Target-strength measurements of hake and jack mackerel

Abstract

Target-strength (TS) measurements of dispersed shoals of jack mackerel (Trachurus symmetricus murphyi Nichols), Chilean hake (Merluccius gayi Guichenot), and southern hake (Merluccius australis Hutton) were made using a 38 kHz split-beam echo-sounder. TS and length distributions were obtained from night hauls taken with midwater and bottom trawls. The estimated regressions for the TS and fish length relationships indicated that TS was proportional to the squared length, using a least-squares linear regression fitted between TS and log fish length.