Antarctic toothfish, *Dissostichus mawsoni* Norman, 1937, and, Patagonian Toothfish, *Dissostichus eleginoides* Smitt, 1898.

Antarctic toothfish, Dissostichus mawsoni Norman, 1937, and, Patagonian Toothfish, Dissostichus eleginoides Smitt, 1898.


Map of the management areas within the CAMLR Convention Area. Subarea 48.2, the region discussed in this report is shaded in green. Throughout this report, “2021” refers to the 2020/21 CCAMLR fishing season (from 1 December 2020 to 30 November 2021).

Map of the management areas within the CAMLR Convention Area. Subarea 48.2, the region discussed in this report is shaded in green. Throughout this report, “2021” refers to the 2020/21 CCAMLR fishing season (from 1 December 2020 to 30 November 2021).



1. Introduction to the fishery

1.1. History

Research fishing for Dissostichus spp. in Subarea 48.2 was first conducted by Chile in 1998, when seven hauls were conducted and 36kg of Patagonian toothfish (Dissostichus eleginoides) were caught.

In 2015, Ukraine began a multi-year research program and conducted 29 hauls with a total catch of 31 tonnes of Antarctic toothfish (D. mawsoni) and 4 tonnes of D. eleginoides. Research has continued since 2016 in two Research Blocks (Fig. 1) as part of a multi-year research program in the east of Subarea 48.2.

1.2. Conservation Measures currently in force

Directed fishing for Dissostichus spp. in Subarea 48.2 is prohibited under Conservation Measure 32-02 at least until further scientific information is gathered and reviewed by the Scientific Committee and the Working Group on Fish Stock Assessment (WG-FSA).

Figure 1: Location of the Research Blocks in Subarea 48.2. The fishable depth range (600m-1800m) is highlighted in shades of green.

Figure 1: Location of the Research Blocks in Subarea 48.2. The fishable depth range (600m-1800m) is highlighted in shades of green.


1.3. Active vessels

In 2019, when fishing last occurred, 3 vessels participated in this fishery.


2. Reported catch

2.1. Latest reports and limits

The total catch reported from research surveys that have been conducted in Subarea 48.2 are shown in Table 1. In this fishery, the catch of D. mawsoni reached a maximum of 35 tonnes in 2019. In 2019, 1 tonnes of D. eleginoides were caught.

The catches reported in Subarea 48.2 include catch data that CCAMLR has agreed should be quarantined as there is no confidence in the amount and/or the location of those catches (SC-CAMLR-38, paragraph 3.56). All ancillary data associated with these vessels (e.g., by-catch, tagging, observer data) are also quarantined and are not included in the data presented in this report.


Table 1. Catch (tonnes) and effort history for Dissostichus spp. in this fishery. Source: Fine scale data and past estimates for IUU catch (-: no IUU estimate available; q: catch data currently quarantined).
Season Number of vessels D. eleginoides D. mawsoni Estimated IUU catch (tonnes)
1998 1 0
2015 1 0 (q: 4) 0 (q: 31)
2016 2 1 (q: 2) 6 (q: 66)
2017 3 0 (q: 7) 11 (q: 56)
2018 5 1 (q: 2) 8 (q: 56)
2019 3 1 35




2.2. By-catch

Table 2. Reported catch for by-catch species (Macrourus spp., skates and rays, and other species) in this fishery. Source: fine-scale data.
Macrourus spp.
Skates and rays
Other catch
Season Catch Limit (tonnes) Reported Catch (tonnes) Catch Limit (tonnes) Reported Catch (tonnes) Number Released Catch Limit (tonnes) Reported Catch (tonnes)
1998 0 <1 0 <1 0 0 <1
2015 12 <1 q 3.75 <1 q 1 q 12 <1 q
2016 12 <1 q 3.75 <1 82 12 <1 q
2017 12 3 q 3.75 <1 452 12 <1 q
2018 12 3 q 3.75 <1 206 12 <1 q
2019 12 5 3.75 <1 371 12 <1


2.3. Vulnerable marine ecosystems (VMEs)

All Members are required to submit, within their general 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. All of the VMEs in CCAMLR’s VME Registry are currently afforded protection through specific area closures.

By the end of the 2019 fishing season, there were 16 VMEs and no VME Risk Areas designated in Subarea 48.2.


2.4. Incidental mortality of seabirds and marine mammals

There has been no observed seabird mortality reported by vessels from Subarea 48.2 in this fishery.

There has been no observed mammal mortalities reported by vessels from Subarea 48.2 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

Illegal, unreported and unregulated (IUU) fishing gear was recovered from Subarea 48.2 in March 2016 (CCAMLR-XXXV/10). There has been no other recorded evidence of IUU activities in this region since 2006.


4. Data collection

4.1. Data collection requirements

The collection of biological data under Conservation Measure 23-05 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 3 and 4.

Table 3. Summary of VME indicator taxa by-catch, by-catch of other species and biological data reported by vessels crew and observers in each of the last five seasons. By-catch records correspond to the number of observations of total weight and count of individuals for each taxon identified. Observers may take further biological measurements on toothfish and by-catch taxa. Taxonomic identification may occur at different levels.
Data source Data class Variable 2017 2018 2019 2020 2021
Vessel crew VME line segments 63 54 380 0 0
VME indicator units > 5 and < 10 0 0 0 0 0
VME indicator units > 10 0 0 0 0 0
by-catch taxa identified 7 8 8 0 0
records 35 52 129 0 0
Observer VME line segments 63 56 212 0 0
taxa identified 1 9 15 0 0
weight or volume measurements 63 26 55 0 0
toothfish specimens examined 207 191 886 0 0
length measurements 207 191 885 0 0
weigth measurements 197 190 758 0 0
sex identifications 178 189 886 0 0
maturity stage identifications 178 190 791 0 0
gonad weight measurements 176 176 246 0 0
otolith samples 75 80 543 0 0
by-catch specimens examined 274 213 752 0 0
taxa identified 8 5 9 0 0
length measurements 254 198 228 0 0
weigth measurements** 274 207 345 0 0
standard length measurements* 0 0 15 0 0
wingspan measurements* 2 35 25 0 0
pelvic length measurements* 2 35 25 0 0
snout to anus measurements* 229 130 631 0 0
sex identifications** 274 167 712 0 0
maturity stage identifications** 274 130 689 0 0
gonad weight measurements** 0 8 0 0 0
otolith samples** 0 0 185 0 0
**: Voluntary records
*: Species-dependent records
Table 4. Summary of biological data for predominant by-catch groups reported by observers (from random subsets of lines) in each of the last five seasons. Taxonomic identification may occur at different levels.
By-catch group Variable 2017 2018 2019 2020 2021
Macrourus spp. specimens examined 214 130 631 0 0
taxa identified 4 2 3 0 0
length measurements 194 115 110 0 0
weigth measurements** 214 130 254 0 0
snout to anus measurements* 214 130 631 0 0
sex identifications** 214 100 606 0 0
maturity stage identifications** 214 100 606 0 0
gonad weight measurements** 0 8 0 0 0
otolith samples** 0 0 185 0 0
Skates and rays specimens examined 2 35 25 0 0
taxa identified 1 1 1 0 0
length measurements 2 35 25 0 0
weigth measurements** 2 35 25 0 0
wingspan measurements* 2 35 25 0 0
pelvic length measurements* 2 35 25 0 0
sex identifications** 2 35 25 0 0
maturity stage identifications** 2 0 25 0 0
gonad weight measurements** 0 0 0 0 0
Other fish specimens examined 58 48 96 0 0
taxa identified 3 2 5 0 0
length measurements 58 48 93 0 0
weigth measurements** 58 42 66 0 0
standard length measurements* 0 0 15 0 0
sex identifications** 58 32 81 0 0
maturity stage identifications** 58 30 58 0 0
gonad weight measurements** 0 0 0 0 0
otolith samples** 0 0 0 0 0
**: Voluntary records
*: Species-dependent records


4.3. Length frequency distributions

The length frequency distributions of D. mawsoni caught during research are shown in Figure 2. 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 125 to 175cm.


Figure 2. Annual length frequency distributions of *D. mawsoni* caught in Subarea 48.2. 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.

Figure 2. Annual length frequency distributions of D. mawsoni caught in Subarea 48.2. 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.


4.4. Tagging

To date in this area, 1359 D. mawsoni have been tagged and released (17 have been recaptured, 15 of which were released in this area; Table 5), and, 88 D. eleginoides have been tagged and released (0 have been recaptured).


Table 5. Number of Dissostichus mawsoni tagged and recaptured in the area for each fishing Season.
Recaptured
Season Tagged 2016 2017 2018 2019 Total
2015 156 1 1
2016 346 4 4
2017 349 2 1 1 4
2018 323 3 3 6
2019 185
Total 1359 15


5. Research

5.1. Status of the science

In 2014, the Scientific Committee endorsed the advice of the Working Group on Fish Stock Assessment (WG-FSA) (SC-CAMLR-XXXIII, Annex 7, paragraph 5.48) that the research plan of Ukraine in Subarea 48.2 proceed in 2015 with an effort limit of 30 lines and catch limit of 75 tonnes of Dissostichus spp. and a tagging rate of 5 toothfish per tonne. This research program was continued in 2016 with the following specific objectives:

  1. to utilise the expertise and experience of crew aboard vessels to explore and locate fishable habitat and sample toothfish in Subarea 48.2

  2. to document the spatial distribution of toothfish species in the area to east of the South Orkney Islands, thus providing catch and biological observations to test and develop the functionality of spatial population models of the north Weddell Sea region

  3. to tag toothfish and collect biological samples to further understand toothfish movement, migration, spawning and stock linkages within Area 48 and adjacent waters.

In 2019, Ukraine reported on its research progress, including data on the distribution of Antarctic toothfish and by-catch, and, biological characteristics (length, weight and age) of Antarctic and Patagonian toothfish (WG-FSA-19/51).


5.2. Research plans

Objectives

Ukraine initiated a three year (2015-2017) research plan using longline gear (trotline) to sample the toothfish populations in Subarea 48.2. The purpose of the research is to characterise the toothfish populations found in that region to better understand stock structure, movement patterns and improve estimates of population characteristics in the northern Weddell/Scotia Sea. The distribution of the two species of Dissostichus overlaps in this area. Additional outcomes of the research relate to mapping of the fishable area, documenting relative abundance of D. eleginoides and D. mawsoni, tagging toothfish for biomass estimation and for stock linkage studies, input into spatial population models and collecting information on distribution, relative abundance and life history of by catch species.

The Ukrainian research was continued after 2017 and the vessel Simeiz undertook research fishing in 2018.

In 2016, the United Kingdom proposed to undertake a 3-year research survey in the eastern part of Subarea 48.2 (also extending into Subarea 48.4). The aim of the UK study is to understand the connectivity of toothfish stocks between Subareas 48.2 and 48.4. The specific objectives of the survey are:

  1. determine population connectivity of D. eleginoides and D. mawsoni between Subareas 48.2 and 48.4 adjacent to the established fishery in Subarea 48.4,

  2. expand information on population structures of D. eleginoides and D. mawsoni in Subareas 48.2 and 48.4 adjacent to established fishery in Subarea 48.4,

  3. improve data on bathymetry and associated distributions of target and benthic by-catch species, improve data available to CCAMLR on bathymetric features.

The UK vessel Argos Froyanes and the New Zealand vessel San Aspiring undertook research fishing in 2018 for the UK research survey.


5.3. Advice by the Scientific Committee

Research fishing in Subarea 48.2 is conducted under Conservation Measure 24-01.


6. Stock status

6.1. Summary of current status

As a data-limited fishery, this fishery does not have such estimates.


6.2. Year of last assessment, year of next assessment

Research plans for data-limited fisheries are reviewed annually.


7. Climate Change and environmental variability

A recent summary of the potential impacts of climate change on Southern Ocean fisheries (FAO 2018) highlights the following key points:

The Antarctic region is characterized by complex interaction of natural climate variability and anthropogenic climate change that produce high levels of variability in both physical and biological systems, including impacts on key fishery taxa such as Antarctic krill.

The impact of anthropogenic climate change in the short-term could be expected to be related to changes in sea ice and physical access to fishing grounds, whereas longer-term implications are likely to include changes in ecosystem productivity affecting target stocks.

There are no resident human populations or fishery-dependent livelihoods in the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) Area, therefore climate change will have limited direct implications for regional food security. However, as an “under-exploited” fishery, there is potential for krill to play a role in global food security in the longer term.

The institutional and management approach taken by CCAMLR, including the ecosystem-based approach, the establishment of large marine protected areas, and scientific monitoring programmes, provides measures of resilience to climate change.

There is no formal evaluation of the impacts of climate change and environmental variability available for this particular fishery.


Additional Resources