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    Estimates of abundance of Dissostichus eleginoides and Champsocephalus gunnari from the random stratified trawl survey in the waters surrounding Heard Island in Division 58.5.2 for 2019

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    Document Number:
    G.B. Nowara, T.D. Lamb and P. Ziegler
    Submitted By:
    Dr Philippe Ziegler (Australia)
    Approved By:
    Dr Dirk Welsford (Australia)

    During late March to early April 2019, the annual random stratified trawl survey (RSTS) around Heard Island and McDonald Islands (HIMI) was conducted in CCAMLR Division 58.5.2, with the completion of 150 stations. The survey was conducted on the FV Atlas Cove. 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. However, only 5 of 18 stations were sampled in Gunnari Ridge since the catch limit for Champsocephalus gunnari (mackerel icefish) in Division 58.5.2 was reached prior to the completion of the survey.

    The catch of Dissostichus eleginoides (Patagonian toothfish) was 30.5 t which, while lower than last year’s survey, was still twice the average catch. The catch of mackerel icefish was higher than last year’s catch even though less than a third of the stations were completed in Gunnari Ridge. The catches of the other managed bycatch species, Channichthys rhinoceratus (unicorn icefish), Lepidonotothen squamifrons (grey rockcod) and Macrourus spp. (macrourids combined) were less than those of last year. Catches of skates were similar to those of the last three years, which have been higher than average. Invertebrate catch (including jellyfish) in the 2019 survey was lower than that of 2018, with anemones, poriferan sponges and sea stars in greatest abundance.

    The calculated biomass for 2019 of the target species D. eleginoides and C. gunnari in the survey area were close to the highest estimates for the past 10 years. Biomass estimates for the managed by-catch species C. rhinoceratus and Macrourus spp. remained at a high level and the estimate for L. squamifrons remained as low as it was for the last 4 years. The 2019 biomass estimates for each of the three Bathyraja spp. (skates) were the highest in the last 10 years.

    Length measurements and sex were taken for nearly 15 000 fish and for more than half of those, biological measurements were also recorded. Otoliths were collected from D. eleginoides (283) and a number of other species, and 466 toothfish were tagged and released.