 ♀) and females prevailed to males in Big Sevan (1 ♂:1.6 ♀), which is the result of different spawning conditions in different parts of the lake. The highest role in the catch had individuals at the age of 3+. It has been established that the Crucian carp from Lake Sevan with large nuclei of erythrocytes do not differ statistically from individuals with small nuclei for all studied plastic and meristic characteristics and absolute individual fecundity.