Density and sound speed contrasts (g and h , respectively), and swimming angle were measured for sandfish (Arctoscopus japonicus) without swimbladder. The density contrast was measured by the volume displacement method while the sound speed contrast was measured by the acoustic measurements of travel time (time-of-flight method). The swimming angle was measured by dividing it into daytime, nighttime, daytime feeding and nighttime feeding. The g was 1.001 to 1.067 with an average (± standard deviation) of 1.032 (± 0.017), and the h was 1.007 to 1.022 with an average (± standard deviation) of 1.015 (± 0.003). The swimming angles (mean ± standard deviation) were 16.8 ± 10.3° during the daytime, 1.9 ± 12.3° during the nighttime, 30.2 ± 12.6° in the daytime feeding and 35.0 ± 13.2° in the nighttime feeding. These results will provide important parameters input to calculate theoretical scattering models for estimating the acoustic target strength of sandfish.

서 론
재료 및 방법
실험 샘플
    밀도비
    음속비
    유영자세각 관측
결 과
    밀도비 및 음속비
    유영자세각
고 찰
    어류의 밀도비와 음속비
    어류의 유영자세각
결 론
사 사
References

• 윤은아(국립수산과학원 수산자원연구센터 연구원) | Euna YOON (Researcher, Fisheries Resource Research Center, National Institute of Fisheries Science, Tongyeong 53064, Korea)
• 황두진(전남대학교 해양생산관리학과 교수) | Doo-Jin HWANG (Professor, Department of Marine Production Management, Chonnam National University, Yeosu 59626, Korea)
• 오우석(전남대학교 수산과학과 학생) | Wooseok OH (Student, Division of Fisheries Science, Chonnam National University, Yeosu 59626, Korea)
• 이형빈(국립수산과학원 수산자원연구센터 연구원) | Hyungbeen LEE (Researcher, Fisheries Resource Research Center, National Institute of Fisheries Science, Tongyeong 53064, Korea)
• 이경훈(전남대학교 해양생산관리학과 교수) | Kyounghoon LEE (Professor, Department of Marine Production Management, Chonnam National University, Yeosu 59626, Korea) Corresponding author