Juvenile Sturgeon Research Articles

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.

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.

Effects of dietary protein levels on growth performance, hemato–biochemical, and immune parameters in ship sturgeon (Acipenser nudiventris) juveniles

A feeding trial was conducted to detect the optimal dietary protein requirement for ship sturgeon (Acipenser nudiventris) juveniles. Four isoenergetic diets were formulated to contain different protein levels i.e. 40 % (P40), 45 % (P45), 50 % (P50), and 55 % (P55). A total of 180 ship sturgeon juveniles, with an average weight of 63.5 ± 1.3 g, were randomly distributed into triplicated groups (15 fish per tank) and fed on the experimental diets for 10 weeks. Significant (P < 0.05) increases in growth indices and feed intake were noted with increasing dietary protein levels up to 50 % after which (P55) fish growth was declined. The highest values of protein and lowest value of lipids and ash contents were noted in the whole-body of fish fed on the P50 diet. The levels of red blood cells, hemoglobin, and hematocrit were markedly influenced (P < 0.05) by varying dietary protein concentrations, and the most elevated values were identified in the P50 treatment. Linear increases were observed in alanine aminotransferase and alkaline phosphate levels; while quadratic increases were observed in aspartate aminotransferase activities due to the increase in dietary protein levels. Quadratic increases in total protein (TP), total immunoglobulin (total Ig), and lysozyme (LYZ) were observed due to feeding the fish on higher protein levels. The highest level of TP was significantly (P < 0.05) found in P50 and P55 with no significant (P > 0.05) difference between them. Levels of total Ig and LYZ were significantly (P > 0.05) highest in the P50 treatment. Based on the regression fitting curves of growth indices, the optimum dietary protein level for ship sturgeon (A. nutiventis) juveniles is found to be 46.5 % – 50 %. Data AvailabilityAll data of this study are included in this article.

Влияние кормовой пробиотической добавки «Ветоспорин-Ж» (Bacillus subtilis) и минеральной добавки «Цеолит» (опока) на проявление генотоксических эффектов в клетках крови молоди стерляди (Acipenser ruthenus) в условиях аквакультуры

In modern conditions of declining natural sturgeon populations in the Volga-Caspian basin, the role and importance of aquaculture is increasing. In the Astrakhan region, due to the presence of a large natural water fund, cage farming of fish, including sterlet, is widely developed. Cage farming of sturgeon in natural water bodies is associated with the impact of anthropogenic pollution, in this area it is associated with water pollution in the river delta Volga, and the deterioration of the hydrochemical regime, which directly affects fish farming. One of the factors of the negative impact of these changes in the aquatic environment is genotoxicity, the degree of manifestation of which can be assessed using accessible and modern methods, which include micronuclear and DNA comet tests. A serious consequence of the genotoxic effect of pollution is the formation of damage to the DNA of the fish body. The purpose of this work was to assess the frequency of appearance of micronuclei and the degree of DNA damage in the blood cells of juvenile sterlet, as well as the selection of functional additives in food that will reduce the effects of genotoxic pressure from a natural water source. In a scientific laboratory, a series of experiments was carried out on feeding juvenile sterlet delivered from a fish farm in the Volga delta. All juvenile sterlet, both at the beginning and at the end of the experiment, were characterized by a normal physiological state, low levels of DNA comets, and the number of erythrocytes with micronuclei was slightly higher than normal. As a result of experimental feeding, reliable data were obtained that food with the addition of the probiotic drug “Vetosporin-Zh” based on the bacteria Bacillus subtilis contributed to a significant increase in weight gain and body length. All analyzed indicators of DNA comets were significantly lower in the group that was fed with the introduction of a probiotic (the micronucleus test turned out to be less sensitive in this case). The mineral additive “Zeolite” did not show such effectiveness. Thus, the addition of Bacillus subtilis-based preparations when feeding juvenile sturgeon can be reasonably recommended to effectively reduce genotoxic stress for fish, mainly to reduce DNA damage.

Physiological and biochemical studies of young sterlet sturgeon (Acipenser ruthenus L.) in the lower reaches of the Volga river

In conditions of a decrease in the number of rolled sturgeon larvae in the lower reaches of the Volga River, an urgent issue is the study of the physiological and biochemical parameters of the fish organism. The purpose of this work is to conduct physiological and biochemical studies of juvenile sterlet (Acipenser ruthenus L, 1758). The study of fish was carried out using the methods of classical histology and biochemistry. The degree of damage to the gills and liver was assessed on a scale from 1 to 5 points. The content of total lipids and water-soluble protein in the muscle tissue of sterlet fingerlings was studied as biochemical parameters. The morphological picture of the gills of 80% of the fish corresponded to a weakly pronounced character of changes (2 points), while in others it was characterized by the presence of a borderline state between weakly pronounced changes and moderate injuries (2–3 points). Six types of disorders were found in the gills: hyperplasia of the respiratory epithelium of lamellae, dilation of the blood vessel of the filament, goblet-shaped swellings of the apical part of the filament, invasions, expansion of the apical part of the lamellae, proliferation of connective tissue of lamellae. In the liver of 80% of fish, a borderline state was recorded between mild changes and moderate damage (2–3 points), in 13.3% of individuals the liver had mild damage (2 points), in 6.7% there were medium damage (3 points). Four types of disorders were found in the liver of juvenile sterlet: fullness of the liver capillaries, pronounced venous fullness, cavities, capillary dilation. In the muscle tissue of fingerlings, the concentrations of total lipids were in the range of 1.39–5.28%, and water-soluble protein — 45.59–57.97 mg/g. The study of the physiological and biochemical parameters of juvenile sturgeon in the lower reaches of the Volga River is very important for the biology of the species and monitoring the natural reproduction of these valuable fish species.

Anadromous sturgeon fish of the Azov Sea under conditions of natural and anthropogenic transformations of the water ecosystem

The aim: assessment of the state of populations of anadromous sturgeon in the Sea of Azov, the efficiency of their reproduction and the possibility for the existence of populations in the medium term until 2030–2040. Methods: the calculation of the biomass and population size of sturgeon in the Sea of Azov was carried out using the direct counting method and a modified cohort solution of the Baranov equation. 18and 25-meter bottom trawls were used as standard fishing gear. The assessment of the number of juvenile sturgeon in the Don River was carried out with 3and 2-meter beam-trawls. Molecular genetic methods for the analysis of microsatellite loci and sequencing of a fragment of the control region of mitochondrial DNA were used.Novelty: materials are presented on natural reproduction of sturgeon in the Don River after flow regulation, and the rate of decline in the survival rate of generations of Russian sturgeon and stellate sturgeon under the influence of illegal fishing is shown. Based on the results of a study of the genotypes of Russian sturgeon individuals, migrations sturgeon from Azov to the Black Sea, as well as Black Sea populations to the Sea of Azov, were confirmed.Results: an analysis of the dynamics and current state of anadromous sturgeon in the Sea of Azov is presented under the conditions of anthropogenic transformation of their habitat, loss of natural reproduction and climate-related fluctuations in the salinity of the sea waters. A retrospective overview of their commercial use from the mid-19th century to the present is given. The prospects for restoring commercial stocks of sturgeon fish are considered.Practical significance: the possibility of restoring commercial stocks of sturgeon in modern conditions is shown by increasing the number of released juveniles and increasing the effectiveness of fish conservation measures to a level of more than 90 thousand tons and creating an commercial population of sturgeon in the Sea of Azov.

Evaluation of non-penetrative captive bolt stunning as a method of slaughter for white sturgeon (Acipenser transmontanus)

IntroductionPercussive stunning is a widely used and ethically supported method of stunning fish per welfare standards as part of a one- or two-step slaughter process. In this study, the use of a non-penetrative captive bolt (NPCB) gun was evaluated as an effective one-step method of improving welfare for juvenile and adult farmed white sturgeon (Acipenser transmontanus) at slaughter.MethodsA Jarvis HPS-1 NPCB was operated at pressures of 120, 135, and 145 PSI (827.37, 930.79, and 999.74 kPa, respectively) for juvenile sturgeon (n = 3 sturgeon per operating pressure) and 175, 200, and 225 PSI (1206.58, 1378.95, and 1551.32 kPa, respectively) for adult sturgeon (n = 3 sturgeon per operating pressure). Following a single strike, fish were assessed for jaw relaxation and a somatic response before being exsanguinated and transferred to an ice slurry. An hour after slaughter, fish heads were collected, and a section of cartilage containing the brain was removed and fixed in formalin for histological analysis of brain death. To evaluate fish recovery, juveniles (n = 100) and adult female sturgeon (n = 65) were monitored for two hoursafter a single exposure to 145 and 225 PSI, respectively.ResultsHistology results showed there was an effect between operating pressure and intracranial hemorrhage in juvenile sturgeon (p = 0.024). There was a greater meningeal-to-cerebral hemorrhage at 135 PSI compared to the 120 PSI group (p = 0.020) and a trend towards increased tissue damage from 120 PSI to 145 PSI (p = 0.056). Adults showed no significant difference in meningeal hemorrhage at any operating pressure. When investigating recovery rates, NPCB successfully stunned 100% of juvenile sturgeon at 145 PSI, and 225 PSI stunned 90% of adult sturgeon without recovery.DiscussionThese results demonstrate that the use of an NPCB gun is an improvement in animal welfare compared to repeated strikes, but a single application did not produce histological brain death; further research should be conducted to determine optimal pressures that result in immediate brain death.

Effect of dietary chitosan on the growth performance, intestinal histology and growth-related gene expression in stellate sturgeon (Acipenser stellatus) juveniles.

As sturgeon breeding has proliferated, there has been a heightened demand for growth stimulators in their diets. This study aimed to determine the impact of dietary chitosan on growth performance, whole-body proximate composition, growth-related gene expression, and intestinal histology in juvenile Acipenser stellatus. A total of 180 A. stellatus juveniles with an average weight of 31.90 ± 0.73 g were fed with diets containing 0 (control), 1.5, 3.0, 4.5, and 6.0 g chitosan.kg-1 basic diet for eight weeks. The findings revealed a significant enhancement in growth performance with rising chitosan concentrations. Furthermore, chitosan supplementation upregulated the expression of the growth hormone gene in both brain and liver tissues. In liver samples, the most pronounced expression of the insulin-like growth factor-1 gene was noted at 6.0 g chitosan.kg-1, while in brain samples, peak expressions were observed in both the 4.5 and 6.0 g chitosan.kg-1 treatments. While the whole-body proximate composition remained relatively stable, there was a notable decrease in whole-body lipids with the escalation of chitosan dosage. Intestinal villi dimensions, both height and width, were amplified in the chitosan-supplemented groups compared to controls. In summation, chitosan supplementation showed promise in bolstering growth performance, refining intestinal morphology, and enhancing growth-related gene expression. Analysis of the polynomial regression of weight gain and specific growth rate revealed that the optimum dietary chitosan requirements in A. stellatus were 5.32 and 5.21 g chitosan.kg-1, respectively.

Influence of predators on the survival of released juvenile sturgeon fish

Influence of predators on the survival of released juvenile sturgeon fish

Supplementing lysolecithin in corn-oil based diet enhanced growth and improved body biochemical composition in juvenile stellate sturgeon (Acipenser stellatus)

A 56-days nutritional trial was conducted to examine the influence of including a corn-oil based diet with lysolecithin (LL) on stellate sturgeon (Acipenser stellatus) juveniles. Fish were fed four experimental diets (44% crude protein, 15% crude lipid) containing graded levels of LL [0 (control), 0.5, 1 and 2%)]. One hundred and eighty juvenile fish (45.3 ± 0.1 g, mean ± standard deviation) were stocked in twelve 300 L-polyethylene tanks containing ground water at 18.9 ± 0.5°C. Feeds were offered to fish at apparent satiation four times daily. Fish fed 1% LL-supplemented diet had higher growth and better feed conversion ratio than the control group (P < 0.05). The amounts of protein and lipid levels in the whole body increased in fish fed LL-supplemented diets compared to control, whereas the levels of n-6 PUFA, particularly linoleic acid, increased in fish fed 0.5 and 1% LL-supplemented diets. Total long chain polyunsaturated fatty acids increased in fish fed 1% LL-supplemented diet. Regarding digestive enzymes, trypsin (alkaline pancreatic proteases) and pepsin (acid gastric protease) activities decreased with increasing LL in the diet. Overall, these results indicated that 1% LL is recommended for better growth performance of stellate sturgeon juveniles.

Preliminary rearing outcomes of Siberian sturgeon, Acipenser baerii Brandt, juveniles in autonomous hatching and rearing modules

Abstract This study analyzed the rearing indicators of Siberian sturgeon (Acipenser baerii) juveniles reared in tanks of different shapes and at various stocking densities. Rearing was conducted in autonomous hatching and rearing modules. Fish of an average body weight of 47.3±1.0 g were divided into four experimental groups: CL, RL, CH, and RH, which differed in stocking density (20 specimens and 50 specimens) and tank shape (C – circular, R – rectangular). The experiment ran for 28 days. Two-factor analysis indicated that lower stocking density significantly affected the final body weight of juvenile Siberian sturgeon, while tank shape had no effect on growth. The results of the current study on rearing Siberian sturgeon juveniles indicated that tanks of different shapes can be applied, but faster growth was obtained at a lower stocking density.

ОСОБЕННОСТИ НЕРЕСТОВЫХ МИГРАЦИЙ ПРОХОДНЫХ ВИДОВ РЫБ КАСПИЙСКОГО МОРЯ ЧЕРЕЗ МОРСКОЙ СУДОХОДНЫЙ КАНАЛ ЗА ПЕРИОД 2001–2022 ГГ.

Background. Anadromous species of sturgeons, salmonids and clupeids inhabiting the Caspian Sea migrate to their spawning grounds predominantly through the Volga-Caspian Sea Shipping Canal (VCSSC), which hydrological and hydrographic features have an effect on the abundance dynamics of the anadromous fish species. Along the entire delta sea edge, the Volga-Caspian Sea Shipping Canal (around 200 km in length) provides the conditions required for fish migration. Relevance. The current decrease in the Caspian Sea level and extensive accumulation of the fluvial and marine drift sediments impede navigation due to insufficient depth of the waterway and affect the entering of the anadromous breeders. This work is aimed at the assessment of the VCSSC use by sheefish, black-spined herring, beluga sturgeon, Russian sturgeon and stellate sturgeon during various seasons within 2001–2022 time range. Methods. Trawling and net fishing have been conducted in the marine part of the canal. Based on the data from seine catches in the river, the seasonal dynamics of fish migrations has been identified. Results. Despite the existence of extensive riverine network of the River Volga Delta suitable for the entering of anadromous fish species (Kirovsky, Belinsky, Igolkinsky, Karaysky and other banks), the Volga-Caspian Sea Shipping Canal (Main Bank) provides the anadromous fish species with a primary transit waterway to their spawning grounds—up to 90 % sheefish and black-backed herring breeders out of the total spawning stock abundance. The share of stellate sturgeon migrating along this waterway is 76–78 %, for the Russian sturgeon it is 83–85 %, and for beluga sturgeon it is 90–95 % of the spawning populations in the year of their entering into the Volga River. In recent years, the ecosystem of the Volga River has been developing in the context of low water content, which leads to the decrease in the water level of fish passage channels and tj a weakened flow, which, exacerbated by abiotic factors, in turn results in the reduction in the spawning stock abundance and decline in the yield of juveniles of the anadromous fish species [1]. Conclusion. During their pre-spawning season, sturgeons, sheefish and anadromous herring use the Volga-Caspian Sea Shipping Canal as the main migratory passageway to their spawning grounds. After the spawning, the canal provides juveniles and mature breeders with the passageways to the feeding sites in the Northern Caspian Sea. Sturgeon juveniles and the individuals skipping the spawning actively feed in the marine part of the canal [2].

Small but mighty: juvenile sturgeon beat the heat

Small but mighty: juvenile sturgeon beat the heat

К ЮБИЛЕЙНОМУ ДЕСЯТОМУ МЕЖДУНАРОДНОМУ СИМПОЗИУМУ ПО ОСЕТРОВЫМ (ISS10) (Г. ИЧАН, КИТАЙ, 20-25 ОКТЯБРЯ 2025 ГОДА): АКТУАЛЬНЫЕ ВОПРОСЫ

Background. The decline in the population and the threat of extinction that is currently applicable to most sturgeon species, as well as changes in their habitat and spawning environment have been the focus of attention for scientists and governments of different states for many years. Relevance. The preservation and restoration of fishing stocks of valuable sturgeon species and conservation of other vulnerable species are urgent tasks within the scope of rational use of natural resources and conservation of biological diversity and require international efforts. The aim of this work is to consider the main subject matters and focal areas of the upcoming Tenth International Symposium on Sturgeon, which will be held on October 2025 in Yichang (China). Methods. The main topics of the preliminary reports of the participants and speakers of the symposium have been analyzed, as well as the problems set out to be discussed over its duration. Results. This article is intended to familiarize the scientific community of Russia and other countries with the international-level matters associated with the upcoming symposium. Conclusion. The relevance of the international discussion of the current status of studies concerning sturgeon fish species, of increasing their natural reproduction efficiency, their breeding and rearing in the context of declining population abundance have been emphasized, as well as importance of identification of the prospects and challenges in restoration of some species populations with consideration to the dedicated long-term release of sturgeon juveniles into the natural water bodies and exploration of the approaches to their ex situ conservation.

Ефективність вирощування молоді осетрових (Acipenseridae) видів риб за різної твердості води

Ефективність вирощування молоді осетрових (Acipenseridae) видів риб за різної твердості води

Variability in estuarine habitat use of a threatened species in the northern Gulf of Mexico: implications for coastal restoration

Coastal restoration projects often require sediment resources borrowed from estuarine or marine ecosystems. A generalized additive modeling (GAM) framework was used to characterize fish-habitat relationships and predict spatiotemporal and ontogenetic shifts of Gulf sturgeon distribution within an impacted estuary in the northern Gulf of Mexico, Lake Pontchartrain. Habitat use and movement of Gulf sturgeon (n = 103) was monitored using an array of acoustic receivers (n = 81) from 2016 to 2019. Telemetry data was paired with environmental conditions hindcast from a high-resolution hydrodynamic model to develop GAMs for three life stages of Gulf sturgeon: juvenile, sub-adult, and adult. Model results demonstrated clear spatial, temporal, and ontogenetic shifts in habitat use for Gulf sturgeon in the Lake Pontchartrain estuary. The importance of spatial and temporal variables in the final models of all life stages suggests that distribution of Gulf sturgeon within the estuary is more likely driven by biology (prey distribution) rather than environment. Interestingly, dependence of Gulf sturgeon on the estuary for overwintering habitat declined with ontogeny. The northeastern shoreline of Lake Pontchartrain was identified as potential nursery habitat for overwintering juvenile sturgeon from the Pearl River, while eastern portions of the estuary and associated channels provide critical staging habitat and corridors of connectivity for migrating sub-adult and adult sturgeon. Given the clear need to prioritize conservation of Gulf sturgeon while restoring coastal marshes, findings from this study provide needed information to shape future coastal restoration and inform the siting and timing of future dredging operations in Lake Pontchartrain.

Features of cultivation of hydrid forms of sturgeon fish in quarriers of the Rostov region

The paper presents the results of growing juvenile sturgeon species and their hybrid forms in a mine pit lake in the Rostov region. In the Rostov region, there are many mine pit lake that can be successfully used to organize economic activities for the cultivation of valuable aquaculture objects, such as sturgeon fish. It has been established that the hydrochemical regime of the lake from May to September is favorable for the cultivation of juvenile sturgeon fish species and their hybrid forms. Studies have shown that the highest growth rate for 30 days of growing in pools was shown by beluga juveniles, its absolute increase was 1200 mg with a survival rate of 75%. Lenk and Bester had an increase of 565 mg and 710 mg, respectively. The most highly sensitive was the transition of juveniles to active nutrition, when the yolk sac in the larvae resolved by 2/3. The fastest transition and the least waste was observed in the larvae of bester and lenka. Upon reaching the age of 30 days, the juveniles were transplanted into cages, where good growth of beluga juveniles and hybrids was noted. On June 15 (40 days), the juveniles switched completely to dry food. At the same time, the average weight of the beluga was 3.5 g. It should be noted that with the complete transfer of beluga juveniles to dry food, the waste was from 3 to 5%. The young of Lenka and bester adapted better to dry food, the waste did not exceed 2%. The largest growth was in juveniles of all sturgeon species in August and early September.

Transcriptome Analyses Reveal Expression Profiles of Morphologically Undifferentiated and Differentiated Gonads of Yangtze Sturgeon Acipenser dabryanus.

Sturgeon is known as a primitive fish with the ZZ/ZW sex determination system and is highly prized for its valuable caviar. Exploring the molecular mechanisms underlying gonadal differentiation would contribute to broadening our knowledge on the genetic regulation of sex differentiation of fish, enabling improved artificial breeding and management of sturgeons. However, the mechanisms are still poorly understood in sturgeons. This study aimed to profile expression patterns between female and male gonads at morphologically undifferentiated and early differentiated stages and identify vital genes involved in gonadal sex differentiation of sturgeons. The sexes of Yangtze sturgeon (Acipenser dabryanus) juveniles were identified via the sex-specific DNA marker and histological observation. Transcriptome analyses were carried out on female and male gonads at 30, 80 and 180 days post-hatching. The results showed that there was a total of 17 overlapped DEGs in the comparison groups of between female and male gonads at the three developmental stages, in which there were three DEGs related to ovarian steroidogenesis, including hsd17b1, foxl2 and cyp19a1. The three DEGs were highly expressed in the female gonads, of which the expression levels were gradually increased with the number of days after hatching. No well-known testis-related genes were found in the overlapped DEGs. Additionally, the expression levels of hsd17b1 and cyp19a1 mRNA were decreased with the knockdown of foxl2 mRNA via siRNA. The results further suggested that foxl2 should play a crucial role in the ovarian differentiation of sturgeons. In conclusion, this study showed that more genes involved in ovarian development than testis development emerged with sexually dimorphic expression during early gonadal sex differentiation, and it provided a preliminary understanding of the molecular regulation on gonadal differentiation of sturgeons.

Using Multiple Metal Mixture Models to Predict Toxicity of Riverine Sediment Porewater to the Benthic Life Stage of Juvenile White Sturgeon (Acipenser transmontanus).

Five metal mixture dose-response models were used to predict the toxicity of porewater to young sturgeon at areas of interest in the Upper Columbia River (WA, USA/BC, Canada) and to evaluate these models as tools for risk assessments. Dose components of metal mixture models included exposure to free metal ion activities or metal accumulation by biotic ligands or humic acid, and links of dose to response used logistic equations, independent joint action equations, or additive toxicity functions. Laboratory bioassay studies of single metal exposures to juvenile sturgeon, porewater collected in situ in the fast-flowing Upper Columbia River, and metal mixture models were used to evaluate toxicity. The five metal mixture models were very similar in their predictions of adverse response of juvenile sturgeon and in identifying copper (Cu) as the metal responsible for the most toxic conditions. Although the modes of toxic action and the 20% effective concentration values were different among the dose models, predictions of adverse response were consistent among models because all doses were tied to the same biological responses. All models indicated that 56% ± 5% of 122 porewater samples were predicted to have <20% adverse response, 25% ± 5% of samples were predicted to have 20% to 80% adverse response, and 20% ± 4% were predicted to have >80% adverse response in juvenile sturgeon. The approach of combining bioassay toxicity data, compositions of field porewater, and metal mixture models to predict lack of growth and survival of aquatic organisms due to metal toxicity is an important tool that can be integrated with other information (e.g., survey studies of organism populations, life cycle and behavior characteristics, sediment geochemistry, and food sources) to assess risks to aquatic organisms in metal-enriched ecosystems. Environ Toxicol Chem 2024;43:62-73. Published 2023. This article is a U.S. Government work and is in the public domain in the USA.

Effectiveness of rearing Russian sturgeon with the introduction of highprotein feed concentrate Gorlinka to the diet

Formulating nutritionally balanced aquaculture feed is critical to ensuring that they meet the needs of aquatic animals. Fish is recognized as an essential component of a well-balanced diet as it provides healthy energy, high-quality proteins, vitamins (D, A, E and B12), essential metals (Se,Mn and Cu) and especially Omega-3, which play a vital role in human health from conception to all stages of human development, maturation and aging. The purpose of the research was to increase the effi ciency of growing Russian sturgeon by introducing high-protein feed concentrate Gorlinka into the diet partially or instead of sunfl ower cake. In order to conduct an experiment to study the eff ect of the feed concentrate Gorlinka, 4 groups of juvenile Russian sturgeon (one control and three experimental groups) of 50 animals in each were formed. The average live weight of juveniles at the beginning of the experiment was 100 g; the duration of the experiment was 175 days. In the compound feed for juvenile sturgeon of the experimental groups, the feed concentrate Gorlinka was introduced instead of sunfl ower presscake: the 1st experimental group – 50 %, the 2nd experimental group – 75 %. In the 3rd experimental group, sunfl ower presscake was completely replaced with Gorlinka feed concentrate. As a result of the research, the optimal dosage of replacing sunfl ower presscake with feed concentrate Gorlinka was established in the amount of 75 % (the 2nd experimental group) when growing Russian sturgeon, where the profi tability level was 31,69 %. The use of Gorlinka feed concentrate in aquafeed for Russian sturgeon helps to increase the economic effi ciency of its rearing by increasing productivity and reducing the cost of aquafeed. Thus, the level of profi tability in the experimental groups was higher by 2,47–6,67 abs.% compared to the control group that did not receive this concentrate.