Характеристика структурных изменений ихтиофауны в северной части Аграханского залива за последние 5 лет

Abstract

The northern part of the Agrakhan Gulf, which is a part of the Tersko-Caspian fishery complex of Dagestan, plays an important role in the formation of stocks of commercial fish species, having abundant spawning, nursery and wintering grounds. The efficiency of natural reproduction of fish is determined by the state of the hydrological and hydrochemical regime in the reservoir, which in recent years in this reservoir can be characterised as unfavourable. Studies carried out in North Agrakhan in the period from 2018 to 2022 have shown negative changes in the structure of ichthyofauna, manifested in a decrease in the number of juveniles of passable, semipassable, freshwater fish species and an increase in tuvodny fish of the lake-river complex. The number of juveniles of passable fish species has decreased almost twofold, kutum stocks have reached a critical level, the prevailing semi-passable fish species, which account for up to half of the total volume of recorded juveniles, are also decreasing, although to a lesser extent. Freshwater fish species are in a depressed state, the number of juvenile fish is decreasing from year to year, and has decreased more than twofold over the 5 years under study. The total number of segolets of low-value fishery lake-river fish species for 5 years increased 2 times and was 37% of the total volume of all fish species. In general, in the northern part of the bay the dominance of fish species in the northern part of the bay has become dominant among passable fish species - redfish, semipassable fish species - bream, freshwater fish species - redfish, lake-river fish species - redfish and crucian carp. Such species as kutum, pikeperch and practically all freshwater species are at the stage of extinction, mainly tench, which was recorded in catches only once.