Joint report on exploratory fishing in Divisions 58.4.1 and 58.4.2 between the 2011/12 and 2015/16 fishing seasons

Robust stock assessments and catch limits according to CCAMLR decision rules remain to be determined for Divisions 58.4.1 and 58.4.2, and precautionary management arrangements are in place as set out in Conservation Measures 41-11 and 41-05. Multiple exploratory fishing research plans are currently in place by Australia (commenced 2015/16), France (commencing 2016/17), Japan (commencing 2016/17), Republic of Korea (commenced 2012/13) and Spain (commenced 2012/13). To facilitate progress towards stock assessment for Divisions 58.4.1 and 58.4.2, WG-SAM-16 welcomed plans for increased coordination between all proponents of research in these Divisions (WG-SAM-16 para. 3.12). Accordingly, a single consolidated research plan in being developed that outlines the collective research objectives and activities of Australia, France, Japan, Republic of Korea and Spain (hereafter referred to as the participating Members). This research plan has been submitted as a companion paper to WG-FSA-16. Separate reports on the progress of data collection and/or preliminary data analyses were presented by individual participating Members to WG-SAM-16 (WG-SAM-16/09; 16/01; 16/02; 16/04; 16/05; 16/17 and 16/10). The purpose of this paper is to provide a summary of all exploratory fishing activities and the volume of data collected up to the 2015/16 season in Divisions 58.4.1 and 58.4.2, and evaluate the collective progress towards stock assessments. A total of 897 research lines were completed over 10 fishing expeditions between 3 November 2011 and 14 April 2016. Total catches of Antarctic toothfish (Dissostichus mawsoni) and Patagonian toothfish (Dissostichus eleginoides) were 894.5 and 2.3 tonnes, respectively. Macroscopic evaluation of maturity stage indicated that both immature and mature (gonad stage ≥ 3) D. mawsoni were present across all Research Blocks. The most commonly caught bycatch group was grenadiers (Macrourus spp.), followed by icefish (Channichthyidae), moray cods (Muraenolepis spp.) and violet cod (Antimora rostrata). Target and bycatch species were sampled for total length, whole weight, sex and gonad stage in accordance with Conservation Measure 41-01. A total of 4585 D. mawsoni and 49 D. eleginoides were tagged and released between 5 January 2008 and 20 March 2016, and 19 D. mawsoni were recaptured. The 2015/16 season also included the deployment of underwater video cameras by Australia, along with CTD recorders, to improve our understanding of toothfish habitat use along East Antarctica.