Assessing the vulnerability of sensitive species in Mediterranean fisheries: insights from productivity-susceptibility analysis

Mortality resulting from interactions with fishing gear present a significant threat to sensitive species globally. In this study, we address this issue by defining five functional groups of marine megafauna (marine mammals, seabirds, demersal and pelagic elasmobranchs, and sea turtles), and conducting a productivity-susceptibility analysis (PSA) within the context of data-limited fisheries in the Mediterranean and Black Sea. The productivity (P) of each functional group was determined by evaluating a set of attributes averaged across representative species within each group. Functional groups’ susceptibility (S) to bycatch was assessed through a comprehensive review of existing literature and expert judgment, considering a series of semi-quantitative attributes. Our analysis identified areas and fishing gears posing significant risks to the functional groups assessed, highlighting that sea turtles and elasmobranchs face threats from various fishing gears operating in both neritic (bottom trawls, set nets and bottom longlines) and pelagic (drifting longlines) environments. Marine mammals exhibit moderate risk across most fishing gears, with particular concern for the harbour porpoise Phocoena phocoena relicta in the Black Sea, primarily due to the threat posed by set nets, which can severely impact entire population even capturing few specimens due the species low productivity. Seabirds face reduced risk, irrespective of the type of fishing gear examined or the specific area under investigation. Overall, our study highlights the specific basins and fishing gears requiring focused management measures, mitigation strategies, and enhanced monitoring activities to mitigate the impacts of bycatch on vulnerable marine megafauna.