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    Preliminary results of stock estimation for D. mawsoni using CASAL in the research block 48.6_2

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    Document Number:
    WG-FSA-18/72
    Author(s):
    T. Okuda
    Submitted By:
    Dr Takehiro Okuda (Japan)
    Approved By:
    Ms Belinda Blackburn (CCAMLR Secretariat)
    Abstract

    A preliminal CASAL model was constructed for D. mawsoni at the research block 48.6_2. The model assumes that single sex and age structured model without considering IUU. Tag release data during 2012–2017 was used. Catch data during 2006–2017 was used as fishery data. 

    In the MPD, age and CPUE fit well. On the otherhands, fit of tag release are relatively low level, especiall in 2016. The B0, B2016, and current vulnerable biomass are estimated to be 17718.8, 17007.3, and 6986.2 tonnes. The MCMC estimates of B0 (18143.15t) and current biomass (17431.60 t) are much higher than the latest biomass estimates by CPUE-by-seabed method (3029 t) and Chapman method (4223 t). CCAMLR decision rule risk under the current catch level (170 t) become nearly zero (Table 3). Although the preliminal CASAL model seems to converge well, We need futher discussion to improve the CASAL model for D. mawsoni at Subarea 48.6.