70 및 120kHz에서 쥐노래미와 감성돔에 대한 음향 반사 강도의 체장 의존성

Abstract

Black porgy and fat greenling are commercially important fish species due to the continuously increasing demand in Korea. When estimating acoustically the fish length by a fish sizing echo sounder, it is of crucial importance to know the target strength (TS) to length dependence. In relation to these needs, the target strength experiments for live fishes were conducted in an acrylic salt water tank using two split-beam echo sounders operating at 70 and 120kHz. The target strength under well-controlled laboratory conditions was simultaneously measured with the swimming movement by digital video recording (DVR) system and analyzed as a function of fish length (L) and frequency (or wavelength <TEX>${\lambda}$</TEX>). Equations of the form TS-alog (L)+blog (1)+c were derived for their TS-length dependence. The best fit regression of TS on fork length for black porgy was TS=20.62 log (L, m)-0.62 log (<TEX>${\lambda}$</TEX>, m)-30.68 (<TEX>$r^2$</TEX>=0.77). The best fit regression of TS on fork length for fat greenling was TS=12.06 log (L, m)-5.85 log (<TEX>${\lambda}$</TEX>, m)-22.15 (<TEX>$r^2$</TEX>=0.44).