Settlement of Bivalve Spat on Artificial Collectors (Net Bags) in Two Commercial Mussel Parks in the North-Western Adriatic Sea

Among aquaculture activities, shellfish culture is considered more sustainable and beneficial in terms of food security. Currently, only a few bivalve species are reared and there is a need to explore the possibility to introduce new candidates for shellfish farming. Due to the lack of information on bivalve recruitment in the North-Western Adriatic Sea, in this study, the possibility to collect natural spat of commercial species was investigated. Artificial collectors (net bags) were deployed in two sites, Pellestrina and Caleri (North-Western Adriatic Sea), within two commercial mussel parks, during the spring&ndash:summer and summer&ndash:autumn periods. At both sites, collectors were placed at a distance of 1 m from each other, from 5 to 14 m depth. The influence of season, site and depth on bivalve recruitment was inspected and the presence of invasive species was also evaluated. In all, 28 bivalve taxa were found, and a higher settlement rate was observed in summer&ndash:autumn compared to the spring&ndash:summer period. Mytilus galloprovincialis, Flexopecten glaber, Mimachlays varia and Aequipecten opercularis were the most abundant species in spring&ndash:summer. In the summer&ndash:autumn period, in both sites analysed, a very high quantity of Anadara transversa and F. glaber were found. Indeed, these species were dominant at Pellestrina and Caleri, respectively. Another non-indigenous species, Arcuatula senhousia, was also detected. Relevant amounts of Pectinidae spat, F. glaber in particular, were collected and the optimal depth range for the scallop spat collection was found to be between 8 and 14 m. Our results highlight the relevant potential of Pectinidae spat collection along the North-Western Adriatic coasts, even though the presence of invasive species needs to be monitored.