The annual Random Stratified Trawl Survey was undertaken within Division 58.5.2 during May 2015. Recent work which is presented here has allowed for many of the biological parameters of Channichthys rhinoceratus to be updated from previous assessments (Constable et al. 1998) and many parameters to be calculated which were previously unknown for the area within Division 58.5.2. This paper provides both short (2 years) and long term (20 years) projections of unicorn icefish structure, abundance and yield for the area of Division 58.5.2 to the west of 79°20’ E using standard CCAMLR methods. Short term projections indicate 2208 t for the 2015/16 season and 1689 t for the 2016/17 season, while long term projections (20 year) indicate sustainable yield of 1663 t.

In New and Exploratory fisheries for toothfish, mark-recapture plays a critical role to estimate biomass in the initial stage of developing an assessment. This short paper describes the use of the R package tagr to obtain Petersen / Chapman estimates of abundance. The package implements a non-parametric bootstrap to obtain confidence intervals from single release tag-recapture data.

We recommend that WG-FSA encourage Members to provide estimates of uncertainty associated with indicative biomass estimates, as often calculated for exploratory fisheries without integrated stock assessments. We also recommend that additional functions associated with mark-recapture analysis within CCAMLR’s fisheries be developed and made available to Members.

Season extension trials occur step-wise in the longline fishery for Dissostichus eleginoides in Statistical Division 58.5.2.  This paper presents results of trial fishing season extensions for the periods between 15 and 30 April, and between 1 and 14 November, during 2013/14 and 2014/15.  Based on the results, it proposes a new step-wise trial pre-season extension of the longline fishing season to include the period between 1 and 14 April with day/night setting allowed.  It also proposes that conditions be established as the basis for a further step-wise trial post-season extension of the longline fishing season.  Subject to these conditions being met, the post-season is proposed to be extended to include the period between 15 and 30 November with day/night setting allowed.  Australia will continue to report to SC‑CAMLR each year concerning the progress and outcomes of each step-wise season extension trial.

Age determination of the Patagonian (Dissostichus eleginoides) and Antarctic toothfish (Dissostichus mawsoni) is conducted using otoliths, collected while carrying out the scientific program on board the Ukrainian vessel “Simeiz” in the Northern part of Weddell Sea (statistical Subarea 48.2) in March 2015. 124 otolith pairs of Dissostichus mawsoni and 87 otolith pairs of Dissostichus eleginoides were sampled; one otolith from each pair was used for age determination. Preliminary results of age determination of the caught fish showed that, in the studied fishing area, specimens of older age groups prevailed: their age ranged from 15 to 35 years for both species.

During March-April 2015 Ukraine began the research within statistical subarea 48.2. The research activities on the assessment of the stock state of the Dissostichus spp species in subarea 48.2 will be carried out within three years. Implementation of the tagging program in the long-term prospective will provide the indicators for the procedure of abundance assessment of the studied species in this area based on the repeatedly caught tagged fish specimens according to the CASAL methodology. The certain number of the following bottom long line surveys are proposed to be conducted during March-April 2016. Investigated area will be demarcated on two blocks - Northern and Southern. During the season of year 2016 we propose to remain the majority of surveys in the Northern Block as were conducted in year 2015 in order to repeat them in the same coordinates. In the Southern Block where relatively high quantity of tagged fish were released we propose the creation of the new research block with another conditions of the investigation. On the four sea bottom risings, which are probably enough isolated from each other, we propose to conduct 25 sets. Proposed to tag 3 fish per ton in the Southern Block, remained the ratio 5 fish per ton in the Northern Block.

The stock abundance of Antarctic toothfish in Subarea 48.4 is estimated using tag based mark-recapture analysis. During WG-FSA-14 the recommendation was made that the stock should move from the Petersen estimation method to the use of the Chapman bias corrected estimator; a correction specifically developed to reduce estimation bias in populations with low recaptures, a feature typical of the data available for this species in 48.4. During a review of assessment methodology two main issues have been identified: the appropriate application of the method when applied to estimate low tag recapture rate population abundance, and the mis-identification of species at release. This paper presents a review of assessment data and methods in order to discuss and address the issues.