Exploring farmers' knowledge to trace Non-Native Species in aquaculture

Aquaculture is a major vector for the introduction and spread of Non-Native Species (NNS), with negative ecological and economic implications. Costs generated by biofouling, including that of NNS, in bivalve aquaculture, can represent even 20-30 % of production costs. We used Local Ecological Knowledge (LEK) to assess farmers' awareness of NNS and pest species, as well as their observations of changes in fauna associated with cultivated Mediterranean mussels (Mytilus galloprovincialis) and Pacific oysters (Magallana gigas) in the Adriatic Sea, through questionaries. While most farmers claimed to understand the concept of NNS and reported their presence in farms, only a few could accurately identify a limited number of these species. Farmers observed increases in flatworms, ascidians, barnacles, hydrozoans and spionid polychaete Polydora, which they believe negatively affect mollusks and reduce their marketability. They also reported translocation practices involving seed and adult mollusks between Italy, Greece, France, and Spain, both within and beyond the Mediterranean basin. By combining farmer observations on the abundance of NNS and pests, with their reports of translocation practices, our results suggest that these activities facilitate the introduction and spread of NNS and pests. This highlights that LEK is a valuable tool for identifying challenges related to NNS management in aquaculture. We recommend implementing training programs to improve farmers' capacity to recognize NNS and contribute to their early detection. Furthermore, cross-border collaboration and partnerships among scientists, policymakers, and farmers are crucial for managing the spread of NNS through aquaculture in the Mediterranean.