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    A two-fleet ASPM assessment of the toothfish (Dissostichus eleginoides) resource in the Prince Edward Islands vicinity

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    Document Number:
    A. Brandão and D.S. Butterworth (South Africa)
    Agenda Item(s)

    The ASPM assessment of the Prince Edward Islands toothfish resource by Brandão and Butterworth (2004) that permitted annual fluctuations about a deterministic stock-recruitment relationship is updated to take account of further catch, GLM standardised CPUE and catch-at- length information that has become available for the years 2004 and 2005. The assessment is also generalised to allow for a second fleet to accommodate data from a pot fishery that has been in operation since November 2004. Results obtained show a much greater selectivity for larger toothfish for the pot than for the longline fishery – a feature which has important implications for the status of the population. The possible extent of cetacean predation and its consequences are also investigated. Twenty year biomass projections under the assumption of various constant annual catches for the two-fleet model are computed. Although higher sustainable yields may be possible, it is suggested that a prudent management approach at this stage would be for the annual legal catch not to exceed 500 tonnes for the time being, together with encouragement that this be taken more by pots than by longline to reduce the impact of cetacean predation. Industry observations of the extent of cetacean predation for the longline fishery have proved helpful, and should be extended to a more formal data recording basis in the future.