Commercial split beam echosounder (ES70) installed on a krill fishing vessel was calibrated in order to utilize it in estimating biomass of Antarctic krill (Euphausia superba). The method of calibration was to analyze the difference between the bottom backscattering strength of the commercial split beam echosounder (i.e. ES70) and the scientific echosounder (i.e. EK60) at one of transects near South Shetland Islands designated by CCAMLR. 38 kHz and 120 kHz were used for the calibration, and krill swarm signal levels obtained from multi frequencies, was examined to verify the calibration result. The analysis result indicated possibility of calibration by bottom backscattering strength, since the proportion of krill swarm signals within 2 dB < SV 120 kHz-38 kHz < 12 dB (i.e. a common SV 120 kHz-38 kHz range of 38 kHz and 120 kHz to be an indicator of Antarctic krill) over the total acoustic signals were 26.95% and 92.04%, respectively before and after the calibration.

• 최석관(국립수산과학원 원양자원과) | Seok-Gwan CHOI (Distant Water Fisheries Resources Research Division, National Institute of Fisheries Science, Busan 46083, Korea)
• 이형빈(서해수산연구소 자원관리과) | Hyungbeen LEE (Fisheries Resources and Environment Research Division West Sea Fisheries Research Institute, Incheon 22383, Korea) Corresponding author
• 이경훈(전남대학교 해양기술학부) | Kyounghoon LEE (School of Marine Technology, Chonnam National University, Yeosu, Jeonnam 59626, Korea)
• 이재봉(국립수산과학원 원양자원과) | Jaebong LEE (Distant Water Fisheries Resources Research Division, National Institute of Fisheries Science, Busan 46083, Korea)