Individuals Of Sturgeon Research Articles

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

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

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.

Hepatic Burdens of PCB and PCDD/F Congeners in Federally Endangered Shortnose Sturgeon and Atlantic Sturgeon from the Hudson River, New York, USA: Burden Patterns and Potential Consequences in Offspring.

Sturgeon populations worldwide are threatened with extirpation but little is known about their tendency to bioaccumulate contaminants and their sensitivities to environmental burdens of these contaminants. Shortnose sturgeon and Atlantic sturgeon, two species that are federally endangered in the USA, co-occur in the Hudson River (HR) where high sediment levels of polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzo-p-furans (PCDFs) occur. Previous controlled laboratory studies showed that young life-stages of both species are sensitive to toxicities at low levels of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and PCB126 exposure. The objective here was to measure congener-specific hepatic levels of PCBs and PCDD/Fs in HR specimens in order to determine if in situ bioaccumulation of these compounds is sufficiently high to have caused the early life-stage toxicities previously observed. Estimates of hepatic burdens of PCBs and PCDD/Fs were obtained from a small number of specimens of each species collected between 2014 and 2016 and specimens of shortnose sturgeon collected over 30years earlier and archived in a museum collection. Several significant patterns emerged. Hepatic levels of legacy PCBs and PCDDs were low in specimens of both species but typically higher in shortnose than Atlantic sturgeon, a pattern consistent with their habitat use in the HR. Hepatic burdens in shortnose sturgeon tended to be higher in archived specimens than in more recently collected ones despite expected reduction in archived specimens due to preservation methods. Several inadvertent PCBs congeners were detected at high levels, including PCB11, but their toxicity to natural populations remains unknown. Levels of select PCDFs congeners, 2,3,7,8-TCDF and 2,3,4,7,8 PeCDF, were elevated in some shortnose sturgeon individuals from the HR. Using Relative Potency (ReP) factors derived from white sturgeon, the observed levels of some hepatic PCDFs in HR shortnose sturgeon may have been sufficiently high to impair recruitment of young life-stages in this ecosystem.

Molecular genetic characteristics of Atlantic sturgeon (Acipenser oxyrinchus) cultured in Poland: Report on a bilateral project

Abstract Using 8 microsatellite markers (Spl-106, Spl-101, ATR-113, Aox23, An20, AoxD161, AoxD165, AfuG41) and mtDNA species-specific region flanked by the tRNAThr coding region and D-loop, it was found that Atlantic sturgeon stocking material planned for transport from Poland to Belarus belonged to the species Acipenser oxyrinchus oxyrinchus Mitchill. No interspecific hybrids were found. All of the Atlantic sturgeon individuals examined as part of this study belonged to a Canadian population.

Impact of a Combination of Different Technological Factors on the Effectiveness of the Processes of Ripping and Obtaining in vivo Caviar

The objects of the study are the broodstocks of the siberian (Acipenser baerii) and Russian sturgeon (Acipenser gueldenstaedtii), sterlet (Acipenser ruthenus) and hybrids of rolek (Russian x Lena sturgeon), bester (beluga x sterlet), sturgeon caviar, pools for sturgeon fish producers, closed water supply installations, temperature regime for sturgeon rearing in conditions of installations with a closed water supply cycle. The purpose of the study is to improve the processing of sturgeon caviar obtained in vivo. The intravital method of obtaining sturgeon caviar compared to the traditional method allows saving the broodstock for subsequent reproduction. On the basis of the literature analysis, the influence of a combination of the main technological factors (temperature, hardener and de-sticking conditions) affecting the efficiency of maturation and production of intravital sturgeon caviar has been studied. The positive results of pre-spawning aging of sturgeon producers when grown under controlled conditions are obtained. The authors establish the temperature regime of pre-spawning aging of producers, which contributes to the effective maturation of intravital caviar. The parameters of the preservation of technological factors upon receipt of marketable sturgeon caviar were determined. The main technological factor for obtaining intravital caviar is the temperature regime of pre-spawning aging (temperature regime of artificial wintering) of producers. The studied individuals of sturgeon were tagged with special chips for identification and effective work in determining the stage of maturity and the subsequent production of caviar in vivo. The scope of applying the research results: fishery enterprises, research institutes of fisheries, small and medium-sized businesses, fish farmers

Development and characterization of a duplex PCR assay in Chinese sturgeon (Acipenser sinensis) for genetic analysis

Chinese sturgeon (Acipenser sinensis) has been listed as a critically endangered species on the IUCN Red List and is an endemic fish of China. Five sets of duplex polymerase chain reactions (PCR) assays were developed with 10 tetranucleotide microsatellites for Chinese sturgeon. The size of CS57, ZHX43, ZHX69, AS105, ZHX51, AS074, ZHX2, AS078, AS026 and AS073 products in 184 Chinese sturgeon individuals ranged from 257–305, 191–241, 251–285, 172–244, 236–260, 169–209, 194–234, 92–176, 165–257 and 120–164, respectively. The observed allele number of the 10 microsatellites ranged from 7 to 16, and the total number of alleles was 106. The number of alleles per individual in CS57, ZHX43, AS105, AS074, AS078 and AS026 was 1–4. The number of alleles per individual in ZHX69, ZHX51, ZHX2 and AS073 was 2–4. The mean number of alleles per locus per individual ranged from 2.01–3.76. The expected heterozygosity (HE), observed heterozygosity (HO), polymorphic information content (PIC) and Shannon-Weiner diversity index (H′) ranged from 0.582 to 0.899, from 0.676 to 1, from 0.518 to 0.886 and from 1.034 to 2.34, respectively. Despite many advantages, the use of microsatellites as genetic analysis tools can be limited by the cost of the associated experiment. To solve this problem, this set of five duplex PCRs will provide tools that are more helpful, less expensive and less time consuming than others used for genetic analyses in Chinese sturgeon.

Genetic monitoring of natural sturgeon spawning in the lower Volga for the period 2017-2018

Genetic monitoring of natural sturgeon spawning in the lower Volga for the period 2017-2018

Expression Characterization of Six Genes Possibly Involved in Gonad Development for Stellate Sturgeon Individuals (Acipenser stellatus, Pallas 1771).

Nowadays, in sturgeon's aquaculture, there is a necessity for sex identification at early stages in order to increase the efficiency of this commercial activity. The basis for a correct identification is studying the different factors that influence the gonad development. The research has been directed towards molecular methods that have been employed with various degrees of success in identifying genes with different expression patterns between male and female sturgeons during their development stages. For the purpose of understanding the sexual development of 4-year-old stellate sturgeon (Acipenser stellatus) individuals, we have selected six genes (foxl2, cyp17a1, ar, dmrt1, sox9, and star). We analysed the gene expression of the selected genes for gonads, anal fin, liver, body kidney, and white muscle. The cyp17a1, ar, dmrt1, and sox9 genes have a significant higher expression in male gonads than in female gonads, while the data shows no significant differences in the expression of the investigated genes in the other organs. We investigate these genes to shed light on aquaculture sturgeon sexual development.

Current status of feeding stocks of the kaluga sturgeon Huso dauricus Georgi, 1775, and Amur sturgeon Acipenser schrenckii Brandt, 1889, in Russian waters

Summary Biological parameters of the kaluga Huso dauricus and Amur Acipenser schrenckii sturgeons have been analyzed in their foraging areas in Russian waters. Results show that both species are now sufficiently abundant only in catches from the lower Amur River, its mouth, and the Amur Estuary. The largest Amur sturgeon individuals occur in the estuary, while the largest kaluga sturgeon reside in the estuary as well as in the Sea of Okhotsk. Catches made in the river consist mainly of juvenile fish. The average body sizes of kaluga and Amur sturgeons in catches from the lower Amur River and the Amur Estuary have decreased significantly compared to records from 1929 to 1930. Between 2006 and 2011, the proportions of mature kaluga and Amur sturgeons in the river catches averaged 2.9 and 5.1%, respectively, and at its mouth and in the estuary by 42.6 and 32.8%, respectively. Abundance of kaluga sturgeon (age >1 year) in the lower Amur and the estuary in 2011 reached 345 000 individuals at a biomass of 7110 tonnes (t). Abundance of Amur sturgeon (age >1 year) in the same area and time reached 289 000 individuals at a biomass of 1946 t. The main stocks of the respective species (324 300 individuals or 94% in Kaluga, 263 570 individuals or 91.2% in Amur sturgeon) are concentrated in the Amur Estuary. To restore their populations in the Amur, a ban on all types of commercial fishing at the spawning grounds and juvenile foraging grounds should be implemented. It is also necessary to increase the number of hatchery-reared juveniles and allow them to grow to a greater body size before release into the Amur.

Molecular analysis of phylogeographic subspecies in three Ponto-Caspian sturgeon species

Sturgeons (Order Acipenseriformes) represent an extremely valuable natural resource that is now facing depletion. In the current study we evaluate if the traditional classification in subspecies of Acipenser gueldenstaedtii, Acipenser stellatus and Huso huso, endemic to Ponto-Caspian region is sustained by molecular analysis and if these represent Evolutionary Significant Units (ESUs) that should be managed separately in conservation programs. To examine the classification of taxonomic entities we sequenced a fragment of the mitochondrial control region in case of three sturgeon species that inhabit the North-western of Black Sea and migrate for reproduction in the Lower Danube. Beside these sequences, we used previously published sequences from sturgeon individuals sampled in the Black Sea, Azov Sea and Caspian Sea. We determined the genetic diversity and genetic differentiation, conducted a Population Aggregation Analysis (PAA) and inferred an intraspecific molecular phylogeny and haplotype network. The results indicated a low level of genetic differentiation between the geographically designated subspecies and did not support a significant divergence or reciprocal monophyly between them. Our results confirm previous genetic studies with smaller samples sizes, but additional analyses including nuclear markers should be conducted for proper recommendations aiming at the development of conservation programs.

Site heteroplasmy in the mitochondrial cytochrome b gene of the sterlet sturgeon Acipenser ruthenus

Sturgeons are fish species with a complex biology. They are also characterized by complex aspects including polyploidization and easiness of hybridization. As with most of the Ponto-Caspian sturgeons, the populations of Acipenser ruthenus from the Danube have declined drastically during the last decades. This is the first report on mitochondrial point heteroplasmy in the cytochrome b gene of this species. The 1141 bp sequence of the cytb gene in wild sterlet sturgeon individuals from the Lower Danube was determined, and site heteroplasmy evidenced in three of the 30 specimens collected. Two nucleotide sequences were identified in these heteroplasmic individuals. The majority of the heteroplasmic sites are synonymous and do not modify the sequence of amino acids in cytochrome B protein. To date, several cases of point heteroplasmy have been reported in animals, mostly due to paternal leakage of mtDNA. The presence of specific point heteroplasmic sites might be interesting for a possible correlation with genetically distinct groups in the Danube River.

Processes of Proliferation and Apoptosis in the Brain of the Amur Sturgeon

Using techniques of immunoperoxidase staining of proliferating cell nuclear antigen (PCNA) and TUNEL labeling of fragmented DNA, we studied sites of proliferation and apoptosis in the myelencephalon, cerebellum, tectum opticum, thalamus, and hypothalamus of the Amur sturgeon (Acipenser schrenckii). We found that the processes of proliferation and apoptosis are maintained in the brain of 3-year-old sturgeon individuals; the ratio of these processes in different cerebral regions varied significantly. The maximum intensity of proliferative activity was found in the periventricular zone of the myelencephalon (proliferation index, on average, 21.0 ± 1.3%). This fact allows us to consider this cerebral region a most important zone were adult neurogenesis occurs in the sturgeon. In the medial reticular formation, dorsal thalamic nuclei, inner fibrous layer of the tectum, and lateral hypothalamus, the maximum numbers of apoptotic elements were found. Therefore, these zones in the brain of the sturgeon correspond, apparently, to the regions where postmitotic neuroblasts are localized. In sensory centers (tectum and nuclei of the V, VII, and X nerves), significantly varying ratios of intensities of proliferation and apoptosis were found; this is indicative of dissimilar rates of growth and differentiation in visual and chemosensory centers of the sturgeon brain. The high proliferative activity in sensory and motor cerebral centers of the sturgeon allows us to hypothesize that a neotenic pattern is preserved in these CNS regions of adult sturgeons over a long period after the embryogenesis has been completed.

Species identification of Chinese sturgeon using acoustic descriptors and ascertaining their spatial distribution in the spawning ground of Gezhouba Dam

This study has developed an improved subjective approach of classification in conjunction with Stepwise DFA analysis to discriminate Chinese sturgeon signals from other targets. The results showed that all together 25 Chinese sturgeon echo-signals were detected in the spawning ground of Gezhouba Dam during the last 3 years, and the identification accuracy reached 90.9%. In Stepwise DFA, 24 out of 67 variables were applied in discrimination and identification. PCA combined with DFA was then used to ensure the significance of the 24 variables and detailed the identification pattern. The results indicated that we can discriminate Chinese sturgeon from other fish species and noise using certain descriptors such as the behaviour variables, echo characteristics and acoustic cross-section characteristics. However, identification of Chinese sturgeon from sediments is more difficult and needs a total of 24 variables. This is due to the limited knowledge about the acoustic-scattering properties of the substrate regions. Based on identified Chinese sturgeon individuals, 18 individuals were distributed in the region between the site of Gezhouba Dam and Miaozui reach, with a surface area of about 3.4 km2. Seven individuals were distributed in the region between Miaozui and Yanshouba reach, with a surface area of about 13 km2.

Microsatellite variation among River Sturgeons of the genus Scaphirhynchus (Actinopterygii: Acipenseridae): a preliminary assessment of hybridization

Microsatellite variation from 13 disomic loci is reported for a total of 208 individuals of the genus Scaphirhynchus. This includes 105 individuals of the pallid sturgeon (Scaphirhynchus albus) from the lower Mississippi River, 11 pallid sturgeon from the Upper Mississippi and Missouri rivers, 65 shovelnose sturgeon (S. platorynchus) from the lower Mississippi River, six Alabama sturgeon (S. suttkusi), and 21 individuals of sturgeon identified as intermediate between S. albus and S. platorynchus. Results indicate that all five of the above population/species units are significantly differentiated from one another based on pairwise FST estimates. Locus Spl-7 was diagnostic for the Alabama sturgeon and serves to further differentiate this allopatric species from other Scaphirhynchus. Classification of genotypes with and without a priori designations failed to clearly delineate the species and intermediates in the latter case but was successful for the species but not in the intermediates in the former case. The presence of six unique alleles in five of the 21 morphologically ‘intermediate’ sturgeon examined requires additional evaluation but suggests that these individuals are possibly not the result of hybridization. We hope that raising these important issues will bring all stakeholders to the table to establish a concerted effort needed for both morphological and molecular analyses to adequately address the question of hybridization and the origin of the morphological variation in these fishes.