Bionomical Name: Dissostichus mawsoni
Species: D. mawsoni
Common Name: Antarctic cod fish, Antarctic toothfish,Toothfish
Habitat: Antarctic cod is native to the Southern Ocean. It is often mistakenly referred to as an Antarctic cod, consistent with the misnaming of other notothenioid Antarctic fish as rock cods.
Fully grown, these fish (and their warmer-water relative, the Patagonian toothfish, D. eleginoides) can grow to more than 1.7 m (5 ft 7 in) in length and 135 kg in weight, twice as large as the next-largest Antarctic fish. Being large, and consistent with the unstructured food webs of the ocean (i.e., big fish eat little fish regardless of identity, even eating their own offspring), the Antarctic toothfish has been characterized as a voracious predator. Furthermore, by being by far the largest midwater fish in the Southern Ocean, it is thought to fill the ecological role that sharks play in other oceans. Aiding in that role, the Antarctic toothfish is one of only five notothenioid species that, as adults, are neutrally buoyant. This buoyancy is attained at 100–120 cm in length and enables them to spend time above the bottom without expending extra energy. Both bottom-dwelling and mid-water prey are, therefore, available to them. Most other notothenioid fish and the majority of all Antarctic fishes, including smaller toothfish, are confined to the bottom. Coloring is black to olive brown, sometimes lighter on the undersides, with a mottled pattern on body and fins. Small fish blend in very well among the benthic sponges and corals. The species has a broad head, an elongated body, long dorsal and anal fins, large pectoral fins, and a rudder-like caudal fin. They typically move slowly, but are capable of speed bursts that can elude predatory seals.
Antarctic cods mainly eat fish and are the primary predator of fish in their habitat. They will also eat crustaceans and squid, however. Antarctic cods are preyed on by sperm whales and some species of seals and killer whales.
These fish are commercially fished and are sometimes marketed in the United States as Chilean sea bass. As of 2010, they were in danger of being over-fished. The Convention for the Conservation of Antarctic Marine Living Resources (CCAMLR) put restrictions on fishing them. In addition, the environmental action group Greenpeace added them to its seafood red list.
In addition to being used for food, the Antarctic cod is also useful in medicine. Its heart has been studied in conjunction with cardiac medicines because of its slow beat. Beating only once every six seconds, the Antarctic cod’s heart might help researchers discover better ways to deal with hypothermia and surgeries in which the heart must be slowed.