The 10th International Symposium on Sturgeon (ISS10)

The Adriatic sturgeon (Acipenser naccarii) is a Critically Endangered species endemic to northern Italy. Once considered possibly extinct in the wild, recent monitoring and genetic evidence suggest encouraging signs of persistence and potential recovery.
Between 2019 and 2024, monitoring activities were conducted in the Veneto Region, primarily in the Livenza River, in collaboration with local fishermen. Captured individuals were scanned for microchips, measured, and tissue samples were collected when possible. Genetic analyses combined mitochondrial sequencing, species-specific nuclear markers, and microsatellite genotyping to assess species identity, detect hybrids, and evaluate genetic diversity.
A total of 104 sightings were recorded, including five juveniles smaller than 25 cm—below the size threshold of stocked fish—suggesting natural reproduction. Of 27 tissue samples analyzed, 24 individuals were genetically identified as pure A. naccarii, consistent with the founding broodstock, while three were confirmed as interspecific hybrids (A. gueldenstaedtii × A. naccarii, and A. transmontanus × A. naccarii). Microsatellite analyses revealed low diversity within pure A. naccarii, reflecting their common origin, while hybrids formed distinct clusters.
These findings confirm that restocking programs have maintained A. naccarii in the wild and suggest that spontaneous reproduction is occurring. However, the detection of hybrids highlights risks posed by alien sturgeons and underscores the need for strict genetic screening of broodstocks, biosecurity in aquaculture, and legislative measures to prevent introductions of non-native species. Coordinated monitoring, centralized data collection, and alignment with international conservation frameworks are essential to safeguard the genetic integrity and long-term survival of the Adriatic sturgeon.

 

Adriatic Sturgeon, Hybridization, Restocking