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

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    T. Jarvis, E. van Wijk, N. Kelly, S. Kawaguchi and S. Nicol (Australia)
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    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 (sA <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.