Evaluation of the impacts of small-scale fishery on elasmobranchs in the Ambracian Gulf (Greece): insights for management

In the Mediterranean Sea more than half of elasmobranchs are facing high extinction risk according to the IUCN Red List criteria. Their life-history traits do not allow them to withstand high mortality rates, for this reason, batoids and sharks are jeopardized by human activities, among these fishing. The Ambracian Gulf is a semi-closed basin in the north-west of Greece, and it is considered an area of high ecological importance, due to its peculiar abiotic conditions which differentiate it from the Ionian Sea. This study, conducted from February to August through questionnaires in landing sites and onboard surveys, is the first study on elasmobranchs in the area and on the impacts of small-scale fishery on sharks and rays present. These species are rarely targeted by fishing activities, but they represent from 5.97 to 20.11% of the total catch in trammel nets (GTR). Depending on their commercial value and on the fishers’ behaviour, these species can be landed, immediately released, or discarded during nets cleaning. In a perspective to apply effective management strategies, it is necessary to understand mortality rates of the species as soon as they reach the deck of the boat (At Vessel Mortality, AVM) and after the release (Post Release Mortality, PRM) because stress, physical and physiological damages caused by the capture can have lethal consequences also after several days. For this reason, health conditions of the caught elasmobranchs were evaluated with a score from 1 to 4, correspondent to Good and Dead respectively. From this study, AVM and short-term PRM varied depending on the gear and the species. AVM was equal to 0% in all the species caught with GTR, ranged from 0 to 100% in species caught with gillnets (GNS), and from 81% to 100% in species caught with demersal longlines (LLS). StPRM ranged from 0% to 20% depending on the species and the time of air exposure. The low mortality registered, especially in GTR, which not only is the most widely used gear but also catches almost exclusively immature elasmobranchs, can support the adoption of release as management strategy for non-commercial and protected species, and for juveniles of commercial elasmobranchs. Collaboration with fishers and further studies are necessary to increase sample size, verify the long-term survival and test the feasibility of other management strategies such as magnets and LEDs to successfully achieve the protection of sharks and rays in the Ambracian Gulf.