Continuing research plan for Antarctic toothfish (Dissostichus mawsoni) under CM 24-01, paragraph 3 in Subarea 88.3 by Korea and Ukraine from 2024/25 to 2026/27

The stock structure of Antarctic toothfish (Dissostichus mawsoni) in Area 88 is under investigation to better define stock boundaries relevant to fishery management. Ontogenetic progression has been observed across the Ross, Amundsen, and Bellingshausen Seas, with juveniles showing distinct spatial distributions. Korea initiated a research plan in Subarea 88.3, later joined by New Zealand, focusing on tagged-fish release areas and previously unstudied zones. Following Ukraine’s participation, a joint research framework operated from 2017/18 to 2023/24. Subarea 88.3, designated as a prohibited area for direct fishing for toothfish (CCAMLR CM 32-02), had not undergone stock assessment until now. In 2025, a new phase commenced to develop the first stock assessment for Antarctic toothfish in this data-limited area. Multi-year tagging has been sustained across research blocks, yet tag recaptures remain low, reflecting ice and weather constraints and the scarcity of fish in the 80–100 cm size range. To increase recapture opportunities without raising total removals, operations in slope blocks 883_11 and 883_12 will proceed under catch limits with no effort limits. Within each block, vessels first complete a pre-specified set of depth-stratified randomized stations. Remaining fishing then continues within the catch limit to add sets that improve spatiotemporal overlap between tag release and subsequent fishing and to advance the transition to biomass estimation and stock assessment. This research has four objectives. First, assess the stock status of Antarctic toothfish. Second, improve understanding of toothfish biology, including abundance, distribution, and stock structure. Third, improve information on bycatch species. Fourth, improve understanding of trophic relationships and ecosystem changes.