Patagonian Toothfish, *Dissostichus eleginoides* Smitt, 1898.

Patagonian Toothfish, Dissostichus eleginoides Smitt, 1898.



Map of the management areas within the CAMLR Convention Area. The region discussed in this report is shaded in green. Throughout this report, “2022” refers to the 2021/22 CCAMLR fishing season (from 1 December 2021 to 30 November 2022).

Map of the management areas within the CAMLR Convention Area. The region discussed in this report is shaded in green. Throughout this report, “2022” refers to the 2021/22 CCAMLR fishing season (from 1 December 2021 to 30 November 2022).



1. Introduction to the fishery

1.1. History

This report describes the licensed longline fishery for Patagonian toothfish (Dissostichus eleginoides) in the French exclusive economic zone (EEZ) established in 1978 around the Crozet Island, which includes a portion of Subarea 58.6 and extends into FAO Area 51 (north of 45\(^{\circ}\)S), outside the CAMLR Convention Area.

Trawl fishing was conducted by Japanese vessels prior to 1979 and by French vessels from 1983 to 1996 and in 2000. It has since been discontinued. A joint survey between France and Japan first conducted longline fishing in Subarea 58.6 in 1997, and this method has been used in the fishery since then.

The fishery is open year-round, but most fishing effort takes place in February and March when the fishery in the French EEZ at the Kerguelen Islands (Division 58.5.1) is closed. Fishing effort in this area concentrates on the Crozet shelf slope and on the eastern part of the del Cano Rise. The fishery is also charactrised by a high level of catch depredation (Tixier et al., 2010) by killer whales (Orcinus orca).


1.2. Conservation Measures currently in force

Within the French EEZs, catch limits for target species, as well as vessel licensing, are allocated by France (TAAF). A six-year management was adopted in July 2019 with the overall objective of ensuring conditions for a sustainable and optimal exploitation of Patagonian toothfish. It also sets catch limits for a period of 3 years. The 2020-2022 seasonal catch limit was set at 800 tonnes, and the 2023-2025 seasonal catch limit was set at 930 tonnes.

In the EEZ of Crozet Island, various national conservation and fisheries enforcement measures are applicable, such as:

  • Annual catch limit set triennially since September 2019
  • Demersal longlines and pots are the only authorized fishing gears
  • Fishing season extends from 1 September to 31 August of the following year, which differs from the CCAMLR fishing season
  • A maximum of two vessels fishing simultaneously per 0.5\(^{\circ}\) latitude x 1\(^{\circ}\) longitude rectangle
  • Fishing is prohibited within the strict protection areas of the Marine Reserve which include areas not exceeding 500m in depth
  • Move-on rule to limit catches of D. eleginoides of 60cm and less
  • Cut-off procedure and move-on rules for skates to reduce fishing mortality
  • Mitigation measures to reduce bird mortality
  • Move-on rule on VME
  • One French scientific observer on board each licensed vessel
  • Mandatory vessel logbooks
  • A single catch landings site at Réunion Island
  • Mandatory port inspection

The limits in force and the advice of WG-FSA-2021 to the Scientific Committee for the 2022 season were:

  1. The Working Group agreed that the catch limit set by France of 800 tonnes in 2022, which accounts for depredation, was consistent with the CCAMLR decision rules for the model runs presented,

  2. No new information was available on the state of fish stocks in Subarea 58.6 outside areas of national jurisdiction. The Working Group therefore recommended that the prohibition of directed fishing for D. eleginoides, described in Conservation Measure 32-02, remain in force in 2022.

Figure 1: Map of the region discussed in this report.

Figure 1: Map of the region discussed in this report.


1.3. Active vessels

In 2022, 7 vessels participated in this fishery.


2. Reported catch

Since the CCAMLR fishing season (1 December to 30 November of the following year, UTC time) and the TAAF fishing season (1 September to 31 August of the following year) do not match, data pooled at the annual scale and shown in this document may not match data reported by TAAF. This distinction is particularly relevant if readers wish to compare annual catch in the Convention Area to annual catch limits as set by TAAF.

2.1. Latest reports and limits

Reported catches of Dissostichus eleginoides are shown in Table 1. In this fishery, the catch of D. eleginoides reached a maximum of 1296 tonnes in 2002. In 2022, 699 tonnes of D. eleginoides were caught.


Table 1. Catch and effort history for Dissostichus eleginoides in this fishery (within Subarea 58.6). Source: Fine scale data and past estimates for IUU catch (-: no fishing, or no IUU estimate available).
Season Longline Catch (tonnes) Trawl Catch (tonnes) Pot Catch (tonnes) Total Catch (tonnes) Number of vessels Estimated IUU catch (tonnes)
1987 – – – 488 1 –
1988 – 21 – 21 1 –
1989 – – – – – –
1990 – – – – – –
1991 – – – – – –
1992 – – – – – –
1993 – – – – – –
1994 – 56 – 56 1 –
1995 – 114 – 114 1 –
1996 – 3 – 3 1 –
1997 76 – – 76 1 –
1998 12 0 – 12 1 –
1999 29 109 – 138 4 –
2000 989 – – 989 5 1430
2001 1054 – – 1054 6 685
2002 1296 – – 1296 7 720
2003 532 – – 532 6 302
2004 534 – – 534 7 380
2005 596 – – 596 7 12
2006 1051 – – 1051 8 55
2007 421 – – 421 7 0
2008 823 – – 823 7 224
2009 886 – – 886 8 0
2010 663 – – 663 7 0
2011 703 – – 703 7 0
2012 673 – – 673 7 –
2013 840 – – 840 7 –
2014 778 – – 778 7 –
2015 864 – – 864 7 –
2016 1054 – – 1054 8 –
2017 1143 – – 1143 8 –
2018 1116 – – 1116 7 –
2019 825 – – 825 7 –
2020 818 – – 818 7 –
2021 832 – 2 833 7 –
2022 699 – – 699 7 –



2.2. By-catch

Primary by-catch species from the longline fishery at Crozet Islands are the ridge-scaled grenadier (Macrourus carinatus), rajid skates (Amblyraja taaf) and blue antimora (Antimora rostrata). The latter species is fully discarded, while the others are partly or totally retained.

Avoidance of high level by-catch areas has been promoted with the implementations of move on rules, and the cut-off protocol is in force following CCAMLR recommendations.

The by-catch in the French EEZ at Crozet Islands consists predominantly of Macrourus spp. (Table 2).


Table 2. Reported catch for by-catch species (Macrourus spp., skates and Antimora rostrata) in this longline fishery (within Subarea 58.6). Source: fine-scale data.
Macrourus spp.
Skates
Antimora rostrata
Season Reported Catch (tonnes) Reported Catch (tonnes) Number Released Reported Catch (tonnes)
1997 10 <1 0 <1
1998 2 <1 0 <1
1999 <1 3 0 <1
2000 96 31 0 11
2001 98 6 0 <1
2002 195 35 0 11
2003 148 92 0 19
2004 117 73 0 56
2005 132 93 0 67
2006 147 120 0 52
2007 119 85 2118 43
2008 135 46 11397 64
2009 193 46 17730 79
2010 113 56 6836 78
2011 93 29 2484 23
2012 96 75 2448 21
2013 64 29 273 17
2014 92 53 9684 36
2015 108 17 22575 75
2016 120 33 28395 142
2017 111 23 26718 58
2018 88 20 33859 133
2019 78 13 21800 43
2020 59 2 10465 18
2021 51 5 21942 14
2022 60 9 30681 26


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.

In this fishery, fishery observers follow protocols to collect information about benthos taxa, including VME taxa.

There are no VMEs or VME Risk Areas designated in Subarea 58.6.


2.4. Incidental mortality of seabirds and marine mammals

A summary of recent bird mortalities by longline fisheries in the French EEZ at Crozet Islands is shown in Table 3. The three most common species injured or killed in the fishery were northern giant petrel (Macronectes halli), white-chinned petrel (Procellaria aequinoctialis) and grey petrel (P. cinerea). Night setting requirements have been highly effective in removing the previously high levels of albatross mortality.

The level of risk of incidental mortality of birds in the French EEZ at Crozet Islands in Subarea 58.6 is considered to be high (category 5) (SC-CAMLR-XXX, Annex 8, paragraph 8.1).

Table 3. Number of reported birds caught (killed or with injuries likely to substantially reduce long-term survival) in this fishery (within Subarea 58.6) in each fishing season.
Season Macronectes halli Procellaria aequinoctialis Procellaria cinerea
2007 1
2008 32
2009 3 19 1
2010 27
2011 1 7
2012 17
2013 13
2014 6
2015 11
2016 6
2017 5
2018 4
2019 5
2020 1
2021 1
2022 2

The requirements of Conservation Measure 25-02 ‘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. France applies these CCAMLR mitigation measures.

Additional measures are also applied (WG-IMAF-11/10 Rev. 1), including:

  1. changes to the bird exclusion device to ensure it is effective in all weather conditions,

  2. closure of fishing areas and quota allocation reduction to vessels that have high by-catch rates,

  3. education and training is strengthened by regular meetings between TAAF and fishing masters of vessels with high by-catch.


In 2022, WG-IMAF-2022/P01 (Dasnon et al., 2022) reported on the effects of by-catch mitigation measures on the demography of white-chinned petrels (Procellaria aequinoctialis) at Possession Island (Crozet Islands). This population declined by 40% from 1983 to 2004 because of by-catch in longline and trawl fisheries, and reduced breeding success resulting from predation by rats. Both modelled population growth rate and observed breeding densities increased after the mid-2000s, which could be explained by the improvement in survival following implementation of by-catch mitigation measures, in breeding success following local control of rats, and changes in climatic conditions on foraging grounds.


There was no incidental mortality of marine mammals in this fishery in 2022.


3. Illegal, Unreported and Unregulated (IUU) fishing

Illegal, unreported and unregulated (IUU) fishing was first detected in Subarea 58.6 in 1996 and peaked the following year at an estimated 11,760 tonnes.

IUU fishing activities were not detected in Subarea 58.6 in the Crozet Islands EEZ during 2006 and 2007, however, IUU activities were detected in Subarea 58.6 outside the Crozet Islands EEZ during the winter of 2006. IUU activity in the Crozet Islands EEZ cannot be discounted during 2006 or 2007 due to nearby IUU activity in those years. There was a single IUU vessel sighting in 2008 and two IUU-listed vessels were observed during 2012. A further IUU fishing vessel was sighted during 2013. During the 2014 fishing season, both old and recent IUU fishing gear was recovered on four occasions, however, there were no observations of IUU-listed vessels in this Subarea. No IUU fishing activities were detected during 2015 or 2017, however, IUU fishing gear was found during 2016.

Following the recognition of methodological issues in its assessment, no estimates of IUU catch of Dissostichus spp. have been provided since 2011 (SC-CAMLR-XXIX, paragraph 6.5).


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.

The vessel’s crew report total catch of by-catch 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, and report toothfish length measurements to CCAMLR.

Summaries of data reported to CCAMLR for the past five years are given in Tables 4 and 5.

Table 4. Summary of by-catch and biological data reported by vessels crew and observers in each of the last five seasons in this longline fishery (within Subarea 58.6). By-catch records correspond to the number of observations of total weight and count of individuals for each taxon identified. Taxonomic identification may occur at different levels. Data prior to 2021 was collected but not reported (reporting of weight, sex, maturity, gonad weight and otolith samples started in September 2021).
Data source Data class Variable 2018 2019 2020 2021 2022
Vessel crew by-catch taxa identified 5 5 4 5 7
records 3069 2078 1190 1963 1785
Observer toothfish specimens examined 28685 25994 19534 27768 13689
length measurements 28685 25994 19534 27768 13689
weight measurements 0 0 0 282 755
sex identifications 0 0 0 4867 8864
maturity stage identifications 0 0 0 4867 8860
gonad weight measurements 0 0 0 0 0
otolith samples 0 0 0 272 673
Table 5. 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. Data prior to 2021 was collected but not reported (reporting started in September 2021).
By-catch group Variable 2018 2019 2020 2021 2022
Macrourus spp. specimens examined 0 0 0 231 489
taxa identified 0 0 0 1 3
length measurements 0 0 0 231 489
weight measurements** 0 0 0 0 11
snout to anus measurements* 0 0 0 231 261
sex identifications** 0 0 0 0 81
maturity stage identifications** 0 0 0 0 53
gonad weight measurements** 0 0 0 0 0
otolith samples** 0 0 0 0 11
Skates and rays specimens examined 0 0 0 254 1017
taxa identified 0 0 0 1 1
length measurements 0 0 0 254 1017
weight measurements** 0 0 0 37 124
wingspan measurements* 0 0 0 68 325
pelvic length measurements* 0 0 0 0 75
sex identifications** 0 0 0 254 1001
maturity stage identifications** 0 0 0 49 673
gonad weight measurements** 0 0 0 0 0
Other fish specimens examined 0 0 0 182 292
taxa identified 0 0 0 2 3
length measurements 0 0 0 182 292
weight measurements** 0 0 0 2 4
standard length measurements* 0 0 0 0 0
sex identifications** 0 0 0 2 2
maturity stage identifications** 0 0 0 2 0
gonad weight measurements** 0 0 0 0 0
otolith samples** 0 0 0 0 4
**: 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. \emph{N.B.} Data prior to 2021 was collected but not reported (reporting started in September 2021).

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. Data prior to 2021 was collected but not reported (reporting started in September 2021).


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. \emph{N.B.} Data prior to 2021 was collected but not reported (reporting started in September 2021).

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. Data prior to 2021 was collected but not reported (reporting started in September 2021).


4.3. Length frequency distributions

The recent length frequency distributions of D. eleginoides caught in this fishery are shown in Figure 4. The majority of D. eleginoides caught by longline range from 30 to 150cm in length, with a single strong mode for all seasons at approximately 70cm. 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.


Figure 4. Annual length frequency distributions of *D. eleginoides* caught by longline in this fishery (within Subarea 58.6). 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 4. Annual length frequency distributions of D. eleginoides caught by longline in this fishery (within Subarea 58.6). 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

Within the French EEZ, vessels are required to tag and release toothfish at a rate of 1 fish per tonne of green weight caught throughout the season.

To date in this area, 14406 D. eleginoides have been tagged and released (1239 have been recaptured, 962 of which were released in this area; Table 6).

Table 6. Number of Dissostichus eleginoides tagged and recaptured in the area (within Subarea 58.6) for each fishing Season.
Recaptured
Season Tagged 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 Total
2005 90
2006 1154 1 2 2 1 2 8
2007 518 2 4 4 1 1 3 1 1 17
2008 547 3 14 4 6 1 8 1 1 1 39
2009 679 7 18 10 7 10 5 6 5 4 4 1 1 78
2010 629 5 9 2 3 4 3 3 3 1 1 34
2011 726 4 8 6 3 2 1 24
2012 691 1 20 16 8 5 2 1 1 3 57
2013 852 8 18 23 16 9 6 2 3 2 1 88
2014 839 4 26 21 10 4 10 1 3 2 81
2015 921 5 31 23 11 11 6 3 1 91
2016 1167 13 37 28 26 3 12 5 124
2017 1220 12 34 16 13 16 4 95
2018 1158 15 28 11 22 10 1 87
2019 854 10 16 12 11 1 50
2020 838 2 34 13 49
2021 887 8 22 3 33
2022 636 6 1 7
Total 14406 962

One fish which was tagged in Subarea 58.6 was recaptured in Subarea 58.7 and another in the Southern Indian Ocean Fisheries Agreement (SIOFA) zone. Again, tagged fish from the Kerguelen Plateau (34 from Division 58.5.1 - Kerguelen and 53 from Division 58.5.2 - Heard Island) have been recovered in the Crozet EEZ. Despite these long-distance movements of sub-adult/adult fish, the proportion of exchange between stocks is still unknown and only one fish from Crozet Island has been recovered eastward on the Kerguelen Plateau.

5. Research

An analysis presented in WG-FSA-14/10 estimated that the depredation of D. eleginoides by killer whales and sperm whales (Physeter macrocephalus) over the period 2003 to 2013 was 2,568 tonnes; this implies a depredation rate of 28% of all fish caught for this decade.

A pot trial cruise was conducted in February 2010 (WG-FSA-10/10) to try and find solutions to the depredation problem (and to reduce bird mortality). However, while whale depredation and bird by-catch is eliminated using pot gear, the catch rates of the target species were reduced and the by-catch of king crabs (Lithodes murrayi and Paralomis aculeata) was considerable.

In 2019, catch removals due to killer and sperm whale interactions across subantarctic fisheries were estimated (WG-FSA-2019/33). These estimates are routinely updated as part of the stock assessment (WG-FSA-2021/45).

In 2022, WG-FSA-2022/19 presented an analysis of skate handling practices and condition assessment methods in the longline toothfish fisheries operating in the southern Indian Ocean. Results provided clear guidelines for crew members operating on longline vessels to maximise the survival of released skates. WG-FSA-2022/20 presented a preliminary study on the use of the vertebrae centrum in the age determination of skates (Amblyraja taaf in Crozet, and, Bathyraja eatonii and B. irrasa in Kerguelen waters).


6. Stock status

6.1. Summary of current status

According to the 2021 assessment (WG-FSA-2021/45), SSB0 is estimated at 55,740 tonnes (49,220 - 60,500). The estimate of the current SSB status of the stock is 65.2% (61.4%-68.5%).


6.2. Assessment method

The stock in this fishery is assessed using a fully integrated single-sex CASAL model (WG-FSA-2021/45).


6.3. Year of last assessment, year of next assessment

Assessments are reviewed biennially, the last assessment was in 2021.


7. Climate Change and environmental variability

In 2018, a summary of the potential impacts of climate change on Southern Ocean fisheries (FAO 2018) highlighted 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.

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 also welcomed (CCAMLR-41, paragraph 6.8) the Scientific Committee’s agreement to hold a workshop on climate change in the first half of 2023 (SC-CAMLR-41, paragraph 7.10) and encouraged the inclusion of a range of scientific experts as well as policy makers to foster integration of the best available science into management actions. The Commission adopted (CCAMLR-41, paragraph 6.28) Resolution 36/41.


Additional Resources

References

Dasnon, A., Delord, K., Chaigne, A., Barbraud, C., 2022. Fisheries bycatch mitigation measures as an efficient tool for the conservation of seabird populations. J. Appl. Ecol. 59, 1674-1685. https://doi.org/10.1111/1365-2664.14189

Tixier, P., N. Gasco, G. Duhamel, M. Viviant, M. Authier and C. Guinet. 2010. Interactions of Patagonian toothfish fisheries with killer and sperm whales in the Crozet Islands Exclusive Economic Zone: an assessment of depredation levels and insights on possible mitigation strategies. CCAMLR Science, 17: 179-195.

Tixier, P., et al., Assessing the impact of toothed whale depredation on socio-ecosystems and fishery management in wide-ranging subantarctic fisheries, Rev. Fish Biol. Fish., vol. 30, p. 203‑217, 2020, doi: 10.1007/s11160-020-09597-w