Chilean sea bass, Mero, Icefish, Antarctic cod
The Patagonian toothfish (Dissostichus eleginoides), also known as Chilean sea bass, mero, icefish, and Antarctic cod, is a species of notothen found in cold waters (1–4 °C or 34–39 °F) between depths of 45 and 3,850 m (150 and 12,630 ft) in the southern Atlantic, Pacific, and Indian Oceans and Southern Ocean on seamounts and continental shelves around most Subantarctic islands.
The average weight of a commercially caught Patagonian toothfish is 7–10 kg (15–22 lb), depending on the fishery, with large adults occasionally exceeding 100 kg (220 lb). They are thought to live up to 50 years and to reach a length up to 2.3 m (7.5 ft). Several commercial fisheries exist for Patagonian toothfish, which are detailed below.
A close relative, the Antarctic toothfish (Dissostichus mawsoni), is found farther south around the edges of the Antarctic shelf, and a Marine Stewardship Council-certified fishery is active in the Ross Sea; it is also sometimes marketed as Chilean sea bass.
The Patagonian and the Antarctic toothfishes are sometimes sold under the culinary name "Chilean sea bass" in the United States and Canada.
The name "Chilean seabass" was invented by a fish wholesaler named Lee Lantz in 1977. He was looking for a name to make it attractive to the American market. He considered "Pacific sea bass" and "South American sea bass" before settling on "Chilean sea bass". In 1994, the U.S. Food and Drug Administration accepted "Chilean seabass" as an "alternative market name" for Patagonian toothfish, and in 2013 for Antarctic toothfish.
In the UK, the approved commercial designations for D. eleginoides and D. mawsoni are "icefish" and "toothfish". This has created some confusion, as a genuine "icefish" (Champsocephalus gunnari) caught in subantarctic waters does not resemble toothfish in any way.
In Singapore, the Patagonian toothfish is marketed as a type of cod fish.
The Patagonian toothfish has a streamlined, fusiform body that has a depth that fits into its standard length 5 to 6.4 times. It has a flattened head with a wide, flat area between the eyes. The snout is longer than the diameter of the eyes. The mouth is large, extending past the middle of the eye. There are two rows of teeth in the upper jaw, the teeth in the outer row being the larger and canine-like. The lower jaw has a row of spaced canine-like teeth. Additional canine-like teeth are found outside the teeth rows at the joint of the upper and lower jaws. There are two lateral lines; both made up of tubed scales, an upper one and another along the mid flanks. The upper lateral line has 88-104 scales while the lower line has 61-77 scales. The first dorsal fin has 8 to 10 spines; the second dorsal fin has 28 to 30 soft rays, while the anal fin also has 28-30 soft rays. The caudal fin is emarginate. The pectoral fins are large and shaped like fans. The head and body are covered in ctenoid scales except for the front of the head. This species attains a maximum total length of 215 cm (85 in) although 70 cm (28 in) is more typical, and a maximum published weight of 200 kg (440 lb). The overall colour is brownish-grey with darker blotches.
The Patagonian toothfish is found in the southeastern Pacific and southwestern Atlantic Oceans. It occurs in southern Chile around the coast of Patagonia, in Argentina, and the Falkland Islands. It has also been recorded at Macquarie Island in the southwestern Pacific Ocean and the Southern Ocean at South Georgia and from the sub-Antarctic islands and seamounts of the Indian Sector. There is a single record of a vagrant from the Davis Strait in the northwestern Atlantic Ocean off Greenland, it is thought that this individual migrated over 10,000 km (6,200 mi) and that it transited across the tropical areas in deep, cold regions of the Ocean. The juveniles are semi-pelagic becoming demersal at depths between 150 and 400 m (490 and 1,310 ft). Adults move to deeper habitats, being found at depths in excess of 1,000 m (3,300 ft).
Patagonian toothfish spawn in deep water (around 1,000 m) during the austral winter, producing pelagic eggs and larvae. Larvae switch to a demersal habitat at around 100 m (1 year old) and inhabit relatively shallow water (<300 m) until 6–7 years of age when they begin a gradual migration into deeper water. As juveniles in shallow water, toothfish are primarily piscivorous, consuming the most abundant, suitably sized local prey. With increasing size and habitat depth, the diet diversifies and includes more scavenging of squid, fish, and crustaceans. In turn, toothfish constitute a small part of the diets of sperm whales, southern elephant seals, and colossal squid.
As most toothfish fisheries are managed in accordance with Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) regulations and conservation measures, CCAMLR adopts an “ecosystem approach”, which requires that all other living resources of the Southern Ocean are treated as an integrated system where effects on predator, prey, and related species are considered, and decisions on sustainable harvesting levels are made based on sound, internationally peer-reviewed scientific advice.
