Juvenile Sturgeon Research Articles

Effects of dietary thiamin (vitamin B1) on the growth performance, serum biochemical factors, immune response, and antioxidant activity of great sturgeon (Huso huso) juveniles.

The present research evaluated the positive effects of dietary thiamin (vitamin B1) levels on the growth performance, serum biochemistry factors, immune response, and antioxidant activity of great sturgeon (Huso huso) juveniles. Thiamin was included in diets with levels of 0 (control, T0), 7 (T7), 15 (T15), and 25 (T25) mg/kg diet. Measurements of thiamin levels in diets indicated that they contained 1.80 (T0), 8.02 (T7), 16.2 (T15), and 26.6 (T25) mg thiamin/kg feed. Sturgeon juveniles (240 individuals) with average weight of 44.8 ± 1.96g were distributed into 12 tanks, and fed with the experimental diets for 8 weeks. Final weight, body weight gain (%), specific growth rate, and feed conversion ratio (FCR) of great sturgeon were significantly influenced by dietary thiamin levels, and the maximum fish performance (P < 0.05) was obtained at a level of 15mg/kg diet. The trypsin, chymotrypsin, creatine kinase, lipase, α-amylase, and alkaline phosphatase activities were notably (P < 0.05) affected by the dietary thiamin levels. The glucose content was not significantly (P > 0.05) different among the experimental treatments. Diets supplemented with thiamine increased significantly (P < 0.05) triglyceride, cholesterol, and total protein levels accompanied with significant (P < 0.05) decreases in aminotransferase aspartate and alanine aminotransferase activities. Serum antioxidant enzymes were remarkably (P < 0.05) higher, while serum malondialdehyde was significantly (P < 0.05) lower in the thiamin-treated fish compared with the control group. Total immunoglobulin, lysozyme, and ACH50 values were significantly (P < 0.05) higher in fish fed with thiamin-supplemented diets than in the control group. The results of the present study demonstrated that dietary thiamin have an important role in enhancing the growth performance, immune response, and antioxidant activity of great sturgeon. Based on the regression fitting curve of final weight, weight gain, specific growth rate, and FCR values, the optimal level of thiamin is found to be 15.0-17.5mg/kg diet.

Biological indicators and traceability of the origin of Russian sturgeon juveniles in the lower reaches of the Volga River and the north- western part of the Caspian Sea

The aim of the work: characterization of juveniles released from sturgeon hatcheries into the natural habitat with individual identification of individuals. Methods: Ichthyological researches in the Volga River and its watercourses were surveyed using a 4.5 m fry trawl; in the western part of the Northern Caspian, a trawl survey was carried out using a 9 m trawl and the developed grid of stations, adjusted to take into account the sea level decrease. The trophological material was processed by the quantitative-weight method, followed by the calculation of private and general indices of the filling of the digestive tracts. Molecular genetic methods for the analysis of microsatellite loci and sequencing of a fragment of the control region of mitochondrial DNA were used. Novelty: the origin of the Russian sturgeon and the contribution of artificial reproduction from Russian sturgeon hatcheries to the Volga- Caspian fishery basin were determined by molecular genetic methods. Results: The composition of food organisms and the degree of fattening of Russian sturgeon juveniles after their migration to the sea were determined. The contribution of artificial reproduction from Russian sturgeon hatcheries to the replenishment of the Russian sturgeon population of the Volga- Caspian basin in the period 2016–2021 for fingerlings was averaged 80 %. Practical significance: The intensity of downstream migration in the Volga River and its watercourses of juveniles released from sturgeon hatcheries was studied. The presented data was made it possible to determine the main localization sites of Russian sturgeon juveniles depending on the species composition and abundance of food organisms in the northwestern part of the Caspian Sea. Based on the results of genotyping of spawners at sturgeon hatcheries and juveniles caught in the Northern Caspian, an assessment was made of the effectiveness of the work of the sturgeon hatcheries in 2016–2021.

Captive growth analysis of Siberian sturgeon juveniles (Acipenser baerii J. F. Brandt, 1869) fed on a commercial fodder and its importance to a sustainable development of the aquaculture sector

Sturgeon aquaculture is an important continuously developing sector within freshwater aquaculture and its sustainability is one of the most pressing matters nowadays. Thus, the urge to apprehend the mechanics of sturgeon growth in captivity as well as in nature is of immediate importance, considering the increase in customers’ requests for captive-grown sturgeon meat, caviar, and adjacent by-products. The present study evaluates several canonical growth indices in a controlled, indoor environment that included fluctuations in temperature, dissolved oxygen saturation, and ponderal density (g/L), known to affect sturgeon growth performance. Over the 91 days of evaluation, no significant correlation was found between the weight gain and the ponderal density, dissolved oxygen values, and temperature, among the 4 tanks used in the experiment setup, indicating, along with the lack of significant variance for the RCI per tank, that the growth observed is correlated only with the fodder fed to the fish.

Біологічні особливості організму молоді осетрових (Acipenseridae Bonaparte, 1831) риб за дії синтетичного та органічного імуностимуляторів

Purpose. To analyze the productive-biological and biochemical parameters of sturgeon larvae and fry under conditions of introduction of synthetic (Levamisole) and organic (Chitosan) immunostimulants into their diet. To evaluate the effect of supplements on the stability of homeostatic processes based on the analysis of enzyme activity. Methodology. The study was carried out on juvenile hybrid besters (♀ Huso huso х ♂ Acipenser ruthenus) and sterlet (Acipenser ruthenus) (BSS). Larvae and fry were fed with Artemia nauplii, which were the transfer of immunostimulants after a six-hour enrichment in the respective solution. Pre-larvae, larvae and fry of sturgeon were reared in a RAS at the Lviv Research Station of the Institute of Fisheries of the National Academy of Sciences of Ukraine. During cultivation, the main productive parameters were studied, which included: weight, body length, growth rates, mortality, output from each stage of cultivation. The activity of α-amylase was determined by the Karavey’s method. Alanine aminotransferase activity was determined by the Reitman–Frenkel’s method. Alkaline phosphatase activity was determined by reaction with phenylphosphate. Gamma-glutamyltranspeptidase activity was determined by reaction with L-gamma-glutamyl-p-nitroaniline. All data were statistically processed using Statistica 6.0 and MS Excel. Findings. Addition of Levamisole to the diet during the first week of exogenous feeding had a positive effect on the growth processes of sturgeon larvae. The average weight of experimental fish in the experimental group No. 1 increased during the week by 3.96 times, which was 9% higher than the control values. In the experimental group No. 2, which consumed Chitosan, no significant difference was found compared to the average weight of the control group. Average daily growth was 24.9% in the experimental group No. 1 and 20.7% in the group No. 2, and 22% in the group No. 3, which served as a control. After 21 days of the experiment, the average body weight of juvenile sturgeons in the group No. 1, which consumed Levamisole, increased to 0.794 g, which exceeded the control values by 50.5%. The average weight of juveniles in the experimental group No. 2 was 0.661 g, which was 25.28% higher than the control group. The average growth rates were 9.3% in the group No. 1, 12.1% in the group No. 2, and 11.3% in the group No. 3. The short-term positive effect of immunostimulants on the activity of digestive enzymes of sturgeons in the juvenile period was shown. The activity of α-amylase in the body of fish for 21 days under the action of both Levamisole and Chitosan was higher than in the control by 88.2 and 91.4%, respectively. The analysis of the effect of immunostimulants on the activity of transferases (AlAT, LF, GGTP) of the tissues of internal organs confirmed the strengthening of the nonspecific resistance of the body in the short period of their action due to the activation of the transport processes of dephosphorylation and transamination. In addition, the activity of none of the enzymes indicated the impairment of homeostasis. Originality. The advisability of using synthetic and organic immunostimulants in raising sturgeons has been demonstrated. The effect of these supplements on the productive and biochemical parameters of juvenile sturgeons was evaluated. Practical value. The obtained results will be useful for improving the technology of early rearing of sturgeon larvae and fry. The application of the acquired knowledge will allow reducing mortality during critical periods of their cultivation and will allow strengthening the non-specific immunity of these valuable fish species. Key words: sturgeons, enrichment, non-specific resistance, immunostimulants.

Studies of fish breeding biological and genetic parameters of stellate sturgeon (Acipenser stellatus Pallas, 1771) offspring obtained using native and cryopreserved sperm

Comparative results of experimental work on the study of stellate sturgeon offspring obtained using cryopreserved (experimental) and native (control) sperm, carried out at the scientific and experimental complex of aquaculture “BIOS” of the Volga-Caspian branch of VNIRO (CaspNIRKH) in this article were presented. Molecular genetic studies of cryopreserved sperm, females and males from the brood stock of the complex were carried out. In order to select the optimal parental pairs, calculations of genetic relationship of fish spawners were made. The scheme of the experiment was developed. The technological process of working with stellate sturgeon spawners was described: obtaining mature reproductive cells, insemination, incubation of caviar. Holding and breeding of the studied groups of stellate sturgeon juveniles up to standard weight was carried out. Each stage of the research work was subjected to comparative analysis. The genetic diversity of juveniles was studied. As a result of the work carried out, it was found that the group of fish obtained using of cryopreserved sperm had higher weight indicators, compared with the juveniles of the control group obtained from males from the brood stock of “BIOS”, by an average of 16%. In addition, the experimental group had a higher homogeneity compared to the control group, as evidenced by the values of the coefficients of variation. The survival rate of juveniles of the experimental group of fish was higher than the control group by an average of 10%. The stellate sturgeon obtained using cryopreserved sperm was characterized by higher values of the total number of alleles and the absence of a deficit of heterozygotes compared to the control group of juveniles, which is especially important for preserving the diversity of this valuable sturgeon species. The results of the research work carried out will help develop proposals for the formation of artificially created sturgeon brood stocks by replenishing them with juveniles obtained using cryopreserved sperm and having higher fish breeding biological and genetic indicators. This will allow the herd to have a stock of working material from different generations of sturgeon species, which is a promising factor for the conservation of aquatic biological resources and selection in commercial aquaculture.

Increasing the efficiency of Siberian sturgeon juveniles growing on industrial feeding line by enriching of base feeds with dry garlic powder and humic preparation from peat

Of all representatives of sturgeon aquaculture, Siberian sturgeon Acipenser baerii occupies about 40% of its volume and is grown in 50 countries, including Russia. In 2018, the volume of commercial biomass production of this fish in the world was estimated at about 22–23 thousand tons [17]. In order to increase the efficiency of industrial production of this fish in aquaculture in the extreme conditions of Siberia, it is advisable to use feeds enriched with non-toxic components of natural origin, which increase the viability and productivity of objects and have no adverse affect to products quality and environment. In aquaculture, including sturgeons, the phytobiotic garlic and complex organic molecules of humic compounds are used for this purpose. In this experiment the industrial factory feeds, enriched with the humic additive Humiton from peat at a dose of 25 ml/kg of feed and/or dried garlic powder at a dose of 30 g/kg was used. The effectiveness of these feeds was evaluated for training of the rearing stock of Siberian sturgeon juveniles for maintenance in cages in winter conditions, depending on the initial weight of the objects. In sturgeons with a higher initial weight, by the end of the experiment, the use of feeds enriched with each of the components was effective in terms of safety, weight gain and improvement in the feed conversion rate FCR against the background of cold stress. In small fish, the main effect was an improvement in FCR when fed with garlic powder.

Two Distinct Life History Strategies of Atlantic Sturgeon in the Ogeechee River, Georgia

Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus) is an anadromous, widely distributed, highly migratory sturgeon subspecies that occurs in rivers and marine waters along the North American Atlantic Coast. This fish has shown widespread declines and has been afforded conservation protections, including some based in the U.S. on the delineation of Distinct Population Segments (DPS) under the Endangered Species Act. The management of Atlantic sturgeon will benefit from the knowledge of its population structure as well as the ability to uniquely identify individuals (in relation to population origin) that are vulnerable to anthropogenic stressors at sites outside of their natal estuaries. We used microsatellite analysis to estimate the genetic population structure of Atlantic sturgeon from 13 spawning rivers ranging from the St. Lawrence River, Quebec to the Satilla River, Georgia. Individual Based Assignment (IBA) testing was used to estimate the contribution of each population to mixed-stock aggregations in coastal waters and in a non-natal estuary. An unexpected finding was the discovery of two distinct genetic clusters of juvenile Atlantic sturgeon in the Ogeechee River, Georgia, with specimens in the two clusters differing significantly in terms of mean total length. Additionally, three distinct genetic clusters were detected within the Satilla River juvenile collection, along with two clusters within the Edisto River sample. In F1ST and FST analyses, the extent of the pairwise genetic differentiation between the two genetic clusters in the Ogeechee River and the three in the Satilla River was greater than that between all other pairwise comparisons among rivers in the South Atlantic DPS. In contrast, we found no evidence of the genetic partitioning of juvenile sturgeon within the neighboring Savannah or Altamaha river populations. Using IBA, we found that the overall Ogeechee River population made a moderate contribution (8.3%) to the overall mixed-stock collections (n = 1512) from coastal North Carolina to the Bay of Fundy. Surprisingly, all of the Ogeechee River-assigned specimens (n = 125) in these mixed-stock aggregations were representatives of only one of the two Ogeechee River genetic clusters. These results suggest that the two Ogeechee River genetic clusters exhibit significantly different life history strategies, with one being resident and the second being highly migratory.

Analysis of exterior indices of Russian sturgeon juveniles grown at sturgeon fish factories of the Astrakhan region

The aim of our work was to assess the exterior features of Russian sturgeon juveniles grown at sturgeon fish factories (SFF) of the Astrakhan region. In the process of research, samples of juveniles, obtained from six factories, which are conditionally divided into six groups, were studied: group I - Zhitninsky SFF, group II - Aleksandrovsky SFF, group III - Sergievsky SFF, group IV - Bertyulsky SFF, group V - Kizansky SFF and group VI - Lebyazhy SFF. Assessment of Russian sturgeon juveniles was carried out postmortally on 360 individuals with 60 instances from each factory. According to the data obtained, the following exterior indices were calculated: fatness index, runability index, high back index, long head index and caudal peduncle index. In the process of our research, it was found that the index of long-headedness showed the least variability in all the studied samples. The coefficient of variation of indicators in all six groups did not exceed 10%. The highest coefficient of variation was observed in terms of the average weight (in the studied samples it ranged from 30.0% to 67.0%) and the caudal peduncle index (from 15.0% to 20.0%). Besides, it is worth noting that the sample from group VI had the lowest level of variability among the studied groups, that indicates the uniformity of the obtained juveniles and the high quality of the fish breeding indicators of the released juveniles. In the sample of group IV, on the contrary, the highest level of variability was observed, as evidenced by the maximum values of the coefficient of variation and standard deviation for 4 of the studied indicators out of 7. At the same time, during the study, it was noted that on the quality of the released Russian sturgeon juvenile, and later on the percentage of commercial return, was influenced not only by the hydrochemical regime and the state of the natural food supply in nursery ponds, but also by the high level of inbreeding of the brood stock on sturgeon fish factories.

ВЫПУСК МОЛОДИ ОСЕТРОВЫХ В АЗОВО-КУБАНСКОМ РАЙОНЕ С РЫБОВОДНЫХ ЗАВОДОВ ФЕДЕРАЛЬНОГО АГЕНТСТВА ПО РЫБОЛОВСТВУ В ПЕРИОД С 2016 ПО 2022 Г.

Background. By the end of the 20th and the beginning of the 21st century, artificial reproduction had taken up a key role in the sturgeon stock recruitment in the natural water bodies of the Azov–Kuban region. Relevance. The major part of artificial reproduction of sturgeon species is conducted in the fish hatcheries of the Azov–Kuban region under the authority of the Federal Agency for Fishery (Rosrybolovstvo). The aim of this study was to analyze the volumes of rearing and release of juvenile sturgeons into water bodies of fisheries importance in the Azov–Kuban region by fish hatcheries subordinate to the Federal Agency for Fishery. Methods. This article is based on the data recordings of the Azov-Black Sea Branch of the FSBSI “VNIRO” (“AzNIIRKH”) for the time range from 2016 through 2022. The data on 4 sturgeon hatcheries— Adygea, Achuevo, Grivensk, and Temryuk—are presented and analyzed. Results. An increase in the total number of juveniles of sturgeon species released into the natural habitat has been revealed. The highest values were recorded in 2021–2022. There has also been a disproportion in the number of released juveniles belonging to different species. Each year, sterlet Acipenser ruthenus accounted for a large share of released juveniles, for which the percentage ranged from 47.6 % in 2018 to 64.4 % in 2022. In recent years, the volumes of rearing and releasing the juveniles of this species have been increasing both quantitatively and in percentage terms. This fact can be explained by the earlier maturation of sterlet breeders, shorter intervals between repeated spawning, and the resultant larger number of “active” breeders of this species in the hatcheries. From 2019 through 2022, the share of the juveniles of sturgeon species released by the hatcheries of the Federal Agency for Fishery into the Protoka River, as compared to the Kuban River, increased from 55.0±0.10 % in 2016–2018 to 68.9±0.44 % (2019–2022). It resulted from the increase in the number of the sturgeon juveniles released into this water body, and not from a redistribution of release volumes between the Kuban and Protoka Rivers. Conclusion. In general, the artificial reproduction of sturgeon species by the fish hatcheries of the Federal Agency for Fishery in the Azov–Kuban Basin has shown a positive dynamics. However, it has also been found necessary to increase the scale of artificial reproduction of the most commercially valuable anadromous species: Russian sturgeon Acipenser gueldenstaedtii and stellate sturgeon Acipenser stellatus.

Acipenserid herpesvirus 2 genome and partial validation of a qPCR for its detection in white sturgeon Acipenser transmontanus.

White sturgeon Acipenser transmontanus is the primary species used for caviar and sturgeon meat production in the USA. An important pathogen of white sturgeon is acipenserid herpesvirus 2 (AciHV-2). In this study, 4 archived isolates from temporally discrete natural outbreaks spanning the past 30 yr were sequenced via Illumina and Oxford Nanopore Technologies platforms. Assemblies of approximately 134 kb were obtained for each isolate, and the putative ATPase subunit of the terminase gene was selected as a potential quantitative PCR (qPCR) target based on sequence conservation among AciHV-2 isolates and low sequence homology with other important viral pathogens. The qPCR was repeatable and reproducible, with a linear dynamic range covering 5 orders of magnitude, an efficiency of approximately 96%, an R2 of 0.9872, and an analytical sensitivity of 103 copies per reaction after 35 cycles. There was no cross-reaction with other known viruses or closely related sturgeon species, and no inhibition by sturgeon DNA. Clinical accuracy was assessed from white sturgeon juveniles exposed to AciHV-2 by immersion. Viral culture (gold standard) and qPCR were in complete agreement for both cell culture negative and cell culture positive samples, indicating that this assay has 100% relative accuracy compared to cell culture during an active outbreak. The availability of a whole-genome sequence for AciHV-2 and a highly specific and sensitive qPCR assay for detection of AciHV-2 in white sturgeon lays a foundation for further studies on host-pathogen interactions while providing a specific and rapid test for AciHV-2 in captive and wild populations.

Shyer fish are superior swimmers in Siberian sturgeon (Acipenser baerii)

Differences in individual personality are common amongst animals, which can play an ecological and evolutionary role given links to fitness. Personality affects animal life processes and outputs (e.g., behavior, life history, growth, survival, reproduction), and has become a common theme in animal behavioral ecology research. In the present study, we used Siberian Sturgeon to explore how personality traits of boldness and shyness are related to swimming performance, post exercise recovery and phenotypic morphology. Firstly, our results indicated that the Siberian sturgeon juveniles of shyness were better swimmers, validating evolutionary biology trade-off theory. The critical swimming speed (Ucrit) of the shy groups was higher than that of the bold groups. Secondly, the shy groups were more resilient after exercise fatigue. The swimming fatigue recovery ability, the glucose and lactic acid concentration recovery ability of shy groups were greater than that of bold groups. Thirdly, the shy groups were more streamlined. Compared with bold groups, shy groups had smaller caudate stalk lengths, caudate stalk heights, superior caudal lobes, and inferior caudal lobes. In general, we demonstrated that shy Siberian sturgeon had better swimming performance from physiology and morphology. These research results further enrich the theoretical viewpoints of fish behavior biology, more importantly, which provided a good example for studying the relationship between sturgeon’s “personality” and swimming performance.

Evaluation of growth performance and body composition of great sturgeon (Huso huso) juveniles fed with different levels of Ethylenediaminetetraacetic acid

Evaluation of growth performance and body composition of great sturgeon (Huso huso) juveniles fed with different levels of Ethylenediaminetetraacetic acid

The application of dry garlic powder and humic feed additive Humiton to increase the efficiency of sturgeons stock material growing in aquaculture

Restoring the population of relic fish sturgeons is a priority for international environmental protection measures. This problem is solved by mass production of fish fries in aquaculture for natural water bodies stocking. In this regard the effective technologies of production of such material is elevant. For this purpose the feeds for fries growing are enriches with additives of natural origin, which increase the viability and productivity of objects and have no negative impact on product quality and environment. As such additives, preparations based on food and medicinal plants — phytobiotics, as well as complex natural organic molecules — humic substances are used. In this experiment, Siberian sturgeon (Acipenser baerii Brandt, 1869) fries with an initial weight of 153.8±14.3 mg were fed with standard feed enriched with various doses of dry garlic powder as phytobiotic and humic feed additive Humiton. The inclusion of garlic powder at a dose of 30 g/kg and Humiton at the rate of 1 g/kg of humic acids to feed composition significantly increased the efficiency of fish rearing. After 5 weeks of experiment the survive of objects exceeded the control by 9.9%; the mass of fries was higher by 77.6% against the control and by 50% higher than the value of the calculated indicator of the factory juvenile sturgeons mass intended for stocking. The result obtained makes it possible to increase the efficiency of growing sturgeon fries in aquaculture in order to increase the mass and viability of the fish stock.

Features of kaluga sturgeon Acipenser dauricus and amur stergeon Acipenser schrenckii juvenile feeding in the Lower Amur

The aim of the work is to study the specifics and nutritional spectrum of juvenile kaluga and Amur sturgeon in the Amur on the halfway from the sturgeon hatcheries to the main feeding place — the Amur Estuary. There was Mysidacea in the food spectrum of juvenile kaluga from the Lower Amur, in 350–390 km from the mouth, in the first decade of July 2021. Mysids were found in 70% of the studied gastrointestinal tracts and their mass fraction was almost 44%. Fish played a secondary role in the diet of kaluga. The diet of the Amur sturgeon consisted mainly of Trichoptera (83.33%) and Chironomidae (42%) larvae. Mollusks were not found in the gastrointestinal tract of juveniles of both species feeding in the Amur riverbed. Both in diversity and the index of filling the gastrointestinal tracts, the diet of sturgeons in the Amur at the beginning of July 2021 was significantly inferior to the diet described by previous studies. The average number of identified objects in the gastrointestinal tracts of kaluga and sturgeon was 1.2 and 1.4, respectively; average gastric filling index — 41.1 and 28.8; the average value of the fatness coefficient for kaluga was 0.62, for sturgeon — 0.51. The different type of feeding and the range of food objects show that kaluga and Amur sturgeon juveniles are not food competitors in this section of the Amur. The high content of sand in the stomachs of sturgeons, 2.5 times higher by weight than the mass of the food in bolus, indicates the poverty of the sturgeon feed base on this section of the river in the conditions of abnormal flooding of the spring-summer season of 2021. In such hydrological conditions, food organisms — small fish, insect larvae — dispersed over large areas of the river floodplain, that made them hard-to-get for sturgeons living in the main channel and permanent channels.

Effects of Temperature on the Growth Performance, Biochemical Indexes and Growth and Development-Related Genes Expression of Juvenile Hybrid Sturgeon (Acipenser baerii♀ × Acipenser schrenckii♂)

In order to investigate the effects of temperature on the growth performance, biochemical indexes and genes expression in juvenile hybrid sturgeon (Acipenser baerii♀ × Acipenser schrenckii♂), five temperature treatment groups (18 °C, 21 °C, 24 °C, 27 °C, 30 °C) were set in this study. After 25 days of domestication, the specific growth rate (SGR) and relative weight gain rate of juvenile sturgeon increased at first and then decreased with the increase in temperature in the range of 18–30 °C and reached the highest value at 21 °C. A quadratic equation was used to fit the regression equation of SGR and temperature (T). The result showed that the temperature of the maximum SGR is 23.45 °C. Moreover, the expression level of the growth hormone (gh) and the content of blood glucose (GLU) increased significantly at 21 °C, while the expression level of the growth hormone receptor (ghr) in the liver decreased significantly. When the temperature exceeded 27 °C, the thyroid hormone levels were significantly affected, and the levels of total antioxidants (T-AOC) and reduced glutathione (GSH) were significantly higher than those in the control group. In addition, with the increase in temperature, the expression levels of hsp70 and hsp90 in the liver increased significantly, while the expression level of the luteinizing hormone (lh) in the brain decreased significantly. To summarize, the effect of temperature on the growth and development of juvenile sturgeon mainly occurs through the effects of glucose metabolism, thyroid hormone level, total antioxidant capacity and growth-related genes. Therefore, in a temperature range between 21 and 24 °C, juvenile sturgeon can obtain the maximum growth rate and survival rate.

Quality assessment of young of the hybrids “Lensky sturgeon × Russian sturgeon” and “bester” grown in a circulated water supply unit

The actual direction of modern aquaculture is the optimization of fish breeding processes by monitoring and managing environmental parameters and feeding regimes, reducing the influence of seasonality on technological processes in order to increase the yield of marketable products per unit area. The most optimal option for such industrial aquaculture is the use of recirculating water supply systems, which have proven themselves especially well in the cultivation of sturgeon fish. In commercial aquaculture, aimed at year-round production of high-value delicacy products in the form of meat and caviar, hybrid forms of sturgeon are becoming more common. The article describes the experience of growing juvenile hybrids Lensky sturgeon × Russian sturgeon and Bester in the pools installed in the recirculating water installation of Caspian Bekiresy Limited (Atyrau, Kazakhstan) is described. The article presents the results of monitoring the hydrochemical parameters of water, as well as the characteristics of the types of feed used in the cultivation of sturgeon hybrids at different stages of ontogenesis. The indicators of the initial and final weight, as well as the values of the absolute, average daily and relative growth of the yearlings of sturgeon hybrids were determined. A comparative assessment of the survival of sturgeon hybrid fry when grown in a recirculating water installation pools using water from an artesian well was carried out. The experience of growing sturgeon interspecific hybrids, based on the obtained fish-biological indicators, allows us to recommend them as a full-fledged replacement for parental species, the cultivation of which under artificial conditions has a low efficiency. Moreover, bester, which had high rates of growth and survival, is a more promising object for large-scale commercial cultivation in conditions of recirculating water supply installations.

Movement patterns of juvenile green sturgeon (Acipenser medirostris) in the San Francisco Bay Estuary

Little is known about the distribution and ecology of juvenile green sturgeon throughout their range and specifically within California’s Central Valley and the San Francisco Bay Estuary. The objective of our study was to identify rearing movement patterns of juvenile green sturgeon and their interaction with Delta and Bay habitats. Acoustic biotelemetry was used to record juvenile movements and residence within different regions of this highly modified watershed. We document a diversity of movements exhibited by 31 acoustically tagged juvenile green sturgeon monitored over a 9-month period. The juvenile sturgeon either (1) remained in the Delta or moved (2) into the Carquinez Straits, (3) into San Pablo Bay, (4) into San Pablo Bay but returned to Delta, (5) through the estuary and likely left through the mouth of the bay, (6) or left the estuary only to return later. Spatiotemporal habitat quality varies within and between Delta and Bay habitats. Variation in water year and hydrologic connectivity are likely to influence habitat quality and quantity, and behaviors may be differentially optimized for fitness in response to environmental variation. Our results provide initial evidence supporting multiple behavioral movement patterns and a broad use of regional habitats for green sturgeon in the California Central Valley. This apparent behavioral diversity observed through movement patterns may ensure long-term success of all population segments over time in an extremely variable environment, ultimately supporting overall population stability (i.e., the portfolio effect). Enhanced conservation efforts may be needed to protect juvenile green sturgeon and the habitats they rely upon.

Composition and Content of Fatty Acids in the Biomass of Siberian Sturgeon (Acipenser baerii, Brandt, 1869) Juveniles in Aquaculture Conditions

Composition and Content of Fatty Acids in the Biomass of Siberian Sturgeon (Acipenser baerii, Brandt, 1869) Juveniles in Aquaculture Conditions

A microwave energy meter to estimate energetic reserves in juvenile sturgeon

Energetic stores can be metrics of fish health but are determined using lethal methods. Validation of non-lethal alternatives to estimate energetic stores would facilitate monitoring of wild fish of conservation concern, such as sturgeons. The Distell Fatmeter, a microwave energy meter, has been validated to estimate energetic reserves in a range of fish taxa but has not been tested on sturgeon. Therefore, Fatmeter measurements were tested as a predictor of captive hatchery-origin juvenile pallid sturgeon (fork length: 240–415 mm) energetic reserves determined by lethal proximate analysis. Fatmeter measurements combined with size and condition metrics accounted for 40 to 45% of the variation in whole-body energetic reserves, which is notably lower than reported in previous studies on other fish taxa and a modest improvement on variation explained by size and condition metrics alone in the same sturgeon population. We suggest the low variation accounted for by the Fatmeter may be a result of small body size and low whole-body lipid content and recommend follow-up studies on sturgeon larger than 415 mm in fork length.

A subdermal tagging technique for juvenile sturgeon using a new self-powered acoustic tag

BackgroundA new technology for a self-powered acoustic tag (SPT) was developed for active tracking of juvenile fish, intended to avoid the typical battery life constraints associated with active telemetry technology. We performed a laboratory study to evaluate a subdermal tagging technique for the SPT and effects of the tag on survival, tag retention, and growth in juvenile white sturgeon (Acipenser transmontanus).ResultsSurvival was associated with tag retention. White sturgeon implanted with the SPT (n = 30) had 93% survival and tag retention by day 28, 67% by day 101, and 38% by day 595 post-tagging. Sturgeon implanted with a passive integrated transponder (PIT) tag only (control group) had 96% survival and tag retention by day 28, and through day 101 post-tagging. Fish in the PIT group were repurposed after day 101, so no comparisons with this group were made at day 595 post-tagging. Specific growth rate (SGR) for fork length was a median of 0.25% day−1 by day 28 for the SPT group, which was significantly lower than the PIT group (median: 0.42% day−1; n = 27). The SPT and PIT groups had similar SGR fork length by day 101 post-tagging (0.22 and 0.25% day−1, respectively). SGR weight was also lower for the SPT group compared to the PIT group on day 28 (1.39 and 2.11% day−1, respectively), but the difference again dissipated by day 101 (0.79 and 0.88% day−1, respectively).ConclusionThe tagging technique and placement of the SPT allowed the tag to remain upright along the flank of the sturgeon to ensure maximum battery output of the SPT; however, retention rates of the SPT were not ideal. We provided suggestions to improve the tagging technique. Suggestions included tagging fish that are > 400 mm FL, moving the incision location to extend the cavity and create a pocket for the placement of the SPT, and performing a quantitative wound-healing evaluation. Future studies are therefore recommended to evaluate these suggestions.