Evaluation of genetic polymorphism of proteins in stellate sturgeon Acipenser stellatus (Pall) in aquaculture with reference to economically valuable traits

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.

Marking fin spine of juvenile sturgeon (acipenseriformes: acipenseridae) using oxytetracycline and the comparing of growth performance

ABSTRACT This study aimed to describe and validate the formation of the rings in the spine of the pectoral fin and to determine the coherence of the OTC mark with the rings of three species of Caspian Sea sturgeon, the Persian sturgeon (Acipenser persicus), the Starry sturgeon (Acipenser stellatus) and Ship sturgeon (Acipenser nudiventris). Validation was achieved by comparing the total radius of the fin spine of fish of known age after one and two years of growth with the measured radius of the first and second rings in the zone. There was no overlap between the measured radius for the first year and the increase for the second. The Ship sturgeon showed the largest width of the second ring followed by the Persian sturgeon and Stellate sturgeon. The results indicate that the highest growth parameter belongs to the juvenile Ship sturgeon. This research showed that chemically marking the fin spines of juvenile Acipenseridae leads to unbiased estimates and contributes to the knowledge of the population dynamics of these species. The study found that the combination of the dial ring of the pectoral fin spine with growth validated the age estimation in juvenile sturgeon Ship, Persian, and Starry sturgeon.

Dependence of the duration of the embryonic period of development of the sevryuga (Acipenser stellatus Pallas, 1771) and the thorn (Acipenser nudiventris Lovetsky, 1828) on the temperature regime of wintering of producers

The temperature conditions and the results of wintering of producers, incubation of caviar of sevryuga and thorn in farms on waste warm waters are considered. The studied indicators are compared with similar data obtained when keeping producers from natural populations in the lower reaches of the Volga River. In the considered species, with a shortened and comfortable "warm" wintering (for sevryuga at 5-11, thorn – 3-15°C), an increase in the duration of incubation up to a day or more was recorded in comparison with individuals from natural populations. The temperature regulations of wintering for producers, incubation and maintenance of free embryos are proposed.

Ecological, Biological and Hematological Index of the Blood Analysis of Sturgeons (Acipenser) in the Caspian Sea

The Caspian is a unique drainless water body with no connection to the ocean. This study of the peculiarities of blood cell composition of the Russian sturgeon (Acipenser güldenstädtii) and sevruga (Acipenser stellatus) revealed minor destructive disorders of the blood cells. The number of blood cells also deviated from conditional norms. The study of the leukocyte profile of sturgeons showed the granular forms of leukocytes, band neutrophils and eosinophils, and segmentonuclear neutrophils and eosinophils. The total number of granulocytes in the blood of the Russian sturgeon was increased, which indicated the activation of the body’s protective systems in response to the anthropogenic load. In cytomorphological terms, the destructive disorders were revealed. Such phenomena are associated with the ever-increasing anthropogenic load on the biocenoses of natural reservoirs. Summarizing the results, it can be concluded that the quantitative indicators of red blood in the Russian sturgeon (Acipenser gueldenstaedtii) and sevruga (Acipenser stellatus) caught off of the Dagestan coast of the Caspian Sea were reduced in the spring of 2018 compared to 2016, but were in the normal range given in the literature. The concentration of hemoglobin in the Russian sturgeon and sevruga in 2016 was 13% and 15% higher than in 2014, respectively. This phenomenon could be a measure to compensate for the lack of oxygen in various fish tissues and organs. Keywords: Russian sturgeon, red blood cells, lymphocytes, eosinophils, neutrophils, anisocytosis, cytolysis of red blood cells

Assessment of food intensity and growth rate young sevryuga (Acipenser stellatus Pallas, 1771) depending on from the terms of fishing of growing ponds

Artificial reproduction of sturgeon fish in the Volga-Caspian basin in modern conditions is the only real opportunity to replenish natural populations with juveniles, therefore, increasing its efficiency is the key to restoring the stocks of these relict fish species. Improving the technological processes of growing juvenile sturgeon fish, including the Caspian stellate sturgeon, the number of which has been rapidly decreasing in recent years, is one of the main tasks at present. We studied the conditions for growing stellate sturgeon larvae in the nursery ponds for artificial reproduction at different periods of their watering. It is known that the stocking of ponds with larvae that have switched to exogenous feeding occurs at the end of June or the beginning of July, this coincides with the time of maximum water heating in nursery ponds to extreme (26–28 °C) values and with a depletion of the food supply in them. Hydrobiological studies were carried out to assess the food supply in water bodies that were watered in the traditional (June 12–14) terms (control option) and earlier (May 28) 2 weeks earlier than usual (experimental option). In addition, the intensity of feeding and the growth rate of juvenile starred sturgeon in the indicated ponds was studied for 20–24 days. The results of the studies performed showed that the food supply in the experimental pond was higher, so the zooplankton was represented by four orders, the biomass on average ranged from 2,8 to 4,6 g/m³, and in the control variant, planktonic organisms were represented by three orders, total biomass from 0,3 to 2,5 g/m³. The same tendency can be traced for zoobenthos. The feeding intensity of stellate sturgeon fry reared in ponds of early watering had indicators in terms of the gastrointestinal tract filling index, fatness coefficient and growth rates higher than the juveniles kept in water bodies of traditional watering periods.

Oxidative Stress and Antioxidant Defense Mechanisms in Response to Starvation and Refeeding in the Intestine of Stellate Sturgeon (Acipenser stellatus) Juveniles from Aquaculture

Acipenser stellatus is a critically endangered species due to the anthropic influence. It has been intensively captured for decades because of its high economic value, its roe being used in the caviar industry. Therefore, Acipenser stellatus is intensively raised in fish farms for both conservation and economical purposes. Aquaculture aims to optimize the feeding regime of juveniles in order to improve its profitability. The purpose of this study was to investigate if Acipenser stellatus can adapt to a starvation/refeeding regime by assessing the effects of this regime on oxidative stress biomarkers and antioxidant defense mechanisms in juveniles raised under aquaculture conditions. The juveniles were subjected to two regimes: a 7-day starvation period followed by 21 days of refeeding, respectively a 14-day starvation period followed by 21 days of refeeding. The results showed that both starvation/refeeding regimes induced an enhancement of antioxidant enzymes activities in the intestine of the juveniles. The oxidative damage was counteracted at the protein level. However, lipid peroxidation was significantly induced in the intestine of the juveniles subjected to 14/21-day starvation/refeeding regime. The 7/21-day starvation/refeeding regime proved to be more suitable for Acipenser stellatus and therefore, it could be useful to optimize the feeding practice in aquaculture production.