Siberian Sturgeon Research Articles

Effects of chronic heat stress on spleen structure, apoptosis and immune response in Siberian Sturgeon (Acipenser baerii)

Chronic heat stress induced by global warming has important implications for fish survival, and the response of important immune organs, such as the spleen, to chronic heat stress remains to be investigated. In this study, one control group (20 ℃) and two heat stress groups (24 ℃ and 28 ℃) were set up to investigate the effects of heat stress on the spleen of Siberian Sturgeon (Acipenser baerii). As per the histological section analysis, heat stress caused vacuolization, reticulocyte hyperplasia, and macrophage infiltration in the spleen, with hyperplasia being more pronounced in the 28 ℃ group. The flow cytometry results showed that the spleen’s apoptosis level significantly increased at 28 ℃ (p < 0.05). Hematological studies revealed a significant increase in the number of red blood cells in the 28 ℃ group (p < 0.05). Meanwhile, the mRNA expression of immune-related factors (tgf-β, il-1β, and il-8) was significantly higher in the 28 ℃ heat stress group compared with the control group. This study reveals the effects of heat stress on the A. baerii spleen and contributes to the understanding of coping strategies of cold-water fish to chronic heat stress.

Growth, development and commercial traits of sturgeon fish species under industrial fi sh farming conditions when use the feed additive Abiotonic

Artificial fish farming including commercial sturgeon farming using highly nutritious balanced feeds is nothing less than a strategically important area in Russian agriculture. In recent years, methods for increasing animal productivity using highly biologically active additives both natural and artifi cial, which have a growth-stimulating, protective and immune-modulating eff ect on the body of animals at various stages of development, have found wide application. These include the feed additive Abiotonic. In the literature studied by us, we found no information on the eff ect of the feed additive Abiotonic on the growth, development and livability of sturgeon fi sh, as well as on the quality indicators of the resulting fi sh products. In this regard, studies aimed at studying the eff ect of the vitamin-microelement growth immunostimulant Abiotonic on the productivity of sturgeon fi sh are relevant. The purpose of the research was to study the growth, development and commercial traits of sturgeon fi sh species under industrial fi sh farming conditions using the feed additive Abiotonic. The research established the optimal amount of the feed additive Abiotonic for use in the diets of the hybrid Russian and Siberian sturgeon inder industrial fi sh farming conditions. Thus, when rearing sturgeon fi sh with high productive and commercial traits, as well as with low feed costs per unit of fi sh weight gain and the cost of fi sh products under industrial conditions, we recommend that fish farms use the feed additive Abiotonic in the diets of sturgeon fi sh in the mount of 1.0 ml per 1.0 kg of fi sh body weight.

Deciphering the impact of stickwater hydrolysate on growth performance, immune response, and IGF-1/PI3K/AKT/mTOR signaling pathway in Siberian sturgeon (Acipenser baerii) fingerlings.

A feeding trial lasting 56days was carried out to assess how the inclusion of stickwater hydrolysate (SWH) in the diet of Siberian sturgeon (Acipenser baerii) fingerlings affected their growth performance, immunity, digestive enzyme activity, and gene expression linked to the IGF-1/PI3K/AKT/mTOR signaling pathway. Siberian sturgeon fingerlings were acclimatized and fed isonitrogenous, isoenergetic diets with varying SWH concentrations (0%, 0.5%, 1.5%, and 2.5%). Growth parameters, serum proteins, immunological and digestive enzyme activities, and gene expression levels were assessed post-trial. Results demonstrated that 0.5%, and 1.5% SWH treatments significantly improved weight gain, specific growth rate, feed conversion ratio, and protein efficiency ratio. Notably, these diets also elevated serum protein and plasma globulin levels, reduced albumin-to-globulin ratios, and enhanced lysozyme, myeloperoxidase (MPO) activities, and immunoglobulin (Ig) M levels, indicating an immunostimulatory effect. Digestive enzyme activities were markedly increased in the SWH groups, particularly at 1.5%. Gene expression analyses revealed upregulation of mtorc1, s6K, akt, pi3k, and igf1, with concurrent downregulation of 4e-bp1 in the muscle of fish, signifying activation of the IGF-1/PI3K/AKT/mTOR pathway, which is central to protein synthesis and muscle growth. In conclusion, SWH at appropriate levels significantly enhances growth, digestive efficiency, and immune function in Siberian sturgeon fingerlings, while also activating key metabolic pathways.

Exploring a novel toxicological mechanism: Ammonia-N induces neurotoxicity, oxidative damage in brain tissue, and modulates the expression of central appetite factors to suppress feeding in juvenile Siberian sturgeon (Acipenser baerii Brandt)

Ammonia-N is a common toxic factor in aquatic environment, known to inhibit fish feeding, yet its mechanism remains unclear. To investigate the toxicological mechanism of ammonia-N in inhibiting fish feeding, this study conducted experiments exposing juvenile Siberian sturgeon (Acipenser baerii) to ammonia-N at concentrations of 0, 5, 10, and 15 mg/L for 14 days. The results revealed a significant reduction in both daily and cumulative food intake. Obviously decreased condition factor (CF), hepatosomatic index (HSI), and viscerosomatic index (VSI) at 15 mg/L (P < 0.05). Besides, the serum ammonia concentration significantly increased on the 14th day, while the neurotoxic marker acetylcholinesterase (AchE) showed a consistent increase over the 14-day period (P < 0.05). Pathological examination of brain tissue demonstrated that ammonia-N induced damage, particularly evident in 15 mg/L ammonia-N group, where severe nerve fiber dissolution was observed. Moreover, the activity of superoxide dismutase (SOD) was significantly increased in the brain on the 1st, 3rd, and 7th day (P < 0.05). RNA-seq analysis o revealed 1566, 2188, and 2026 differentially expressed genes (DEGs) were obtained in the 5, 10, and 15 mg/L ammonia-N groups, respectively, compared to the control group, and 30 DEGs related to appetite regulation were identified. Further quantitative real-time PCR (qPCR) analysis indicated that ammonia-N exposure changed the expressions of appetite factors, including downregulation of agouti-related protein (agrp) and neuropeptide Y (npy), and upregulation of pro-opiomelanocortin (pomc), cocaine-and amphetamine-regulated transcript peptide (cart), and corticotropin releasing factor (crf) (P < 0.05). Therefore, these results suggest that ammonia-N inhibits feeding via neurotoxicity induced oxidative damage which primarily by downregulating appetite promoting factors and upregulating appetite-inhibiting factors. This study lays the groundwork for deeper understanding of the toxicological mechanism of ammonia-N on aquatic animals, particularly its detrimental effects on fish brain function and feeding behavior.

Next-Generation Sequencing to Determine Changes in the Intestinal Microbiome of Juvenile Sturgeon Hybrid (Acipenser gueldenstaedtii♀ × Acipenser baerii♂) Resulting from Sodium Butyrate, Β-Glucan and Vitamin Supplementation

Background/Objectives: The effect of sodium butyrate (NaB), β-glucan (βG) and vitamins in the diet on gut microbiome, cortisol level, lysozyme activity and growth parameters of juvenile hybrid sturgeon (Acipenser gueldenstaedtii♀ × Acipenser baerii♂) was determined. Methods: Sturgeon hybrids (n = 144) were divided into three groups with enriched feeding (mg/kg of feed): FQV1 (50 NaB; 20 βG; const. vitamins), FQV2 (150 NaB; 20 βG; const. vitamins), FQV3 (50 NaB; 60 βG; const. vitamins) and control (not supplemented), each group in triplicate, 12 fish in each repetition. Rearing was carried out for 30 days in controlled conditions. Gut microbiome was characterized using Next Generation Sequencing (NGS) of DNA samples isolated from intestinal content. Cortisol level was determined using the ELISA test. Lysozyme activity was measured by turbidimetric test. Results: Based on data obtained from NGS, it was determined that the FQV1 group is characterized by the highest values of diversity indices (Shannon, Simpson and Chao-1) and the largest number of ASVs (Amplicon Sequence Variants). The highest abundance of probiotic bacteria (Lactobacillus, Lactococcus) was determined in the FQV1 group. The highest cortisol concentration was determined in the control (33.26 ng/mL), while the lowest was in FQV3 (27.75 ng/mL). The highest lysozyme activity was observed in FQV1 (154.64 U/mL), and the lowest in FQV2 (104.39 U/mL) and control (121.37 U/mL) (p &lt; 0.05). FQV2 was characterized by significantly more favorable values of breeding indicators (p &lt; 0.05). Conclusions: The obtained results prove that an appropriate composition of NaB, βG and vitamins can be used in the commercial breeding of juvenile hybrid sturgeons.

Effect of cortisol through GR regulated inflammatory cytokine expression and apoptosis of Siberian sturgeon (Acipenser baerii) after LPS treatment

AbstractThe various environmental pressures could increase the cortisol levels of sturgeon. However, there is a lack of reports on the mechanism by which elevated cortisol levels affect the immune response of Siberian sturgeon. In this study, a high-level cortisol anti-inflammatory state of Siberian sturgeon after co-treatment with LPS and cortisol was constructed and verified in the primary spleen leukocytes. The glucocorticoid receptor (GR) was cloned and its binding site with Ru486 was analyzed. After adding Ru486 to treat the primary spleen leukocytes, the expression of inflammatory cytokines mediated by GR was explored by qRT-PCR. The structure of spleen after LPS + cortisol injection was observed by histopathology and the changes in apoptotic genes were explored by qRT-PCR. Furthermore, the apoptosis of cells after Ru486 treatment was studied by qRT-PCR, DNA ladder, and Hoechst staining. Firstly, co-treatment with LPS and cortisol led to high levels of serum cortisol and glucose within 24 h after treatment. In this situation, the expression of il-10 and tgf-β1 was upregulated in the LPS + cortisol group, while the expression of il-1β and tnf-α was regulated. However, il-1β, tnf-α, il-10, and tgf-β1 were significantly down-regulated in vitro. Clone analysis of the GR sequence indicated that it is conserved and widely expressed in 18 tissues. Molecular docking simulations suggested that it can bind to cortisol and the GR antagonist Ru486, respectively. Further addition of Ru486 treatment reversed the expression of il-1β, il-10, tgf-β1, and JAK-STAT signaling pathway factors. Histopathological observations showed that LPS + cortisol injection causes splenic cell death. Then, the expression of pro-apoptotic genes p53 and caspase3 increases significantly. After Ru486 treatment in spleen leukocytes, the mRNA expression levels of pro-apoptotic-related genes p53, bax, caspase3, caspase7, and caspase9 were significantly downregulated. GR antagonism could attenuate LPS + cortisol-treated splenic leukocyte DNA fragmentation and nuclear morphological changes. Therefore, cortisol can regulate the production of inflammatory cytokines and promote the process of cell apoptosis through the GR of Siberian sturgeon, thereby inhibiting the inflammatory response.

Application of feed enriched with humic additive from peat and dry garlic powder when growing juvenile Siberian sturgeon on an industrial line of cage aquaculture

Cage aquaculture, used in modern industrial sturgeon farming, differ from recirculating water supply systems (RAS) by more natural habitat conditions of fish growing, which are optimal for broodstocks development and maintaining and producing fish seeding material and is more economical. The dominant species for sturgeon aquaculture in Russia and throughout the world is Siberian sturgeon, Acipenser baerii Brandt, 1869, adapted to extreme temperature conditions. When this fish was grown at industrial cage aquaculture enterprises in the European North of Russia under natural conditions, the survival rate of the objects was 99%; growth rates exceeded those of sterlet, Russian sturgeon and F1 hybrids of Russian and Siberian sturgeon; the feed ratio was better compared to fish kept in cages in the Southern Federal District. Seven-year-old sturgeons reared in cages under such conditions had a maximum live weight of more than 8 kg, their physiological parameters were better than those of objects kept in a RAS; indices of reproductive system corresponded to the normal values. To increase the efficiency of keeping Siberian sturgeon in cage aquaculture in the extreme conditions of the Northern regions, feed enriched with multifunctional biologically active compounds of natural origin is used. In this production experiment, the basic forage included the feed additive Humiton of peat humic compounds origin at a dose of 25 ml/kg and/or dried garlic powder at a dose of 30 g/kg; both components previously have shown effectiveness in growing juvenile Siberian sturgeon under RAS conditions. In the experiment, all additives showed activity in all assessed indicators, but the greatest effect was observed when using garlic powder or its combination with Humiton additive. The effectiveness of additives is due to adaptogenic and immunomodulatory effects, the ability to favorably influence the function of the digestive system and improve the absorption of feed nutrients.

Comparative characteristics of the development of germ cells in Siberian sturgeon and sterlet in the second year of cultivation, obtained using cryopreserved and native sperm in industrial farms

For the first time, the effect of cryopreservation in comparison with native sperm from domesticated forms of Siberian sturgeon and sterlet on the development of germ cells and the body as a whole in the offspring obtained in the second year of cultivation, taken during fertilization of eggs of Siberian sturgeon and sterlet in the conditions of the Konakovsky department of the Branch for the freshwater fisheries of the VNIRO (VNIIPRKH). The correlation of body weight with the mass of the left, right and gonad length is shown, the greater the body weight, the greater the mass and length of the gonads. In the early stages of the body’s development, body weight and the appearance of gonads correlate due to the presence of parenchymal and adipose tissue in the gonads, blood cells — histiocytes (a type of macrophages), which resorb cells unnecessary to the body, are clearly visible in the gonads. In females and males of Siberian sturgeon and sterlet, regardless of body weight, there is a consistent manifestation of the patterns of gametogenesis. In the experimental and control groups, the development of germ cells is similar, and anatomical differentiation of sex takes place. The Siberian sturgeon has the I stage of gonad maturity, the sterlet has the I, the beginning of the II stage of gonad maturity, they are species–specific and regular. No violations were noted, the appearance of hermaphrodite in sturgeons is a known fact and is not a violation, because the process of germ cell development in the “female” and “male” gonads is proceeding in a timely manner. The good quality of spermatozoa in domesticated forms of Siberian sturgeon and sterlet, which have passed several stages of breeding and are located in the Konakovsky department, is also important.

IR spectra simulations by anharmonic DFT and CDFT-saturated and unsaturated fatty acids of Siberian sturgeon (Acipenser baerii Brandt,1869)

The Siberian sturgeon is one of the most remarkable species in the field of aquatic biology which also has ecological importance, commercial significance, and nutritional characteristics. The purpose of this study is to determine the fatty acid content of different organs of Siberian sturgeon through both theoretical and experimental techniques to compare oxidative stability of the samples in terms of fatty acid profile. For this purpose, the fatty acid content of flesh, brain, caviar and liver of sturgeon was determined by gas chromatography and the middle infrared spectra of tissues were collected by an infrared spectrofotometer. The fatty acid content of samples was also computed by anharmonic DFT and CDFT calculations using IR spectra. Oleic acid was the most abundant fatty acid in all tissues. All tissues accumulated by docosahexanoic, eicosapentanoic and linolenic acids. The PCA model was able to classified the tissues with respect to fatty acid contents. Comprehensive anharmonic DFT calculations were performed to better understand the fatty acid of samples at the atomistic level and to predict the spectra of more complex food samples with varying fatty acid compositions. Oxidative stabilities of fatty acids were also investigated through Conceptual DFT based computations. Maximum Hardness and Minimum Electrophilicity Principles accurately predicted saturated and unsaturated fatty acids of sturgeon as the experimental data revealed.

Globular adiponectin, acting via AdipoR1, regulates food intake of Siberian sturgeon (Acipenser baerii) in a mTOR dependent manner

Adiponectin (AdipoQ) is a hormone that regulates food intake and energy homeostasis in mammals. The globular adiponectin (gAd) has been reported involved in the regulation of appetite, but the regulatory role and mechanism in fish remains unelucidated. Using Siberian sturgeon as a model of Chondrostei, the recombinant gAd protein of Siberian sturgeon (SsgAd) was produced by Escherichia coli expression system and verified using western blotting. Intraperitoneal injection of recombinant SsgAd protein at 100 ng/g BW suppressed food intake 1 h after administration. Peripheral injection of SsgAd protein caused the upregulation of anorexigenic pyy expression in the valvula intestine, but did not affect cck expression in the valvula intestine and orexigenic ghrelin expression in the stomach. The SsgAd administration significantly increased the hypothalamic expressions of pomc and decreased npy, agrp, and cart expression. In addition, SsgAd recombinant protein promoted adipor1, ampkα2, akt, and mtor mRNA expressions within the hypothalamus, whereas inhibited ampkβ1, ampkβ2 and ampkγ2 mRNA expression, suggesting AMPK and mTOR signaling pathways might be related to SsgAd protein-mediated anorexia activity. Furthermore, the injection of an mTOR antagonist (rapamycin) reversed the reduced food intake and npy, agrp, and cart expression due to the peripheral injection of SsgAd, as well as the increased pomc expression induced by SsgAd, which were not observed after AMPK antagonist (dorsomorphin) treatment. In summary, the current study, for the first time, suggest that the anorexigenic function of SsgAd might bind with AdipoR1 and activate the mTOR signal pathway to affect the expression of hypothalamic appetite factors in Siberian sturgeon. This study provides new insight into the molecular mechanism of AdipoQ in feeding regulation in fish, and a basis for further exploration on physiological function of AdipoQ.

The feasibility of using white lupin meal in the feed of juvenile Siberian sturgeon (Acipenser baerii)

Abstract As with other fishes farming, sturgeon farming depends on the use of well-balanced feed to maintain production. Commercial feeds available on the market are often based on soy protein, which, unfortunately, has many adverse effects on these fish. Therefore, alternative constituents are being sought that could be used in sturgeon fish farming. This study was designed to assess the feasibility of using diets containing white lupin meal at levels of 5% and 10% for juvenile Siberian sturgeon, compared to a formulated control group without lupin inclusion and a reference group fed commercial feed. Histological and immunohistochemical analyses were performed, combined with digestive enzyme activity assays. This study showed that feeding with white lupin meal did not adversely affect the rearing parameters, histology, or enzyme metabolism of sturgeons. An increase in the length of intestinal folds in the anterior intestine was observed in the group with 10% lupin meal inclusion, while this trend was not present in the spiral intestine, which may be indicative of a compensatory physiological mechanism when fish are fed less digestible feed. Antioxidative mechanism impairment was also noted in the two experimental groups. However, further research is still required to determine the possibility of using white lupin meal in the feeding of sturgeon fish, especially for more mature specimens.

Transcriptome analysis reveals high concentration of resveratrol promotes lipid synthesis and induces apoptosis in Siberian sturgeon (Acipenser baerii)

Resveratrol has been reported to promote immunity and decrease oxidative stress, but which demonstrates biphasic effects relied on the use concentration. In this study, the effects of diet supplement with a relative high concentration of resveratrol (0.32 mg/kg) on metabolism, antioxidation and apoptosis of liver were investigated in Siberian sturgeon. The results showed that resveratrol significantly increased the lipid synthesis and the apoptosis, but did not either activate the antioxidant NRF2/KEAP1 pathway or enhance the antioxidant enzyme activity. Transcriptome analysis revealed significant changes in regulatory pathways related to glycolipid, including PPAR signaling pathway, Insulin signaling pathway, Fatty acid biosynthesis, and Glycolysis/Gluconeogenesis. In addition, resveratrol significantly increased the lipid synthesis genes (accα and fas), fatty acid transport gene (fatp 6) and gluconeogenesis gene (gck), but decreased the survival-promoting genes (gadd45β and igf 1). These findings highlight a significant effect of resveratrol on glycolipid metabolism in Siberian sturgeon. Moreover, this study also demonstrated that 0.32 mg/kg resveratrol has physiological toxicity to the liver of Siberian sturgeon, indicating that this dose is too high for Siberian sturgeon. Thus, our study provides a valuable insight for future research and application of resveratrol in fish.

Supplementation of juvenile Siberian sturgeon (Acipenser baerii) diet with different levels of selenium: Growth performance, digestive enzyme activities, and intestinal histomorphology

This study aimed to investigate the impact of dietary Selenium (Se) on the growth performance, body composition, digestive enzymes, and intestinal histomorphology of Siberian sturgeon, Acipenser baerii. Fish (10.0±0.5 g) were randomly assigned to fifteen 1000-L tanks (30 fish per replicate) in a flow-through system and fed three times a day (08.00, 13.00, 18.00) with isonitrogenous (54.21 % crude protein) and isolipidic (15.63 % crude lipid) diets supplemented with selenomethionine at levels of 0, 0.2, 0.4, 0.8, and 1.6 mg kg−1 providing the analyzed Se of 0.10, 0.29, 0.49, 0.88, and 1.70 mg kg−1, respectively. Each three tanks were allocated to each treatment. After the eight-week feeding trial, weight gain ratio, specific growth rate, and survival rate of fish significantly increased with increasing dietary Se supplementation (p<0.05) and reached to the highest values of 156.00±0.68 %, 1.68±0.07 % d−1, and 98.33±1.66 %, respectively, while the feed conversion ratio declined to the lowest value of 1.79±0.10. Protein and lipid content increased with Se levels to the highest values of 20.15±0.11 % and 8.23±0.05%, respectively (p<0.05). Activity of all digestive enzymes including trypsin, chymotrypsin, α-amylase, lipase, and alkaline phosphatase significantly enhanced with increasing dietary Se levels (p<0.05). Increasing trends in villus height, villus width, muscle thickness, and crypt depth were found by increasing dietary Se supplementation with the highest values of 502.33±31.25, 134.39±13.12, 194.18±11.37, and 67.29±0.12 µm, respectively, in fish fed diet supplemented with 1.70 mg kg−1 Se (p<0.05). Findings of the present study illustrated the beneficial effects of dietary Se on performance, digestive enzymes, and intestinal histomorphology of Siberian sturgeon. According to the polynomial regression analysis, the optimum dietary requirement of Siberian sturgeon was in the range of 1.47–1.69 g kg−1.

Cryoprotectant-specific alterations in the proteome of Siberian sturgeon spermatozoa induced by cryopreservation

Cryopreservation is crucial for conserving genetic diversity in endangered species including the critically endangered group of sturgeons (Acipenseridae), but it can compromise sperm quality and protein profiles. Although cryopreservation with dimethyl sulfoxide (DMSO) and methanol (MeOH) results in the recovery of good post-thaw motility, DMSO-preserved sperm show reduced fertilization ability. This study was conducted in Siberian sturgeon as a model for Acipenserid fishes to explore the effects of DMSO and MeOH on the proteome of semen using advanced proteomics methods—liquid chromatography‒mass spectrometry and two-dimensional difference gel electrophoresis. We analyzed the proteomic profiles of fresh and cryopreserved spermatozoa and their extracellular medium and showed that cryopreservation decreases motility and viability and increases reactive oxygen species levels, membrane fluidity, and acrosome damage. Despite having similar post-thaw semen motility, sperm treated with DMSO had significantly lower fertilization success (6.2%) than those treated with MeOH (51.2%). A total of 224 and 118 differentially abundant proteins were identified in spermatozoa preserved with MeOH and DMSO, respectively. MeOH-related proteins were linked to chromosomal structure and mitochondrial functionality, while DMSO-related proteins impacted fertilization by altering the acrosome reaction and binding of sperm to the zona pellucida and nuclear organization. Additionally, cryopreservation led to alterations in the proacrosin/acrosin system in both cryoprotectants. This study provides the first comprehensive proteomic characterization of Siberian sturgeon sperm after cryopreservation, offering insights into how cryoprotectants impact fertilization ability.

Prediction of reproductive performance in wintering females of Siberian sturgeon (Acipenser baerii, Brandt) based on in vitro ovulation rate of isolated follicles

Early prediction of the reproductive success of sturgeon females is important both for artificial breeding conditions in sturgeon farms and for monitoring wild fish populations approaching spawning. This study demonstrated that ovarian follicles removed from wintering Acipenser baerii females can undergo in vitro ovulation when exposed to 17α,20β-dihydroxy-4-pregnen-3-one. The research was conducted from 2015 to 2021 and involved the examination of 110 wintering Siberian sturgeon females (A. baerii), with an average weight of 8–11 kg and an age range of 8–10 years. Selection of females for spawning was based on the polarization index (PI) at the time when the river temperature dropped to +8 °C. The selected females were overwintered in concrete flow-through tanks with water from the Volga River for approximately two months. At the end of this period, oocyte samples were collected for in vitro incubation. An increase in water temperature to 15 °C, which precedes spawning, was achieved by mixing with warm effluent from a regional power station. The reproductive success of females was evaluated based on fertilization and embryonic survival rates. High reproductive success was characterized by females with fertilization rates above 70% and hatching rates above 60%. We identified a positive correlation between the percentage of in vitro ovulated follicles and the in vivo fertilization and embryo survival rates, with correlation coefficients of Rsp = 0.60 and Rsp = 0.48, respectively. Statistical analysis showed that females whose in vitro ovulation rate of follicles exceeded 30% displayed high reproductive performance compared to those with an in vitro ovulation rate below 30%. The predictive accuracy of this criterion was determined by calculating the ratio of ranks between females with high and low reproductive performance, averaging 80.9% for fertilization and 77% for embryonic survival. Therefore, we propose a new criterion to select females of A. baerii for spawning based on the in vitro oocyte ovulation rate obtained from wintering individuals.

Comparative fish-breeding and biological characteristics of the offspring of Siberian sturgeon and sterlet obtained using cryopreserved (defrosted) sperm in the second year of cultivation

The first results of research on the assessment of the effect of the cryopreservation process of male sexual products on the fish-breeding, biological, morphological characteristics of the offspring of Siberian sturgeon of the Lena population and sterlet of the Volga population in the second year of cultivation in industrial conditions are presented. The work was carried out in the branch of freshwater fisheries of the VNIRO Federal State Budgetary Scientific Institution (VNIIPRH) on the basis of the Konakovsky department. The objects of research were yearlings of sturgeon fish obtained using native (control) and cryopreserved (defrosted) (experimental) sperm. The cultivation of experimental groups of Siberian sturgeon and sterlet was carried out in direct-flow concrete pools (each group separately). General monitoring of the hydrochemical state of the environment was carried out. The fish were fed with AQUAREX feeds of JSC Melkom holding in accordance with the standards for sturgeon fish. When comparing two groups of Siberian sturgeon by morphological characteristics according to the Student’s criterion, no significant differences were found between the samples, since the calculated t is less than the t-critical (3.46) for the number of degrees of freedom equal to 68. Based on the data obtained, it can be concluded that, despite the increased coefficient of variation based on il and body weight, the samples, and, consequently, the general populations, are equal. A comparison of the two sterlet groups shows that significant differences in the groups are observed only in body weight. In all other cases, there are no significant differences. A comparison of the average mass of labeled individuals of the experimental groups of Siberian sturgeon showed that it is slightly lower than in the total population (control 2.6%, experimental 0.7%), in turn, the sterlet has the opposite picture — the average mass of labeled individuals is higher than in the total population (control 17.0%, experimental 32.0%), which apparently due to a small sample. At this stage of research, the offspring of sturgeon obtained using cryopreserved sperm did not have a negative effect of freezing on growth and morphological parameters.

Genetic health and diversity assessment of Sturgeon species in Kazakhstan's aquaculture and natural habitats

Sturgeon species hold significant commercial and ecological value, with many listed as endangered. Understanding their genetic structure is crucial for developing effective conservation strategies. The main aim of this study is to examine the genetic structure of sturgeon, which can provide a foundation for creating strategies to conserve these species. A total of 121 sturgeon individuals were analyzed using microsatellite molecular markers (STR) to conduct the study on the genetic structure of sturgeon fish species. DNA was extracted from fin tissues using a commercial kit, and genotyping was conducted using seven microsatellite loci. Cluster analysis and principal coordinates analysis (PCoA) were performed to identify genetic differentiation among populations. The analysis showed differences in genetic diversity between the Siberian sturgeon, Russian sturgeon, and beluga samples. A deficiency of heterozygotes was discovered in artificial samples of sturgeon, indicating possible inbreeding. Genetic analysis has also revealed genetic differentiation between populations, possibly due to geographic structure or other factors. The study allows us to recommend increasing genetic diversity by introducing individuals from natural environments into sturgeon populations in aquaculture. Regular monitoring of genetic parameters in aquaculture populations and monitoring diversity dynamics are also crucial for the conservation and sustainability of sturgeon populations. The findings could help shape conservation strategies, especially in managing genetic diversity in aquaculture and reducing the risks associated with inbreeding and genetic drift.

Особливості вирощування плідників сибірського осетра (Acipenser baerii Brandt, 1869) у плавучих садках за природної температури води Лісостепу України

Purpose. Study of the technological processes and results of the cultivation of Siberian sturgeon (Acipenser baerii) in floating cages at the natural water temperature of the forest-steppe of Ukraine to ensure caviar production. Methodology. The study was conducted in the conditions of the cage area of the industrial-type farm (limited liability company - the agricultural aquaculture enterprise “Osetr”) located in the right-bank part of the Kaniv Reservoir on the Dnipro River. Different age groups of sturgeon were grown in floating cages with an area of 24 m2 (4×6 m). The walls of the cages were submerged in water for 2.5–3.0 m. Depending on the fish age, cages with mesh sizes of 10–24 mm were used. Fish of different ages were fed at a water temperature not lower than 5.5–6.0°C with compound feed containing 45–52% crude protein and 12–15% crude fat. Individual and average body weight (g, kg), relative and absolute annual weight gains (%, kg) and fish survival rate (%) were determined. The amount of fish yield per unit area of cages (kg/m2) and the average daily consumption of feed per average body weight of fish (%) were calculated. The study of productive parameters and physicochemical factors of water was carried out according to generally accepted methods in ichthyology and hydrochemistry. Findings. Average monthly values of water temperature in the summer season during 2018–2023 were within 20.9–25.3°C. The period with a water temperature of 15–25°C did not exceed 160 days. The duration of the fish feeding period was 225–260 days. The dissolved oxygen content in the summer ranged from 3.8 to 9.4 mg O2/dm3. Average seasonal oxygen concentration in water were in the range of 5.8–6.3 mg O2/dm3. During the cultivation of different age groups of sturgeon, periodic moderate exceedances of the normative values for certain hydrochemical parameters were registered. No mass death of fish was detected. Feed consumption per day, depending on the age of the sturgeon, was on average within 0.7–2.5% of the fish weight. The average seasonal gains of age-1+ to age-10+ sturgeon were in the range of 0.47–1.11 kg, with maximum values for age-3+ fish. The average weight of age-10+ sturgeon reached 6.8 kg. High survival rates of fish of various ages were recorded (93.5–100.0%). The fish yield of cages with different age groups of sturgeon were 5.7-12.9 kg/m2. Originality. Peculiarities of the formation of the brood stock of Siberian sturgeon with the use of floating cages installed in a reservoir with natural water temperature of the forest-steppe of Ukraine for caviar production were studied. Practical value. The results of the study are of interest for the development of the sturgeon caviar aquaculture in Ukraine in the conditions of industrial-type farms, primarily using water bodies with a natural temperature regime. Keywords: sturgeon Acipenser baerii, brood fish, floating cages, intensive cultivation, caviar, environmental conditions.

Influence of Fish Species and Wood Type on Polycyclic Aromatic Hydrocarbons Contamination in Smoked Fish Meat.

Despite the numerous sensory, organoleptic and nutritional qualities, fish meat may also contain some toxic compounds with negative effects on human health. Polycyclic aromatic hydrocarbons (PAHs) are a class of chemicals resulting from incomplete combustion, found at high levels in thermally processed foods, especially in smoked fish. This research studied the influence of wood type (beech, plum and oak) and fish species (rainbow trout, carp and Siberian sturgeon) on PAH contamination in hot smoked fish. Benzo(a)Piren, Σ4PAHs and Σ15PAHs were considered as main indicators of PAH contamination. All-PAHs was quantified in all samples, indicating a specific dynamic of values due to the influence of variables. Generally, BaP (benzo(a)pyrene) content in the samples ranged from 0.11 µg/kg to 8.63 µg/kg, Σ4PAHs from 0.70 µg/kg to 45.24 µg/kg and Σ15PAHs from 17.54 µg/kg to 450.47 µg/kg. Thus, plum wood promoted the highest levels of PAHs, followed by oak and beech. Carp and Siberian sturgeon presented the highest concentrations of PAHs. Some of these parameters had levels that exceeded the limits allowed by legislation via Commission Regulation (EU) No 835/2011. Results revealed BaP levels > 2 µg/kg when plum wood was used in rainbow trout (4.04 µg/kg), carp (4.47 µg/kg) and Siberian sturgeon (8.63 µg/kg). Moreover, the same trend was found for Σ4PAHs, which exceeded 12 µg/kg in rainbow trout (17.57 µg/kg), carp (45.24 µg/kg) and Siberian sturgeon (44.97 µg/kg).

Effects of Environmental Hypoxia on Serum Hematological and Biochemical Parameters, Hypoxia-Inducible Factor (hif) Gene Expression and HIF Pathway in Hybrid Sturgeon (Acipenser schrenckii ♂ × Acipenser baerii ♀).

Hypoxia is a globally pressing environmental problem in aquatic ecosystems. In the present study, a comprehensive analysis was performed to evaluate the effects of hypoxia on physiological responses (hematology, cortisol, biochemistry, hif gene expression and the HIF pathway) of hybrid sturgeons (Acipenser schrenckii ♂ × Acipenser baerii ♀). A total of 180 hybrid sturgeon adults were exposed to dissolved oxygen (DO) levels of 7.00 ± 0.2 mg/L (control, N), 3.5 ± 0.2 mg/L (moderate hypoxia, MH) or 1.00 ± 0.1 mg/L (severe hypoxia, SH) and were sampled at 1 h, 6 h and 24 h after hypoxia. The results showed that the red blood cell (RBC) counts and the hemoglobin (HGB) concentration were significantly increased 6 h and 24 h after hypoxia in the SH group. The serum cortisol concentrations gradually increased with the decrease in the DO levels. Moreover, several serum biochemical parameters (AST, AKP, HBDB, LDH, GLU, TP and T-Bil) were significantly altered at 24 h in the SH group. The HIFs are transcription activators that function as master regulators in hypoxia. In this study, a complete set of six hif genes were identified and characterized in hybrid sturgeon for the first time. After hypoxia, five out of six sturgeon hif genes were significantly differentially expressed in gills, especially hif-1α and hif-3α, with more than 20-fold changes, suggesting their important roles in adaptation to hypoxia in hybrid sturgeon. A meta-analysis indicated that the HIF pathway, a major pathway for adaptation to hypoxic environments, was activated in the liver of the hybrid sturgeon 24 h after the hypoxia challenge. Our study demonstrated that hypoxia, particularly severe hypoxia (1.00 ± 0.1 mg/L), could cause considerable stress for the hybrid sturgeon. These results shed light on their adaptive mechanisms and potential biomarkers for hypoxia tolerance, aiding in aquaculture and conservation efforts.