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The case of the Patagonian toothfish

The Patagonian toothfish (Dissostichus eleginoides) is a large pelagic predator, belonging to the family Nototheniidae. It is widely distributed and occurs off islands and banks in the Southern Atlantic, Indian and Pacific Oceans, notably within the influence of the Antarctic Circumpolar Current. It ranges from the slope waters of Chile and Argentina to the sub-Antarctic islands, Macquarie Island just above the Antarctic Convergence and the Indo–Pacific boundary of the Southern Ocean (CCAMLR 2002). In the South Atlantic, it occurs as far south as the South Sandwich Islands. The closely related species, Antarctic toothfish (Dissostichus mawsoni), occurs further south and is generally restricted to Antarctic waters of 65°S (Agnew 2000).

 

The distribution of the Patagonian toothfish in the Southern Ocean.
Scientists are studying how the Antarctic toothfish Dissostichus mawsoni keep their blood from freezing in the -2.0°C water. (Photo © B. Galbraith)

The Patagonian toothfish is grey or brownish grey in colour with darker blotches. It is found in waters warmer than 2°C and lacks anti-freeze, although it has other unusual adaptations to achieve neutral buoyancy, including highly mineralised bones and abundant lipids in their flesh (Cascorbi 2002; Eastman and deVries 1981). It is the largest predatory fish in the mid-waters of the Southern Ocean and has strong muscles to chase down prey (Eastman 1985).

 

The life history, age, population structure and other measurements required for sustainable management of the Patagonian toothfish in ways that are based in scientific certainty remain largely unknown, underscoring the need for precaution. For example, otoliths growth rings are difficult to age when members of the species are young. However, the species typically matures at 8 to 10 years (Kock 2001). Everson (2001) considers that the Patagonian toothfish lives for at least 40 years, although other commentators suggest it can live up to 70 to 80 years (refer to Fallon and Stratford 2003). As a result, age validating techniques are still being investigated, although current scientific research has generally established that this species lives for at least 45 to 50 years (refer to Fallon and Kriwoken submitted; Constable 2002; Williams 2001; Constable et al. 2000).

 

The Patagonian toothfish matures between approximately 6 to 9 years of age (Kock 1992). Its reproductive strategy is characterised by low fecundity and large egg size that indicates a relatively large maternal investment in each egg (Cascorbi 2002; Chikov and Melnikov 1990). Patagonian toothfish eggs and larvae are pelagic, free swimming and float near the sea surface to about 500 m. Once the eggs have hatched after about three months, the larvae feed on krill and gradually shift to fish. The diet of adults consists of small fish, squid, crabs and prawns (AAD 2002).

 

Both the Patagonian toothfish and Antarctic toothfish occur in the Convention for the Conservation of Antarctic Marine Living Resources (CCAMLR) Area. While Patagonian toothfish is caught both inside and outside the CCAMLR Area, the Antarctic toothfish is found only inside CCAMLR waters (Kock 1992). Up to 96 per cent of Patagonian toothfish stocks are found in waters regulated by CCAMLR or Coastal State jurisdiction that include the EEZs of Argentina and Peru and waters adjacent to sub-Antarctic islands under the sovereignty of Australia, France, New Zealand, South Africa and the United Kingdom. Only four per cent of Patagonian toothfish stocks are found outside these areas on the high seas.

 

 

 

References:

 

AAD (2002). Toothfish: 10 facts. Australian Antarctic Division, Hobart, Australia, Accessed 7 October 2002.

 

Agnew, D.J. (2000). The illegal and unregulated fishery for toothfish in the Southern Ocean, and the CCAMLR catch documentation scheme. Marine Policy, 24, 361-374.

 

Cascorbi, A. (2002). Seafood watch, seafood report: Chilean seabass: Patagonian toothfish (Dissostichis eleginoides) and Antarctic toothfish (Dissostichis mawsoni). Draft Report No 1, Monterey Bay Aquarium, USA.

 

CCAMLR (2002). Understanding CCAMLR’s approach to management. Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR), Hobart, Australia, Accessed 26 November 2002.

 

Chikov, V. N. and Melnikov, Y.S. (1990). On the question of fecundity of the Patagonian toothfish in the region of the Kerguelen Islands. Journal of Ichthyology, 30(3), 122-125.

 

Constable, A.J. (2002). The status of Antarctic fisheries research. In Jabour-Green, J. and Haward, M. (eds), The Antarctic: Past, present and future, Antarctic CRC Research Report No 28, University of Tasmania, Hobart, Australia, 71-84.

 

Constable. A.J., de la Mare, W.K., Agnew, D.J., Everson, I. and Miller, D. (2000). Managing fisheries to conserve the Antarctic marine ecosystem: Practical implementation of the Convention on the Conservation of Antarctic Marine Living Resources (CCAMLR). ICES Journal of Marine Science, 57, 778-791.

 

Eastman, J.T. (1985). The evolution of neutrally buoyant notothenioid fishes: Their specialisations and potential interactions in the Antarctic marine food web. In Siegfried, W.R., Condy, P.R. and Lawes, R.M. (eds), Antarctic nutrient cycles and food webs, Springer-Verlag, Heidelberg, Germany.

 

Eastman, J.T. and deVries, A. (1981). Buoyancy adaptations in a swim-bladderless Antarctic fish. Journal of Morphology, 167, 91-102.

 

Everson, I. (2001). A comparison between otoliths and scales for use in estimating the age of Dissostichus eleginoides from South Georgia. CCAMLR Science, 8, 75-92.

 

Fallon, L.D. and Kriwoken, L.K. (submitted). International influence of an Australian non-governmental organisation in the protection of Patagonian toothfish. University of Tasmania, Hobart, Australia.

 

Fallon, L.D. and Stratford, E. (2003). Issues of sustainability in the Southern Ocean fisheries: The case of the Patagonian toothfish. Report for the Lighthouse Foundation, School of Geography and Environmental Studies, University of Tasmania, Hobart, Australia.

 

Kock, K-H. (1992). Antarctic fish and fisheries. Cambridge University Press, Cambridge, UK.

 

Kock, K-H. (2001). The direct influence of fishing and fishery-related activities on non-target species in the Southern Ocean with particular emphasis on longline fishing and its impact on albatrosses and petrels: A review. Reviews in Fish Biology and Fisheries, 11, 31-56.

 

Williams, R. (2001). About Patagonian toothfish. Australian Antarctic Magazine, Australian Antarctic Division (AAD), Hobart, Australia.

 

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