We measured the target strength according to the swimming tilt angle and size change for Pacific herring at the frequency of 70 kHz as the basic database in order to estimate its abundance as well as density in the survey area using the hydroacoustical method. The number of the sample used in this study was 14 individuals, and its size distribution by fork length ranged between 20.3 and 29.8 cm and wet weight was measured between 187.6 and 269.9 g. The variation of TS according to the swimming angle (-30~30°) was measured between 10.3 and 18.8 dB in frequency range, the highest value was measured at head-down of Pacific herring in the tilt angle range between 5 and 9 deg. of its swimbladder. The relationship between TS–FL of herring was the same as TS = 20log10 (FL) – 66.79 when its swimming tilt angle in the daytime (3.8 ± 6.0°) and nighttime (-3.2 ± 13.6°), respectively.

서 론
 재료 및 방법
 결과 및 고찰
  청어의 유영자세각 변화에 따른 TS
  청어의 체장 및 체중 변화에 따른 TS 변동
 결 론
 사 사
 References

• 박미선(남동해수산연구소) | Miseon PARK
• 윤은아(전남대학교 해양기술학부) | Euna YOON
• 황강석(국립수산과학원 연근해자원과) | Kangseok HWANG
• 이동길(국립수산과학원 수산공학과) | Donggil LEE
• 오우석(전남대학교 수산과학과) | Wooseok OH
• 이경훈(전남대학교 해양기술학부) | Kyounghoon LEE Corresponding author