Proposal for an extension to the mark-recapture experiment to estimate toothfish population size in the South of Subarea 48.4

A three‐year tagging study in the South of Subarea 48.4 was initiated in the 2008/09 fishing season with the aims of  providing the data required for assessments of the population structure, size, movement and growth of both Dissostichus eleginoides and Dissostichus mawsoni in the South of 48.4; A total of 186 D. eleginoides and 202 D. mawsoni were tagged and released in 2010, leaving a total of 794 tagged fish in the water, respectively. A total of 13 D. eleginoides and 22 D. mawsoni were recaptured in the latest season, including three and six within‐season recaptures, respectively. Macrourids and rajids again dominated bycatch, comprising 15.4% and 1.2% of toothfish catch, respectively. A total of 238 Amblyraja georgiana were tagged and released in 2010 and 3 were recaptured; Approximately 20% of sets were undertaken during daylight hours and no bird entanglements or mortalities were reported; Preliminary stock assessments by different methods estimate a lower stock size of Dissostichus spp. in the South than previously anticipated. In addition there are signs of significant stock depletion towards the northern boundary of the Southern management area. The UK proposes to complete the mark‐recapture experiment in the South of Subarea 48.4 in 2010/11 with a reduced TAC of 30 tonnes.