Acoustic deterrence to facilitate the conservation of pantropical spotted dolphins (Stenella attenuata) in the Western Pacific Ocean

Abstract

Commercial fishing constitutes an important food source but induces undesirable bycatch on animals worldwide. This study extends bycatch research geographically to the Western Pacific Ocean, filling a knowledge gap regarding bycatch and mitigation measures in the region. Bycatch has caused many lethal consequences to the pantropical spotted dolphins (Stenella attenuata) during their interaction with fisheries in the research area. We provided a self-developed acoustic deterrent system and conducted field experiments, suggesting its effectiveness as a potential useful conservation tool to reduce bycatch. Dolphins departed the area and the number of dolphins in sight declined to zero after the deployment of the system. Additional evidence was reflected in acoustic recordings, showing the number of clicks emitted by dolphins decreased from 1,502 to 136 per minute after the ADS was activated. Meanwhile, click amplitude was reduced by 84%, indicating an increase in the distance between dolphins and the system. These combined results indicate that the system was effective in driving dolphins away to facilitate the conservation of the species by protecting them from potential bycatch.