Invasive blue crabs and small-scale fisheries in the Mediterranean sea: Local ecological knowledge, impacts and future management

The recent expansion of the two invasive Portunidae blue crabs Callinectes sapidus and Portunus segnis has generated great concern in the western Mediterranean basin. Here, we collected perception from artisanal small-scale fishermen on the socio-economic issues associated with this invasion. Professional fishers from France, Italy, and Tunisia were interviewed to survey their perception on: (i) the potential drivers of spatial expansion of blue crabs, (ii) the impact on the small-scale fisheries, and (iii) the management measures expected. The main reported impacts were the damage of fishing nets (median = 4.3), followed by a consequent associated increase in work intensity (median = 3.6) and by physical injuries to fishers (median = 3.1). Fishermen reported to have caught less fish (median = 3.4) in presence of blue crabs, as well fish damaged by blue crabs' bite (median = 3.8) inducing a decrease in the quality and value of catches (median = 3.5). The negative effects induced a decrease on global revenues (median = 3.6) as well despite the negative impacts of blue crabs on the fishery, the presence of these new species has been generally perceived as positive, being considered as a new revenue resource for some fishermen (median = 2.8). The majority of them (72 %) proposed fishing and marketing as main man-agement measures. Despite the interested expressed for exploitation of this new resource, many questions emerged to promote and develop management strategies.