Hydroacoustic assessment of pelagic fish around Bidong Island, Terengganu, Malaysia

Abstract

The first phase of this study investigates the average dorsal aspect (side) target strength of three commercially important fish species, namely Rastrelliger kanagurta, Atule mate and Thunnus tonggol, which are mostly captured by commercial fishermen in waters around Bidong Island. Target strength experiments were carried out in a controlled tank at Universiti Putra Malaysia Tcrengganu by using a digital transducer split beam echo sounder at 200 kHz. Fish size for this experiment varied from 13.6 to 24.5 cm total length (avg. 18.8 cm) for Rastrelliger kanagurta, 13.8 to 27.5 cm (avg. 20.0 cm) for Atule mate and 28.5 to 52.0 cm (avg. 39.6 cm) for Thunnus tonggol. Significant differences (a = 0.05) were observed between fish total length and weight of all species tested.