According to the lactadehydrogenase locus, the genetic diversity of 9 samples of the Volga sevryuga of different origin was studied. In total, 733 pieces of young sevryuga, 99 pieces of producers and 107 pieces were studied. four-year-olds of sevryuga with MPERZ. To assess the genetic variability of lactate dehyrogenase allozymes, the method of polyacrylamide gel electrophoresis was used, as the most appropriate for assessing the influence of the environment in natural and domesticated populations. It is shown that the young sevryuga, grown in the conditions of 6 Astrakhan sturgeon hatcheries, differs significantly from the control group of natural producers. The LDH-3 lactate dehydrogenase locus is represented by 6 genotypes. 5 genotypes were found in producers, in the absence of only genotype 100/112. Genotypes 70/112 and 112/122 are missing in the samples from all plants and MPERZ, while genotype 70/70, which was found in excess at MPERZ, is also missing in three plants. However, in general, only 2 genotypes out of 6 are missing for all ARI. A study of the dynamics of the frequency of alleles in this set of samples showed that in 4 samples with ARI and on MPRZ there is no allele 112. However, in general, the ARI allele persists. Thus, it is shown that due to the different genetic variability of LDH-3 in juveniles from different acute respiratory infections, the genetic diversity in the samples as a whole approaches the indicators of producers. Therefore, the preservation of a variety of growing conditions for young sevryuga will contribute to the preservation of its genetic diversity.

One of the main goals of sturgeon aquaculture is the restoration and renewal of wild populations of sturgeon fish in nature, which creates a tension between selective breeding with maintenance of valuable economic traits in a homozygous state and the need to conserve genetic diversity ensuring fitness in natural environments. It is generally assumed that important economic characteristics, such as body weight and size, growth rate, fecundity, etc., as well as fitness in fish, are associated with heterozygosity and genetic polymorphism of some key metabolic enzymes. It remains unclear whether aquaculture conditions can be as a whole selection factor in favor of certain allelic variants of these enzymes. To establish the relationship between some economic traits and enzymatic polymorphism, we studied the distribution of allelic variants of LDH-3, AAT-2, FGM, and Est enzymes in stellate sturgeon reared in aquaculture. We revealed a frequency bias of some allelic variants of the studied enzymes in a cohort of fish from the generation bred in aquaculture compared to the frequencies of those alleles in wild natural populations. Our study suggests that industrial breeding promotes selection in the direction of reducing size but increasing survival rates, which correlates with certain allelic variants.

Morphometric studies are fundamental in the domestication of new fish species. Despite the obvious dependence of the morphological parameters of fish on habitat conditions, they are currently used as the main criteria for the approval of breeding achievements, and a measure of the processes of domestication and selection. In this regard, we have begun work to study the variability of morphological characters in the process of domestication of stellate sturgeon (Asipenser stellatus, Pall) in a closed water supply. Researched sturgeon of Volga origin grown from caviar in artificial conditions in a closed water supply installation. At the first stage, 25 morphological parameters of stellate sturgeon underyearlings were studied. At the second stage, six years later, morphological studies were repeated in the same group of fish. Comparison of the average values of the indicators indicates the following trends in their change with the age of the fish: the relative length and height of the head, the rostrum (rr), and the diameter of the eye, the width of the mouth and the width of the break of the lower lip decrease; the indicators of the distance between the fins relative to the end of the snout and between themselves increase, the smallest and largest body height. At the same time, the most significant significant differences between underyearlings and six-year-olds were found in body height and head length. Similar changes are observed with age in most fish, including sturgeon. They are associated with the development of swimming muscles, physiological changes and demonstrate the expected biological age-related changes. The presented data on age-related changes in morphological parameters show the erroneousness of using sturgeon underyearlings as a control group for assessing uniformity and stability for distinctness.