경남 하동에 출현하는 상괭이(Neophochaena asiaeorientalis)의 혼획저감장치 반응 연구

Abstract

This study analyzed the occurrence frequency and behavioral changes of finless porpoises (Neophocaena asiaeorientalis) in Hadong, Gyeongsangnam-do, Republic of Korea, to assess their response to bycatch reduction devices. Sighting survey and passive acoustic surveys were conducted from November 2023 to January 2024 to compare the click patterns and behavioral changes of finless porpoises before and after the deployment of acoustic deterrent devices (ADDs). Results showed that adding ADDs significantly reduced porpoise occurrence and click frequency. Before ADD deployment, click frequency typically peaked after sunrise, suggesting increased foraging activity. However, their occurrence and click frequency decreased significantly after ADD deployment, and the intervals between clicks (inter-click interval, ICI) also increased. Additionally, the noise emitted by ADDs overlapped with the primary echolocation frequency of finless porpoises, reducing their detection efficiency and altering their activity patterns and spatial distribution. These findings suggest that ADDs may deter porpoises from certain areas and contribute to bycatch reduction in the long run. However, their use may cause ecological disturbances, such as displacing porpoises from essential feeding grounds. Therefore, a long-term management plan that considers potential habitat changes and behavioral alterations in porpoises should be developed before deploying bycatch reduction devices.