Acoustic deterrent devices as mitigation tool to prevent dolphin-fishery interactions in the Aeolian Archipelago (Southern Tyrrhenian Sea, Italy).

In a test-control study conducted in the Aeolian Archipelago (Southern Italy), acoustic deterrent devices (pingers) were applied to four gear types typical of local artisanal fisheries to assess their effectiveness in mitigating dolphin-fishery interactions. In this area ecosystem degradation and overfishing have been increasing bottlenose dolphin (Tursiops truncatus) and striped dolphin (Stenella coeruleoalba) conflict with fishers. Banana Pingers were applied to Spicara maena gillnets, trammel nets, "lampara" nets and hand-operated squid jig lines ("totanara") in trials conducted from April to September 2017. Dolphin depredation events were greatly reduced in the gillnet (100%) and the "lampara" net (86%), resulting in a strong increase in catch weight (kg) and revenue (EUR). In the squid hand-jig line trials, severe depredation events (60%) markedly reduced catch and revenue. In the trammel net, catch weight and revenues were not significantly different in the test and control nets. Despite the absence of dolphin damage, the fish species that are part of the dolphin diet were more abundant in the test net. Our findings suggest that pinger effectiveness may be influenced by a variety of factors including dolphin species, season, habitat and fish species distribution. Notably, the discards of trammel nets account for nearly 50% of the catch and include potentially valuable bycatch species, like Sparisoma cretense, which however commands a low price on the local market. We suggest that together pingers and the local sale of non-target species could mitigate the economic loss due to dolphin damage, although this requires appropriate planning.