Recently, domestic fishing production of Japanese horse mackerel has been continuously decreasing. To achieve sustainable fishing of this species, it is essential to acquire its target strength (TS) for accurate biomass estimation and to study its ecological characteristics. To date, there has been no TS research using a broadband echosounder targeting Japanese horse mackerel. In this study, for the first time, we synchronized an underwater camera with a broadband frequency (nominal center frequency of 200 kHz, range: 160-260 kHz) to measure the TS according to the body size (16.8-35.5 cm) and swimming angle of the species. The relationship between Japanese horse mackerel length and body weight showed a general tendency for body weight to increase as length increased. The pattern of the frequency spectra (average values) by body length exhibited a similar trend regardless of body length, with no significant fluctuations in frequency observed. The lowest TS value was observed at 243 kHz while the highest TS values were recorded at 180 and 257.5 kHz. The frequency spectra for the swimming angles appeared to be flat at angles of –5, 0, 30, 60, 75, and 80° while detecting more general trends of frequency spectra for swimming angle proved challenging. The results of this study can serve as fundamental data for Japanese horse mackerel biomass estimation and ecological research.

서 론
재료 및 방법
    현장조사
    자료 분석
결과 및 고찰
결 론
사 사
References

• 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)
• 김한수(한국해양과학기술원 해양영토, 방위연구부 선임연구원) | Hansoo KIM (Senior Research Scientist, Marine Domain and Security Research Department, Korea Institute of Ocean Science & Technology, Busan 49111, Korea)
• 강동하(경상국립대학교 대학원 해양경찰시스템학과 학생) | Dongha KANG (Student, Department of Maritime Police and Production System, Graduate School, Gyeongsang National University, Tongyeong 53064, Korea)
• 정지훈(경상국립대학교 대학원 해양경찰시스템학과 학생) | Jihoon JUNG (Student, Department of Maritime Police and Production System, Graduate School, Gyeongsang National University, Tongyeong 53064, Korea)
• Fredrich Simanungkalit(경상국립대학교 대학원 해양경찰시스템학과 학생)
• 강돈혁(한국해양과학기술원 해양영토, 방위연구부 책임연구원) | Donhyug KANG (Principal Research Scientist, Marine Domain and Security Research Department, Korea Institute of Ocean Science & Technology, Busan 49111, Korea) Corresponding author