The Antarctic toothfish of the fish family Nototheniidae, is famous for producing antifreeze glycoprotein that allows it to survive in the ice-laden waters of the Southern Ocean surrounding Antarctica. With a heartbeat once every six seconds, research involving Antarctic toothfish may lead to advances in cardiac medicine involving conditions where human hearts beat slowly during certain medical procedures or fail to beat fast enough due to hypothermia.^{[citation needed]}

The Antarctic toothfish is sometimes incorrectly referred to as Antarctic cod, however it is quite unrelated to a cod. It does not even belong in the same order, nor does it bear any significant resemblance. It is classified as a perciform rather than a gadiform.

These large fish are probably mesopelagic and have been caught in waters deeper than 2000 metres. Fully grown, these grayish fish are among the biggest in the Antarctic; adults of more than 2 metres in length and weighing over 135 kg (298 lbs) have been recorded during New Zealand research work carried out in the Ross Sea. The flesh is white with a high oil content. The taste is said to be similar to cod, which led to species sometimes being called Antarctic cod. They are closely related to, and sometimes confused with the Patagonian toothfish, Dissostichus eleginoides. Aging data collected during an ongoing CCAMLR tagging programme in the Ross Sea indicate Antarctic toothfish are relatively fast growing. They reach about 60 cm after five years, 1 meter after 10 years, and about 1.5 m at about 20 years. The maximum age recorded so far has been 48 years, with a maximum weight of 150 kg - there are few fish older than about 30 years caught in the fishery. Indications from this current research are that fish mature at about age 10.^[1]

They are generally piscivorous (fish-eaters), but are known to eat almost anything, including the remains of penguins caught by seals and orca on the surface.^[2] Stable isotope studies on Antarctic food webs by New Zealand scientists from the National Institute of Water and Atmospheric Research (NIWA) indicate Antarctic toothfish appear to occupy a similar trophic level in the Antarctic food web as orca and Weddell seals in McMurdo Sound, bluefin tuna in the Atlantic, and sperm whales from the Gulf of Mexico. Smaller juveniles may also be prey of the Weddell seal, the leopard seal, large squid, and orca.^[3]

Antarctic toothfish have a lightweight, cartilaginous skeleton, lack a swim bladder, and have fatty deposits which may act as a stored energy source, particularly during spawning.^[4] They also have retinas well adapted to the low light levels. Since snow and ice cover the surface of the ocean even in summer, their specialized eyes are evolved to work in the reduced light levels found in the great depths of the Antarctic ocean. Coloring is black to olive brown, sometimes lighter on the undersides, with a mottled pattern on the fins. They have a broad head, an elongated body with an extended bifurcate caudal fin, a long anal fin, large pectorial fins and a rudder-like caudal fin. Its distribution range is generally below latitude 60 degrees south. It is mainly caught in the Ross Sea in the austral summer but has also been recorded from Antarctic coastal waters south of the Indian Ocean sector, in the vicinity of the Antarctic peninsula, and near the South Sandwich Islands.

The Antarctic Toothfish Fishery

Antarctic toothfish is managed by the Convention for the Conservation of Antarctic Marine Living Resources (CCAMLR), which has limited fishing to a precautionary catch level in the Ross Sea; fishing takes place with the aim of collecting sufficient biological and stock size information to effectively manage this fishery in the future. This multi-national Convention is administered by a Commission which uses an ecosystem approach to manage marine resources with the Convention Area. This area is generally the seas south of the Antarctic convergence from 45°S - 60°S southward to the Antarctic continent. The Antarctic Convergence is where colder polar waters meet more temperate waters to the north forming an effective biological barrier to most Southern Ocean species.

Antarctic toothfish are found in high seas sectors outside areas of national jurisdiction within the CCAMLR Convention Area.

The most common method of fishing is by demersal longline. This is a low impact fishing method and is the only fishing method allowed in CCAMLR exploratory fisheries where Antarctic toothfish are typically found. Generically the method uses a long mainline from which shorter snoods and baited hooks are attached with downlines and floats at either end of the mainline to retrieve gear from the bottom.

The total catch of Antarctic toothfish in 2011/12 was around 3,800 tonnes. Over 3,500 tonnes of this was taken from the Ross Sea (FAO Statistical Divisions 88.1 and 88.2) with the remainder taken from other high seas areas within the CCAMLR Convention Area ^[5].

Environmental and Mitigation Measures in Antarctic Toothfish Fisheries

CCAMLR imposes stringent environmental protection and by-catch mitigation measures to Antarctic toothfish fisheries including:

• Monitoring of daytime setting and movement of vessels from the fishery should any vessel catch more than three seabirds ^[6];
• Use of streamer lines during setting to keep birds away from baited hooks ^[7];
• Weighting of lines to ensure fast sink rates to prevent seabirds from accessing baited hooks ^[8];
• The use of bird exclusion devices (BEDs) to prevent birds from accessing hooks whilst lines are being hauled ^[9];
• Limitations on the release of fish offal overboard at the same time as setting and hauling of lines to avoid attracting seabirds. There is an additional requirement that prohibits the dumping of all offal south of 60°S, the region where Antarctic toothfish are caught ^[10];
• Prohibition on the dumping of oil, plastic, garbage, food waste, poultry, eggs or eggshells, sewage and ash by fishing vessels ^[11];
• Prohibition of the use of plastic packaging bands on fishing vessels ^[12].

Incidental mortality of seabirds as a result of fishing has fallen to near-zero levels in the CCAMLR Convention Area. No mortality of seabirds or marine mammals was recorded as a result of fishing for Antarctic toothfish in 2011/12 and only one seabird has been killed as a result of fishing in the Ross Sea since 1996/97^[13].

Compliance in Antarctic Toothfish Fisheries

Compliance measures adopted by CCAMLR apply to all Antarctic toothfish fisheries. These include:

• At-sea inspections of fishing vessels^[14];
• Vessel licensing ^[15];
• Port inspections of fishing vessels^[16];
• Continuous reporting of fishing vessel positions via satellite linked Vessel Monitoring Systems (VMS)^[17];
• Catch Documentation Scheme for Toothfish which tracks toothfish from the point of landing through to the final point of sale and requires verification and authorisation by government authorities at each step^[18].

Independent Certification

In November 2010, the Marine Stewardship Council certified the Ross Sea Antarctic Toothfish fishery as a sustainable and well managed fishery.^[19]

Potential for unsustainable consumption

In 2010, Greenpeace International added the Antarctic toothfish to its seafood red list. "The Greenpeace International seafood red list is a list of fish that are commonly sold in supermarkets around the world, and which have a very high risk of being sourced from unsustainable fisheries."^[20] Noting that this approach is at variance with the high score given the fishery when it was granted certification by the Marine Stewardship Council. http://www.msc.org/track-a-fishery/certified/southern-ocean/ross-sea-toothfish-longline

References

• "Dissostichus mawsoni". Integrated Taxonomic Information System. http://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=642808. Retrieved 30 January 2006.
• Froese, Rainer, and Daniel Pauly, eds. (2005). "Dissostichus mawsoni" in FishBase. 10 2005 version.