Fish diversity of the Utlytsky estuary

Abstract

Article deals with characteristic of the Utlytsky estuary’s ichthyocenosis. Utlytsky estuary is one of the biggest estuaries of the Sea of Azov, which located in the north-west part of the sea. In modern conditions 48 species of fish from 22 families was observed. Nowadays, such species as longsnouted seahorse, thick-snouted pipefish, narrow-snouted pipefish, river burbot, common vimba, common bream aren’t registered. Their absence is related to the low numbers or their total absence in the Azov Sea in recent years. The enrichment of the estuary fish fauna was due to new invasive species, such as soiyu mullet, sunfish, prussian carp and by extending the range of Black Sea species – atlantic bonito, mediterranean horse mackerel, sand sole etc. The basis of the estuary ichthyocenosis by the number of individuals is the european anchovy, the round goby and the Black Sea sand smelt. These species account for more than half of the catch by number of individuals in catches of gill nets and fry trawls. Secondary species are golden gray mullet and soiyu mullet, prussian carp, round goby, monkey goby, tubenose goby, grass goby, greater pipefish and others. Changes in the salinity of the estuary waters, which influenced the structure of the aquatic fauna of the reservoir, were noted. Thus, the catches have a high number of silver carp, gossip ordinary and not even typical of marine waters freshwater species – northern pike, sunfish, common rudd and others, in the conditions of relatively low salinity. On the other hand, catches of marine fish species are increasing in the estuary in the salinity rise conditions. So, the numbers in the catch of european anchovy, golden gray mullet, flathead mullet, grass goby and others increased from 1–2 % to 10–12 % of the total number of individuals caught.