Russian Sturgeon Research Articles

The history of industrial development of sturgeon fish in the Volga-Caspian basin and the problems of reducing the number of Russian sturgeon

The Volga-Caspian basin is the most important fishery reservoir, in which about 90% of the world’s sturgeon stock was concentrated. The highest catches of sturgeon in the Caspian Sea were recorded at the beginning of the XX century. Unfavorable climatic conditions, a decrease in freshwater runoff and a drop in sea level in the mid-30s and 40s worsened the conditions for reproduction and feeding of sturgeon fish. During the Great Patriotic War, sturgeon fish were mainly harvested in rivers. Sturgeon fish were caught as by-catch in the fishing nets of other commercial fish. However, when using nets, many beluga, sturgeon and sturgeon juveniles died. Later, river flows were regulated, hydroelectric dams disrupted the migration routes of sturgeon fish. Intensive commercial marine production of sturgeon fish moved into rivers and in the 70s and 80s was concentrated in the rivers of the basin. With the development of the Caspian littoral states and the destruction of the unified system of sturgeon farming in the Caspian basin, illegal fishing began to develop. The powerful pressure of poaching in the 90s and 2000s throughout the Caspian Sea and rivers led to a deterioration in the state of sturgeon populations and a decrease in their stocks. Leading scientists have sent their recommendations for the conservation and restoration of sturgeon populations.

The size and weight composition of by-catches of sturgeon fish by stationary seines in the near-shore area of the southeastern sector of the Sea of Azov

The aim: the characteristics of the species, size and weight composition of sturgeon fish in the near-shore zone of the Sea of Azov.Material: bycatch data from scientific monitoring of So-iuy mullet fisheries with stationary seines in the waters of the Temryuk Bay and in the Kerch Strait near the Chushka Spit in April 2024.Results: sturgeon species were encountered in stationary seines in 100% of cases. The average catch per seine was 2–11 specimens per day. Starry sturgeon in Temryuk Bay accounted for more than 40% of the sturgeon bycatch, but it was not encountered in the Kerch Strait. Beluga Huso huso was noted in the Kerch Strait. The size range of Russian sturgeon varied from 30 cm to 133 cm; Starry sturgeon — from 102 to 118 cm. The average size of Russian sturgeon was 92.1 and 99.8 cm with an average weight of 9.2 and 6.4 kg, respectively, near the Chushka Spit and at the mouth of the Kuban. The average size of Starry sturgeon was 110.1 cm with an average weight of 6.7 kg. The length of the Beluga was 73 and 190 cm. The share of Russian sturgeon of commercial size (>90 cm) near Chushka Spit was 55%, in Temryuk Bay — 79%. 100% individuals of Starry sturgeon at the mouth of the Kuban were of commercially acceptable size (>80 cm).Practical value: Observations of bycatch in stationary seines in the near-shore zone are the important source of data on the qualitative characteristics of sturgeon populations in the Sea of Azov.

Commercial sturgeon farming in Russia (review)

The review contains a brief description of the history of sturgeon aquaculture development in Russia, information on the main directions of Russian sturgeon aquaculture: artificial propagation of natural populations and commercial farming with an explanation of the cause-and-effect relationships between the formations of these two directions. Much attention is paid to a special way of creating biotechnology for commercial sturgeon farming in the Russian research space, associated with a unique concentration of the most powerful sturgeon populations in the Caspian Sea basin. The main production systems for sturgeon rearing, biotechnical features of working with brood stocks, requirements for sturgeon feeds, the state of breeding work in sturgeon farming and the main difficulties in creating new cultured strains in sturgeon farming are characterized. It is shown that at the present stage, the bulk of commercial products in sturgeon farming is produced using industrial production systems in cages and tanks, while pond farming of sturgeon is still used in Russia. The use of different production systems has species specificity: large sturgeon species are reared mainly in cage conditions using artificial compound feeds, while the aquaculture of American paddlefish is represented exclusively by the pond production systems without feeding, small sturgeon fish (sterlet) are often grown in tanks with recirculating water exchange. Data on the structure of the assortment of commercial products in different sturgeon production systems are provided: fish stocking material of various categories, caviar and fish meat, as well as replacement and breeding stock. The current list of cultured strains of sturgeons in Russia is considered in detail, indicating new trends. The characteristics of the production volumes of caviar and meat, as well as the types of commercial products from them are given.

Содержание химических элементов в костистых лучах плавников Acipenser gueldenstaedtii (Brandt, 1833)

One of the reasons for the decline in the number of sturgeon fish species is the complex ecological situation in the Volga-Caspian basin. Changes in the hydrochemical composition of the Volga-Caspian basin water are accompanied by critical disturbances in the microelement balance of the fish organism and lead to irreversible pathological consequences in the populations of valuable fish species. In order to preserve the population and monitor the condition of sturgeon fish species, a detailed study of the microelement composition of their organs and tissues is necessary. The concentration of chemical elements in the bony rays of the fins of Russian sturgeon Acipenser gueldenstaedtii (Brandt, 1833) of different sexes and age composition (3-10 years) was determined using the atomic absorption method according to GOST 30178-96. Iron, copper, manganese, zinc, nickel, cobalt, chromium, lead, cadmium were determined in each sample. It is noted that all nine studied metals are able to accumulate in sturgeon bone rays to one degree or another. Iron in sturgeon bone rays was present in large quantities relative to other chemical elements. Lead occupied the second place in terms of content in the rays, followed by zinc and cobalt in descending order, and cadmium was found in the lowest concentrations. Copper, zinc, and manganese were shown to have higher metal concentrations in the rays of males, and nickel, chromium, cobalt, lead, and cadmium in the rays of female Russian sturgeon. The differences revealed between the average iron concentrations in the studied organs of females and males of all studied age groups are statistically insignificant. It was noted that with increasing age, weight, and length, the metal content in the bone rays of both males and females increased.

Особенности морфофункционального и физиологического состояния осетровых рыб с нефрокальцинозом в условиях садковой аквакультуры

When growing sturgeon fish in cages, which are especially valuable nowadays, great attention should be paid to their health. Along with other pathological manifestations of various natures, a disease such as kidney nephrocalcinosis can pose a potential danger to these aquaculture objects. This pathology was recorded in juvenile sterlet (age – 0+ years), in immature individuals of Russian sturgeon (age – 2 years), in which clinical and pathological examinations were carried out, including pieces of kidneys were selected for histological analysis, blood samples for carrying out hematological and biochemical studies. The appearance of nephrocalcinates in the kidneys of sturgeon fish was confirmed using histological methods: corresponding pathological transformations were found on micropreparations of the kidneys of Russian sturgeon and sterlet. Morphophysiological changes in the condition of the kidneys of the studied sturgeon fish can be assessed as moderate and minor, not life-threatening. Thus, 60% of the examined individuals of Russian sturgeon did not have any detected pathohistological changes in the organ; among sterlet there were 80% of such individuals. When analyzing hematological and biochemical blood parameters, deviations of some indicators were found. Thus, the sterlet had a low level of hemoglobin, all fish had an insufficient number of red blood cells in the blood; in Russian sturgeon, a high level of pathologically altered erythrocytes was determined, the amount of serum protein was increased, deviations were found in the ratio of its fractions, high levels of uric acid, low levels of triglycerides, β-lipoproteins, ALT and AST activity in the blood. Indirectly, these changes in the physiological state of sturgeon fish with nephrocalcinosis indicate that this disease most likely arose as a result of the influence of a complex of factors on the fish, among which the main ones may be disturbances in the hydrochemical regime and the balance of feeding.

A Repetitive Acipenser gueldenstaedtii Genomic Region Aligning with the Acipenser baerii IGLV Gene Cluster Suggests a Role as a Transcription Termination Element Across Several Sturgeon Species.

This study focuses on the common presence of repetitive sequences within the sturgeon genome that may contribute to enhanced immune responses against infectious diseases. A repetitive 675 bp VAC-2M sequence in Russian sturgeon DNA that aligns with the Siberian sturgeon IGLV gene cluster was identified. A specific 218 bp long portion of the sequence was found to be identical between Acipenser gueldenstaedtii, A. baerii and A. stellatus species, and NCBI blast analysis confirmed the presence of this DNA segment in the A. ruthenus genome. Multiple mutated copies of the same genomic region were detected by PCR analysis, indicating that different versions of this highly repetitive sequence exist simultaneously within the same organism. The selection toward specific genetic differences appears to be highly conserved based on the sequence variations within DNA originating from fish grown at distant geographical regions and individual caviar grains from the same fish. The corresponding A. baerii genomic region encompassing the 357 bp DNA sequence was cloned either ahead or after the human cytomegalovirus immediate early promoter (HCMV-IE) into a pBV-Luc reporter vector expressing the luciferase gene. The DNA segment significantly reduced luciferase expression in transient transfection/expression experiments. The results indicate that this genomic region functions as a transcription termination element that may affect antibody production in sturgeons.

Sturgeon Biological Parameters in the Ural River (Zhaiyk) of the Republic Kazakhstan

The dynamics of capture of 4 Sturgeon species (family Acipenseridae): Russian sturgeon Acipenser gueldenstaedtii, Sterlet A. ruthenus, Stellate Sturgeon A. stellatus, Beluga Acipenser (Huso huso) in the IUU catches of the Ural (Zhaiyk) River within of the Republic of Kazakhstan borders is done. The annual number of Sturgeons estimated by arrested IUU catches in the period 2012–2018 which demonstrate the fluctuation of the Ural River Sturgeons number as well as male dominance is given. The biological indicators of Ural’s Sturgeons during the period of maximum catches in 2018: sex ratio, age, weight, length, length-weight relationship are given.

Understanding the spleen response of Russian sturgeon (Acipenser gueldenstaedtii) dealing with chronic heat stress and Aeromonas hydrophila challenge

Sturgeon aquaculture has grown in recent years, driven by increasing global demand for its highly valued products. Russian sturgeon (Acipenser gueldenstaedtii), recognised as one of the most valuable species for caviar production, is farmed in several warm-temperate regions. However, the substantial temperature increase due to global warming represents a challenge for developing sturgeon aquaculture. Previously we demonstrated that Russian sturgeon under chronic heat stress (CHS) exhibited a liver metabolic reprogramming to meet energy demands, weakening their innate defences and leading to increased mortality and economic losses. Here, we used RNA-seq technology to analyse regulated genes in the spleen of Russian sturgeons exposed to CHS and challenged with Aeromonas hydrophila. The assembly gave 253,415 unigenes, with 13.7 % having at least one reliable functional annotation. We found that CHS caused mild splenitis and upregulated genes related to protein folding, heat shock response, apoptosis and autophagy while downregulated genes associated with the cell cycle. The cell cycle arrest was maintained upon A. hydrophila challenge in heat-stressed fish, potentially inducing cell senescence. Surprisingly, immunoglobulin heavy and light chains were upregulated in the spleen of stressed sturgeons but not in those maintained at tolerable temperatures; however, no changes in IgM serum levels were observed in any condition. Our findings indicate that long-term exposure to non-tolerable temperatures induced a heat shock response and activated apoptosis and autophagy processes in the spleen. These mechanisms may enable the control of tissue damage and facilitate the recycling of cell components in a condition where the nutrient supply by the liver might be insufficient. Stressed sturgeons challenged with A. hydrophila maintain these mechanisms, which could culminate in cellular senescence.

Extracellular vesicles and citrullination signatures are novel biomarkers in sturgeon (Acipenser gueldenstaedtii) during chronic stress due to seasonal temperature challenge

Acipenser gueldenstaedtii is one of the most cultured sturgeon species worldwide and of considerable economic value for caviar production. There are though considerable challenges around chronic stress responses due to increased summer temperatures, impacting sturgeons’ immune responses and their susceptibility to opportunistic infections. The identification of molecular and cellular pathways involved in stress responses may contribute to identifying novel biomarkers reflective of fish health status, crucial for successful sturgeon aquaculture. Protein citrullination is a calcium-catalysed post-translational modification caused by peptidylarginine deiminases (PADs), altering target protein function and affecting protein interactions in physiological and pathobiological processes. PADs can also modulate extracellular vesicle (EVs) profiles, which play critical roles in cellular communication, via transport of their cargoes (proteins, including post-translationally modified proteins, genetic material and micro-RNAs).This study identified differences in EV signatures, and citrullinated proteins in sera from winter and summer farmed sturegeons. EVs were significantly elevated in sera of the summer chronically stressed group. The citrullinated proteins and associated gene ontology (GO) pathways in sera and serum-EVs of chronically heat stressed A. gueldenstaedtii, showed some changes, with specific citrullinated serum protein targets including alpa-2-macroglobulin, alpha globin, calcium-dependent secretion activator, ceruloplasmin, chemokine XC receptor, complement C3 isoforms, complement C9, plectin, selenoprotein and vitellogenin. In serum-EVs, citrullinated protein cargoes identified only in the chronically stressed summer group included alpha-1-antiproteinase, apolipoprotein B-100, microtubule actin crosslinking factor and histone H3. Biological gene ontology (GO) pathways related to citrullinated serum proteins in the chronically stressed group were associated with innate and adaptive immune responses, stress responses and metabolic processes. In serum-EVs of the heat-stressed group the citrullinome associated with various metabolic GO pathways.In addition to modified citrullinated protein content, Serum-EVs from the stressed summer group showed significantly increased levels of the inflammatory associated miR-155 and the hypoxia-associated miR-210, but significantly reduced levels of the growth-associated miR-206.Our findings highlight roles for protein citrullination and EV signatures in response to chronic heat stress in A. gueldenstaedtii, indicating a trade-off in immunity versus growth and may be of value for sturgeon aquaculture.

Effects of nighttime LED supplementary lighting on growth, ovarian development and serum hormone levels of Acipenser gueldenstaedtii in flow-through system

Effects of nighttime LED supplementary lighting on growth, ovarian development and serum hormone levels of Acipenser gueldenstaedtii in flow-through system

Aroma-active compounds in Russian sturgeon (Acipenser gueldenstaedtii) raised in recirculating aquaculture systems

The rearing system affects the nutritional and sensorial qualities of the Russian sturgeon (Acipenser gueldenstaedtii), a niche yet commercially valuable aquaculture species for caviar production. In the present work, we aimed to comprehensively characterize the odorant composition of fillets from Russian sturgeon raised in a recirculating aquaculture system (RAS) and discuss potential sources and formation pathways. A total of 114 odorants were detected through the application of combined sensory-instrumental analyses, of which 88 were successfully identified and 20 substances were found to be among the most potent odor constituents. The most dominant odorants were assigned to several specific substance classes, including aldehydes, alcohols, terpenes, ketones, organic acids, lactones, heterocycles, aromatic hydrocarbons, and sulfur-containing aldehydes. The compounds (E)-hex-2-enal, (Z)-hept-4-enal, cuminaldehyde, non-3-yn-1-ol, 3-carene, 2-methylisoborneol, geosmin, oct-1-en-3-one, nonan-3-one, (Z)-1,5-octadien-3-one, octane-2,3-dione, nonan-2-one, hexanoic acid, γ-crotonolactone, γ-octalactone, 2-acetyl-thiazoline, methional, and (2E,4Z,7Z)-trideca-2,4,7-trienal had high flavor dilution factors and are described for the first time as potent odor-active compounds associated with the Russian sturgeon. Overall, oct-1-en-3-one, (Z)-1,5-octadien-3-one, octane-2,3-dione, nonan-2-one, 2-methylisoborneol, and hexanoic acid had the highest flavor dilution factors. This study offers a basis for future development in the sturgeon RAS industry from the perspective of flavor characterization by providing deep insights into the fundamental composition and origins of the complex world of aquaculture fish aroma.

The effectiveness of sodium chloride for the treatment of Russian sturgeon (Acipenser gueldenstaedtii) caviar from saprolegniosis

The article presents the results of experimental work on the treatment of fertilized oocytes and developing embryos of the Russian sturgeon (Acipenser gueldenstaedtii) with 0,8% sodium chloride solution by various methods in order to suppress the growth and development of the family micromycetes sem. Saprolegniaceae, which cause saprolegniosis of eggs during factory incubation. Due to the intensive development of commercial aquaculture, an increase in the scale of artificial reproduction, as well as taking into account the limitations of the use of previously used veterinary drugs to combat saprolegniosis of incubated caviar, this research area is relevant. The purpose of the research work was to evaluate the effectiveness of using three different methods of treating caviar infected with micromycetes sem. Saprolegniacea with a solution of sodium chloride. Experimental work was carried out in factory conditions in the incubation apparatus «Sturgeon» under optimal hydrochemical conditions for the development of Russian sturgeon embryos. The experimental groups corresponded to the methods used (therapeutic baths and drip method in the apparatus, therapeutic baths outside the incubation system). The experiment was carried out in parallel in 2 repetitions in the presence of a control. In the course of the work, fish-breeding, biological and hydrochemical research methods were used. The effectiveness of the effect of sodium chloride solution by three different methods (drip method, therapeutic baths in an incubation apparatus of the «Sturgeon» type, short-term therapeutic baths outside the incubation system) on the embryonic development of sturgeon and micromycetes was assessed by such indicators as the percentage of fertilization of eggs, normally and abnormally developing embryos, hatched pre-larvae, the proportion of embryos infected with saprolegnium micromycetes at two stages of caviar development (stages 16 and 22). The most effective method that improves the fish-breeding and biological parameters of incubated Russian sturgeon caviar and reduces the extent of its invasion by family micromycetes sem. Saprolegniaceae is a drip method.

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 < 0.05). FQV2 was characterized by significantly more favorable values of breeding indicators (p < 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.

Current state of sturgeon fish off the eastern coast of the Sea of Azov

The aim: the characteristics of sturgeon fish that make seasonal migrations to the near-shore zone of the Azov Sea.Material — scientific monitoring of commercial fishing with stationary seines in the water area of the Sea of Azov adjacent to the Primorsko-Akhtarsk district in October 2022, 2023 and April 2023, 2024.The results: Russian Sturgeon and Starry Sturgeon (Sevruga) were encountered in stationary seines from 50% to 100%, and the average catch of these species per facility was 1.3–7 sp./day in the autumn and spring periods, respectively. In the fall of 2022, the prevalence of Sevruga in bycatch was almost double — 63% of the total bycatch; in the spring and fall of 2023, 2024, the superiority was with Sturgeon — 63–83% of the bycatch. Size range of Sturgeon in 2022–2024 was from 22 to 148 cm; Sevruga — from 23 to 123 cm. The weight range of Sturgeon was from 0.1 to 30.0 kg, Sevruga — from 0.2 to 7.8 kg. The share of fish that reached the commercial length was on average 20.7% of Sturgeon and 36.6% of Sevruga. The age of the fish varied from fingerlings to 16+ for Sturgeon and up to 8+ for Sevruga. The average fullness coefficient of Russian Sturgeon in the autumn was 0.72; in spring, — 0.79; Sevruga: in the autumn of 2022 and 2023–0.45, in the spring of 2023–0.58. The state of Russian Sturgeon in the near-shore aggregations indicates the formation of its full-fledged mixed-age population in the Sea of Azov, that allows to expect its commercial fishing in the near future, on the background of the increasing its stock. The state of the Sevruga requires more in-depth research. A high fish fatness coefficient indicates their sufficient food supply.Practical value: Observations of bycatch in stationary seines in the near-shore area of the sea are an important addition to the accounting trawl survey data for understanding the structure of the Russian Sturgeon population in the Azov Sea and practically the main source of information on the state of the Sevruga population.

Physiological research of young Russian sturgeons in modern ecological conditions of the Caspian sea

In the Volga-Caspian fisheries basin, artificial reproduction of sturgeon species is the primary source of replenishing their natural populations. The aim of this study is to conduct physiological research on juvenile Russian sturgeon (Acipenser gueldenstaedtii) in the western part of the Northern Caspian Sea, to establish the features of fish homeostasis. The physiological condition of the specimens was studied using a set of physiological and biochemical parameters. Hematological, biochemical, and morpho-histological parameters were evaluated. In the blood of the fish, the contents of hemoglobin, total protein, glucose, inorganic phosphorus, calcium, creatinine, bilirubin, total lipids, cholesterol, and triglycerides were determined. In the muscle tissue of juvenile Russian sturgeon, the physiological and biochemical indicators studied included the content of the main reserve substances of the body — total lipids and water-soluble protein. Histological methods were used to assess the morpho-functional state of the gills. The variability of physiological and biochemical parameters in juvenile Russian sturgeon was calculated using descriptive statistics based on parametric and non-parametric criteria in the blood and muscles. According to the results of correlation statistical analysis, significant changes were observed in the tissues of the sturgeon juveniles, aimed at providing the body with sources of energy and nutrients used for the functioning of body tissues and serving as reserve stocks, as well as maintaining regulatory mechanisms of metabolism and its changes depending on fluctuating environmental conditions. The morphological examination of the gills revealed vascular disorders, hyperplasia, swelling, and hypertrophy of the respiratory epithelium cells, corresponding to borderline disturbances from mild to moderate damage, which was the organ’s response to external environmental influences.

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.

GWAS Enhances Genomic Prediction Accuracy of Caviar Yield, Caviar Color and Body Weight Traits in Sturgeons Using Whole-Genome Sequencing Data.

Caviar yield, caviar color, and body weight are crucial economic traits in sturgeon breeding. Understanding the molecular mechanisms behind these traits is essential for their genetic improvement. In this study, we performed whole-genome sequencing on 673 Russian sturgeons, renowned for their high-quality caviar. With an average sequencing depth of 13.69×, we obtained approximately 10.41 million high-quality single nucleotide polymorphisms (SNPs). Using a genome-wide association study (GWAS) with a single-marker regression model, we identified SNPs and genes associated with these traits. Our findings revealed several candidate genes for each trait: caviar yield: TFAP2A, RPS6KA3, CRB3, TUBB, H2AFX, morc3, BAG1, RANBP2, PLA2G1B, and NYAP1; caviar color: NFX1, OTULIN, SRFBP1, PLEK, INHBA, and NARS; body weight: ACVR1, HTR4, fmnl2, INSIG2, GPD2, ACVR1C, TANC1, KCNH7, SLC16A13, XKR4, GALR2, RPL39, ACVR2A, ADCY10, and ZEB2. Additionally, using the genomic feature BLUP (GFBLUP) method, which combines linkage disequilibrium (LD) pruning markers with GWAS prior information, we improved genomic prediction accuracy by 2%, 1.9%, and 3.1% for caviar yield, caviar color, and body weight traits, respectively, compared to the GBLUP method. In conclusion, this study enhances our understanding of the genetic mechanisms underlying caviar yield, caviar color, and body weight traits in sturgeons, providing opportunities for genetic improvement of these traits through genomic selection.

Polyculture of pikeperch (Sander lucioperca) and Russian sturgeon (Acipenser gueldenstaedtii) using an artificial common pellet – Implications on feed to fish nutrient transfers in recirculating aquaculture system (RAS)

The purpose of this research was to investigate the effects of monoculture and polyculture on the utilization of an artificial common pellet to produce nutritious products, specifically pikeperch and Russian sturgeon, in a recirculating aquaculture system (RAS) for 84 days. The experiment was conducted under controlled conditions, with specific parameters for: water temperature (21.8±0.4 °C), initial weight of the fish (pikeperch: 18.17±2.65 g; sturgeon: 18.23±3.62 g), volume of the containers (working volume of 272 litres) and feeding rate (1.5 %). Five experimental groups were tested in triplicates, including monoculture groups (pikeperch: 63.46±18.49 g; sturgeon: 93.52±50.40 g) and three polyculture combinations [P90: 90 % pikeperch (68.63±13.79 g) + 10 % sturgeon (86.10±33.38 g); P80: 80 % pikeperch (76.88±18.06 g) + 20 % sturgeon (103.53±44.60 g); P70: 70 % pikeperch (81.51±19.24 g) + 30 % Russian sturgeon (94.48±33.25 g)]. The results indicated that the addition of Russian sturgeon to pikeperch tanks could lead to efficient transfer of feed lipid to fish biomass through sturgeons, but not pikeperch. Polycultures showed better lipid absorption (P70 lipid-ADC 96.06±1.96 %) from the common pellet than monocultures (pikeperch: lipid-ADC 91.93±6.37 %; sturgeon: lipid-ADC 97.08±2.07 %). Fillet lipid content of pikeperch remained unaltered across RAS monocultures and polycultures but changed positively in Russian sturgeon in polyculture (P70 2.64±0.71 % > P0 1.75±0.75 %). In both species, polyculture fillets accumulated 5–7 % higher MUFA (oleic acid, C18:1n-9) than monoculture fillets. The major conclusions drawn from this research are that polyculture group P90 had both fish species flesh with highest muscle reserves of glycine and proline. In polyculture, critically indispensable muscle lysine reserves depleted in pikeperch, but Russian sturgeon muscle amino acid profile was stable. Given the global constraints on land availability, the study proposes RAS polyculture as a potentially productive and nutritious aquaculture system of the future. The research also suggests that resilient species for RAS polyculture need to be identified, proposing Russian sturgeon as a possible candidate.

Микроэлементный состав крови русского осетра

Establishing quantitative levels of chemical elements in the blood plays a leading role in studying the mi-croelement status of the body. The purpose of the work was to study the microelement composition of the blood and spleen of the Russian sturgeon Acipenser gueldenstaedtii (Brandt, 1833). The objects of the study were females and males of Russian sturgeon of different ages. The determination of metals was carried out using atomic absorption spectrometry. In each sample, iron, copper, manganese, zinc, nickel, cobalt, chromium, lead, and cadmium were determined. Specific features of the accumulation of chemical elements in the blood and spleen of Russian sturgeon have been revealed. The content of iron and zinc in the blood and spleen of fish is in the greatest quantities. At the same time, the concentration of zinc in the blood of fish, as well as the concentration of iron, depends on the systematic position of the fish, and falls within the limits of the concentrations of chemical elements according to A. P. Vinogradov: the content of iron and zinc in the blood of Teleostei is generally higher than in the blood of Elasmobranchii. Russian sturgeon belongs to the subclass Chondrostei and has characteristics of cartilaginous and bony fish, perhaps this can explain the amount of iron and zinc found in the blood. A positive correlation was revealed between iron and copper in the blood of female and male Russian sturgeon. At the same time, no gender differences were found in the content of chemical elements in the blood of female and male Russian sturgeon, with the exception of nickel, the concentration of which is higher in the blood of males. It has been shown that as fish age, the concentration of nickel, manganese, lead and copper in the blood increases.

Biokinetics of Americium-241 in the euryhaline diamond sturgeon Acipenser gueldenstaedtii following its uptake from water or food

Americium-241 whole body and internal biokinetics were experimentally investigated in the euryhaline diamond sturgeon Acipenser gueldenstaedtii during its uptake from water and food, in fresh (FW) and brackish water (BW; 9 psu). Whole-body uptake rates of 241Am from water and subsequent depuration rates were quantified over 14 and 28 days, respectively, and assimilation efficiency (AE) of 241Am from diet (chironomid) was determined over 28 days. FW reduced the biological half-life of 241Am following aqueous uptake by an order of magnitude. In contrast BW greatly reduced 241Am assimilation efficiency (AE) from diet (chironomid) by several orders of magnitude (from an AE of 8.5% (FW) down to 0.003% (BW)). Hence, salinity per se is indicated as a major environmental variable in determining the radiological exposure of A. gueldenstaedtii to 241Am. During aqueous exposure BW appreciably increased 241Am activity concentrations in most body components, but aqueous or dietary exposure pathway at either salinity did not determine marked differences in how 241Am was distributed among six body components. The highly mineralized skin of A. gueldenstaedtii recurred as a major repository of 241Am in all experimental treatments, as high as 50% among body components, due to its internal transfer from diet, surface adsorption and/or active absorption from water. The indicated prominence of the aqueous, compared to the dietary, exposure pathway for 241Am accumulation by A. gueldenstaedtii suggests its radiological exposure would be enhanced by BW as it leads to its greater long-term retention, due to a much longer biological half-life.