The Antarctic cod is a large fish that lives in the open ocean around Antarctica. Also called the Antarctic toothfish, this fish is not actually a species of cod, which is in the family Gadidae. Instead, it belongs to the family Notothenidae. This toothfish is often called a cod, however, because its flesh tastes similar. The scientific name for the Antarctic cod is Dissostichus mawsoni.
Normally found in the Ross Sea, the Antarctic cod often lives at depths of about 5,000 feet (1,524 m), though some have been documented as deep as 6,500 feet (1,981 m). In order to live in the extremely cold waters of its environment, this fish has glycoprotein, an antifreeze, in its blood, which allows it to swim without freezing. All members of the Notothenidae family possess glycoprotein.
The Antarctic cod is silvery-brown and can have spots. It has a large head, a narrow body and eyes adapted for low light. Unlike many fish, this toothfish does not have a swim bladder. Instead, it has fatty deposits that it uses to store energy. Its skeleton is cartilaginous and lightweight, and its white flesh has a high concentration of oil.
On average, these fish can be as big as 5.7 feet (1.7 m) and weigh about 176 pounds (80 kg). The largest recorded Antarctic cod was more than 6.5 feet (2 m) long and weighed about 300 pounds (136 kg). These fish live 20-25 years and do not reach maturity until they are about eight years old.
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.