Development and application of genetic methodologies for Beluga sturgeon conservation (Huso huso)

The Beluga sturgeon (Huso huso) is one of the most iconic sturgeon species. It is well known for its impressive size, making it the largest freshwater fish worldwide, and its caviar, which is a valuable delicacy. Like most sturgeon species, H. huso is endangered and actively threatened, mainly by anthropogenic factors such as pollution, habitat degradation and overexploitation. This species is considered extinct in the Adriatic Sea, while it is still extant, with rarified populations, in the Azov-Black Sea, the Caspian Sea and respective tributaries. The populations of these two basins have been assessed as two separate conservation units by the 2b-RAD approach. Here, a new genotyping method is proposed, which can be used for reliable and cost-effective geographical allocation of a large number of individuals. With the aim of guiding the establishment of captive broodstock, in order to avoid reproductions between animals belonging to different conservation units, in this thesis the geographical origin of potential breeders reared in captivity was performed. Samples included captive individuals, except for a single one of unknown origin which was recently captured in the Po River, in Italy. Relying on mitochondrial and nuclear markers, the analyses performed allow us to better understand the composition of the available broodstocks used for reintroductions. This work highlights the importance of informing operational decisions when implementing conservation measures.