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    Research plan for toothfish in Division 58.4.4a & b by Shinsei Maru No. 3 in 2013/14

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    Номер документа:
    Delegation of Japan
    Представлено (имя):
    Sarah Mackey (Секретариат АНТКОМ)

    We made stock status assessments of Dissostichus eleginoides in SSRUs C and D in Division 58.4.4 a & b. Regarding SSRU C, the stock size was estimated by using following six methods; 1) comparative CPUE analysis, 2) modified Lincoln-Petersen 3) CASAL_base model, 4) CASAL_YCS_fix model, 5) CASAL_0_IUU model, and 6) CASAL_all_IUU model. This approach was made based on the WG-FSA’s recommendation stating that the sensitivity run of the CASAL model should be made by using levels of IUU ranging from zero to all observed IUU fishing, and using constant YCS (year class strength)  in SSRU C. The CASAL_base model includes estimated variability of YCS for the period from 1989 to 2005, and assumed that a quarter of observed IUU fishing in the division had occurred in SSRU C. High estimated stock levels were obtained from CASAL_base (1230 tonnes), CASAL_YCS_fix (1230 tonnes) and CASAL_all_IUU models (1360 tonnes), medium level from CASAL_0_IUU model (710 tonnes), and low level from CPUE comparison (542 tonnes) and modified Lincoln-Petersen (446 tonnes).

    The catch and tagging data in SSRU D were not enough to be applied to modified Lincoln-Petersen and CASAL models. Thus the stock sizes of D. eleginoides in SSRU D is estimated only by using CPUE comparison with the stock size estimates in SSRU C obtained from each method.

    Since we have not obtained enough evidence to estimate plausible stock size, and accordingly have not been able to determine catch limit yet, we would like to conduct research repeated for at least 3-4 years in the same locations as in the 2012/13 season, with the same survey design and sample size of a total of 50 tonnes in SSRUs C and D for the 2013/14 as in the 2012/13, in order to promote successful stock assessment