Dissostichus, the toothfish, is a genus of marine ray-finned fish belonging to the family Nototheniidae, the notothens or cod icefish. These fish are found in the Southern Hemisphere. Toothfish are marketed in the United States as Chilean sea bass (or Chilean seabass) or less frequently as white cod.[3] "Chilean sea bass" is a marketing name coined in 1977 by Lee Lantz, a fish wholesaler who wanted a more attractive name for selling the Patagonian toothfish to Americans.[4][5][6] In 1994, the U.S. Food and Drug Administration (FDA) accepted "Chilean sea bass" as an "alternative market name" for Patagonian toothfish.[6] The toothfish was remarkably successful in the United States, Europe and Asia, and earned the nickname "white gold" within the market.[6] Toothfish are vital to the ecological structure of Southern Ocean ecosystems.[7] For this reason, on 4 September a national day is dedicated to the toothfish in South Georgia.[8][9]
Dissostichus was first described as a genus in 1898 by the Swedish zoologist Fredrik Adam Smitt, he was describing a new species from waters off Tierra del Fuego, Dissostichus eleginoides, which he placed as the only species in the new genus.[2][10] Some authorities place this taxon in the subfamily Pleuragrammatinae,[11] but the 5th edition of Fishes of the World does not include subfamilies in the Nototheniidae.[12] The name of the genus Dissostichus is a compound of dissos which means "twofold" or "double" and stichus which means "row" or "line". an allusion to the two lateral lines of D. eleginoides.[13]
The Patagonian toothfish is distributed circumpolarly near the Antarctic Convergence, spanning the Atlantic, Pacific and Indian sectors of the Southern Ocean, with a few populations near the Antarctic Peninsula as well as the coasts of Chile and Argentina.[15] The Antarctic toothfish is distributed around the Antarctic continental shelf and in the Ross Sea, generally south of 60°S.[16]
Both species are benthopelagic as adults. The Patagonian toothfish has been found between 600 and 1500 m, and the Antarctic toothfish tends to be found between 1300 and 1900 m.[17] The Patagonian and Antarctic toothfish populations overlap geographically in the southern Indian Ocean, north of the Ross Sea and several south Atlantic islands.[18] The Southern Ocean has not yet been fully sampled, so both species may extend further throughout the region.[19]
The Patagonian toothfish and the Antarctic toothfish are markedly similar in appearance, but can be identified via several morphological features. The Patagonian toothfish has a characteristic scaleless patch between the eyes and a longer visible lateral line.[20]
Both species are long-lived and relatively slow-growing. The Patagonian toothfish can live up to at least 50 years of age and the Antarctic toothfish can live to at least 35 years of age.[21] Both species show the fastest growth in the first 10 years of life, and reach maximum body size around 20 years of age.[21] The Patagonian toothfish grows at an average rate of 2 cm and 1 kg per year.[22] Toothfishes are large in size, with both species reaching maximum sizes exceeding 100 kg.[23] This trait distinguishes the toothfishes from other notothenioids.