Sturgeon Populations Research Articles

The Antibacterial Efficacy and Mechanism of Tea Polyphenol Against Drug-Resistant Aeromonas veronii TH0426 In Vitro.

The emergence of Motile Aeromonas Septicemia (MAS) caused by Aeromonas veronii in sturgeon farming has become a significant concern due to its high mortality impact on the aquaculture industry. The threat posed by MAS highlights the urgent need for effective control measures to combat bacterial infections in sturgeon populations. Tea polyphenol (TP) has demonstrated promising antibacterial properties against livestock and poultry bacterial infections. However, its antibacterial efficacy and mechanism in bacterial diseases of aquatic animals remain largely unexplored. This study aimed to investigate the in vitro antibacterial effect and mechanism of TP on fish-borne drug-resistant A. veronii TH0426 by assessing the impact of TP on TH0426 cell growth, antibiofilm activity, morphology, as well as measuring electrical conductivity, DNA extravasation, lactate dehydrogenase (LDH) activity, protein, and DNA contents. Results demonstrated that the minimum inhibitory concentration and the minimum bactericidal concentration of TP on TH0426 were 1024 and 2048 μg/mL, respectively. After a 4 h treatment, the growth of TH0426 was completely inhibited at the concentration of 1024 and 2048 μg/mL of TP. Meanwhile, TP exhibited a significant antibiofilm activity. Both scanning electron microscope and transmission electron microscope analyses revealed disrupted cell membrane structure, irregular cell morphology, and loss of intracellular contents following TP treatment. Moreover, increased cell membrane permeability induced by TP led to intracellular ion and DNA leakage, resulting in elevated electrical conductivity and DNA extravasation. Furthermore, TP decreased LDH activity, protein concentration and content, DNA fluorescence intensity, and density in a time-dependent manner, indicating inhibition of protein metabolism and DNA synthesis. In conclusion, TP exhibits potent antibacterial properties by inhibiting biofilm formation, disrupting cell membrane integrity, and interfering with protein metabolism and DNA synthesis in drug-resistant A. veronii TH0426 in vitro.

Effects of Alkalinity Stress on Amino Acid Metabolism Profiles and Oxidative-Stress-Mediated Apoptosis/Ferroptosis in Hybrid Sturgeon (Huso dauricus ♀ × Acipenser schrenckii ♂) Livers

Alkaline water is toxic to cultured aquatic animals that frequently live in pH-neutral freshwater. Overfishing and habitat destruction have contributed to the decline in the wild sturgeon population; consequently, the domestic hybrid sturgeon has become an increasingly important commercial species in China. Hybrid sturgeons are widely cultured in alkaline water, but little is known about the effects of alkalinity stress on hybrid sturgeon liver tissues. We exposed hybrid sturgeons to four alkaline concentrations (3.14 ± 0.02 mmol/L, 7.57 ± 0.08 mmol/L, 11.78 ± 0.24 mmol/L and 15.46 ± 0.48 mmol/L). Histopathology, biochemical index assessment, gene expression level detection and metabolomics analysis were used to investigate the negative effects on liver functions following exposure to NaHCO3. Livers exposed to alkaline stress exhibited severe tissue injury and clear apoptotic characteristics. With increased exposure concentrations, the hepatic superoxide dismutase, catalase, glutathione peroxidase and alkaline phosphatase activities significantly decreased in a dose-dependent manner. NaHCO3 exposure up-regulated the transcriptional levels of apoptosis/ferroptosis-related genes in livers. Similarly, the expression trends of interleukin-1β and heat shock protein genes also increased in high-alkalinity environments. However, the expression levels of complement protein 3 significantly decreased (p < 0.05). Hepatic untargeted metabolomics revealed the alteration conditions of various metabolites associated with the antioxidant response, the ferroptosis process and amino acid metabolism (such as beta-alanine metabolism; alanine, aspartate and glutamate metabolism; and glycine, serine and threonine metabolism). These data provided evidence that NaHCO3 impaired immune functions and the integrity of hybrid sturgeon liver tissues by mediating oxidative-stress-mediated apoptosis and ferroptosis. Our results shed light on the breeding welfare of domestic hybrid sturgeons and promote the economic development of fisheries in China.

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.

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.

Динамика биологических показателей возвратных гибридов на основе кастера (калуга Huso dauricus × стерлядь Acipenser ruthenus) (Acipenseridae)

Due to the lack of conditions for industrial sturgeon fishing in the near future, the current artificial reproduction programs play a leading role in replenishing sturgeon populations and commercial sturgeon breeding. It may take a long time to bring the number of individuals and the total biomass of sturgeon fish species in different water basins into proper condition. It is important, along with the implementation of programs for the stocking of young sturgeons of various types of natural habitats, to develop commercial cultivation. Modern aquaculture is the use of environmental control systems, timely feed supply, rapid growth of juveniles with a minimum feed ratio, high survival rate at all stages of growth, greater yield of edible body parts during processing. The dynamics of size and mass indices and the Fulton fatness coefficient in recurrent hybrids of different ages (K × St) are considered × K, (K × St) × St, (St × K) × K and (St × K) × St. It is noted that the fastest growing hybrids turned out to be returnable hybrids based on K × St, and the hybrid (St × K) × St has the highest fatness coefficient with a slight growth rate of weight and length.

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.

Reclaiming the Xhotsa: climate adaptation and ecosystem restoration via the return of Sumas Lake

Sumas Lake (Xhotsa), located in the Fraser Valley, British Columbia, Canada, was the heart of Semá:th Nation Territory and the epicenter of a complex Indigenous food system. For the Semá:th people, the lake represented life and livelihood. In 1924, the lake was stolen and drained in an instance of land theft that occurred during a nationwide campaign of land dispossession and genocide, decimating an ecology that supported a rich and diverse Indigenous food system and replacing it with a settler food system. A century later, in November 2021 climate change induced flooding caused the lake to return, resulting in the evacuation of thousands of people and causing millions in damages to homes and infrastructure. Since the flood, the response has been a continuation of the status quo to protect settler agricultural lands via increased investment in hard structures that control the flow of water based on assumptions of the predictability of future flow conditions. We offer a missing narrative by bringing together an analysis of Indigenous laws and oral tradition with an assessment of the economic costs of “managed retreat”, defined as the purposeful relocation of people and infrastructure out of harm’s way. We find that the cost of buying out properties in the lakebed and allowing the lake to return is close to half the cost ($1 billion) of maintaining the status quo ($2.4 billion), while facilitating climate adaptation, and restoration of a floodplain ecosystem that supported thriving populations of people, salmon, sturgeon, ducks, and food and medicinal plants– including many species which are now endangered. Returning Sumas Lake by centering ‘Water Back’ as a climate resiliency solution, enacts both food systems and ecological reconciliation, addressing the harms caused by the loss of the lake to the Semá:th People that is still felt to this day. In a time when climate change induced flooding is predicted to increase, this study demonstrates how the inclusion of Indigenous laws and knowledges are critical to the development of solutions toward a more sustainable and just future.

Spawning run estimates and phenology for an extremely small population of Atlantic Sturgeon in the Marshyhope Creek–Nanticoke River system, Chesapeake Bay

AbstractObjectiveOnce thought to be extirpated from the Chesapeake Bay, fall spawning runs of Atlantic Sturgeon Acipenser oxyrinchus have been rediscovered in the Marshyhope Creek (MC)–Nanticoke River (NR) system of Maryland, United States. High recapture rates in past telemetry surveys suggested a small population in the two connected tributaries. This study aims to generate estimates of abundance and understand within system connectivity for spawning runs in 2020 and 2021.MethodsData from mobile side‐scan sonar surveys and detections of acoustically tagged adults on stationary telemetry receivers were analyzed in an integrated model to estimate spawning season abundance and examine run timing and system connectivity for this population. An array of acoustic receivers was deployed throughout the MC–NR system to monitor the movement of tagged fish during the spawning run period from mid‐August to late October. Side‐scan sonar surveys were conducted weekly in September in an area of high spawner aggregation to generate count data on spawning run abundance.ResultIn 2020 and 2021, 32 (95% credible interval [CRI] = 23–47) and 70 (95% CRI = 49–105) Atlantic Sturgeon, respectively, used the MC–NR system. The lower estimate for 2020 coincided with an earlier end to the spawning run related to cooler September temperatures in that year.ConclusionIn both years, high spawning run connectivity between MC and the upper NR was observed. Overall, run estimates supported previous hypotheses that the MC–NR system supports a very small population and that both MC and the upper NR serve as important areas for spawning activity.

Long‐term trends in abundance and recruitment of Shortnose Sturgeon in the Altamaha River, Georgia

AbstractObjectiveThe objective of this study was to estimate the population size and annual recruitment of Shortnose Sturgeon Accipenser brevirostrum in the Altamaha River estuary in Georgia, United States, during an 11‐year period. The Shortnose Sturgeon is an endangered fish species that occupies rivers on the east coast of North America. Previous studies have suggested that the Altamaha River supports the largest population of Shortnose Sturgeon in the southern United States; however, the status of the population has not been assessed in 11 years.MethodsWe used entanglement gears to capture Shortnose Sturgeon in the Altamaha River estuary, marked them, and used an established statistical method (closed‐population capture–mark–recapture models) to annually estimate total population size and age‐1 recruitment from 2012 to 2022.ResultWe were able to estimate the size of age‐1 cohorts in 7 of the 11 years of data collection. Point estimates of annual age‐1 recruitment varied between 113 and 1021 individuals, and total population size varied between 452 (95% confidence interval [CI]: 116–2277) and 5054 individuals (95% CI: 2155–13,267).ConclusionRecruitment of age‐1 juveniles was variable, suggesting that reproduction success is inconsistent between years in the Altamaha River. The results of this study, in combination with previous work, do not show any clear trends in Altamaha River Shortnose Sturgeon population abundance or recruitment. The population seems to be stable, but in the absence of historical population numbers, it is unclear whether the population should be considered recovered or is stagnated in its recovery.

An integrated population model and sensitivity assessment for a data-poor population of green sturgeon

Conservation planning requires understanding population sizes and trajectories. As with many imperiled species, green sturgeon ( Acipenser medirostris) census data are limited, making it difficult to contextualize current threats and promote quantitative conservation goals. We combined spawning census, growth, and demographic data for the southern population of green sturgeon to build a population size and trajectory estimate. We generated a distribution of population size estimates and trajectories reflecting uncertainty from multiple sources. We then propagate these estimates through a demographic model to assess the potential impact of fishing bycatch. Our model suggests the population is below the recovery goal of 3000 adults. The most probable current total population estimate (including juveniles) is approximately 10 000 fish (5300–18 400 95% high density interval (HDI)), with 2400 adults (2197–2624 95% HDI). Simulated fishing bycatch pressure on the adults and subadults reduced abundance by a median value of 0.4% per year, which could be an impediment to recovery. Fisheries bycatch is one of many threats this population faces; this integrated framework may be used to assess how other threats may affect this population.

Occupancy, movement, and behaviour of namew (lake sturgeon Acipenser fulvescens) in an intact river in Canada

Most sturgeon populations are imperilled and living in fragmented rivers. Here, we studied namew (lake sturgeon Acipenser fulvescens), fish important to Ililiwak (Moose Cree Peoples), in the North French River: a free-flowing, intact river in Kit Aski Nahnuun (the Moose Cree Homeland) in northern Ontario, Canada. This study was co-created alongside members of Moose Cree First Nation and used acoustic telemetry to passively track 20 tagged namew over 6 yr (2016-2022). Namew occupied the entire monitored river reach: about 45 km. Namew used 2 overwintering areas and occupied more overall river sections during spring and summer (out of 6 total seasons often used by Ililiwak). We did not detect namew moving upstream or downstream during freeze-up and winter. Generally, namew showed the greatest acceleration and travelled the longest distances during spring and summer, and they occupied shallower water during summer at lower water levels and deepest waters during freeze-up. We found an interaction between season and diurnal period, where namew occupied shallower depths and had higher acceleration at dawn and night relative to morning and afternoon in most seasons; dusk behaviour was variable among seasons. However, this pattern was absent in spring, when namew showed no diurnal pattern in acceleration and were in shallower water during morning and afternoon. Diurnal patterns were less pronounced, but detectable, during ice-affected seasons. This river provides year-round habitat for namew, and our data reveal distinct patterns of namew occupancy, movement, and behaviour in a free-flowing, intact river. Our work is an example of successfully co-creating research that addresses both scientific and community priorities.

The carryover effects of embryonic incubation temperature on subsequent growth and thermal tolerance in white sturgeon

Environmental variation experienced during early periods of development can lead to persistent phenotypic alteration, known as carryover effects. Such effects increase concern for threatened or endangered species such as the white sturgeon (Acipenser transmontanus), particularly considering expected thermal changes due to climate change. We evaluated how temperature during embryonic development affects physiological parameters such as larval and early juvenile growth and thermal tolerance. Nechako River white sturgeon embryos were incubated at different environmental temperatures (Te) of 12 °C (the natural spawning temperature of this population), 15 °C (the hatchery incubation temperature), and 18 °C (representing potential increases in river temperatures given global climate change). After hatch, fish were reared at a common 15 °C for 80 days post-hatch (dph). Individuals from each temperature treatment were tested for thermal tolerance using the critical thermal maximum method (CTmax), euthanized, and measured. Fish were examined at regular intervals from 13 to 80 dph, which bridged the time from the start of exogenous feeding through the transition into early juveniles. We found carryover effects of high embryonic Te in the short term for both thermal tolerance and growth. Fish that developed at 18 °C had the lowest thermal tolerance during the start of exogenous feeding. However, differences in thermal tolerance were small for early juveniles and were unlikely to be ecologically relevant in the longer term. Fish that developed at 18 °C were smallest over the observation period, indicating a possible cost for survival from increasing environmental temperatures during embryonic development. This research represents a window into a critical period of development during which fish are particularly vulnerable to climatic variation, and shows that cooler temperatures (12 °C) during incubation are optimal for this population. The results can inform environmental managers on the best strategies to help conserve current white sturgeon populations across their range.

Effects of Acipenserid herpesvirus 2 on the outcome of a Streptococcus iniae co-infection in white sturgeon (Acipenser transmontanus)

Acipenserid herpesvirus 2 (AciHV-2) is a large double-stranded DNA virus in the family Alloherpesviridae that causes catastrophic outbreaks in young naive white sturgeon (Acipenser transmontanus) populations, with mortalities of up to 80%. Survivors of these infections are suspected to remain latently infected. The gram-positive zoonotic bacterium Streptococcus iniae is another important sturgeon pathogen that causes severe myositis and up to 50% mortality during natural outbreaks. Throughout the last decade, co-infections of AciHV-2 and S. iniae have been reported in cultured white sturgeon in California resulting in severe presentations of piscine streptococcosis. This phenomenon of herpesvirus and streptococcus co-infection appears to span multiple taxa since in humans, it is recognized that a Human herpesvirus 3 infection (VZV) is a negative prognostic indicator for pediatric Invasive Group A Streptococcal infections (IGASI). While a decrease in humoral immunity caused by VZV has been hypothesized as a potentially important factor in IGASI cases, no natural animal model exists to study this process. Moreover, no studies have investigated these reported co-infections in white sturgeon. Therefore, the goal of this study was to investigate the effects of a recent AciHV-2 infection on the outcome of a subsequent S. iniae challenge in white sturgeon fingerlings. When fish were infected with 108 colony forming units (CFU) of S. iniae intramuscularly (IM), a statistically significant decrease in survival of 41% was detected in the co-infection group compared to the S. iniae group (p-value < 0.001). This difference was not observed when fish were infected with 106 CFU of S. iniae IM. At this lower infection dose, however, a statistically significant downregulation of tnfα was observed in the spleen of fish in the co-infection group compared to the S. iniae group (p-value = 0.0098). Analysis of serum from survivors revealed a statistically significant reduction in anti-S. iniae serum IgM and serum serotransferrin in fish from the co-infection group compared to the S. iniae group (p-value = 0.0134 and p-value = 0.0183, respectively). Further studies are indicated to determine what interactions lead to the decreased production of pathogen-specific IgM, serotransferrin, and TNFα in the host.

Collateral benefits: River flow normalization for endangered fish enabled riparian rejuvenation

AbstractLike most rivers worldwide, the transboundary North American Kootenay/i River has experienced multiple impacts including watershed developments, river channelization, and floodplain clearing, draining, and diking. Construction of Libby Dam was authorized by the 1964 Columbia River Treaty (CRT) between the United States and Canada, and in 1975 began regulating downstream flows for flood risk management and hydropower generation. Following cumulative impacts, the endemic Kootenai River White Sturgeon population collapsed and was designated as endangered in 1994 (U.S. Endangered Species Act). Subsequent Biological Opinions from the U.S. Fish and Wildlife Service prescribed Libby Dam operations to provide springtime flow pulses for sturgeon spawning. These provided the unanticipated benefit of substantial seedling recruitment of native and introduced riparian cottonwoods and willows. The regulated flow regime was further adaptively managed to provide a more normative (natural) regime, to balance ecological functions with flood risk management and hydropower generation. The broadened ecological considerations would be consistent with the proposed priorities for the modernization of the international CRT. The observed responses revealed that (1) diverse aquatic and riparian organisms are dependent on common river flow characteristics; (2) a normalized flow regime provided substantial ecological benefits; and (3) due to multiple influences, hybrid ecosystems develop along regulated rivers, with a blending of natural and altered processes and communities. For other regulated rivers, we recommend that (1) high springtime flows be allowed, as feasible; (2) followed by the gradual post‐peak recession; and (3) the maintenance of sufficient flows through the warm and dry interval of mid to late summer.

The influence of channel morphology and hydraulic complexity on larval pallid sturgeon (Scaphirhynchus albus) drift and dispersal dynamics in the Fort Peck Segment, Upper Missouri River: insights from particle tracking simulations

Longitudinal dispersal of migratory fish species can be interrupted by factors that fragment rivers, such as dams and reservoirs with incompatible habitats, and indirect alterations to variables, such as water temperature or turbidity. The endangered pallid sturgeon (Scaphirhynchus albus) population in the Upper Missouri River Basin in North Dakota and Montana is an example of such fragmentation and alteration due to the construction of dams. We applied a high-resolution, 2+-dimensional modelling framework composed of hydrodynamic and Lagrangian particle tracking components to simulate pallid sturgeon larval drift and dispersal along a 33-km section of the Upper Missouri River to evaluate three main issues: a comparison between multidimensional models and traditional 1-dimensional models, the sensitivity of hydrodynamics to channel morphology, and the implications of channel morphology on retention and transport-time metrics for larval fish. The results indicate that multidimensional models better represent breakthrough curves of transporting larvae compared to 1-dimensional models, especially for the long tail of slow drifters in the population. Results also indicate that channel morphology and hydraulic complexity play significant roles in larval dispersal with certain flow conditions and channel features increasing larval retention and providing potential management options to increase survival rates by adjusting flow conditions during spawning events. For example, modelling indicates increased retention times at discharges 23–38% daily flow exceedance, coincident with emergence of mid-channel sandbars. Findings additionally emphasize the need for improved understanding of biological factors that affect larval drift and dispersal.

State of the Siberian sturgeon population in the Middle Lena in summer

The purpose: to obtain modern data on the distribution, abundance, size composition and biological state of the sturgeon in the middle reaches of the Lena River.Material: data of scientific accounting survey using bottom drift nets in summer 2022.The results: Siberien sturgeon is dstributed irregularly on a 400‑kilometer stretch of the river from the city of Yakutsk to the Vilyui River, with the highest average density near the Vilyui River mouth 163 ind./km2, while sturgeon densities in the areas of Yakutsk and the Aldan River mouth were 71 and 44 ind./km2 respectively. The highest density of fish with the smallest average size in the area near the Vilyui mouth indirectly indicates the presence of a separate herd in the Vilyui River. The average density of fish over the entire 400‑km area was 93 ind./km2. The sturgeon length to the end of the middle rays (ac) was from 21 to 86 cm; on average 43.4 ± 10.7 cm. The modal size class for the sturgeon in catches in 2022 was 41–50 cm (44% of the total catch). The fish weight ranged from 40 to 3800 g. The average weight of individuals was 0.557. More than 80% of fish from all catches weighed up to 700 g. The weight of fish with a length ac 62–71 cm ranged from 0,400 to 1.415 kg, on average 1.0 kg. There were only 2.5% of commercial individuals in the total harvest. Sexually mature females were noted only near the Aldan mouth, where their share was 11% that may indicate the presence of spawning grounds in its channel. In the sample of fish that underwent a complete biological analysis (one third of the catches), sexually mature males were not observed. Estimated number of sturgeon: in Yakutsk city area — 17000 ind., in the Aldan mouth area — 47000 ind., in the Vilyui mouth area — 55000 ind. The total number of Siberian sturgeon on a 400‑kilometer stretch of the Lena River was at least 120000 ind. The state and structure of sturgeon population corresponds to the average statistical retrospective data.Practical value: the results obtained will improve the efficiency of assessing the distribution and stock of sturgeon in the Lena River.

A genetic approach to assessing the biodiversity of Atlantic sturgeons <I>Acipenser oxyrinchus</I> and <I>A. sturio</I> (review of modern literature)

The purpose of the review is to summarize modern data on the phylogenetic relationships of two sturgeon species, the North American Atlantic sturgeon Acipenser oxyrinchus and the European Atlantic sturgeon A. sturio, living in the Baltic Sea, due to the complete loss of A. sturio and the presence of a small number of individuals of A. oxyrinchus. Methods used: comparative analysis of modern literature data, a deconstruction method in which studies reflecting the molecular genetic characteristics of species have been carefully selected.The result of the review is structured data on molecular genetic studies of two sturgeon species. Combining research methods conducted with these species in one review.Significance: The results of the generalization are necessary for organizing measures to restore the lost population of sturgeon that lived in the water bodies of the Baltic Sea basin and was lost due to overfishing and changes in the habitat. A systematic approach to the molecular genetic labeling of fish both in the wild and in fish farms will ensure the control of the released juveniles, which will facilitate further research in this field of science.

The Effects of Tachykinin1 Gene Products on Prepubertal Dabry's Sturgeon (Acipenser dabrynus) Pituitary Hormone Secretion and Gene Expression.

As an ancient and endangered species unique to the Yangtze River in China, the wild population of the Dabry's sturgeon has become scarce. Due to the long time till the first sexual maturity of Dabry's sturgeon, the population of artificially bred Dabry's sturgeon recovered slowly. As a member of the tachykinin family, TAC1 has been reported to have a variety of functions in mammals such as pain control, smooth muscle contraction and reproductive cycle regulation, but the function of Tac1 in fish has been rarely reported. In this study, we synthesized two tac1 gene products, Substance P (SP) and neurokinin A (NKA), and further verified the effect of two tac1 gene products on the secretion of related hormones in the pituitary of Dabry's Sturgeon by intraperitoneal injection and co-culture of primary cells. Expression studies revealed that the newly cloned tac1 were mainly distributed in the hypothalamus and pituitary tissue of the brain. In prepubertal Dabry's sturgeon, this study showed that the two gonadotropins' mRNA levels in pituitary tissue can be significantly increased by SP and NKA through intraperitoneal injection, and the LH protein level in serum was also increased. Further study showed that both NKA and SP could promote the two gonadotropins' mRNA expression in pituitary cells of Dabry's sturgeon. In addition, we explored the optimal dose and time of SP and NKA on pituitary cells is 24 h and over 10 nM. These results, as a whole, suggested that tac1 gene products play an important role in gonadotropin release and gonadal development in prepubertal Dabry's sturgeon.

Leveraging Angler Effort to Inform Fisheries Management: Using Harvest and Harvest Rate to Estimate Abundance of White Sturgeon

Abstract Traditional methods for estimating abundance of fish populations are not feasible in some systems due to complex population structure and constraints on sampling effort. Lincoln’s estimator provides a technique that uses harvest and harvest rate to estimate abundance. Using angler catch data allows assumptions of the estimator to be addressed without relying on methods that could be prohibitively field-intensive or costly. Historic estimates of White Sturgeon Acipenser transmontanus abundance in the Sacramento–San Joaquin River basin have been obtained using mark–recapture methods; however, White Sturgeon population characteristics often cause violations of model assumptions, such as population closure and independent capture probabilities. We developed a version of Lincoln’s estimator using a joint likelihood, estimated abundance of White Sturgeon in the Sacramento–San Joaquin River basin in 2015 using this method and empirical data and assessed accuracy and precision of estimates in a simulation study. Estimating abundance using harvest and harvest rate, as represented by our model framework, has the potential to be precise and accurate. The joint likelihood–based approach fitted using Bayesian methods is advantageous because it includes all sources of variation in a single model. Precision of abundance estimates was low with application of the model to White Sturgeon in the Sacramento–San Joaquin River basin and to similar conditions in a simulated dataset. Using simulation, precision and accuracy increased with increases in the number of high-reward and standard tags released, tag reporting rate, tag retention rate, and harvest rate. Results demonstrate potential sources of error when using this approach and suggest that increasing the number of tagged fish and tag reporting rate are potential actions to improve precision and accuracy of abundance estimates of the model.