Revised proposal for continuing research on Antarctic toothfish (Dissostichus mawsoni) in Statistical Subarea 48.6 in 2021/22 from a multiyear plan (2021/22–2023/24): Research Plan under CM 21-02, paragraph 6(iii)

A collaborative research program has been undertaken by Japan and South Africa since 2013 to enhance data collection and analysis in the subarea 48.6 under CM 21-02. Spain joined the proposal starting from 2018/19 fishing season in order to contribute to the data acquisition and to speed up the integrated assessments of the Antarctic toothfish (Dissostichus mawsoni) stock in this subarea (WG-FSA-18/34).

The continuation of the three-member research proposal for 2021/22 season is presented to ensure continuity of previous research activities. Data and investigations about the population structure and various demographic parameters of D. mawsoni using trotline (JPN and ZAF) and Spanish longline (ESP) gears, established tagging techniques, pop-up tags and genetic analysis will provide the basis for the development of spatial population models and assessments in support of management advice. An Integrated Stock Assessment (ISA) which takes into account the tag time series from southern research areas of Subarea 48.6 is going to be continually developed until the end of the 2023/24 season.

Based on suggestion from WG-SAM-2021 (report of WG-SAM-2021, para 8.4), the research plan have been revised as follows:

• Explaining the importance of understanding stock connectivity between research blocks in the area (seamounts versus continental shelf),
• indicating further details about how the stock structure will be represented in the planned CASAL assessment for the region,
• increasing the otolith sampling rate from “10 otoliths per 5 cm length bin” to “20 otolith per 5 cm length bin), and
• indicating minimum sampling requirements for by-catch species and designed to meet the research objectives.

The WG-SAM-2021 recalled that a structured fishing design was necessary to optimise tagging performance evaluation (report of WG-SAM-2021, para 8.4). However, as already described in 3(a) “Research survey/fishing design”, the area is not suitable to set a stratified sampling design as the fishing grounds with broad environmental characteristics such as a complex of seamounts, hills and ridges is expected to be small relative to the size of the research block. Therefore, no depth stratification is proposed in the current research plan.

The updated CCAMLR Research Plan – Research Proponent Self-Assessment can be found in Appendix 1.