Incidental by-catch represents a major conservation concern for Protected, Endangered, and Threatened (PET) marine species in the Mediterranean Sea. Within the framework of the TALASSA project, interactions between professional fishery and PET species were investigated along the Ligurian coast, encompassing four Special Areas of Conservation (SACs). The study focused on elasmobranchs, cetaceans, seabirds, and marine turtles, aiming to assess the frequency, distribution, and characteristics of incidental bycatch events while integrating scientific data with fishers’ local ecological knowledge (LEK). Data was collected through interviews with professional fishers operating in the Ligurian Sea. The study examined from an historical perspective, fishing areas and gear types, fishers’ responses to incidental captures, perceptions of vulnerable species protection, and practices related to the reporting and recording of bycatch events. Results indicated that small-scale fisheries dominated the area, with gillnets and bottom longlines most associated with by-catch. Elasmobranchs (mainly Prionace glauca, Hexanchus griseus, Mobula mobular, and Alopias spp.) were the most frequently reported by-catch group, followed by seabirds (Larus michahellis, Gulosus aristotelis, and Phalacrocorax carbo) and marine turtles (Caretta caretta). Bycatch events were generally perceived as stable over time. Despite not being involved in by-catch events, cetaceans, particularly Tursiops truncatus, were reported to have increased over the last 15 years and to interact frequently with fishing gears, causing depredation of catches and structural damage. Fishers declared the importance of protecting by-catch species and an interest in sharing their observations, although the majority showed no interest in participating in training events on this subject. Although fishers’ knowledge proved to be a valuable source of information, limitations emerged regarding spatial precision and species identification. Despite these constraints, the study highlights the importance of integrating local knowledge with scientific monitoring to improve understanding of by-catch dynamics and support more effective conservation and management strategies in the Ligurian Sea.

Keywords: Citizen science, bycatch, local ecological knowledge (LEK), Protected, Endangered, and Threatened (PET) species, fisheries interactions, Ligurian Sea