Search Results (10)

Beluga sturgeon (Huso huso Linnaeus, 1758, acipenseridae) and Adriatic sturgeon (Acipenser naccarii, Bonaparte, 1836, acipenseridae) within the Po River basin have been recently assessed for the IUCN Red List of Threatened Species and were found to be Extinct in the Wild and Critically Endangered, respectively. Significant declines in both species’ abundance have spurred major research efforts and management actions in recent decades. Recently, specific actions have been conducted to recover habitat connectivity through projects of river defragmentation and reintroduction plans have been implemented for both sturgeon species. To manage effective conservation efforts, knowledge of a species’ distribution and abundance is critical, especially for adult sturgeon that are able to move hundreds of kilometers away from release sites. Here, two new quantitative PCR (qPCR) assays to detect beluga sturgeon and Adriatic sturgeon environmental DNA (eDNA) in water samples have been developed with the goal of providing an alternative method to monitor their presence. Two Taqman-based assays targeting the mitochondrial cytochrome b region were developed and showed no amplification of other related and co-occurring fishes. A mesocosm within the Ticino Park on the Ticino River (a main tributary of the Po River), where both species are bred, was used to develop and validate the assays. The LOQ for H. huso assay corresponded to C_t = 41 (7.33 × 10⁷ DNA counts/µL of reaction) and for A. naccarrii it was Ct = 37 (2.23 × 10¹⁶ DNA counts/µL of reaction). Additionally, water samples were taken from the discard drainage, which flows directly into the Ticino River, testing positive detection of eDNA within a distance of up to 2 km. Overall, the results suggested that the two assays developed in this study could represent a promising new tool for monitoring both beluga and Adriatic sturgeon. Full article

In the present study, 10 allotriploid (3nALT) and 10 allopentaploid (5nALP) six-month-old hybrid fish and two 3nALT and four 5nALP 40-month-old hybrid fish, which resulted by crossing female Russian sturgeon Acipenser gueldenstaedtii (Brandt and Ratzeberg, 1833) and male American paddlefish Polyodon spathula (Walbaum, 1792), were investigated. It was revealed that six-month-old 3nALT and 5nALP hybrids initially had “undifferentiated” gonads, while in the 40-month-old hybrids, only testes were observed in one case of 3nALT and one case of 5nALP hybrids. The testis of 3nALT hybrids was partially developed with spermatogonia, while the testis of one 5nALP hybrid was in the second developmental stage with low spermatogonia density. We could not determine gonad differentiation in any of the cases when the hybrid individuals had the W sex chromosome. We concluded that the gonad differentiation of these interfamilial hybrids follows a similar pattern to interspecific hybrids of different ploidy parent species of the family Acipenseridae, which is consistent with the classical Haldane’s rule. However, it cannot be excluded that the testis of this/these hybrid(s) may produce fertile sperm after sexual maturity, depending on additional genetic, hormonal and environmental factors, and further research is required for its evaluation. Full article

The aim of this study was to analyze the survival and growth of intergeneric (Acispenser ruthenus × Huso huso L.) sterbel hybrids obtained by fertilizing sterlet eggs with cryopreserved beluga semen. The rate of embryonic development did not differ between sterbel hybrids (experimental groups) and sterlets (control groups), and the hatching period was identical in all groups. The survival rate of hybrid larvae was higher in the experimental groups than in the control groups. Body weight and body length measurements revealed that sterbel hybrids grew at a faster rate than the control group sterlets. The hybrid origin of sterbels produced with the use of cryopreserved beluga semen was confirmed in a genetic analysis based on species-specific DNA fragments. To the best of the authors’ knowledge, this is the first study to analyze the growth of sterbel hybrids derived from cryopreserved semen. The research findings indicate that this type of intergeneric hybridization delivers satisfactory results and can be applied in sturgeon aquaculture. Full article

Sturgeons (Family: Acipenseridae) are among the most endangered taxa worldwide. Significant resources have been invested into the conservation of global sturgeon populations, including the development of commercial aquaculture programs. These programs are intended to improve conservation outcomes by reducing the harvest of wild populations while still meeting commercial demand for sturgeon products. However, there is growing concern that commercial aquaculture programs may contribute to wild population declines through continued, illegal harvest and the escape and/or release of captive individuals into wild environments. These concerns may be particularly acute in the country of Georgia which, despite its small territory and altered landscape, is a globally significant hotspot for sturgeon diversity. In order to understand the potential threat of captive culture on wild sturgeon populations in Georgia, we used mitochondrial DNA sequencing and microsatellite analyses to identify the species and origin of sturgeons encountered in commercial settings. Microsatellite analyses showed significant differentiation between wild and commercial Russian sturgeon populations and highlighted the potential for wild-caught individuals to be present in coastal markets in Georgia. The analyses of mitochondrial haplotypes also suggested that commercial markets may contain sturgeon species that are not native to the region. Overall, our results suggest that wild sturgeon populations may still be exploited to support captive aquaculture programs and commercial sales. Full article

Rivers and their watersheds have been subject to various changes, including biodiversity, caused by anthropogenic activities. The Danube River and Black Sea basin overlap the geographic range of six species of anadromous fish belonging to the family Acipenseridae. Nowadays, they are endangered or at risk of extinction in the wild due to fragmentation and destruction of natural habitats, blocking their migration to spawning grounds, water pollution, and poaching. This paper presents a review of the historical and current distribution and evolution of the sturgeon populations of sturgeon species in the Danube River basin. Conservation status and measures for species protection, conservation, and restoration at the national, regional, and global levels are presented. Full article

The fish leech Acipenserobdella volgensis (Hirudinea: Piscicolidae) is a rare and poorly known freshwater species, which is thought to be an obligate parasite of sturgeons. This leech has a disjunctive range in Europe and Eastern Siberia. Here, we estimate the phylogenetic affinities and host range of A. volgensis using a set of DNA sequences (COI and 18S rRNA gene fragments), field observation data, and a review of the body of literature. Based on a time-calibrated Bayesian phylogeny, we show that the European and Siberian lineages of A. volgensis have been separated since the latest Pliocene (mean age = 2.7 Ma). The analysis of available host records indicates that this leech is characterized by a broader host range as it was collected from fish belonging to four families (Acipenseridae, Cyprinidae, Salmonidae, and Esocidae). Conversely, only a few suitable primary hosts (six sturgeons, one cyprinid, and one salmonid fish) were confirmed by earlier research. Moreover, this leech could be considered a facultative mussel-associated species that uses bivalves (duck mussel Anodonta anatina; Unionidae) as shelter. Globally, three other piscicolid leeches have been recorded from the mantle cavity of bivalve molluscs, that is, the freshwater taxa Caspiobdella fadejewi and Alexandrobdella makhrovi, and the marine species Austrobdella coliumicus. Full article

Purpose: Review the experience, principles and parameters of the sturgeon assessment quality by anomalies in early ontogeny. Results: Maintaining the number of sturgeon fish in the transboundary Caspian Sea is provided by five states (Russia, Iran, Azerbaijan, Turkmenistan, Kazakhstan) at 16 Sturgeon hatcheries, where their artificial reproduction is carried out. FAO recognizes Russia’s leadership in creating the basic technology for the sturgeon artificial reproduction, but the other four Caspian states also make a significant contribution to its modern optimizations. There is almost a century of tradition behind the technological development of artificial reproduction in sturgeons. During the artificial reproduction of sturgeons, anomalies in the structure and functions may occur, such as deformities, defects in organs and tissues, edema, hematomas, etc. The sturgeon anomalies classification is based on structural and functional principles. Identification of anomalies is carried out on the basis of a previously created classification, divided into nine large classes. Identification of sturgeon anomalies during the period of their artificial reproduction makes it possible to clarify the real value of replenishment of their stock. Methods: Analysis of professional scientific literature and practical guides. Conclusions: The presence and number of Sturgeon anomalies make it possible to determine their death percentage to calculate the real number of replenishment of the Caspian Sturgeon stock. Full article

The first case of infection of Streptococcus iniae in Adriatic sturgeon (Acipenser naccarii) was recently reported in a raceway system located in Northern Italy. A second episode of infection in sturgeons with absence of mortality and evident clinical signs, was registered in November 2020 in the same farm and is reported in this study. Histopathological changes observed in infected organs are described. The strains isolated in the two episodes were compared using molecular analysis based on PCR, phylogeny and virulence factors analysis. Not all the major virulence factors were detected for the two strains; in particular the strains 78697, isolated in November, lacks cpsD, compared to the strains 64844, isolated in September. Moreover, genetic variations were reported for lctO and pmg genes. These findings let us hypothesize a different virulence of the strains in accordance with clinical findings related to the sturgeons. Full article

Two species from the families Acipenseridae and Polyodontidae, Russian sturgeon (Acipenser gueldenstaedtii, Brandt and Ratzeberg, 1833; functional tetraploid) and American paddlefish (Polyodon spathula, Walbaum 1792, functional diploid) were hybridized. The hybridization was repeated using eggs from three sturgeon and sperm from four paddlefish individuals. Survival in all hybrid family groups ranged from 62% to 74% 30 days after hatching. This was the first successful hybridization between these two species and between members of the family Acipenseridae and Polyodontidae. Flow cytometry and chromosome analysis revealed two ploidy levels in hybrids. The chromosome numbers of the hybrids ranged between 156–184 and 300–310, in “functional” triploids and “functional” pentaploids, respectively. The hybrid origin and the ploidy levels were also confirmed by microsatellite analyses. In hybrids, the size and the number of dorsal and ventral scutes correlated with the ploidy levels as well as with the calculated ratio of the maternal and paternal chromosome sets. An extra haploid cell lineage was found in three hybrid individuals irrespective of the ploidy level, suggesting polyspermy. Although the growth performance showed high variance in hybrids (mean: 1.2 kg, SD: 0.55), many individuals reached a size of approximately 1 kg by the age of one year under intensive rearing conditions. Full article

We report the first case of Acipenser iridovirus European (AcIV-E) infection in starry sturgeon (Acipenser stellatus) and in sterlet (A. ruthenus) reared in Northern Italy. During 2018, mortality began in A. stellatus and A. ruthenus specimens reared in co-habitation with Russian sturgeon positive for AcIV-E. Molecular analyses were done on the gills to amplify a fragment of the major capsid protein (MCP) gene using real-time PCR against AcIV-E. DNA of the positive samples was further sequenced and phylogenetic analyses were performed. The MCP gene sequences were highly similar to a virus previously identified in Italy (nucleotide identities between 99.38% and 99.69%). Phylogenetic analysis confirmed our hypothesis of passage of the virus from the infected Russian sturgeon. The detection of AcIV-E in new species of the Acipenseridae family may impact on sturgeon production, with relevant economic losses. Full article