Fishery Report 2023:
Dissostichus mawsoni in Subarea 88.3
CCAMLR Secretariat
03 May 2024
Antarctic Toothfish, Dissostichus mawsoni Norman, 1937.
Map of the management areas within the CAMLR Convention Area. Subarea 88.3, the region discussed in this report is shaded in green. Throughout this report, “2023” refers to the 2022/23 CCAMLR fishing season (from 1 December 2022 to 30 November 2023). Coastlines and ice shelves: UK Polar Data Centre/BAS and Natural Earth. Projection: EPSG 6932.
1. Introduction to the fishery
1.1. History
Research fishing for Antarctic toothfish (Dissostichus mawsoni) in Subarea 88.3 has been occasionally conducted by Chilean, New Zealand and Russian flagged vessels between 1998 and 2012. Since 2016 research fishing has been led by the Republic of Korea in Research Blocks (Fig. 1) in this Subarea, joined by New Zealand from 2017 to 2019 and by Ukraine since 2018.
1.2. Conservation Measures currently in force
Directed fishing for Dissostichus spp. in Subarea 88.3 is prohibited under Conservation Measure 32-02 until further scientific information is gathered and reviewed by the Scientific Committee and the Working Group on Fish Stock Assessment (WG-FSA). Research fishing in this area is regulated under Conservation Measures 24-01 and 24-05.
Figure 1: Location of the Research Blocks in Subarea 88.3. The fishable depth range (600m-1800m) is highlighted in shades of green. Coastlines and ice shelves: UK Polar Data Centre/BAS and Natural Earth. Bathymetry: GEBCO. Projection: EPSG 6932 (rotated).
1.3. Active vessels
In 2023, 2 vessels participated in this fishery.
1.4. Timeline of spatial management
Following a proposal from Korea to begin research fishing under Conservation Measure 24-01 in 2016 (WG-SAM-16/11), Research Blocks 1 to 5 were defined (Fig. 1). Additional Research Blocks (6-10) were proposed by New Zealand in 2017 (WG-FSA-17/40).
2. Reported catch
2.1. Latest reports and limits
The total catch reported from the research surveys that have been conducted in Subarea 88.3 is shown in Table 1. In this fishery, the catch of D. mawsoni reached a maximum of 129 tonnes in 2022. In 2023, 0 tonnes of D. eleginoides and 97 tonnes of D. mawsoni were caught.
| Season | Number of vessels | Catch limit (tonnes) | D. eleginoides | D. mawsoni | Estimated IUU catch (tonnes) |
|---|---|---|---|---|---|
| 2011 | 1 | 65 | 0 | 5 | – |
| 2012 | 1 | 65 | 0 | 4 | – |
| 2013 | – | 0 | – | – | – |
| 2014 | – | 0 | – | – | – |
| 2015 | – | 0 | – | – | – |
| 2016 | 1 | 171 | 0 | 106 | – |
| 2017 | 1 | 171 | 0 | 119 | – |
| 2018 | 1 | 245 | 0 | 39 | – |
| 2019 | 1 | 245 | 1 | 63 | – |
| 2020 | 2 | 254 | 0 | 96 | – |
| 2021 | – | – | – | – | |
| 2022 | 2 | 254 | 0 | 129 | – |
| 2023 | 2 | 484 | 0 | 97 | – |
| Research Block | Catch limit | Catch (% of catch limit) |
|---|---|---|
| 883_1 | 16 | 14 (87.5%) |
| 883_3 | 48 | 48 (100%) |
| 883_4 | 48 | 28 (58.3%) |
| 883_6 | 36 | 4 (11.1%) |
| 883_7 | 36 | 4 (11.1%) |
2.2. By-catch
Catch limits for by-catch species groups (Macrourus spp., skates and rays, and other species) are defined in Conservation Measure 33-03 and provided in Table 3.
If the by-catch of any one species is equal to, or greater than, 1 tonne in any one haul or set, then the fishing vessel must move at least 5 nautical miles away for a period of at least five days (Conservation Measure 33-03).
Skates thought to have a high probability of survival are released at the surface in accordance with Conservation Measure 33-03.
| Season | Catch Limit (tonnes) | Reported Catch (tonnes) | Catch Limit (tonnes) | Reported Catch (tonnes) | Number Released | Catch Limit (tonnes) | Reported Catch (tonnes) |
|---|---|---|---|---|---|---|---|
| 2016 | 39.2 | 3 | 12.25 | <1 | 0 | 39.2 | 1 |
| 2017 | 39.2 | 7 | 12.25 | <1 | 0 | 39.2 | <1 |
| 2018 | 39.2 | 7 | 12.25 | <1 | 0 | 39.2 | <1 |
| 2019 | 39.2 | 5 | 12.25 | <1 | 197 | 39.2 | 2 |
| 2020 | 43 | 11 | 16 | <1 | 69 | 43 | <1 |
| 2021 | – | – | – | – | |||
| 2022 | 38.4 | 4 | 11.5 | <1 | 494 | 38.4 | 2 |
| 2023 | 33 | 8 | 9.7 | <1 | 389 | 33 | 2 |
2.3. Vulnerable marine ecosystems (VMEs)
All Members are required to submit, within their general new (Conservation Measure 21-01) and exploratory (Conservation Measure 21-02) fisheries notifications requirements, information on the known and anticipated impacts of their gear on vulnerable marine ecosystems (VMEs), including benthic communities and benthos such as seamounts, hydrothermal vents and cold-water corals. For research fisheries notified under Conservation Measure 24-01, exemptions from specific Conservation Measures can be made, as recorded each year under Conservation Measure 24-05. All of the VMEs in CCAMLR’s VME Registry are currently afforded protection through specific area closures.
The proponents of this research indicated that CCAMLR standard methods for the identification of VMEs will be applied on board during the survey (WG-FSA-2021/34).
There are no VMEs or VME Risk Areas designated in Subarea 88.3.
2.4. Incidental mortality of seabirds and marine mammals
There have been no reported bird or mammal mortalities reported by vessels from Subarea 88.3 in this fishery.
The requirements of Conservation Measure 25-02, including the ‘Minimisation of the incidental mortality of seabirds in the course of longline fishing or longline fishing research in the Convention Area’ apply to this fishery. There is an exemption to the requirement for night setting by achieving the sink rates described in Conservation Measure 24-02 and subject to a bird by-catch limit.
3. Illegal, Unreported and Unregulated (IUU) fishing
There are no records of illegal, unreported and unregulated (IUU) fishing activities in Subarea 88.3.
4. Data collection
4.1. Data collection requirements
The collection of biological data as part of the CCAMLR Scheme of International Scientific Observation (SISO) includes representative samples of length, weight, sex and maturity stage, as well as collection of otoliths for age determination of the target and most frequently taken by-catch species.
4.2. Summary of available data
Both the vessel’s crew and observers collect fishing effort, catch, and by-catch information.
Following Conservation Measure 22-07, vessels participating in this fishery must report the occurrence of VME indicator organisms on hauled lines. To do so, the vessel’s crew observe lines in segments (1000-hook sections or 1200m sections, whichever is the shorter) and report the number of VME indicator units (either one litre of those VME indicator organisms that can be placed in a 10-litre container, or one kilogram of those VME indicator organisms that do not fit into a 10-litre container). Depending on the number of VME indicator units landed, vessels must immediately report and potentially cease fishing in the area (termed a Risk Area) until further review of the data is completed (see Conservation Measure 22-07). Based on the portion of the line monitored, observers further identify VME indicator organisms to the lowest taxonomic level possible.
The vessel’s crew report total catch of non-VME by-catch (mostly fishes) by coarse taxonomic groups given the taxonomic expertise required to discriminate similar species. Observers collect biological information on toothfish and by-catch specimens at a finer taxonomic resolution, as well as data on individual specimens such as size and maturity.
Summaries of data reported to CCAMLR for the past five years are given in Tables 4 and 5.
| Data source | Data class | Variable | 2019 | 2020 | 2021 | 2022 | 2023 |
|---|---|---|---|---|---|---|---|
| Vessel crew | VME | line segments | 1303 | 935 | – | 1395 | 1723 |
| VME indicator units > 5 and < 10 | 0 | 0 | – | 0 | 0 | ||
| VME indicator units > 10 | 0 | 0 | – | 0 | 0 | ||
| by-catch | taxa identified | 11 | 14 | – | 12 | 17 | |
| records | 313 | 253 | – | 369 | 423 | ||
| Observer | VME | line segments | 1392 | 276 | – | 817 | 1364 |
| taxa identified | 8 | 6 | – | 3 | 9 | ||
| weight or volume measurements | 47 | 19 | – | 3 | 27 | ||
| toothfish | specimens examined | 2031 | 2186 | – | 3700 | 3593 | |
| length measurements | 2031 | 2186 | – | 3700 | 3593 | ||
| weight measurements | 2031 | 2165 | – | 3700 | 3593 | ||
| sex identifications | 2031 | 2156 | – | 3700 | 3592 | ||
| maturity stage identifications | 1999 | 2144 | – | 3678 | 3575 | ||
| gonad weight measurements | 1975 | 2141 | – | 3678 | 3583 | ||
| otolith samples | 897 | 1158 | – | 1153 | 2235 | ||
| by-catch | specimens examined | 1798 | 951 | – | 1494 | 4939 | |
| taxa identified | 12 | 16 | – | 15 | 14 | ||
| length measurements | 1797 | 455 | – | 800 | 3814 | ||
| weight measurements** | 1797 | 951 | – | 1494 | 4939 | ||
| standard length measurements* | 1 | 0 | – | 360 | 0 | ||
| wingspan measurements* | 75 | 2 | – | 16 | 244 | ||
| pelvic length measurements* | 75 | 2 | – | 16 | 244 | ||
| snout to anus measurements* | 981 | 686 | – | 1047 | 2574 | ||
| sex identifications** | 1760 | 909 | – | 1115 | 4456 | ||
| maturity stage identifications** | 1531 | 905 | – | 1107 | 3055 | ||
| gonad weight measurements** | 0 | 14 | – | 207 | 17 | ||
| otolith samples** | 0 | 321 | – | 400 | 320 | ||
| **: Voluntary records | |||||||
| *: Species-dependent records |
| By-catch group | Variable | 2019 | 2020 | 2021 | 2022 | 2023 |
|---|---|---|---|---|---|---|
| Macrourus spp. | specimens examined | 977 | 686 | – | 1046 | 2574 |
| taxa identified | 1 | 3 | – | 4 | 3 | |
| length measurements | 977 | 191 | – | 356 | 1507 | |
| weight measurements** | 977 | 686 | – | 1046 | 2574 | |
| snout to anus measurements* | 977 | 686 | – | 1046 | 2574 | |
| sex identifications** | 956 | 676 | – | 946 | 2574 | |
| maturity stage identifications** | 863 | 675 | – | 945 | 2042 | |
| gonad weight measurements** | 0 | 14 | – | 119 | 2 | |
| otolith samples** | 0 | 321 | – | 400 | 175 | |
| Skates and rays | specimens examined | 75 | 2 | – | 15 | 188 |
| taxa identified | 1 | 1 | – | 1 | 1 | |
| length measurements | 75 | 2 | – | 15 | 186 | |
| weight measurements** | 75 | 2 | – | 15 | 188 | |
| wingspan measurements* | 75 | 2 | – | 15 | 188 | |
| pelvic length measurements* | 75 | 2 | – | 15 | 188 | |
| sex identifications** | 75 | 2 | – | 15 | 188 | |
| maturity stage identifications** | 37 | 2 | – | 10 | 36 | |
| gonad weight measurements** | 0 | 0 | – | 0 | 0 | |
| Other fish | specimens examined | 716 | 261 | – | 429 | 2121 |
| taxa identified | 8 | 11 | – | 8 | 9 | |
| length measurements | 716 | 260 | – | 429 | 2121 | |
| weight measurements** | 716 | 261 | – | 429 | 2121 | |
| standard length measurements* | 1 | 0 | – | 360 | 0 | |
| sex identifications** | 715 | 229 | – | 154 | 1638 | |
| maturity stage identifications** | 631 | 227 | – | 152 | 977 | |
| gonad weight measurements** | 0 | 0 | – | 88 | 15 | |
| otolith samples** | 0 | 0 | – | 0 | 145 | |
| **: Voluntary records | ||||||
| *: Species-dependent records |
The counts of by-catch taxa reported above (Table 5) correspond to specimens that have been individually sampled by observers. These are a subset of all the specimens counted by observers and are generally identified at a more precise taxonomic level. The figures below (Figs. 2 and 3) display the distribution of the most frequently examined by-catch taxa in time and space. It is important to note that observers sample a random subset of lines and do not individually examine all taxa; as such these figures are more representative of the distribution of biological observations than the catch of these taxa or their spatial distribution. At a coarse taxonomic level, the total catch of by-catch species groups is provided in section 2.2 above.
Figure 2. Relative frequencies of the most commonly examined by-catch taxa in each of the last five seasons, from the observer data (unweighted raw counts of individually examined specimens). Taxonomic identification may occur at different levels.
Figure 3. Spatial distribution of the most commonly examined by-catch taxa across the last five seasons, from the observer data (unweighted raw counts of individually examined specimens in each cell). The data were aggregated using equal area (100 km x 100 km) cells. Taxonomic identification may occur at different levels. Refer to Figure 1 for more details on the boundaries shown. Coastlines and ice shelves: UK Polar Data Centre/BAS and Natural Earth. Bathymetry: GEBCO. Projection: EPSG 6932 (rotated).
4.3. Length frequency distributions
The length frequency distributions of D. mawsoni caught during research activities are shown in Figure 4. These length frequency distributions are unweighted; they have not been adjusted for factors such as the size of the catches from which they were collected. The interannual variability exhibited in the figure may reflect changes in the fished population but is also likely to reflect changes in the gear used, the number of vessels in the fishery and the spatial and temporal distributions of fishing.
The majority of D. mawsoni caught during research fishing ranged from 50 to 175cm with two broad modes at approximately 60cm and 150cm.
Figure 4. Annual length frequency distributions of D. mawsoni caught in Subarea 88.3 and its Research Blocks. The number of hauls from which fish were measured (N) and the number of fish measured (n) in each year are indicated. Note: length frequency distributions are only shown where more than 150 fish were measured in a given season/area.
4.3. Tagging
Since 2012, vessels have been required to tag and release Dissostichus spp. at a rate of 5 fish per tonne of green weight caught.
To date in this area, 3484 D. mawsoni have been tagged and released (25 have been recaptured, 25 of which were released in this area; Table 6), and, 6 D. eleginoides have been tagged and released (0 have been recaptured).
| Season | Tagged | 2019 | 2020 | 2022 | 2023 | 2024 | Total |
|---|---|---|---|---|---|---|---|
| 2005 | 8 | ||||||
| 2011 | 30 | ||||||
| 2012 | 63 | ||||||
| 2016 | 566 | 1 | 1 | ||||
| 2017 | 597 | 1 | 1 | 2 | |||
| 2018 | 203 | 2 | 2 | 1 | 1 | 6 | |
| 2019 | 342 | 4 | 1 | 5 | |||
| 2020 | 495 | 4 | 1 | 5 | |||
| 2022 | 668 | 1 | 1 | 1 | 3 | ||
| 2023 | 512 | 2 | 1 | 3 | |||
| Total | 3484 | 25 |
5. Research
5.1. Status of the science
There were a total of 95 research hauls and 131 tagged fish as part of surveys conducted by Chilean, New Zealand and Russian flagged vessels up to 2012. This level of research activities meant that there was insufficient data to assess the toothfish stock in this Subarea. The previous surveys were restricted by sea-ice. However, as the ice concentration in the west of the Antarctic is reducing, this led the Republic of Korea to propose a multi-year research plan for Subarea 88.3 starting in 2016.
New Zealand (in 2017) and Ukraine (in 2018) joined the Republic of Korea in these research efforts.
In 2019, an integrated research proposal for Dissostichus spp. in Subarea 88.3 was submitted by the Republic of Korea, New Zealand and Ukraine (WG-SAM-2019/02).
In 2021, an updated research proposal was submitted by the Republic of Korea and Ukraine (WG-FSA-2021/34).
In 2022, the Republic of Korea and Ukraine reported on the progress and continuation of their research proposal (WG-FSA-2022/26). WG-FSA-2022/27 and WG-FSA-2022/28 presented analyses of diet composition, feeding strategy and spatial diet variations of Antarctic toothfish. Chionobathyscus dewitti, Macrouridae and Mollusks were found to be dominant prey items, and diet was found to differ between slope and shelf areas, reflecting the different prey assemblages between these areas. Also, a genetic study using microsatellite markers (WG-FSA-2022/29 Rev. 1) reported a higher genetic diversity in the Ross Sea region than other areas within Area 88.
In 2023, the Republic of Korea and Ukraine reported on the progress and continuation of their research proposal (WG-SAM-2023/23 and WG-FSA-2023/20 Rev. 1). WG-FSA-2023/25 presented analyses of diet composition and feeding strategy of Antarctic toothfish, and WG-FSA-2023/32 Rev. 1 investigated molecular and morphological traits of 338 individuals of macrourids collected in Subareas 88.1 and 88.3 between 2021 and 2022.
5.2. Research plans
5.2.1. Background
The main objective of the proposal is to determine the abundance and distribution of Antarctic toothfish in Subarea 88.3. Secondary objectives are to improve understanding of stock and population structures of toothfish in Area 88, to carry out calibration trials among the vessels, to collect data on the spatial and depth distributions of by-catch species, and to trial scientific electronic monitoring technologies.
5.2.2. Objectives
The research proposal (WG-FSA-2022/26) aims at achieving five objectives:
Determine the abundance and distribution of Antarctic toothfish in Subarea 88.3,
Improve understanding of stock structure of toothfish in Area 88,
Carry out calibration trials among vessels,
Collect data on the spatial and depth distributions of by-catch species,
Trial scientific electronic monitoring technologies.
5.3. Advice by the Scientific Committee
The advice from the Scientific Committee in 2016 on this research proposal is presented in SC-CAMLR-XXXV, paragraphs 3.255 and 3.256. The Scientific Committee recommended that the catch limits and priority for each Research Block should be as in 2016 should ice conditions allow.
In 2017, the Scientific Committee recommended that the catch limits for the Korean and New Zealand joint research plan in Subarea 88.3 be endorsed for 2018 (Table 5 and SC-CAMLR-XXXVI, paragraph 3.142).
In 2019, the Scientific Committee endorsed the Research proposal as described in [WG-SAM-19/02] (SC-CAMLR-38 paragraphs 4.59 to 4.61).
In 2020, the Scientific Committee and the Commission did not reach consensus on this research proposal (CCAMLR-39 paragraphs 5.32 and 5.33).
In 2021, the Scientific Committee endorsed the Research proposal as described in WG-FSA-2021/34, with an updated sampling rate requirement for by-catch species of 30 specimens per species per line, or the entire catch for a line if this was less than 30 specimens (SC-CAMLR-40 paragraphs 3.107).
In 2022, the Scientific Committee endorsed (SC-CAMLR-41, paragraph 4.8) the Research proposal as described in WG-FSA-2022/26.
6. Stock status
6.1. Summary of current status
As a data-limited fishery, this fishery does not have such estimates.
6.2. Assessment method
Stock biomass and catch limits in data-limited fisheries are estimated using the trend analysis.
6.3. Year of last assessment, year of next assessment
Research plans for data-limited fisheries are reviewed annually.
7. Climate Change and environmental variability
In 2022, the Commission recognised that climate change is already having effects in the Convention Area (CCAMLR-41, paragraph 6.3) and agreed that it needed to act urgently to prepare for, and adapt to, the effects of climate change on the marine ecosystems within the Convention Area (CCAMLR-41, paragraph 6.5). The Commission noted (CCAMLR-41, paragraph 6.4) that the Scientific Committee had incorporated climate change into its advice (SC-CAMLR-41, paragraph 7.8) and through discussions at the SC-Symposium (SC-CAMLR-41, Annex 11) had also added climate change to the work plans and terms of reference of its Working Groups (SC-CAMLR-41, paragraph 7.14). The Commission adopted (CCAMLR-41, paragraph 6.28) Resolution 36/41.
In 2023, the Scientific Committee held a workshop on Climate Change (WS-CC-2023) which made recommendations regarding monitoring and management actions CCAMLR could progress to document and track the effects of climate change in the Convention Area. The recommendations were incorporated into the workplan of the Scientific Committee. Further, the Scientific Committee recommended that summaries of evidence for changes in stock assessment parameters or processes that could be due to the effects of environmental variability or climate change be developed for all fisheries (SC-CAMLR-42, paragraph 2.149).