TARGET-STRENGTH MEASUREMENTS OF HAKE AND JACK MACKEREL

Target-strength (TS) measurements of dispersed shoals of jack mackerel (Trachurus symmetricus murphyi Nichols), Chilean hake (Merluccius gay i Guichenot), and southern bake (Merluccius australis Hutton) were mad e 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 ind icated that TS was proportional to the squared length, using a least-s quares linear regression fitted between TS and log fish length. (C) In ternational council for the Exploration of the Sea