Crassostrea gigas (Thunberg 1793) cultivation in southern Adriatic Sea (Italy): A one-year monitoring study of the oyster health

Pacific oyster (Crassostrea gigas) farming has developed in recent years along the Italian coasts of the Adriatic sea. This is particularly true in sites located in the northern area and only recently becoming more common in the southern area, which is different particularly in regards to temperature and trophic conditions. There is a lack of studies on the status of the oysters farmed in this area; therefore, the present research aimed to monitor the health conditions of adult triploid oysters that were kept in offshore longline culture system over one year. Environmental parameters were daily estimated from satellite. Biometric, immunological and oxidative stress parameters were measured monthly, looking also for the presence of pathogens, such as OsHV-1, Vibrio aestuarianus and Vibrio splendidus. During summer months, high temperatures and low food availability had a detrimental impact on the growth and immunological parameters which showed a progressive recovery during the autumn and winter months. Overall, no abnormal mortality was observed, and no histological alterations were evident. The presence of pathogens was negligible, and the oxidative stress parameters were poorly detected, except for the digestive glands during the autumn and winter seasons. On this basis, the data herein reported suggest that the area could be suitable for the development of triploid Pacific oyster farming, although animals would require a longer time to reach commercial size.