CCAMLR

The time series of relative abundance and age structure from the Ross Sea shelf survey is an important input to the Ross Sea stock assessment, providing information about year class strength and variability. In 2020, the estimated relative biomass index of toothfish showed an increase, the highest recorded in the survey time series. Biological data and samples were collected from more than 3,000 toothfish and bycatch species. A total of 232 toothfish were tagged and released with a 91% tagging length overlap statistic. Although the catch limit of 45 t was not exceeded, the experimental stratum N could not be sampled. Otoliths collected will be aged for the upcoming stock assessment in 2021.

The 2019 stock assessment for Antarctic toothfish in the Ross Sea region estimated the precautionary yield using the CCAMLR decision rules and by  applying the total catch limit of 3140 t between north of 70° S (19%), south of 70° S (66%), and the Special Research Zone (15%)  in accordance with conservation measure 91-05 (2016) and 41-09 (2019). That stock assessment excluded data for vessels that had been previously quarantined by the Scientific Committee of CCAMLR due to data accuracy concerns. However, after the stock assessment had been completed, the Scientific Committee recommended that data from three additional vessels (Calipso, Koreiz and Simeiz 2015-2018) be quarantined pending an assessment of the implication of catch revisions from those vessels on the management advice.

Based on an analysis by Ukraine in 2020 the total DCD reported greenweight was 203 t greater than the reported C2 greenweight (12%) across Subareas 88.1, 88.2, and 48.2 from 2014–2018 for the three vessels combined. In the Ross Sea region, the difference totalled 78 t in 2014–2018 with the greatest difference occurring in 2018 (52 t).

A sensitivity model was run using the 2019 stock assessment incorporating the DCD estimated greenweight from the three vessels to revise the catch history in the assessment model. Both the MPD and MCMC estimates of initial biomass (B₀) and current biomass for models with revised catch for the three vessels in trips between 2014 and 2018 were almost identical to the 2019 base case assessment model. Therefore, the differences for these trips resulted in a negligible impact on the estimated precautionary yield.  We recommend that the Scientific Committee does not need to revise its 2019 advice for the toothfish catch limit for the 2020/21 season for the Ross Sea region.

This report summarises fishing catch and effort in the Ross Sea region (Subarea 88.1 and SSRUs 88.2A–B) together with biological characteristics of the catch of Antarctic toothfish through the 2019–20 season. The implementation of the Ross Sea region Marine Protected Area from the 1^st December 2017, has concentrated subsequent fishing on the continental slope south of 70° S, with recent effort extending into Subarea 88.2, SSRUs A and B. Data from all years are summarised with respect to the current management areas.

The scaled length distributions showed no decrease in the size of fish caught over time in any of the management areas, although there was a strong pattern of interannual variability in the area south of 70° S that was likely driven by changes in the fine scale spatial distribution of fishing effort or the influence of strong and week year classes entering the fishery. There was a small change in the ratio of males to females over time, with a gradual pattern of more males caught in all areas. The number of fish recaptured in 2019–20 was similar to the annual average number of recaptures over the past decade. A tagged fish was recaptured after 16 years at liberty, which indicates that tags can remain in the fish over long time periods.

The Amundsen Sea region toothfish fishery has been operating since 2003. Fishery catch showed a truncation of the right-hand limb of the age distribution between 2004 and 2014 with no further age data available after 2016. We recommend that further ageing of toothfish in the Amundsen Sea region be made a priority to develop annual age-length keys and age frequencies. We further recommend that catch limits in the Amundsen Sea region be calculated following the trend analysis rules developed by WG-FSA for research blocks (CAMLR-XXXVI 2017, Annex 7 paragraph 4.33).

Division 58.4.4b has been a closed area since 2002 (CM 32-02) and scientific research has been conducted with a research plan submitted under CM 24-01 since 2008 by Japan. France joined this research plan in 2015 and a joint proposal was submitted for the first time in 2016 (WG-SAM-16/06 and WG-FSA-16/33 Rev. 1) for a period of 5 years.

Compared to last year (WG-FSA-2019/64), this research plan has been updated with 2020/21 operating details especially the replacement of Japanese fishing vessel from Shinsei-maru No.3 to Shinsei-maru No.8 with same crew and fishing gears (fishing method: Trot system) and the withdrawal of the French vessel Ile Bourbon, which will not notify this year. Furthermore, milestone tables have been updated to account for the postponement of the WG-SAM due to the COVID 19 situation.

In 2009, the marine predator research community was invited to provide tracking data to the Scientific Committee for Antarctic Research’s Expert Group on Birds and Marine Mammals. Over the next decade, the Retrospective Analysis of Antarctic Tracking Data (RAATD) team collated and painstakingly quality-controlled and filtered over 4,000 tracks (3 million locations) from 17 marine predator species, studied between 1991 and 2016. This dataset, published in a recent data paper (Ropert-Coudert et al. 2020), includes contributions from more than 70 scientists from 12 National Antarctic Programs and represents the field efforts of hundreds of individuals. An important feature of the dataset is that it is freely available to everyone. The data underpinned a second paper, published in the journal Nature this year (Hindell et al. 2020), wherein the RAATD team identified ‘Areas of Ecological Significance’ in the Southern Ocean, and highlighted the relevance of these areas for management and conservation of the region.

This paper presents a brief update on recent climate change-related research that is relevant to discussion and decision making by the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) and the Scientific Committee (SC-CAMLR). It complements the SCAR Antarctic Climate Change and the Environment (ACCE) Reports, initially published in 2009, and updated annually through submissions to the CEP/ATCM. It is not intended as a synthesis report, but a summary of research that is likely to be of relevance and interest to CCAMLR.

SCAR is an interdisciplinary body of the International Science Council (ISC), with a membership of 44 countries and nine ISC unions and comprising an extensive international network of scientists. SCAR is charged with initiating, developing and coordinating high quality international scientific research in, from and about the Antarctica and the Southern Ocean.

SCAR’s Mission is to advance Antarctic research, including observations from Antarctica, and to promote scientific knowledge, understanding and education on any aspect of the Antarctic region and its role in the Earth System. SCAR also provides independent and objective scientific advice and information to the Antarctic Treaty System and other bodies and facilitates the international exchange of Antarctic information within the scientific community.

Here, SCAR reports on recent and future activities of relevance to CCAMLR.

The global biodiversity and climate crisis (IPBES 2019; IPCC 2019) underscores the responsibility of CCAMLR in contributing to climate change response and mitigation, given its mandate to conserve marine life in approximately 10% of the global ocean. CCAMLR must ensure its decision-making processes and conservation measures anticipate and respond adequately to climate-driven changes in the Southern Ocean. In this paper, we describe specific actions CCAMLR should take in the next two to three years to respond to the threat of climate change in the Convention Area, based on the Climate Change Response Work Program (CCRWP) introduced in 2018 (CCAMLR XXXVII/23). ASOC recommends prioritizing the following actions to address the impacts of climate change:

1. Enhance ecosystem resilience through suitable mechanisms, including establishing a representative system of marine protected areas (MPAs).

2. Explore plausible scenarios for changes in AMLR populations over the next 2-3 decades, including methods to evaluate fishing impacts and improve baseline data.

3. Develop and adopt ecosystem-based management for krill fisheries, including regularly updating biomass estimates, stock assessments, and risk assessments.

4. Undertake spatially explicit stock assessment to account for changes in spatial distribution of species due to sea ice changes.

5. Reinvigorate the Climate Change e-Group, including updating its Terms of Reference and updating the CCRWP.

6. Continue to work to identify reference areas for climate related research, including research specified in MPA Research and Monitoring Plans.

An appendix to this paper lists additional actions/responses from the CCRWP identified by ASOC as a priority.