A comparison between the estimated density of krill from an acoustic survey with that obtained by scientific nets on the same survey

This work presents the initial comparative analysis of acoustic and net haul krill density estimates for the RMT 8 oblique (0 to 200m depth) trawls conducted during January-March 1996 as part of a hydroacoustic biomass survey for Antarctic krill in CCAMLR Division 58.4.1.
The acoustic krill density estimates were consistantly larger than the net estimates, otherwise no relationship was found between the two data sets. Several orders of magnitudes were seen in the range of variation between acoustic and net krill density estimates. This variation was reduced by subsampling the data set, excluding sites where krill represented less than 90% of the catch. This reduction in variation was thus largely attributed to the removal of the mixed species component of the samples.