Chub mackerel (Scomber japonicus) is an important commercial fish in the Northwest Pacific
Ocean. Accurate target strength (TS) underpins acoustic stock assessment but the TS of S.
japonicus is still poorly understood. In this study, the Kirchhoff-ray mode (KRM) model was
used to estimate the TS of S. japonicus and its relationship with sound wave frequency and
fish morphology. The results revealed that TS values varied with pitch angle shifts, with the
impact on fish scattering strength being greater at higher frequency. This is less important …