We presented foundational findings regarding the occurrence and acoustic characteristics of the finless porpoise through passive acoustic and visual surveys conducted on the southern coast of Korea, specifically at Hadong Jungpyeong Port. Over a survey period spanning from July 8 to August 16, 2023, totaling 40 days, we observed peaks in the number of clicks produced by this species on July 15, July 24, August 4, August 11, and August 16. The highest count, totaling 18,924 clicks, was recorded on July 15th, while the lowest count, at 3,888 clicks, occurred on August 8th. Examining the acoustic characteristics throughout the diurnal cycle, we found that the peak activity in terms of DPM (detection positive minute for one hour), DP10M (DPM for ten minutes), and overall number of click sounds was observed between 05:00 and 08:00, with a secondary peak occurring from 17:00 to 18:00. The quietest period was noted between 23:00 and 02:00. Furthermore, there was a significant increase in the number of clicks from sunrise, with the maximum count of 21,581 clicks recorded at 6 AM. This count gradually decreased until noon, experienced a slight increase thereafter, peaked again at sunset, and then declined. The dominant frequency mode of this species was 126 kHz, with a concentration ranging from 112 to 136 kHz. The average duration of a click sound was 127 ㎲, with approximately 16 sinusoids (cycles) within each click sound and an average cycle length of approximately 7.9 ㎲. These findings from our study are anticipated to serve as foundational data for the development of a Korean pinger and acoustic warning system.

서 론
재료 및 방법
    현장조사
    데이터 처리
결과 및 고찰
결 론
사 사
References

• 김현영(국립수산과학원 수산공학과 연구관) | Hyunyoung KIM (Senior researcher, Fisheries Engineering Division, National Institute of Fisheries Science, Busan 46083, Korea)
• 정지훈(경상국립대학교 대학원 해양경찰시스템학과 학생) | Jihoon JUNG (Student, Department of Maritime Police and Production System, Graduate School, Gyeongsang National University, Tongyeong 53064, Korea)
• 강동하(경상국립대학교 대학원 해양경찰시스템학과 학생) | Dongha KANG (Student, Department of Maritime Police and Production System, Graduate School, Gyeongsang National University, Tongyeong 53064, Korea)
• Fredrich Simanungkalit(경상국립대학교 대학원 해양경찰시스템학과 학생)
• 강명희(경상국립대학교 해양경찰시스템학과, 해양산업연구소 교수) | Myounghee KANG (Professor, Department of Maritime Police and Production System/Institute of Marine Industry, Gyeongsang National University, Tongyeong 53064, Korea) Corresponding author