Genetic monitoring of sterlet juveniles (Acipenser ruthenus) in the Volga river

Abstract

The aim of the work was to carry out genetic monitoring of the natural reproduction of juveniles (larvae and underyearlings) of sterlet (Acipenser ruthenus Linnaeus, 1958), caught in the middle and lower spawning zones of the Volga River for the period 2021–2022, which is necessary and relevant in the context of a decrease in the number of sturgeon species of fish. The study of fish was carried out according to five nuclear markers and a fragment of the control region of mitochondrial DNA.According to the results of microsatellite analysis, sterlet individuals were characterized by species-specific dominant alleles and high values of the main indicators of genetic diversity: the number of alleles, allelic diversity and heterozygosity, and a slight deficit of heterozygotes was noted. By analyzing of the nucleotide sequences of the mtDNA D-loop region a high level of diversity of maternally inherited haplotypes was revealed, reflecting the number of females involved in natural reproduction. According to the monitoring data, no differences in the distribution and number of identified variants of the D-loop region were registered in the interannual aspect. During the study period, 48 sterlet mitochondrial haplotypes were recorded, of which 18 mtDNA variations were unique, occurring in the Volga-Caspian fishery basin. In the study of sterlet larvae by molecular genetic methods in the Volga River was revealed the process of hybridization between stellate sturgeon and sterlet (Acipenser stellatus × Acipenser ruthenus).