Potential effect of the chosen length-frequency distribution on acoustic biomass estimates of Antarctic krill

Length frequency distribution (or length PDF) of Antarctic krill is an important input for converting the acoustic density to biomass estimate. For the 2019 Area 48 multi-national krill survey, various sources of length data were combined to provide the krill PDF for biomass estimation, and its potential effect was also discussed. To address this issue further, the potential effect of krill length PDF on krill biomass estimate was presented for a series of different mean and standard deviation (SD) of the length distribution assuming a normal PDF distribution. The actual krill length PDF sampled by two different gears (IKMT vs RMT8) during the Chinese R/V Xuelong2 survey in January 2021 in Area 58 was also compared to provide some insight on the matter.