In situ measurements of orange roughy (Hoplostethus atlanticus) target strength

Abstract

Orange roughy (Hoplostethus atlanticus) support one of New Zealand's most valuable commercial fisheries, and its assessment poses many problems. Acoustic estimation using echo integration has become one of the main sources of biomass information, and for this an estimate of orange roughy target strength (TS) is needed. Its schooling characteristics together with patterns in the rate of change of phase vs. TS plots are used to identify ensembles of orange roughy targets from in situ TS data collected from a wide range of fishing areas off eastern New Zealand. The results suggest a TS of 249.3 dB for an orange roughy of 35 cm standard length. © 2007 International Council for the Exploration of the Sea.