Fish length dependence of target strength for striped beakperch, bluefin searobin and konoshiro gizzard shad caught in the artificial reef ground of Yongho Man, Busan

Abstract

Species of fish such as striped beakperch, bluefin searobin and konoshiro gizzard shad are commercially very important due to their high demand in the Korean market. When estimating acoustically the abundance of stocks for these species, it is of crucial importance to know the target strength (TS) to the length dependence. In relation to these needs, the TS experiments were conducted on three different species in an acrylic salt water tank using two split-beam echo sounders of 70 and 120 kHz. The TS for these three species under the controlled condition was simultaneously measured with the swimming movement by a DVR system and analyzed as a function of fish length (L) and frequency (or wavelength λ). The equation of the form TS a log (L) b log (λ) c was derived for their TS-length dependence. The best fit regression of TS on fork length for striped beakperch was estimated as TS 35.67 log (L, m) 15.67 log (λ, m) 46.69 (r