Atlantic Sturgeon Research Articles

Archaeogenomic analysis of Chesapeake Atlantic sturgeon illustrates shaping of its populations in recovery from severe overexploitation.

Atlantic sturgeon (Acipenser oxyrinchus ssp. oxyrinchus) has been a food resource in North America for millennia. However, industrial-scale fishing activities following the establishment of European colonies led to multiple collapses of sturgeon stocks, driving populations such as those in the Chesapeake area close to extinction. While recent conservation efforts have been successful in restoring census numbers, little is known regarding genomic consequences of the population bottleneck. Here, we characterize its effect on present-day population structuring and genomic diversity in James River populations. To establish a pre-collapse baseline, we collected genomic data from archaeological remains from Middle Woodland Maycock's Point (c. 200-900 CE), as well as Jamestown and Williamsburg colonial sites. Demographic analysis of recovered mitogenomes reveals a historical collapse in effective population size, also reflected in diminished present-day mitogenomic diversity and structure. We infer that James River fall- and spring-spawning populations likely took shape in recent years of population recovery, where genetic drift enhanced the degree of population structure. The mismatch of mitogenomic lineages to geographical-seasonal groupings implies that despite their homing instinct and differential adaptation manifested as season-specific behaviour, colonization of new rivers has been a key ecological strategy for Atlantic sturgeon over evolutionary timescales.

Non-natal Adult Atlantic Sturgeon Are Common in the Altamaha River Estuary, Georgia, USA

Non-natal Adult Atlantic Sturgeon Are Common in the Altamaha River Estuary, Georgia, USA

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.

Spatiotemporal patterns in habitat use of natal and non-natal adult Atlantic sturgeon in two spawning rivers

BackgroundMonitoring movement across an organism’s ontogeny is often challenging, particularly for long-lived or wide-ranging species. When empirical data are unavailable, general knowledge about species’ ecology may be used to make assumptions about habitat use across space or time. However, inferences about habitat use based on population-level ecology may overlook important eco-evolutionary contributions from individuals with heterogenous ethologies and could diminish the efficacy of conservation and management.MethodsWe analyzed over a decade of acoustic telemetry data to understand individual differences in habitat use of federally endangered adult Atlantic sturgeon (Acipenser o. oxyrinchus) in the Delaware and Hudson rivers during spawning season. In particular, we sought to understand whether sex or natal origin could predict patterns in habitat use, as there is a long-held assumption that adult Atlantic sturgeon seldom stray into non-natal rivers.ResultsIn both rivers, migration timing, spawning habitat occupancy, and maximum upstream migration distance were similar between natal and non-natal individuals. While non-natal individuals represented only 13% of fish detected in the Hudson River, nearly half of all tagged fish detected in the Delaware River were non-natal and generally occupied freshwater habitats longer than natal individuals. In both systems males had more heterogenous patterns of habitat use and longer duration of occupancy than did females.ConclusionsThis study demonstrates the importance of non-natal rivers for fulfilling ontogenetic habitat requirements in Atlantic sturgeon. Our results may also highlight an opportunity to improve conservation and management by extending habitat designations to account for more heterogenous patterns in individual habitat use in non-natal freshwater environments.

Evaluation of the effects of glucose concentration in extender and sperm concentration in straw for cryopreservation of Atlantic sturgeon (Acipenser oxyrinchus) semen

The Atlantic sturgeon (Acipenser oxyrinchus) faces unique conservation challenges due to its extended maturation period and irregular spawning patterns, which restrict its reproductive capacity. Therefore, in order to overcome these difficulties we have made a first attempt to develop effective cryopreservation procedure for Atlantic sturgeon through evaluation of the effects of the glucose concentration in extender and final sperm concentration in straw on sperm motility parameters. A remarkably high (81 ± 8%) postthaw sperm motility was obtained. The other sperm velocity and trajectory parameters were differentially affected both by concentrations of glucose or sperm and cryopreservation process. Our results undoubtedly show that the post-thaw sperm motility of Atlantic sturgeon is highly influenced by the final glucose and sperm concentration. The recommended cryopreservation procedure includes 0.05 M glucose and 7.5% methanol at 1.0×109 spermatozoa ml−1. We have confirmed that our elaborated protocol can be used for cryopreservation of Atlantic sturgeon semen which can be subsequently used for long-term conservation of this endangered species, offering a valuable tool in efforts to safeguard its genetic diversity and contribute to its survival.

Integrating genetic and demographic data to refine indices of abundance for Atlantic sturgeon in the Hudson River, New York

Critical to Atlantic sturgeon Acipenser oxyrinchus oxyrinchus recovery and monitoring is the ability to estimate abundance and identify age- and stock-specific threats to survival. As adult Atlantic sturgeon spend much of their lives broadly distributed in marine and estuarine environments, it is challenging to collect data needed to estimate these demographic parameters in the adult population. Alternatively, data collected from juveniles and subadults before emigration may be used to calculate indices of abundance and provide insights into recruitment dynamics and stage-specific survival. However, uncertainty about stock mixture during early life stages may limit the use of juvenile and subadult data for monitoring recovery. To better understand early life stage stock composition, we conducted a genetic mixed-stock analysis of over 500 juvenile and subadult Atlantic sturgeon captured in an overwintering area in the Hudson River, New York, USA, from 2017 to 2022. The majority of Atlantic sturgeon in our study were natal to the Hudson River population, regardless of sex, size, or age. As such, indices of relative abundance estimated from survey data are expected to primarily characterize the demographic trends of Hudson River juvenile and subadult Atlantic sturgeon. We also found a small proportion of individuals that were most likely to have originated from more distantly located rivers, highlighting the potential for long-distance migration in juvenile and subadult Atlantic sturgeon. Results of this study strengthen our understanding of juvenile and subadult Atlantic sturgeon habitat use in the Hudson River and improve our ability to use data from early age classes to monitor recovery and stage-specific survival.

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.

Arrival and departure windows of Atlantic sturgeon in Chesapeake Bay in Virginia

Arrival and departure windows of Atlantic sturgeon in Chesapeake Bay in Virginia

The influence of water, diet, and temperature on 87Sr/86Sr in fin spines of juvenile Atlantic Sturgeon Acipenser oxyrinchus oxyrinchus

Analysis of microchemistry in fish fin spines offers a non-lethal approach to address key questions about life history specific movement and habitat use. Reconstruction of life history is based on chemical changes within calcified structures with an underlying assumption of elemental incorporation relative to environmental concentration. However, information on the relative contributions of water and diet to trace elements in calcified structures of fishes, including fin spines, is limited. Strontium (Sr) is commonly used in trace element studies because of its predictable changes within watersheds, with recent applications showing utility of 87Sr/86Sr for greater spatial resolution. In this study we evaluated the influence of water and diet 87Sr/86Sr on pectoral fin spines of Atlantic Sturgeon A. oxyrinchus oxyrinchus in controlled laboratory experiments. To understand the extent to which water and diet 87Sr/86Sr contribute to levels in fin spines, we exposed fish to one of four treatments for 12 weeks; a control, water spiked with 87Sr, and diet spiked with medium and high levels of 87Sr. To determine the amount of time it takes to elicit a shift in fin spine 87Sr/86Sr following a change in 87Sr/86Sr, fish were maintained in water- or diet-spiked treatments for up to 6 weeks. Lastly, we investigated how temperature may influence fin spine 87Sr/86Sr by holding fish at either 16 °C or 24 °C for 12 weeks. Our experiments indicated water is the primary contributor of 87Sr/86Sr levels in fin spines of Atlantic Sturgeon, and these levels shifted 1 week and 12 weeks following changes in water and diet, respectively. Water temperature did not have an effect on 87Sr/86Sr fin spine chemistry, although sample size was low (n = 3). These results provide guidance for interpretation of 87Sr/86Sr in pectoral fin spines of sturgeon and indicate usefulness of the technique for retrospectively estimating movement and habitat use.

Seasonal migration cues differ for dual‐spawning Atlantic Sturgeon in the Great Pee Dee River

AbstractObjectiveWe investigated environmental variables associated with spawning migration behavior for a dual‐spawning population of endangered Atlantic Sturgeon Acipenser oxyrinchus oxyrinchus in the Great Pee Dee River, South Carolina.MethodsFrom 2016 to 2021, 147 Atlantic Sturgeon were captured, implanted with acoustic transmitters, and monitored using a stationary array of 40 receivers located every 5–20 km along a 302‐km section of the Great Pee Dee River from the river mouth at Winyah Bay to the first movement barrier at Blewett Falls Dam, North Carolina.ResultWe observed 47 Atlantic Sturgeon attempting 74 spring migrations and 39 Atlantic Sturgeon attempting 76 fall migrations across 4 years of telemetry observations (2018–2021). Mixed‐effects models indicated that discharge interacted with water temperature to affect both migration initiation and upriver movement, and these interactions differed between the spring and fall runs. Spring runs were cued by rising temperatures and high river discharge, whereas fall runs were cued by falling temperatures and low discharge. Within migrations, spring‐run fish migrated further upriver when discharge was falling, and fall‐run fish moved further upriver when discharge was rising. Overall, fall‐run sturgeon migrated significantly further upriver than spring‐run sturgeon.ConclusionDifferences in migratory behavior between the two runs suggest potentially unique adaptations to ambient river conditions during the respective spawning seasons. Identifying the environmental factors that drive—and thereby limit—Atlantic Sturgeon migrations in the Great Pee Dee River informs regional recovery efforts and highlights the importance of studying and managing this species at the population level.

Recruitment of juvenile Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus) in the Savannah, Ogeechee, and Satilla Rivers in Georgia

Recruitment of juvenile Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus) in the Savannah, Ogeechee, and Satilla Rivers in Georgia

Recruitment of juvenile Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus) in the Savannah, Ogeechee, and Satilla Rivers in Georgia: Supplementary table

Recruitment of juvenile Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus) in the Savannah, Ogeechee, and Satilla Rivers in Georgia: Supplementary table

Evaluating population trends of juvenile Atlantic Sturgeon at low abundance in a dynamic estuarine environment (Hudson River, New York)

AbstractEvaluating population trends in dynamic estuarine environments can be challenging, especially when survey data include a high percentage of zero observations. In fishery‐independent surveys, zeros that come from reduced susceptibility to sample gears and reduced availability of the population to the survey impact survey catchability and negatively bias relative abundance indices. A zero‐inflated negative binomial model was used to standardize a juvenile Atlantic Sturgeon (Acipenser oxyrinchus oxyrinchus) relative abundance index (Hudson River, New York) that included a high proportion (42%) of zero observations and intra‐ and interannually variable covariates. Reduced susceptibility was related to low water temperature, with the percentage of zeroes increasing rapidly below 7°C. Availability was influenced by temperature and distance to salt front, as catch rates increased with temperature and peaked in mesohaline waters ~27 km downstream of the predicted salt front. An alternative index suggested significant population growth (r = 0.15; p‐value = 0.007) occurred from 2004 to 2015. The zero‐inflated model helped better understand Hudson River juvenile Atlantic Sturgeon ecology and relative trends in abundance, to better inform future management and monitoring decisions along the Atlantic Coast.

The history of the Atlantic sturgeon, Acipenser oxyrinchus Mitchill, 1815, in the Warta River of Central and Western Poland in the nineteenth century based on Polish sources

Abstract An analysis of Polish historical sources indicates that there are no references to sturgeon in the Warta River basin before 1810. It is hypothesized that there was no autochthonic sturgeon population in this river in historic times. The occasional occurrence of fish in the Warta River stemmed from their straying from the Oder River, especially during high waters. The situation changed in the second half of the nineteenth century because increasing pollution in the Oder River meant increasing numbers of fish entered the Warta River. Peak catches by fishers in Poznań were in the 1880s and early 1890s, after which the population collapsed and never recovered. Overfishing in this period stemmed primarily from the effects of regulating the Warta River for navigation. The data presented herein might have implications for the current sturgeon reintroduction program being conducted in the Warta River basin.

Hypothalamus-pituitary-interrenal (HPI) axis signaling in Atlantic sturgeon (Acipenser oxyrinchus) and sterlet (Acipenser ruthenus)

In vertebrates, the hypothalamic–pituitaryadrenal/interrenal (HPA/HPI) axis is a highly conserved endocrine axis that regulates glucocorticoid production via signaling by corticotropin releasing hormone (CRH) and adrenocorticotropic hormone (ACTH). Once activated by ACTH, Gs protein-coupled melanocortin 2 receptors (Mc2r) present in corticosteroidogenic cells stimulate expression of steroidogenic acute regulatory protein (Star), which initiates steroid biosynthesis. In the present study, we examined the tissue distribution of genes involved in HPI axis signaling and steroidogenesis in the Atlantic sturgeon (Acipenser oxyrinchus) and provided the first functional characterization of Mc2r in sturgeon. Mc2r of A. oxyrinchus and the sterlet sturgeon (Acipenser ruthenus) are co-dependent on interaction with the melanocortin receptor accessory protein 1 (Mrap1) and highly selective for human (h) ACTH over other melanocortin ligands. A. oxyrinchus expresses key genes involved in HPI axis signaling in a tissue-specific manner that is indicative of the presence of a complete HPI axis in sturgeon. Importantly, we co-localized mc2r, mrap1, and star mRNA expression to the head kidney, indicating that this is possibly a site of ACTH-mediated corticosteroidogenesis in sturgeon. Our results are discussed in the context of other studies on the HPI axis of basal bony vertebrates, which, when taken together, demonstrate a need to better resolve the evolution of HPI axis signaling in vertebrates.

Extensive search of genetic sex markers in Siberian (Acipenser baerii) and Atlantic (A. oxyrinchus) sturgeons

Sturgeons belong to an extraordinarily old and highly endangered group of fish. Although the sex determining region in this taxon was recently discovered, there is still a great need for the development of reliable gene expression markers for sturgeon sexing in their different life stages which could be easily applied in field conditions. In this study an extensive screening of the Atlantic sturgeon genome was performed using: AFLP (202 PC) and MS-AFLP (256 PC) markers likewise the Siberian sturgeon transcripts deriving from the Whole Transcriptome Sequencing (WTS) and cDNA-AFLP (128 PC). Genetic material extracted from female and male fins was used. AFLP reactions were minimized and automatized and a novel method for SCAR identification was proposed (SCAR-NGS). The 204 primary selected markers were subjected to gDNA or cDNA PCR amplifications, semi- and RT-qPCRs in order to confirm the presence of unique sex-marker sequences in the genomes or sex-linked expression differences. We identified eleven loci in the Atlantic sturgeon genome which exhibited sex-linked polymorphisms of the restriction sites (SNP based). In case of the Siberian sturgeon, 41 transcripts were confirmed to be expressed in a sex specific manner; three of which were also significantly differentially amplified in the female and male genomes. Six of those markers were highly overexpressed in males, which was quantified using RT-qPCRs. The approach enabled the discovery of DNA and RNA candidate sequences suitable for application in sturgeon sexing, being important both for commercial aquaculture optimization and genetic variability maintenance of sturgeons.

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.

Atlantic sturgeon and shortnose sturgeon exhibit highly divergent transcriptomic responses to acute heat stress

In comparison to most modern teleost fishes, sturgeons generally display muted stress responses. While a muted stress response appears to be ubiquitous across sturgeon species, the mechanisms unpinning this muted response have not been fully described. The objective of this study was to determine the patterns of hematological and transcriptomic change in muscle tissue following an acute high temperature stress (critical thermal maxima; CTmax) in two locally co-occurring but evolutionarily distant sturgeon species (Atlantic and shortnose sturgeon). The most striking pattern found was that Atlantic sturgeon launched a vigorous transcriptomic response at CTmax, whereas shortnose sturgeon did not. In contrast, shortnose sturgeon have significantly higher cortisol than Atlantics at CTmax, reconfirming that shortnose have a less muted cortisol stress response. Atlantic sturgeon downregulated a number of processes, included RNA creation/processing, methylation and immune processes. Furthermore, a number of genes related to heat shock proteins were differentially expressed at CTmax in Atlantic sturgeon but none of these genes were significantly changed in shortnose sturgeon. We also note that the majority of differentially expressed genes of both species are undescribed and have no known orthologues. These results suggest that, while sturgeons as a whole may show muted stress responses, individual sturgeon species likely use different inducible strategies to cope with acute high temperature stress.

The presence of Acipenser sturgeons in the Iberian Peninsula: a review of the existing literature

The conservation status of sturgeon species is highly alarming. Six of the European Acipenser species are critically endangered. Several studies developed in the last decades have analysed the distribution of sturgeons in the Iberian Peninsula, questioning the possibility of the native character of some Acipenser species there, with a special focus on the Adriatic sturgeon, A. naccarii. We review the available knowledge on the distribution on Iberian Acipenser sturgeons, in order to ascertain their nativeness status, as a necessary tool to implement measures for their management and conservation. One vagrant specimen of A. oxyrinchus, and several released or escaped specimens of A. baerii and A. naccarii have been recorded in the Iberian Peninsula. Our results show that the Atlantic sturgeon A. sturio is the only native sturgeon species that has had breeding populations in the past in the Iberian Peninsula. Regarding A. naccarii, further evidence is required to prove its dubious native character in the Iberian Peninsula. Although the reviewed studies have solidly shown that A. naccarii has been present outside the Adriatic basin, the presence of isolated individuals does not constitute sufficient evidence to sustain the existence of past breeding populations.

Refining capture-recapture recruitment estimation methods for Atlantic sturgeon

Refining capture-recapture recruitment estimation methods for Atlantic sturgeon