Research program in data-poor Subarea 48.5 (Weddell Sea) have been carried out for the first time. New commercial and biological data on the target (Dissostichus mawsoni Norman, 1937) and by-catch species have been collected. Toothfish tagging program have been executed. Distribution of Antarctic toothfish and by-catch species by depth ranges has been investigated. Data on CPUE and commercial density have been collected. Calculation of stock assessment has been done by areal method that is recommended by CCAMLR (SC-CCAMLR-XXX/5 п. 2.40 (ii)). Calculated stock of toothfish in Subarea 48.5 equal 428 thousand tons.