Environmental DNA reveals the ecology and seasonal migration of a rare sturgeon species in the Ural River

Environmental DNA (eDNA) technology is an essential tool for monitoring living organisms in ecological research. The combination of eDNA methods with traditional methods of ecological observation can significantly improve the study of the ecology of rare species. Here we present the development and application of an eDNA approach to identify rare sturgeons in the lower reaches of the Ural River (Zhaiyk) (~1084 km). The presence of representatives of the genus Sturgeon was detected at all sites in spring (nine sites) and autumn (ten sites), while they were absent during the summer period, consistent with their semi-anadromous ecology. Detection in spring and autumn indicates the passage of spring and winter forms to the lower and upper spawning grounds respectively. This study confirms the difficulties of species-specific identification of Eurasian sturgeon and provides the first documented eDNA detection of specimens of the genus Sturgeon in the Ural River. It also provides a biogeographic snapshot of their distribution, experimentally confirming their seasonal migrations in the lower reaches of the river. The successful detection of sturgeon motivates further eDNA surveys of this and other fish species for accurate species identification and population assessment, opening up prospects for the management of these threatened species.