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    A comparison of gear selectivity among three fishing gears for Antarctic krill with notes on the demographic patterns and productivity of Antarctic krill during summer 2014

    Request Meeting Document
    Document Number:
    C. Reiss (USA) and M. Espino Sanchez (Peru)
    Submitted By:
    Mr Doug Cooper (CCAMLR Secretariat)

    Three different trawls were used to sample Antarctic krill for the determination of demographic and abundance patterns around the South Shetland Islands during Austral summer 2014. A 60cm BONGO net (333 and 505 µm mesh), a 1.8m IKMT (505 µm mesh); and a pelagic ENGEL trawl (594m2 mouth area, 10mm cod end liner) were used and their selectivities are compared. Despite very different apparent selectivities, length frequency distributions were generally similar. Median lengths based upon Empirical Distribution Functions (EDFs) for the three gears varied over about 7mm, with the BONGO net catching the largest range of krill (15mm to 60mm), while the ENGEL trawl captured the narrowest (27 to 61), and the size was shifted to larger animals. These differences suggest that tradeoffs between gear size and number of tows should be considered when designing fishery based sampling to augment research surveys using fishing vessels if research gear cannot be accommodated. The patterns of krill length frequency showed that krill collected in Bransfield Strait and Elephant Island areas of the South Shetlands in summer 2014 were about 42 mm in length (3yrs old), and few small (<25mm) krill (1 year old) were captured. The majority of krill were mature and in spawning condition.