Antarctic toothfish
Largest bony fish in the Southern Ocean, adapted to subzero waters.
The Antarctic toothfish (Dissostichus mawsoni), sometimes called Antarctic cod, is a large fish that lives in the frigid, often subzero, waters of the Southern Ocean around Antarctica. It is the biggest bony fish in that ocean, eating mostly smaller fish and crustaceans, while orcas, other toothed whales, and seals hunt it. People catch it for food and sell it as Chilean sea bass, along with its relative, the Patagonian toothfish.
Its common name comes from the two rows of teeth in its upper jaw, which give it a shark-like look. The genus name *Dissostichus* means "twofold line" in Greek, referring to the two long lateral lines that help it sense prey. The species name *mawsoni* honors Australian geologist Douglas Mawson, whose 1911–1914 expedition collected the first specimen. English ichthyologist John Roxborough Norman first described it in 1937, with the type location off MacRobertson Land in Antarctica.
Fully grown, this fish can reach over 1.7 meters and 135 kilograms, twice the size of the next largest Antarctic fish. It is a voracious predator, and as the largest midwater fish in the Southern Ocean, it fills the ecological role sharks play elsewhere. It is one of only five notothenioid species that become neutrally buoyant as adults, which happens when they reach 100–120 centimeters. This lets them stay above the seafloor without wasting energy, so they can hunt both bottom and midwater prey. Most other Antarctic fish, including smaller toothfish, stay near the bottom. Their color ranges from black to olive brown, sometimes lighter underneath, with a mottled pattern on the body and fins. Small fish blend in well with sponges and corals. They have a broad head, long body, long dorsal and anal fins, large pectoral fins, and a rudder-like tail. They usually move slowly but can burst into speed to escape seals.
On the continental shelf, Antarctic toothfish eat shrimp and small fish, especially the Antarctic silverfish, another neutrally buoyant nototheniid. That same silverfish is also a key prey for Adélie and emperor penguins, Weddell seals, and Antarctic minke whales, so competition for food among these predators could be significant. Large toothfish are eaten by sperm whales, killer whales, Weddell seals, and possibly colossal squid. Bottom-dwelling toothfish, especially those caught in summer on the continental slope, mainly eat grenadiers but al
- Scientific name
- Dissostichus mawsoni
- Maximum length
- over 1.7 m (5 ft 7 in)
- Maximum mass
- 135 kg
- Maximum recorded age
- 48 years
- Age at maturity
- 13 years for males, 17 years for females
- First formally described
- 1937 by John Roxborough Norman
- Type locality
- off MacRobertson Land at 66°45'S, 62°03'E, Antarctica
Lore & Background
The Antarctic toothfish was first formally described in 1937 by the English ichthyologist John Roxborough Norman, with the type locality given as off MacRobertson Land at 66°45'S, 62°03'E in Antarctica. The genus name Dissostichus is from the Greek dissos (twofold) and stichus (line), referring to the presence of two long lateral lines that enable the fish to sense prey. The species name mawsoni honors the Australian geologist Douglas Mawson, who led the 1911–1914 Australasian Antarctic Expedition that explored the Antarctic coast and obtained the species' type specimen. The common name 'toothfish' refers to the two rows of teeth in the upper jaw, thought to give it a shark-like appearance.
Reader's Guide
The Antarctic toothfish is significant as the largest bony fish in the Southern Ocean, filling the ecological role that sharks play in other oceans. It is one of only five notothenioid species that, as adults, are neutrally buoyant, enabling them to spend time above the bottom without wasting energy. This adaptation allows them to prey on both bottom-dwelling and mid-water organisms. The species produces antifreeze glycoproteins, allowing it to thrive in subzero waters, a feature not seen in its closest relative, the Patagonian toothfish. A fishery for Antarctic toothfish, managed by the Convention for the Conservation of Antarctic Marine Living Resources (CCAMLR), has existed since 1997, primarily in the Ross Sea. This fishery is contentious due to a lack of accurate population parameters, such as original stock size, fecundity, and recruitment. The bycatch of other fish can be significant, with the ratio of toothfish caught averaging 9.3% in CCAMLR Subarea 88.1 and 12.4% in Subarea 88.2 from the 1999/2000 season to 2013/14.
Did You Know?
- The Antarctic toothfish can grow to more than 1.7 m in length and 135 kg in mass, twice as large as the next-largest Antarctic fish species.
- It is one of only five notothenioid species that, as adults, are neutrally buoyant, attained at 100–120 cm in length.
- The species produces antifreeze glycoproteins, a feature not seen in its closest relative, the Patagonian toothfish.
- The maximum recorded age for an Antarctic toothfish is 48 years.
Frequently Asked Questions
What is the Antarctic toothfish?
The Antarctic toothfish (Dissostichus mawsoni) is the largest bony fish in the Southern Ocean, thriving in the freezing, often subzero waters surrounding Antarctica. It was first formally described by John Roxborough Norman in 1937.
Why is it called a 'toothfish'?
The name refers to its two prominent rows of teeth in the upper jaw, which give the fish a shark-like silhouette. The genus name Dissostichus is Greek for 'twofold line,' a direct nod to that same double row of teeth.
How big can an Antarctic toothfish get?
These fish can exceed 1.7 metres (roughly 5 ft 7 in) in length and reach a mass of up to 135 kilograms. They are also remarkably long-lived, with a maximum recorded age of 48 years, and males do not reach maturity until about 13 while females wait until around 17.
What does the Antarctic toothfish eat, and what preys on it?
It feeds mainly on smaller fish and crustaceans in the cold Southern Ocean. On the other side of the food web, orcas, other toothed whales, and seals are its principal predators.
Why is the Antarctic toothfish sold as 'Chilean sea bass'?
Fishermen harvest it for the human food market, and it is marketed under the label Chilean sea bass alongside its close relative, the Patagonian toothfish. Despite the name, the species has no connection to Chile or to true sea bass—it is simply a commercial branding choice.
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