Patagonian toothfish *Dissostichus eleginoides* Smitt, 1898.

Patagonian toothfish Dissostichus eleginoides Smitt, 1898.


Distribution of reported catch

Distribution of cumulative reported catch of *Dissostichus eleginoides* at the ASD scale. (Source: C1 and C2 data). Coastlines and ice shelves: UK Polar Data Centre/BAS and Natural Earth. Projection: EPSG 6932.

Distribution of cumulative reported catch of Dissostichus eleginoides at the ASD scale. (Source: C1 and C2 data). Coastlines and ice shelves: UK Polar Data Centre/BAS and Natural Earth. Projection: EPSG 6932.


Life-history

Dissostichus eleginoides (Patagonian toothfish) is a large long-lived species belonging to the family Nototheniidae, or Antarctic cods, characterised by slow growth, low fecundity and late maturity (Collins et al., 2010). Dissostichus eleginoides appears to have protracted spawning periods, taking place mainly in winter, but which may start as early as late autumn and extend into spring. Dissostichus eleginoides are thought to spawn in deep water around sub-Antarctic islands, around the islands in Subarea 48.3, Bouvet Island (Subarea 48.6), Prince Edward Islands (Subarea 58.7) and on the Kerguelen Plateau (Divisions 58.5.1 and 58.5.2), but data in Crozet Islands (Subarea 58.6) are still not available. Patagonian toothfish show distinct depth preferences with age, with juveniles (<50 cm) living on the continental shelf and moving into deeper water (>500 m) as they reach maturity (~90 cm). They are associated with cold water and are found around the sub-Antarctic and South America, as far north as Equador in the cold Humboldt current. They are important predators, feeding primarily on fish, cephalopods and crustaceans; they also scavenge.


Movements inferred from tagging data

While the vast majority of tagged individuals is recaptured in the area they were released in, some have been recaptured in a different area, as shown below.

*Dissostichus eleginoides* movements between areas (tagging release and recapture locations were buffered by 50 nautical miles and merged). Areas are coloured based on the number (top) or percentage (bottom) of individuals that were recaptured in their area of release (non-migrants). Arrows indicate the direction of movements and their sizes depend on the number (top) or percentage (bottom) of releases that moved. Coastlines and ice shelves: UK Polar Data Centre/BAS and Natural Earth. Projection: EPSG 6932.

Dissostichus eleginoides movements between areas (tagging release and recapture locations were buffered by 50 nautical miles and merged). Areas are coloured based on the number (top) or percentage (bottom) of individuals that were recaptured in their area of release (non-migrants). Arrows indicate the direction of movements and their sizes depend on the number (top) or percentage (bottom) of releases that moved. Coastlines and ice shelves: UK Polar Data Centre/BAS and Natural Earth. Projection: EPSG 6932.


Biological parameters estimates

In Subarea 48.3

The biological parameters (Table 1) used in the Subarea 48.3 stock assessment are taken from the scientific literature, where available. These values are derived from analyses of the biological data collected by scientific observers on board fishing vessels. Where derived values are not available (e.g., natural mortality and the steepness of the stock and recruit relationship), values have been assumed that are consistent with those used in other toothfish assessments conducted by CCAMLR.

Table 1: Biological parameters assumed for Dissostichus eleginoides in Subarea 48.3.
Component Parameter Value Unit
Natural mortality M 0.13 /y
VBGF K 0.0653 /y
VBGF t0 -1.4869 y
VBGF L_inf 154.1977 cm
Length to mass A 6.76 x 10-9 t/cm
B 3.085
Maturity range 1 to 41
Tag-related growth retardation 0.75
CASAL tag-loss rate 0.0061 over 4 years
Immediate tagging survivorship Applied as a vector to length-based tag-release data
Tag probability of detection 1
Stock-recruit relationship steepness h 0.75
Lognormal recruitment SD Estimated

In Subarea 48.4

The biological parameters (Table 2) used in the Subarea 48.4 stock assessment are taken from the scientific literature, where available. These values are derived from analyses of the biological data collected by scientific observers on board fishing vessels. Where derived values are not available (e.g., natural mortality and the steepness of the stock and recruit relationship), values have been assumed that are consistent with those used in other toothfish assessments conducted by CCAMLR.

Table 2: Biological parameters assumed for Dissostichus eleginoides in Subarea 48.4.
Component Parameter Value Unit
Natural mortality M 0.13 /y
VBGF K 0.052 /y
t0 0 y
L_inf 206 cm
Length to mass a 3.44 x 10-9 t/cm
b 3.237
Maturity range 7 to 41
Tag-related growth retardation 0.75
CASAL tag-loss rate 0.0061
Initial tag mortality 0.1
Tag probability of detection 1
Stock-recruit relationship steepness h 0.75
Lognormal recruitment SD estimated

In Division 58.5.1

The biological parameters used in the Division 58.5.1 stock assessment are shown in Table 3.

Table 3: Biological parameters assumed for Dissostichus eleginoides in Division 58.5.1.
Component Parameter Value Unit
Natural mortality M 0.155 /y
VGBF K 0.0662 /y
t0 -1.12 y
L_inf 170 cm
Length to mass A 9.61 x 10-9
B 3.02
Maturity A50 9.25
Ato95 8.07
Stock recruit steepness (Beverton-Holt) h 0.75
Recruitment variability sigmaR 0.89
Tag detection 0.999
Tag-release M 0.1 /y
Tag related growth retardation 0.5 y
Tag shedding 0.004

In Division 58.5.2

The biological parameters used in the Division 58.5.2 stock assessment are shown in Table 4.

Table 4: Biological parameters assumed for Dissostichus eleginoides in Division 58.5.2.
Component Parameter Value Unit
Natural mortality M 0.155 /y
VBGF K 0.0658 /y
t0 -3.002 y
L_inf 1412.94 mm
Length to mass A 3.61 x 10-12 t/mm
B 3.1518
Maturity (logistic) a50 13.7
ato95 10.6
Stock recruit steepness (Beverton-Holt) h 0.75
Tag detection 1
Tag-release mortality 0.1
No-growth period 0.5 y
Tag shedding 0.006

In Subarea 58.6

The biological parameters used in the Subarea 58.6 stock assessment are shown in Table 5.

Table 5: Biological parameters assumed for Dissostichus eleginoides in Subarea 58.6.
Component Parameter Value Unit
Natural mortality M 0.155 /y
VGBF K 0.039 /y
t0 -2.3 y
L_inf 197 cm
Length to mass A 6.699 x 10-9
B 3.095
Maturity A50 9.25
Ato95 8.07
Stock recruit steepness (Beverton-Holt) h 0.75
Recruitment variability sigmaR 0.89
Tag detection 0.999
Tag-release M 0.1 /y
Tag related growth retardation 0.5 y
Tag shedding 0.004

In Subarea 58.7

There are no specific life-history parameters for D. eleginoides in the South African EEZ. However, for the purposes of stock assessment, the parameters estimated by Agnew et al. (WG-FSA-06/53) for this species in Subarea 48.3 have been adopted.

Relevant Conservation Measures

In addition to Conservation Measures that apply to all Areas and all Species, the following Conservation Measures apply:

Description Species Area Conservation Measure
Limits on the exploratory fishery for Dissostichus eleginoides on Elan Bank (Statistical Division 58.4.3a) outside areas of national jurisdiction in the 2023/24 season Dissostichus eleginoides Division 58.4.3a CM 41-06
Limits on the fishery for Dissostichus eleginoides in Statistical Division 58.5.2 in the 2023/24 season Dissostichus eleginoides Division 58.5.2 CM 41-08
Mesh size Dissostichus eleginoides, Gobionotothen gibberifrons, Lepidonotothen squamifrons, Notothenia rossii All Areas CM 22-02
Catch Documentation Scheme for Dissostichus spp. Dissostichus spp. All Areas CM 10-05
Prohibition on fishing for Dissostichus spp. in depths shallower than 550 m in exploratory fisheries Dissostichus spp. All Areas CM 22-08
Prohibition of directed fishing for Dissostichus spp. except in accordance with specific conservation measures in the 2023/24 season Dissostichus spp. Subarea 48.5 CM 32-09
General measures for exploratory fisheries for Dissostichus spp. in the Convention Area in the 2023/24 season Dissostichus spp. All Areas CM 41-01
Limits on the fishery for Dissostichus spp. in Statistical Subarea 48.4 in the 2023/24 season Dissostichus spp. Subarea 48.4 CM 41-03

Additional Resources

References

Collins M.A., Brickle P., Brown J. & Belchier M., 2010. The Patagonian toothfish: Biology, ecology and fishery. Advances in Marine Biology 58, 227-300.