BIOLOGICAL CHARACTERISTICS OF THE Rutilus caspicus (Yakovlev, 1870) IN THE CASPIAN SEA
The article examines the biological and trophic parameters of the Rutilus population in the Caspian Sea basin. During the study, 442 individuals were selected from 10 fixed stations in the northern waters of the Caspian Sea. For these fish, an analysis of length and weight, fatness coefficients, age and sex structure, as well as an assessment of the degree of intestinal fullness on a point scale was carried out. The study was performed using standard ichthyological methods. The results showed that the growth of the Rutilus is based on a close dependence of length and mass and has an allometric character. This confirms that with sufficient food supply, the mass increases faster than the length. In addition, the stability of fatness coefficients indicates a good physiological condition of the fish and favorable living conditions. The analysis of the population structure revealed the predominance of young individuals, which indicates an active process of natural reproduction. A relatively small number of large and older fish can be associated with both natural factors and anthropogenic impact. The characteristics of the sexual structure are also an important indicator of population stability. The analysis of feeding activity showed that the Rutilus get enough food in their natural habitat and that the feeding process proceeds evenly. In general, the current state of the Rutilus population is assessed at a satisfactory level and it has been established that it is well adapted to the environmental conditions of the Caspian Sea. The results of the study can serve as a scientific basis for improving measures for the rational use, protection and management of fish resources.