Acipenser Stellatus Research Articles

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

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

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

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

Standardized Sperm Cryofreezing Technique for Caspian Sea Sturgeons (Huso huso, Acipenser persicus, Acipenser stellatus, Acipenser nudiventris)

Sturgeons, considered `living fossils,` face extinction due to various factors, according to the International Union for Conservation of Nature's Red List. The present study describes a uniform sperm cryopreservation method for the endangered Caspian Sea sturgeon species, which are beluga (Huso huso), Persian (Acipenser persicus), stellate (Acipenser stellatus), and ship (Acipenser nudiventris) sturgeons for both artificial reproduction and ex-situ conservation attempts. For this aim, sperm samples were diluted 1:1 in extender composed of 118 mM Tris buffer (pH=8) and 23.4 mM sucrose-based extender containing 15% DMSO and equilibrated for one hour at 4°C. Then, sperm samples were placed into 0.50-ml straws and multi-stage cooling was applied to freeze with the help of a programmable freezer with an accuracy of ±0.1C/min, and finally stored in liquid nitrogen (-196C) tank. Thawing was performed at 40°C water baths for 25 s. The results indicated that storage for two years resulted in a 24.7% fertilization rate for the stellate sturgeon, while the Persian sturgeon had a remarkable rate of 58.2% after five years storage.

A complete study of neuroendocrine regulation of fish reproduction. 4. Migration impulse as a starting mechanism of spawning

The participation of the hypothalamo-hypophysial neurosecretory system (NS) in the initiation of anadromous fish spawning migration was established on the basis of ecological-histophysiological analysis the results of histomorphological, immunohistochemical and electron microscopic studies for the first time. Activation of the neurosecretory products synthesis in the neurosecretory cells perikaryons and their excretion into the cerebrospinal fluid of the III brain ventricle in anadromous migrants forms at the beginning of the river spawning migration, spring-spawning: Russian sturgeon, stellate sturgeon and autumn-spawning: pink salmon and chum salmon, was shown. Transport and mass accumulation of neurosecretory products in the neurohypophysis were discovered at the same time. It is concluded, that the NS impacts a complex synchronous effect, which consists: firstly, in the neurotropic effect of nonapeptide neurohormones (NPh) on behavioral centers, which causes a dominant state of CNS excitation corresponding to the “Migration impulse”; secondly, in the violation of the long-term adapted marine “Pastured” level of osmoregulation; and thirdly, in the cessation of the well-known antigonadotropic effect of NPh, which contributes the organism transition to the energyconsuming energy type of metabolism. A comparative analysis (cross-analysis) of our own and literature data confirms the commonality and points to the universality of this metabolic mechanism for different forms of migration in fish ontogeny, which allows us to consider it as the most important aromorphosis type of phylogenetic adaptations, aimed at the species biological progress achieving. In the subsequent navigational mechanisms of homing, widely covered in the world literature, the leading role is played by the luliberinergic centers of the hypothalamus. The ecological diversity of these population-level mechanisms and the presence of straing in fish allow us to consider them as specializations of microevolutionary origin. The most promising direction for the further neuroendocrinological research development seems to be the analysis of the mechanisms of imprinting in connection with the enhancement of growth and survival of juveniles in the critical salinity medium, and for the purpose of homing control (development of the commercial fish-return biotechnology management) — the mechanisms of interaction between the NS and the luliberinergic centers in the neuroendocrine complex of CNS.

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.

Sturgeons in materials from archaeological sites of Ukraine: A review

AbstractThe article presents a critical review of all published data on findings of the skeletal elements of sturgeons (Acipenseridae) during archaeological excavations conducted in the territory of Ukraine. Sturgeon remains are present in materials from 41 archaeological sites, the age of which covers the stage from the Neolithic (4 kyr bc) up to the Modern Period (17th century ad). Five species (Acipenser gueldenstaedtii, Acipenser nudiventris, Acipenser ruthenus, Acipenser stellatus, and Huso huso) are recognized. Of them, the Russian sturgeon, the sterlet, and the stellate sturgeon are the most abundant, while beluga is somewhat less numerous, and the fringebarbel sturgeon is represented by the smallest number of remains. The presence of the latter species (and the absence of the European sturgeon Acipenser sturio) in the historical past of Ukraine is discussed. We also highlight the importance of original and published data accessibility in archaeozoological research and discuss the issues of species identification, body length, and weight reconstruction of sturgeons based on skeletal elements.

The Early Ontogeny of Some Pancreatic and Brush Border Enzymes in the Hatchery Produced Stellate Sturgeon, Acipenser stellatus

The Early Ontogeny of Some Pancreatic and Brush Border Enzymes in the Hatchery Produced Stellate Sturgeon, Acipenser stellatus

Archaeozoology Supports a Holistic View on Fish Assessments in Large Rivers—A Case Study from the Volga River: From Quantitative Data and Ancient DNA to Biodiversity Analysis

Knowledge of the historical and present dynamics of populations of migratory fish can promote our understanding of factors affecting their recruitment and abundance. Taxonomic identification of 23,802 bone remains and 13,539 scales of fish from 30 archaeological sites along Volga River revealed that they belonged to 41 different fish species. These data allow for retrospective comparisons and highlight the potential of archaeozoology in conservation biology. Sturgeons and salmonids are vulnerable to the impacts of fishery and climatic change. The sharp decline in the numbers of Starry sturgeon (Acipenser stellatus), Caspian trout (Salmo caspius), and Caspian Inconnu (Stenodus leucichthys) from the Volga in the 17th and 18th centuries was likely related to a cooling period (“Little Ice Age”). At present, the population numbers of all anadromous sturgeons and salmonids of the Volga River are critically low. In the Volga basin over the past two millennia, the sterlet (Acipenser ruthenus) has had a very large population number, high genetic (haplogroups and haplotypes) diversity, and large body sizes. Genetic analysis (aDNA and eDNA) have great potential to expand the knowledge of fish populations along large rivers and to improve long-term biomonitoring. Therefore, analyses of historical data, conventional surveys, as well as the inclusion of genetic approaches complement each other in the development of effective conservation strategies.

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.

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.

Aliphatic hydrocarbons in fin spines of adult sturgeon (Acipenser stellatus) and their relationship with potentially toxic elements in the northern and southern regions of the Caspian Sea

Currently, the pollution of the Caspian Sea by the oil industry is one of the highest problems in this area. Critically endangered species inhabit this sea, such as sturgeons, whose ecological value is incalculable. Thus, we aimed to evaluate the level of contamination of aliphatic hydrocarbons of petroleum and its relation with several toxic elements directly on sturgeons spines. A total of 40 adult starry sturgeons (Acipenser stellatus) were obtained within a repopulation programme in the northern and southern coastal waters of the Caspian Sea. The marginal pectoral fin was extracted from each fish to determine aliphatic hydrocarbons, arsenic, cadmium, mercury, nickel, lead, and vanadium. Subsequently, the sturgeons were released. Clearly, the presence of hydrocarbons was evidenced in all the sampled areas finding higher concentrations in the northern areas (N1 = 1.35 ± 0.4; N2 = 1.65 ± 0.46; N3 = 1.27 ± 0.40; S1 = 0.61 ± 0.22; S2 = 0.85 ± 0.43 mg/kg). Furthermore, to a greater or lesser extent, some toxic elements, mainly Hg and As, have been linked to aliphatic hydrocarbons.

Protection against thermal stress: the role of Tex-OE® in inducing HSP70 and boosting defense mechanisms in Acipenser stellatus fry

Protection against thermal stress: the role of Tex-OE® in inducing HSP70 and boosting defense mechanisms in Acipenser stellatus fry

Spatial Planning of Marine Protected Areas (MPAs) in the Southern Caspian Sea: Comparison of Multi-Criteria Evaluation (MCE) and Simulated Annealing Algorithm

Protected areas are referred to around the world as the basis of conservation strategies. Designation of marine protected areas (MPAs) is to preserve marine biodiversity and protect species, habitats in the seas, and oceans. The simulated annealing algorithm (SAA) with other algorithms (swap iterative improvement, normal followed by two step, two step iterative improvement, and normal iterative improvement) in MARXAN conservation solutions software and the multi-criteria evaluation (MCE) method were used to locate MPAs in the Southern Caspian Sea. Then, four methods were examined for site selection that include: (1) Simulated annealing algorithm, (2) MCE with zonal land suitability (ZLS), (3) MCE with compactness and contiguity, and (4) combined method of multi-criteria evaluation with spatial constraints and a simulated annealing algorithm (improved MCE). In the MCE method, we applied different weighted scenarios to locate MPAs. The criteria for determining the desired regions of MPAs included 12 factors gathered in three groups, including: (1) Ecological criteria (distribution of fish Huso huso, Acipenser persicus, Acipenser stellatus, Rutilus frisii kutum, and Alosa braschnikowi; location of coastal protected areas, distance from coastal rivers (Coastline), distance from estuaries and deltas); (2) Physical criteria (distance from the coast, shore sensitive areas); and (3) Socio-economic criteria (distance from densely populated coastal cities, distance from industries near the coast). The results of comparing the algorithms in MARXAN 4.0.6 software showed that the simulated annealing algorithm has a better ratio of border-length/area than other algorithms. Also, the combined method of MCE (improved MCE) selects the best protection patches in terms of location, taking into account the seascape ecology metrics (e.g., patch compactness, edge density, normalized entropy, area metric for patches). Moreover, the results of the comparison of four methods for proposing MPAs based on seascape metrics showed that the combined method of MCE considers a protection network with more contiguity and compactness than the simulated annealing algorithm. The use of seascape ecology can help to preserve and create larger and denser patches in the arrangement of protective areas, because such a selection of protective areas is nature-inspired and can be more bold and appropriate in the course of conservation planning.

Effect of Iron Nanoparticles on the Intestinal Bacterial Flora and Histology of the Intestine and Kidney in Stellate Sturgeon (Acipenser stellatus Pallas, 1771)

Effect of Iron Nanoparticles on the Intestinal Bacterial Flora and Histology of the Intestine and Kidney in Stellate Sturgeon (Acipenser stellatus Pallas, 1771)

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].

Potential Assessment of Sturgeon Muscle Tissue as a Development Basis for Specialized Athletes Nutrition

Specialized food products use in the athlete diet developed considering the needs for nutrients is one of the most important factors in achieving high sports results and rapid recovery after physical activity. The study aims at possibility assessment of the muscle tissue use of sturgeon fish as a basis for the specialized food products development for athletes. Total chemical composition analysis of 13 sturgeon muscle tissue samples demonstrated that these fish species belong to the protein one with 15.73–19.38% protein content. According to the fat content, there are two groups to be identified: Sib×Sevr, BS×AO, bester Burtsevsky, bester vnirovsky, RO×L belong to fatty fish species (8.22–13.49% fat), and bester Aksai, K, K×A, St×K, AO – to medium-fat fish (4.70–7.92% fat). The study of the amino acid score of muscle tissue proteins has shown their high biological value. Only Burtsevsky bester and Siberian sturgeon differed in the presence of a limiting amino acid (valine), the rest of the samples studied had an amino acid score of more than 100%. The highest content of carnosine dipeptide is observed in hybrids between Siberian sturgeon and stellate sturgeon (385 mg/100 g), between Kaluga and Amur sturgeon (382.6 mg/100 g), as well as in bester vnirovsky (331.2 mg/100 g) and Amur sturgeon (308.8 mg/100 g). The fatty acid composition analysis of lipids showed the unsaturated fatty acids prevalence in it and a high total content of polyunsaturated eicosapentanoic and docosahexaenoic fatty acids (5.79–12.70%). A comprehensive assessment of the chemical composition coefficient and structural and mechanical characteristics of minced meat based on sturgeon muscle tissue revealed that this type of raw material is efficient in product manufacture for athletes.

Protective effects of HSP Inducer on diazinon-exposed stellate sturgeon (Acipenser stellatus) fry: Insights on HSP70 gene expression, immune response, and enzyme indices.

Aquatic environments face frequent exposure to organophosphate pesticides, such as diazinon, which are frequently utilized in agriculture. The goal of this study was to evaluate the effects of diazinon exposure on fish and to investigate the potential of the HSP inducer (HSPi) in developing a defense mechanism. To achieve this, several factors were analyzed, including the HSP70 gene expression, levels of immunity markers (lysozyme, IgM, and C3), antioxidant status, and the activity of acetylcholine esterase (AChE). Stellate sturgeon (Acipenser stellatus) fry, was exposed to diazinon (25, 50, and 75% of 96h-LC50) for 6 days after pre-treatment with an HSP inducer (HSPi), TEX-OE® (a prickly pear cactus extract), for 4 hours. Two HSPi concentrations, 100 and 200 mg.L-1, were used. Pre-treatment with HSPi significantly enhanced HSP70 gene expression in the gill and liver, as well as immune markers in the blood of Acipenser stellatus. Diazinon-treated groups exhibited higher antioxidant activities of SOD, CAT, and T-AOC. Increased activity also observed in control fish pre-treated with HSPi. However, stellate sturgeon receiving both diazinon and HSPi+diazinon experienced a significant decrease in AChE activity in comparison with control group. Cortisol levels were elevated in the fish that were subjected to diazinon. Those subjected to diazinon after receiving HSPi showed a significant decrease in cortisol levels. In conclusion, the study suggests that HSPi-mediated HSP70 induction may have a protective effect. The presence of an HSP inducer offers a potential strategy to mitigate the consequences of diazinon exposure in stellate sturgeon.

Investigating the effect of type of fish and different cooking methods on the residual amount of polycyclic aromatic hydrocarbons (PAHs) in some Iranian fish: A health risk assessment.

The aim of this study was to assess the level of PAHs and associated health risks in different types of fish cooked with different methods, using the MSPE-GC/MS technique (magnetic solid phase extraction with gas chromatography/mass spectrometry). The limits of detection (LODs), limits of quantification (LOQs) and recovery percentages ranged from 0.1 to 0.63μg/kg, 0.3-1.89μg/kg, and 93.7 to 102.6%, respectively. The results showed that the mean of ƩPAHs in all samples was 20.31±6.60µg/kg. Additionally, PAH4 and BaP levels in all samples were 4.58±1.40 and 1.08±0.36µg/kg, respectively, which were below the European Union (EU) standard level (12 and 2µg/kg, respectively). The results showed that among 5 types of fish, starry sturgeon had highest average total PAHs (13.24±1.84µg/kg), while Caspian Sea sprat had the lowest average total PAHs (1.24±0.8µg/kg). In terms of cooking methods (charcoal-grilled fish, fried fish and oven-grilled fish), charcoal-grilled fish had the highest average total PAH level at 25.41±7.31µg/kg, while the lowest average total PAH was found in the raw fish sample at 16.44±4.63µg/kg. The Monte Carlo Simulation was used to determine the 95% ILCRs (Incremental Lifetime Cancer Risk) due to ingestion of fish. The results showed that the ILCR for adults was 2.85E-9, while for children it was 1.32E-8. Therefore, based on these findings, it can be concluded that the consumption of fish cooked with different methods does not pose a risk to human health in terms of the amount of PAHs (ILCR<1×10-4).

An Overview of the Status of Sturgeons and Cetaceans Accidentally Captured in Southern Black Sea Coastal Zone of Türkiye

This study was conducted out in the southern Black Sea coastal zone, in 2011-2016 fishing seasons. In the study, bycatch of sturgeons and cetaceans were examined both in small scale (turbot gillnets) and large scale (trawlers) fisheries. During the fishing operations within the study, 66 sturgeons (41 Danube sturgeon - Acipenser gueldenstaedtii and 25 starry sturgeon - Acipenser stellatus) and 49 cetaceans (40 harbor porpoises - Phocoena phocoena relicta and 9 short beaked dolphin - Delphinus delphis ponticus) were captured. Length-weight relationships of Danube sturgeon and starry sturgeon were determined as W=0.0123L2.8808 (R=0.9964, negative allometric growth) and W=0.0345L2.5351 (R=0.9961, negative allometric growth), respectively. Mean total length were calculated as 60.02±1.04 cm for Danube sturgeons, 46.42±1.17 cm for starry sturgeon and mean fork length were established as 126.75±3.36 cm for harbor porpoises, 163.74±1.42 cm for short beaked dolphins in the study.

Fin-spine microchemistry discriminates regional stocks of Caspian Sea starry sturgeon

Chemical markers in otoliths have been used to assess the stock structure of many marine fishes, but these natural markers have yet to be widely evaluated in the spines of sturgeon fishes in the Caspian Sea, which has six endangered sturgeon species. We used inductively coupled plasma mass spectrometry to quantify B, Ba, Ca, Cu, Fe, Li, Mg, Mn, Si, Sr, and Zn in pectoral fin spines of starry sturgeon (Acipenser stellatus) in the northern and southern Caspian Sea, where depth, salinity, and temperature vary from north to south. Fin spines showed significant regional differences in B/Ca, Cu/Ca, Mn/Ca, Si/Ca, Sr/Ca, and Zn/Ca (Scheirer–Ray–Hare test, p < 0.05). Principal component analysis indicated distinct north/south groups when considering all significant elements in ratio to calcium. The centroids of these regional groups differed significantly (PERMANOVA, p < 0.05). Flexible discriminant analysis classified 85.3% of fish into their correct regions using all element-to-calcium ratios. These results suggest that individuals in different regions share common lifetime environmental histories and may represent unique stocks in the Caspian Sea. Moreover, the findings suggest that pectoral fin-spine microchemistry can be used to identify stocks of starry sturgeon, thus providing a non-lethal approach to elucidating life-history details that are critical to the comprehensive management of sturgeon resources.