The plan submitted to the WG-SAM-09 (Document 09/11) for fishing surveys on stock status and biological characteristics of Dissostichus spp. in Division 58.4.4 a & b has been revised according to the recommendations of the working group. The working group recommended the consecutive research focusing on tagging program for a period of 3-5 years to estimate current stock size accurately, and on fishing trials using both Trot line and Spanish line systems so that their properties can be better understood. We recalculated the necessary sample size as 120,000 kg for Dissostichus spp. for this division that includes 4 SSRUs, taking into account the conservative exploitation rate (less than 3.8 % of the total estimated biomass). Distributing research hauls across all SSRUs rather than concentrating the effort on a smaller subset of this Division is thought to be more reasonable in terms of minimizing localized impacts on the stock, avoiding predation of tagged and released toothfish by toothed whales, and accomplishing the objectives of the survey. To apply the mark-and-recapture studies, sufficient tagging rate was calculated to be 5 fish/ton, which can predict the CV of a Petersen estimate of population abundance to be sufficiently 0.31 when over-dispersion value is assumed to be 2.0. A total of 117 research hauls are allocated on 10-minute latitude x 20-minute longitude grid points, taking into account the need to deploy research hauls and tagging releases evenly throughout the survey area. A Trot line system will be employed for 88 research hauls in order to make an evaluation of the stock status and biological characteristics of Dissostichus spp. and to compare the information to be obtained in this survey with the information collected by the Trot line system used in the same Division in the previous research in 2007/08. In 29 hauls (a quarter of total sets), the experimental gear, which consists of three segments of Trot line system and Spanish line system respectively within one fishing line, will be used in order to standardize the CPUE of Trot line accurately in this Division and collect information on various properties of the two gears.
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