Modern assessment of the state of the fish fauna in the northern part of Agrakhanskaya bay, river Dagestan

Abstract

The northern part of the Agrakhan Bay is of great fishery importance for the Tersko-Caspian region of the Dagestan, there are the main spawning grounds foralmost all types of fish, including valuable passing and semi-passing (roach, bream, carp, pike perch) as well as freshwater (perch, pike, catfish, rudd, silver crucian, gustera and perch). Studies were conducted to assess the qualitative structure of populations of commercial fish species in 2021, age and morpho-biological indicators were studied, as well as the sex ratio of semi-migratory fish species (for example, roach and walleye) and freshwater (perch and rudd). The results obtained indicate that all aquatic fish were in satisfactory condition, and semi-aquatic (roach, bream, carp and pike perch) — to a lesser extent met the required qualities. Younger age groups (3–5 years old) dominated in the structure of semi-passable fish — roach and walleye, which accounted for over 50%, males dominated in younger age groups, unlike older (6–8 years old), the proportion of females was over 80%. According to morpho-biological parameters, the roach and pike perch were superior to the Volga fish of the same species, and in terms of fatness by almost 2.5 times. Freshwater fish (perch, rudd) were represented by five age categories, of which 3–4-year-olds accounted for over 60%. In the qualitative structure of the perch of 2021, the indicators of length, weight and fatness were worse than the individuals caught in 2020. Morphometric indicators of the rudd had no significant discrepancies with the data of the previous year, which once again confirms the absence of the influence of the hydrological regime on the number and biological indicators of this little whimsical fish species.