基于高频窄波束宽带声学系统的鳜鱼体目标强度分区测量研究OA

Target strength(TS)is a fundamental parameter for acoustic monitoring and biomass estimation of cultured fish.To address the difficulty of resolving localized scattering characteristics of fish bodies in small-scale,high-density aquaculture environments using conventional wide-beam acoustic systems,this study developed a high-frequency narrow-beam broadband acoustic measurement system with a center frequency of 700 k Hz,a bandwidth of 100 k Hz,and beam widths of 1°(horizontal)×20°(vertical).By combining pulse compression,mainlobe detection,and resampling methods,high-resolution partitioned measurements of fish-body TS were realized for Siniperca chuatsi.The system was calibrated using a 10.3 mm tungsten carbide standard sphere,and one mandarin fish specimen(body length:26.1 cm;body weight:438.3 g)was measured under different incidence angles(0°-90°)to obtain the distributions of echo intensity and TS in different body regions.The results showed that TS exhibited clear directional dependence,with the whole-body TS ranging from-53.18 to-43.66 dB.When the acoustic wave insonified the lateral side of the fish body,the whole-body TS was 8.39 dB higher than that measured in the head-tail direction.Combined with X-ray image analysis,distinct differences in TS were observed among body regions.The abdominal region containing the swimbladder had a TS of-49.80 dB,which was on average 9.31 dB higher than that of the head(-59.13 dB)and tail(-59.09 dB),indicating that the swimbladder was the dominant scattering source.The results demonstrated that the proposed high-frequency narrow-beam broadband acoustic system could be used for partitioned measurements of localized fish-body TS and may provide a useful reference for TS parameter acquisition and related acoustic measurement studies in aquaculture species.