Fishery Report 2020:
Dissostichus eleginoides in Divisions 58.4.4a and 58.4.4b
CCAMLR Secretariat
16 March 2021
Patagonian Toothfish, Dissostichus eleginoides Smitt, 1898.
Map of the management areas within the CAMLR Convention Area. Divisions 58.4.4a and 58.4.4b, the regions discussed in this report are shaded in green. Throughout this report, “2020” refers to the 2019/20 CCAMLR fishing season (from 1 December 2019 to 30 November 2020).
1. Introduction to the fishery
1.1. History
This report describes the closed fishery for toothfish (Dissostichus spp.) in Division 58.4.4. In 1995, Division 58.4.4 was subdivided into Division 58.4.4a (Ob Bank) and Division 58.4.4b (Lena Bank) (SC-CAMLR-XIV, Annex 5, paragraph 5.175). These divisions were managed as a single area and a catch limit for Dissostichus spp. applied to fishing north of 60\(^{\circ}\)S, and in waters outside areas of national jurisdiction (The South African EEZ at Prince Edward and Marion Islands extends into the northern part of Division 58.4.4a, see Fig. 1). The longline fishery for Dissostichus spp. in Division 58.4.4 began as a new fishery in 1998 (Conservation Measure 138/XVI). Following the Commission’s recognition that high levels of illegal, unreported and unregulated (IUU) fishing for Dissostichus spp. in the Convention Area had rendered it unrealistic to consider this fishery as ‘new’ (CCAMLR-XVIII, paragraph 10.14), the fishery was reclassified as exploratory in 1999.
Expressing concern regarding the low levels of stocks of Dissostichus spp. in Divisions 58.4.4a and 58.4.4b and the high levels of IUU fishing in that region (CCAMLR-XXI, paragraph 11.36), the Commission prohibited directed fishing for Dissostichus spp. in these divisions and closed the fishery in 2002 (Conservation Measure 32-02). The Commission agreed that such prohibition shall apply at least until further scientific information is gathered and reviewed.
1.2. Conservation Measures currently in force
Directed fishing for Dissostichus spp. in Divisions 58.4.4a and 58.4.4b 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 and Small Scale Research Units in Divisions 58.4.4a and 58.4.4b. The fishable depth range (600m-1800m) is highlighted in shades of green.
1.3. Active vessels
To this day, 3 vessels have conducted research fishing in accordance with a research plan submitted under Conservation Measure 24-01 in this area. Research fishing was conducted by a Japanese-flagged longliner from 2008 to 2017, and in 2019. The vessel was joined by 2 French-flagged vessels, one in 2015, 2017 and 2019, and another in 2018.
For the 2020 fishing season, 1 Japanese-flagged vessel and 3 French-flagged vessels were included in the research plan in this fishery.
1.4. Timeline of spatial management
In 1999, the whole of Division 58.4.4 was subdivided into Small-Scale Research Units (SSRUs) A, B, C and D (Fig. 1).
Research fishing in 2008 occurred in all SSRUs in Divisions 58.4.4a and 58.4.4b. Subsequently it was considered that this spatial extent was too large to have adequate probability of recapturing tagged fish and that research effort should be concentrated on a subset of the area and focus on SSRUs 58.4.4bB and 58.4.4bC. However, due to high levels of depredation by killer whales Orcinus orca in block B in 2011/12, the area for research moved to SSRUs 58.4.4bC and 58.4.4bD. In 2014 research blocks 58.4.4b_1 and 58.4.4b_2 were defined and have subsequently been used in this research fishery.
2. Reported catch
2.1. Latest reports and limits
In 2008 and from 2010 onward, a catch limit has been allocated to research fishing only.
Reported catches of Dissostichus eleginoides are shown in Table 1. In this fishery, the catch of D. eleginoides reached a maximum of 141 tonnes in 2000. In 2020, 0 tonnes of D. eleginoides were caught.
| Season | Number of vessels | Catch limit (tonnes) | Catch | Estimated IUU catch (tonnes) |
|---|---|---|---|---|
| 2000 | 2 | 141 |
|
|
| 2001 | 1 | 8 |
|
|
| 2008 | 1 | 80 | 77 |
|
| 2010 | 1 | 60 | 59 | 80 |
| 2011 | 1 | 53 | 35 |
|
| 2012 | 1 | 70 | 28 |
|
| 2013 | 1 | 50 | 31 |
|
| 2014 | 1 | 60 | 27 |
|
| 2015 | 2 | 35 | 35 |
|
| 2016 | 1 | 42 | 42 |
|
| 2017 | 2 | 42 | 31 |
|
| 2018 | 1 | 42 | 2 |
|
| 2019 | 2 | 41 | 11 |
|
| 2020 | 1 | 41 | 0 |
|
| Research Block | Catch limit | Catch (% of catch limit) |
|---|---|---|
| 5844b_1 | 23 | 0 (0%) |
2.2. By-catch
Catch limits for by-catch species groups (macrourids, skates (Rajids) 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.
If the catch of Macrourus spp. taken by a single vessel in any two 10-day periods in a single SSRU exceeds 1,500 kg in a 10-day period and exceeds 16% of the catch of Dissostichus spp. in that period, the vessel shall cease fishing in that SSRU for the remainder of the season.
The by-catch in Divisions 58.4.4a and 58.4.4b consisted predominantly of macrourids (Table 3).
| Season | Catch Limit (tonnes) | Reported Catch (tonnes) | Catch Limit (tonnes) | Reported Catch (tonnes) | Number Released | Catch Limit (tonnes) | Reported Catch (tonnes) |
|---|---|---|---|---|---|---|---|
| 2010 | 9.6 | 1 | 3 | <1 | 55 | 9.6 | <1 |
| 2011 | 8.48 | 2 | 2.65 | <1 | 73 | 8.48 | <1 |
| 2012 | 11.2 | 2 | 3.5 | <1 | 0 | 11.2 | <1 |
| 2013 | 8 | 1 | 2.5 | <1 | 1 | 8 | <1 |
| 2014 | 9.6 | 1 | 3 | <1 | 7 | 9.6 | <1 |
| 2015 | 5.6 | 4 | 1.75 | <1 | 189 | 5.6 | 2 |
| 2016 | 6.72 | 1 | 2.1 | <1 | 84 | 6.72 | <1 |
| 2017 | 6.72 | 7 | 2.1 | <1 | 1426 | 6.72 | 4 |
| 2018 | 6.72 | <1 | 2.1 | <1 | 842 | 6.72 | <1 |
| 2019 | 6.56 | 2 | 2.05 | <1 | 39 | 6.56 | <1 |
| 2020 | 7 | <1 | 2 | <1 | 32 | 7 | <1 |
A recent analysis of bycatch data in Division 58.4.4b indicated strong effects of gear, bathymetry and locations on bycatch composition and biomass (WG-FSA-19/53). A high proportion of Rajids were caught and released in cut-off, particularly in Research Block 5844b_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. All of the VMEs in CCAMLR’s VME Registry are currently afforded protection through specific area closures.
There are no VMEs or VME Risk Areas designated in Divisions 58.4.4a and 58.4.4b.
However, in 2019, the research plan was modified to avoid areas with high densities of sea pens (WG-FSA-18/23) and skates in the eastern region of research block 5844b_2 (WG-FSA-19/53).
2.4. Incidental mortality of seabirds and marine mammals
There have been no observed bird or mammal mortalities reported by vessels from Divisions 58.4.4a and 58.4.4b 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
An estimated total of 7,196 tonnes of Dissostichus spp. has been removed by Illegal, Unreported and Unregulated (IUU) fishing since the fishery began with >500 tonnes being removed since 2004. In 2010, the last year in which IUU catch was recorded, an estimated 80 tonnes was taken from Division 58.4.4a.
IUU fishing activities were observed in Division 58.4.4a (Ob Bank) during 2008, 2009, 2010 and 2011. French surveillance information suggested that IUU activities have been persistent until 2014. IUU fishing activities were observed in Division 58.4.4b (Lena Bank) during each year from 2006 to 2011, however, given the history of IUU fishing activities in this division, it is possible that IUU activities do still occur, but were undetected from 2011 to 2016. Information from satellite surveillance trials indicated the presence of unidentified vessels in this division in 2016. Since 2011, following the recognition of methodological issues in its assessment, no estimates of the IUU catch of Dissostichus spp. have been provided for this division (SC-CAMLR-XXIX, paragraph 6.5).
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. Length frequency distributions
The length frequency distributions of D. eleginoides caught in this fishery 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. eleginoides caught in the fishery during research fishing ranged from 50 to 150cm with a broad mode shifting from approximately 75cm to 110cm (Fig. 2).
Figure 2. Annual length frequency distributions of D. eleginoides caught in Division 58.4.4 and 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.
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. The tag-overlap statistic estimates the representative similarity between the size distributions of those fish that are tagged by a vessel and of all the fish that are caught by that vessel (Table 4). Each vessel catching more than 10 tonnes of each species of Dissostichus is required to achieve a minimum tag-overlap statistic of 60% (Annex 41-01/C).
| Flag State | Vessel name | 2010 | 2011 | 2012 | 2013 | 2014 | 2015 | 2016 | 2017 | 2018 | 2019 | 2020 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| France | Ile Bourbon | 6.2 (NC) | ||||||||||
| France | Le Saint Andre | 6.2 (79.1) | 10 (82) | 25 (NC) | 10 (NC) | |||||||
| Japan | Shinsei Maru No. 3 | 5.1 (82.8) | 5.3 (85.1) | 6.1 (75.3) | 7.5 (73.1) | 5.9 (74.2) | 6.4 (73.2) | 5.3 (79.5) | 6.3 (73.6) | 11.3 (88.6) |
To date, 2333 D. eleginoides have been tagged and released (59 have been recaptured) in this fishery (Table 5).
| Flag State | Vessel name | 2010 | 2011 | 2012 | 2013 | 2014 | 2015 | 2016 | 2017 | 2018 | 2019 | 2020 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| France | Ile Bourbon | 10 (3) | ||||||||||
| France | Le Saint Andre | 36 (3) | 156 (8) | 10 (0) | 4 (0) | |||||||
| Japan | Shinsei Maru No. 3 | 300 (1) | 189 (4) | 172 (3) | 233 (3) | 159 (9) | 183 (10) | 218 (5) | 99 (4) | 115 (6) | ||
| Total | 300 (1) | 189 (4) | 172 (3) | 233 (3) | 159 (9) | 219 (13) | 218 (5) | 255 (12) | 10 (3) | 125 (6) | 4 (0) |
5. Research
5.1. Status of the science
Catch limits for CCAMLR’s fisheries for D. mawsoni and D. eleginoides for the ‘assessed’ fisheries are set using fully integrated assessments; more basic approaches are used for the ‘data-poor’ fisheries (in Subarea 48.6 and in Area 58 outside the exclusive economic zones (EEZs)). The management of these data-poor fisheries has been a major focus of attention in CCAMLR in recent years after the acknowledgement that commercial fishing by itself had resulted in too few data to develop a full assessment of the targeted stocks in these areas. CCAMLR has developed a framework for designing and undertaking research fishing designed to lead to an assessment of these toothfish stocks in the short to medium term, established under the provisions of Conservation Measure 41-01. This research planning framework has three phases: prospecting phase, biomass estimation phase and assessment development phase, with a set of decisions and review for the progression between stages.
In order to obtain the data necessary for a stock assessment, catch limits for research fishing by commercial vessels are set at a level intended to provide sufficient information (including sufficient recaptures of tagged fish) to achieve a stock assessment within a time period of 3 to 5 years. These catch limits are also set so that they provide reasonable certainty that exploitation rates at the scale of the stock or research unit will not negatively impact the stock. Appropriate exploitation rates are based on estimates from areas with assessed fisheries and are not more than 3-4% of the estimated stock size.
In 2012 and 2013, CCAMLR put in place a more structured approach to setting catch limits, and spatially constraining research, in data-poor fisheries. This process attempts to use all available information combined with a regular review process to make progress, while recognising the inherent uncertainties and data limitations in data-poor fisheries.
A sample of 2407 otolith have been read over the 2007/08-2016/2017 fishing seasons (WG-SAM-2019/30). The growth curve and age-length keys have been also updated based on these aging data (WG-SAM-2019/30). Furthermore, Japanese scientists are currently reading 200 otoliths collected in previous fishing season (2009/10, 2015/16, and 2016/17).
In 2019, Japan and France presented a CASAL model evaluation incorporating the calculation of harvest rate for D. eleginoides at Division 58.4.4b (WG-FSA-19/62).
5.2. Research plans
5.2.1. Background
WG-FSA noted that this is a closed area and requested that the Scientific Committee consider the viability of this research plan and the sustainability of this stock given: (i) that proposed research designs have not been implemented, (ii) low and declining catch rates, (iii) low numbers of historical tag recaptures, (iv) low expected numbers of future recaptures due to low catches, and (v) limited milestone achievement (SC-CAMLR-XXXVII, Annex 9, paragraph 4.137).
In 2019, a revised research plan for Division 58.4.4b was submitted by Japan an France (WG-SAM-19/08), and a CASAL model evaluation incorporating the calculation of harvest rate for D. eleginoides at Division 58.4.4b was presented by those Members (WG-FSA-19/62).
5.2.2. Objectives
The 2019 revised research plan for Division 58.4.4b aims at achieving five objectives (WG-SAM-19/08):
Investigate population structure of Patagonian toothfish (D. eleginoides).
Provide an assessment of the status and productivity of Patagonian toothfish stock.
Investigate population structure of bycatch species and inform bycatch mitigation measures.
Improve knowledge on benthic invertebrates and VME in data poor areas of the area 58.
Contribute to scientific research programs on killer whales (O. orca) ecology and depredation.
5.3. Advice by the Scientific Committee
In 2016, the Scientific Committee supported the continuation of this research program and recommended that the catch limit for Division 58.4.4b remained unchanged (from the previous season) at 25 tonnes in Research Block 5844b_1 and 35 tonnes in Research Block 5844b_2 for the 2017 season (SC-CAMLR-XXXV, paragraph 3.254).
The Scientific Committee noted in 2017 that WG-FSA-17 had reviewed the joint proposal by France and Japan to continue research in Division 58.4.4b and agreed that it is appropriate to achieve the research objectives (SC-CAMLR-XXXVI, paragraph 3.123).
In 2018, in response to concerns about the progress of research in this division, the Scientific Committee agreed a revised research plan for this division.
In 2019, the Scientific Committee noted the progress made with a stock assessment model in this division, and that the level of the estimated yields was consistent with the CCAMLR decision rules and would allow a yield substantially higher than the catch limit set using the Chapman estimate of biomass (WG-FSA-2019 report, Table 7). The Scientific Committee agreed that a 20% increase from the existing catch limit in research block 5844b_1 to 23 tonnes would be consistent with the trend analysis procedure. It also agreed on catch limits to be calculated for research block 5844b_2 using the trend analysis rules.
The Scientific Committee recommended that catch limits for Division 58.4.4b be set using the trend analysis rules and CASAL model.
The Scientific Committee agreed that by-catch limits for this research fishing should be set at 16% of the research catch limit for D. eleginoides in this Division.
The Scientific Committee requested that discussions on fishery status and the regulatory framework in relation to the status of this area changing from a closed area under Conservation Measure 32-02 to an exploratory fishery be considered by the Commission with this advice.
6. Stock status
6.1. Summary of current status
As a data-limited fishery, this fishery does not have such estimates. However recent stock evaluations have been carried out using CASAL (WG-FSA-19/62). Preliminary results indicate that the 2017 statut ranged between 67 and 71% of B0 in Research Block 58.4.4b_1 (WG-FSA-19/62).
6.2. Assessment method
Although there has been no integrated stock assessment for this data-poor exploratory fishery, initial biomass estimates were undertaken using the catch rate and seabed area analogy method, as recommended by SC-CAMLR-XXX, Annex 5, paragraph 2.40(ii). Since this estimate was highly uncertain due to the inherent difficulty of CPUE standardisation and the assumption of a comparable reference area, a precautionary discount factor of 0.3 was applied, similar to that used for D. mawsoni in the Ross Sea. Using this approach, the precautionary biomass was estimated at 4,078 tonnes. Applying a precautionary exploitation rate of 0.01 (consistent with assuming that the current status of this potentially depleted stock is 30% B0 under the generalised yield model application described in WG-FSA-10/42 Rev. 1), resulted in a precautionary research catch limit of 41 tonnes.
Stock biomass and catch limits in data-limited fisheries are estimated using the trend analysis.
In 2019, catch limits for Research Block 58.4.4b_1 were set according to the conclusions of the new CASAL assessment that has been presented during WG-FSA 2019 (WG-FSA-19/62).
6.3. Year of last assessment, year of next assessment
This research plan is ongoing (2016/17-2020/21) and from 2019 onward, its stock assessment will be reviewed every second year at WG-FSA, unless otherwise specified (CCAMLR-38, paragraph 5.64).
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.