Toothfish
Patagonian Toothfish model
There are two species of Toothfish: the Antarctic Toothfish (Dissostichus mawsoni) and the Patagonian Toothfish (Dissostichus eleginoides). They are very similar in appearance and habits but the Antarctic Toothfish is found in the high latitude region close to the Antarctic continent whereas the Patagonian Toothfish is found in subantarctic waters on shelves around islands and submarine banks.
Toothfish are bottom-living, in depths of 300m to 2500m, but move off the bottom on occasion to feed.
The Antarctic Toothfish has antifreeze proteins in its tissues and blood because the seawater is below the normal freezing point of tissue. The Patagonian Toothfish does not have these proteins because it lives in warmer water.
Toothfish eggs and larvae are pelagic (free swimming/floating near the sea surface) and the larvae feed on zooplankton.
Toothfish eat small fish and squid in midwater and a range of fish, crabs, prawns etc. on the bottom.
Toothfish reach sexual maturity (can produce eggs and sperm) when they are between 70cm and 95cm long. At this size the fish are between 8 and 10 years old.
The maximum size of Toothfish is 2.2m in length and about 120kg in weight. The maximum recorded age is about 45 years.
Both species of Toothfish are known to be eaten by sperm whales and elephant seals, but the extent of this is unknown. The fish are usually too large to be eaten by other types of predators.
Commercial fishing of the Patagonian Toothfish is managed by CCAMLR (the Commission for the Conservation of Antarctic and Marine Living Resources) around most of the subantarctic Islands, but not off the southern coast of South America. Long-lining (the most common fishing method) causes serious problems in that it catches large numbers of albatrosses and other seabirds. Fishing by trawling does not usually harm seabirds but tends to catch fish in the smaller size range. In some circumstances trawls can damage the seabed. There is currently only a very small fishery for the Antarctic Toothfish, mostly because it occurs far south in waters where sea ice occurs.
Illegal fishing of the Patagonian Toothfish has become a very serious problem in recent years. In 1997/98 about 11 000 tonnes were caught legally in the CCAMLR area, but the illegal catch was estimated to be 32 000 tonnes. In some areas the illegal activities have reduced the stocks of Toothfish markedly. Several nations have arrested a number of boats fishing illegally.
Links
Patagonian Toothfish research
Taxonomic information on the Antarctic Toothfish and Patogonian Toothfish
Australian Antarctic publications relating to Toothfish
Antarctic Marine Living Resources (AMLR) program
Commercial toothfish fisheries
Illegal fishing of Patagonian Toothfish
Research tools for Patagonian Toothfish
|
