Acoustic Data Analysis for Density Estimation of Antarctic Krill (Euphausia superba) Resources Around South Shetland Islands

This study estimated the density distribution of Antarctic krill inhabiting an area near the South Shetland Islands using two acoustic analysis methods recommended by the Commission for the Conservation of Antarctic Marine Living Resources, based on data collected using an echosounder installed on commercial fishing vessels. Mean Antarctic krill density for the entire survey area was estimated with two methods recommended by the Commission for the Conservation of Antarctic Marine Living Resources. The mean body length of krill collected using trawl gear was 49.06 ± 4.15 mm (range: 22.0–67.0 mm), with mode of krill observed at 50 mm body length. Using the swarm-based method and the frequency differences according to krill size, the mean densities of krill for stations and transects were 14.86 g/m2 (CV = 47.09%) and 13.10 g/m2 (CV = 41.16%), respectively. Furthermore, using the dB-difference method for the entire survey area, the average densities were 10.76 g/m2 (CV = 43.83%) and 10.14 g/m2 (CV = 53.48%), respectively, using the frequency difference based on krill size determined at all stations and per transect.