Preliminary assessment of long-term yield of Patagonian toothfish (Dissostichus eleginoides) for the Heard Island region (CCAMLR Division 58.5.2) based on a random stratified trawl survey in June 2005

A survey of Patagonian toothfish, Dissostichus eleginoides,was undertaken in Division 58.5.2 in the vicinity of Heard Island in June 2005 to provide the information for an assessment of short-term annual yield in the 2005/2006 CCAMLR season. This paper provides a preliminary assessment of yield for the area of Division 58.5.2 to the west of 79°20’ E using standard CCAMLR methods. It also considers the sensitivity of the assessment to (i) further consideration of the survey series and the sensitivity to exclusion of observations of older cohorts in recent surveys, (ii) implementation of revised growth parameters, including the use of a length-at-age vector, (iii) consideration of a vulnerability function for the future projections based on full selection of adult fish, and (iv) consequence of reducing the range of natural mortality from 0.13-0.2 to 0.13 – 0.165, consistent with slower growth rates of fish.