Biomass of Antarctic krill (Euphausia superba) off east Antarctica (30–80°E) in January–March 2006

A multidisciplinary, single-ship survey of CCAMLR Division 58.4.2 was conducted in January-March 2006, during which time multifrequency echosounder data were collected for the purposes of estimating the biomass (B₀) of Antarctic krill (Euphausia superba). The mean density of E. superba, integrated to 250 m depth across the survey area (1,566,157 km²), was 10.15 g m^-2. The total biomass was estimated to be 15.89 million tonnes with a CV of 47.93%. Most of the E. superba detected (80%) were in relatively weak aggregations (s_A <100 m² nmi^-2 for each 2 km-alongtrack integration interval), with 50% of integration intervals containing backscattering values <10 m² nmi^-2. Half of the biomass was found within 100 km of the 1000 m isobath, although aggregations often extended to the Northern ends of the transects at 62°S. The majority of acoustic detections were in the top 100m of the water column, centred around 50 m depth.