Comparison of Target Strength of Pacific Herring (Clupea pallasii Valenciennes, 1847) from Ex-Situ Measurements and a Theoretical Model

Pacific herring (Clupea pallasii Valenciennes, 1847) is a commercially important species that inhabits the coastal waters of the North Pacific from Korea to California, USA. This study analyzed the target strength (TS; dB re 1 m(2)) of Pacific herring individuals (n = 14, total length (L-T) = 21.3-32.3 cm) at 38 and 120 kHz using ex-situ measurements and the Kirchhoff-ray mode (KRM) model. The least-squares regressions of the TS-L-T relationship for the ex-situ measurements were TS38kHz = 20 log(10)(L-T) - 70.10 (r = 0.17) and TS120kHz = 20 log(10)(L-T) - 70.59 (r = 0.10). The least-squares regressions for the KRM model were TS38kHz = 20 log(10)(L-T) - 68.39 (r = 0.40) and TS120kHz = 20 log(10)(L-T) - 69.74 (r = 0.49). The b(20) value of the KRM model was 1.71 dB higher than that of the ex-situ measurement at 38 kHz but similar at 120 kHz. These results provide basic data to evaluate the distribution and abundance of Pacific herring using fisheries' acoustic technology.

Automated summary

This study analyzed the target strength of Pacific herring individuals at 38 and 120 kHz using ex-situ measurements and KRM model, providing basic data for evaluating the distribution and abundance of Pacific herring using fisheries' acoustic technology.