Genetic polymorphism of mitochondrial DNA of beluga throughout its range and genetic monitoring of restocking in the Caspian Sea

The purpose of the work: to study the genetic structure and genetic heterogeneity inherent in various beluga populations for the competent construction of the restocking process of the species. Scientific novelty: for the first time, the results of studying the genetic diversity of mtDNA control region of beluga in its entire range and brood stock of beluga in the SFF of the Caspian region are presented. Materials and methods: the work uses material from the RNCRGM FGBNU VNIRO (Russian National Collection of Reference Genetic Materials). The mtDNA control region was sequenced using ABI3500xL genetic analyzers (Applied Biosystems, USA). The collection and analysis of fish-breeding and biological indicators, materials on artificial spawning of producers in the period from 2016 to 2021 was carried out, the effectiveness of crosses was assessed by the degree of development of eggs at the stage of 4 blastomeres. Results: 100 different mitochondrial haplotypes with a length of 614 bp were identified in 246 beluga individuals. The largest number of haplotypes is found in the Caspian population, the smallest in the Azov one. The total haplotypic diversity for beluga was Hd=0.983, standard deviation 0,002, and nucleotide diversity π=0,0138±0,00712. Comparison of populations showed high intra-population and low inter-population variability. There is no genetic differentiation between the beluga populations of the Caspian and Azov Seas, the most pronounced differentiation is between the Caspian and Black Sea belugas. Such fish-breeding and biological characteristics as average weight, inter-spawning interval, relative and working fertility, generative index, and other data were evaluated and entered into the register of beluga producers. It has been shown that the genetic polymorphism of belugas used in SFF to produce juveniles is sufficient for the formation of genetically diverse offspring. Practical significance : the data are used in genetic monitoring and restocking of the natural beluga population.