Antarctic Toothfish Fishery
There are two main species of toothfish in the Southern Ocean.
- Patagonian toothfish (Dissostichus eleginoides). The Patagonian toothfish lives in predominantly subantarctic waters and is the target for important fisheries (2,000–5,000 tonnes per year) around South Georgia (Subarea 48.3), Kerguelen Islands (Division 58.5.1) and Heard and McDonald Islands (Division 58.5.2). It is uncommon south of 65°S in the Ross Sea region.
- Antarctic toothfish (Dissostichus mawsoni). The Antarctic toothfish is confined to Antarctic waters and forms a continuous distribution around the Antarctic continent. It is the target of an important fishery for Antarctic toothfish (3,000 tonnes per year) in the Ross Sea region.
Juveniles tend to be found in relatively shallow waters (< 500 m), around subantarctic islands in the case of Patagonian toothfish, and around the Antarctic continent in the case of Antarctic toothfish. Both species undergo an ontogenetic migration into deeper waters as they grow older, with the main adult populations occurring in water depths of 600–1800 m. Both species can grow up to 2 meters in length and up to 100 kg in weight and are mainly piscivorous (feed mainly on fish).
Approximate distributions of Antarctic and Patagonian toothfish in the Southern Ocean, also showing the CCAMLR management areas and the location of the Polar Front (dashed line).
New Zealand were the first country to fish for Antarctic toothfish in the Ross Sea in 1997. Since then, many other countries have targeted this species. In the early days of the fishery the catch limit for the Ross Sea fishery was based on analogy with other toothfish fisheries. However, since 2005 it has been based on an assessment of the Ross Sea region itself using tag-recapture data from the fishery. Catches and catch limits since then have averaged around 3000 metric tonnes per year.
Geographic distribution by size
Subadult toothfish (<100 cm) are found in the shallow waters of the southern Ross Sea, maturing toothfish (100–130 cm) are mainly found on the continental slope of the Ross Sea, whilst large adult toothfish are found in deeper waters of the Ross Sea slope and on the banks, ridges, and seamounts in the north of the Ross Sea region. These bathymetric features in the north also appear to be the main spawning grounds for Antarctic toothfish.
The coloured squares show the median length (cm) of Antarctic toothfish in the fishery catch. The Ross Sea area is divided into different areas, called Small Scale Research Units (SSRU), for the purposes of managing fishing and these are also shown.
NIWA is actively engaged in providing scientific advice to help in managing Antarctic fisheries. This includes research on Antarctic toothfish itself, and working to develop an understanding of the potential effects of the fishery on other parts of the Ross Sea ecosystem.