Abstract
Black rockfish, goldeye rockfish and black scraper are commercially important fish species due to the increasing demand in Korea. When estimating the abundance of stocks for these species acoustically, it is of crucial importance to know the target strength (TS) to length dependence. In relation to these needs, target strength experiments were conducted on three species in an acrylic salt water tank using a 70-kHz split-beam echo sounder. The target strength for these three species under controlled conditions was simultaneously measured with the swimming movement by a DVR system and analyzed as a function of fish length (L). Equations of the form TS=a log (L)+b were derived for their TS-length dependence. The best fit regression of TS on fish length for two species of black rockfish and goldeye rockfish was TS=22.2 log (L)−74.6 (r2=0.73), and in the standard form TS=20 log (L)−71.5 (r2=0.74). The best fit regression of TS on fish length for black scraper was TS=24.1 log (L)−72.5 (r2=0.90), and in the standard form TS=20 log (L)−66.9 (r2=0.76).
