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    Estimating density and biomass of Antarctic krill (Euphausia superba) around South Shetland using the 2-dB difference method

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    Document Number:
    SG-ASAM-18/08
    Author(s):
    S. Choi, K. Lee and D. An
    Submitted By:
    Dr Sangdeok Chung (Korea, Republic of)
    Approved By:
    Dr Seok-Gwan Choi (Korea, Republic of)
    Agenda Item(s)
    SG-ASAM-18 - 4 - Analysis of data collected from fishing vessels
    Abstract

    The distribution and abundance of krill aggregation inhabiting the Subarea 48.1, which includes the Elephant Island peripheries and the west and south of the South Shetland Island, were estimated using an acoustics survey. Acoustic data were collected with 38 and 120 kHz from April 13 to 24 in 2016 and 38 and 200 kHz from March 6 to 14 and 38 and 120 kHz on April 27 and May 5 in 2017. Krill were collected by the commercial middle trawl fishing vessel. The data were processed and analyzed following CCAMLR standard protocols using swarm integration (SHAPES module within that software for swarm identification) based on data from a transect-based survey. The weighted krill density and biomass were estimated to be 0.20 g/m2 and 18 thousand tons (CV=33.8%) applying Sv difference 3.96-5.91 dB and 0.92 g/m2 and 83 thousand tonnes (CV=31.4%) applying Sv difference -3.0-13.8 dB in 2017, respectively. Krill density and biomass were significantly higher in 2016 than those in 2017.