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    Summary of a three year mark-recapture experiment to estimate population size of Antarctic toothfish (Dissostichus mawsoni) in Southern Area of Statistical Subarea 48.4

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    Document Number:
    WG-FSA-11/31 Rev. 2
    R.C. Wakeford, J. Roberts and R.E. Mitchell (United Kingdom)

    A three-year tagging experiment was initiated by the UK in 2008/09 fishing season with the aims of providing the data required for assessments of the population structure, size, movement and growth of both Patagonian toothfish (Dissostichus eleginoides) and Antarctic tooth (Dissostichus mawsoni) in South of Statistical Subarea 48.4. This paper presents the results for D. mawsoni.

    Fishing effort within the south of Subarea 48.4 was relatively evenly spread between each participating fishing vessel between 2008/09 and 2009/10, but the spatial coverage of fishing effort was reduced in 2010/11 due to reduced catches and catch rates during the season. Standardised CPUE trends indicated a slight decline in catch rates over the three year study, more so between 2010 and 2011.

    A total of 476 D. mawsoni have been tagged and released during between 2008/09 and 2010/11.  Tag data show 56% of recaptured fish remain within only 10 km of the area of first capture. Results of the mark-recapture experiment to date indicated that mean estimates of vulnerable biomass for D. mawsoni were similar across recapture years 2010 and 2011, at ~600t.