Sturgeon farming is expanding in Europe, with Italy leading in caviar production. However, wild sturgeon populations have declined due to overfishing and non-native species. Aquaculture enhances caviar and meat output but raises concerns about disease management, especially viral infections like Acipenser iridovirus-European (AcIV-E). Young specimens and fry are particularly vulnerable, and diagnostic methods rely on real-time PCR (qPCR), as conventional virological testing is ineffective.
The sample included 482 sturgeon specimens with various health issues and tank mortalities, collected from eight farms in Northern Italy between January 2021 and December 2023. The fish represented Acipenser spp. and Huso huso, aged 12 months or younger, including A. gueldenstaedtii (n = 257), A. stellatus (n = 56), A. baerii (n = 50), A. naccarii (n = 47), H. huso (n = 33), A. transmontanus (n = 22), and A. ruthenus (n = 17). Samples were refrigerated during transport to the lab, where moribund specimens were euthanized with tricaine methanesulphonate (MS–222) following standard regulations. Each specimen then underwent necropsy, as well as bacteriological, parasitological, and virological assessments, to certify its health status. For the virological analysis, gills were sampled as they contain the highest concentration of the virus. The extracts were then tested using qPCR assay targeting the major capsid protein of iridovirus.
Of the 204 sturgeons that tested positive for AcIV-E, farmers observed symptoms such as anorexia and swimming ataxia, with affected fish exhibiting uncoordinated movements. A. gueldenstaedtii had the highest positivity rate, increasing from over 61% in 2022 to 72% in 2023 (average 63.81%). A. naccarii showed rates of 36% in 2022 and 54% in 2023 (average 40.43%), while A. stellatus had an average positivity of 23.21%. A. baerii and A. ruthenus remained below 15%, peaking at 20% in 2022, whereas A. transmontanus and H. huso tested negative throughout the study.
A three-year study (2021–2023) revealed AcIV-E infection as a significant health issue in sturgeon farming in Italy, with about 42% of the 482 tested specimens testing positive. A. gueldenstaedtii showed the highest positivity rate (63.81%), followed by A. naccarii (40.4%). The virus poses risks to natural populations, especially given the challenges in diagnosing AcIV-E and isolating the virus. The study highlights the economic threat of AcIV-E-induced mortality in aquaculture and its ecological risk to wild sturgeon populations, already endangered due to overfishing and environmental disruptions.
The inability to isolate the virus and lack of specific symptoms hinder timely diagnosis, making continuous health monitoring essential for sturgeon populations, both farmed and wild, to manage disease and ensure conservation.