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    The random stratified trawl survey to estimate the abundance of Dissostichus eleginoides and Champsocephalus gunnari in the waters surrounding Heard Island (Division 58.5.2) for 2017

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    Document Number:
    WG-FSA-17/14 Rev. 1
    G.B. Nowara, T.D. Lamb and P. Ziegler
    Submitted By:
    Dr Philippe Ziegler (Australia)
    Approved By:
    Dr Dirk Welsford (Australia)

    The annual random stratified trawl survey (RSTS) of 2017 at HIMI was conducted during April, with the completion of 163 stations. The survey has been conducted on the FV Atlas Cove since 2015. Sampling protocols such as the design and the duration of the hauls were similar to recent surveys, but with a new set of randomly selected station points.

    The unstratified density of Dissostichus eleginoides (Patagonian toothfish) was 1.5 times greater than that of 2016 and also of the long-term average for the survey. The unstratified density of Champsocephalus gunnari (mackerel icefish) was only slightly larger than that of 2016 and 2.5 times the average. For the managed by-catch species, unstratified densities were lower than the average for Channichthys rhinoceratus (unicorn icefish), Lepidonotothen squamifrons (grey rockcod) and Macrourus sp. (macrourids). Conversely, the unstratified density of aggregated Bathyraja sp. (skates) was higher than both 2016 and the long term average. The catch of invertebrates in the 2017 survey was 70% of the average, which included a low abundance of jellyfish.

    Length measurements were taken for nearly 13,500 fish and for more than half of those biological measurements were taken. Otoliths were collected from 663 D. eleginoides and 159 individuals were tagged and released.