Evaluation on the performance of echosounder on a fishing vessel using maximum seabed backscattering

The performance of echo sounder system is critical for using acoustic data collected from fishing vessel to estimate Antarctic krill biomass. Acoustic data from three surveys (2015, 2016 and 2018) collected at a relatively fixed location with bottom depth around 200 m were used to evaluate the potential to use seabed backscattering as an alternative way to the standard sphere calibration. The largest inter-annual difference of the mean value of the maximum seabed backscattering (S_v, dB) for single ping were less than 1.0 dB with 0.35 dB and 0.78 dB at 120 kHz and 38 kHz, respectively. However, ANOVA analysis indicated that there was no significant difference among years at both frequencies.