Southern bluefin tuna (Thunnus maccoyii)
|French:||Thon Rouge du Sud|
|Spanish:||Aleta Azul del Sur, Atún Rojo del Sur|
|Size||Fork length: up to 225 cm (2)|
|Weight||up to 158 kg (2)|
The southern bluefin tuna is classified as Critically Endangered (CR) on the IUCN Red List (1).
The southern bluefin tuna (Thunnus maccoyii) is one of the largest bony fish in the world (3). The incredibly streamlined and powerful body is deepest near the middle of the first dorsal fin (4) and tapers to a pointed snout (3). The lower half of the body is silvery white, whilst the anal fin is a dusky yellow colour (4). The tail is crescent-shaped (3) and the first dorsal fin has a yellow or blueish hue (4).
Found throughout the southern oceans, mainly between 30 and 50° South. Southern bluefin tuna breeding takes place just southeast of the island of Java, Indonesia (5).
The southern bluefin tuna is pelagic, inhabiting the open oceans mainly in cold temperate waters (4).
Southern bluefin tuna spend their lives swimming constantly through the oceans cruising at two to three kilometres per hour (5), although they are able to reach speeds of 70 kilometres per hour (6). Individuals swim together in shoals and these migrate vast distances from spawning grounds in the Indian Ocean to feeding grounds in colder southern waters (4). It is thought that females do not spawn until they reach around 1.5 metres in length, which corresponds to at least eight years of age (5). A mature female will produce several million eggs in one spawning period (5). The breeding season runs from September and October until March (4), and occurs in Indonesian waters (5). Juvenile southern bluefin tuna are then known to group together during the summer months in coastal waters off the southern coast of Australia until they reach around five years old, after which they are more consistently associated with deeper waters (5).
These oceanic fish are opportunistic feeders, preying on a wide variety of other fish as well as crustaceans, cephalopods (such as squid and octopus) and other marine animals (7). Southern bluefin tuna are thought to be long-lived with a life expectancy possibly as long as 40 years (6).
The southern bluefin tuna has been heavily exploited over the years and has been fished to the brink of extinction (6). During the 1960s, the annual catch was around 80,000 tonnes worldwide (5). The flesh of this species has a particularly high fat content and is prized in Japan especially for 'sashimi' markets (5), where an individual fish can fetch as much as US$ 10,000 (4). Fishing mainly takes the form of purse seine netting in Australia (6), and longline fishing in the other range states; namely New Zealand, Japan, the Republic of Korea, Taiwan and Indonesia (5).
In 1994, Australia, Japan and New Zealand signed the Convention for the Conservation of Southern Bluefin Tuna in an attempt to curb the overfishing of this species (5). The Commission for the Conservation of the Southern Bluefin Tuna (CCSBT) has subsequently formed and in 2001, was joined by the Republic of Korea (5). The objective of the Commission is to ensure the conservation and optimum utilisation of the global southern bluefin tuna fishery, through management measures including reduced fishing quotas and research (5). Some scientists and conservationists are worried, however, that the Commission does not go far enough, and that global breeding stocks, having been reduced by as much as 97%, will require more drastic measures if they are ever to recover (6).
For more information on the southern bluefin tuna:
Commission for the Conservation of the Southern Bluefin Tuna (CCSBT):
This information is awaiting authentication by a species expert, and will be updated as soon as possible. If you are able to help please contact:
- Anal fin: in fish, an unpaired fin on the under surface of a fish, behind the anus.
- Dorsal fin: in fish, the unpaired fin found on the back of the body.
- Purse seine netting: fishing method whereby a school of fish (such as tuna) is encircled with a net, which is then closed at the bottom, or 'pursed', trapping the catch.
IUCN Red List (October, 2002)
Food and Aquaculture Organization of the United Nations - Southern bluefin tuna (April, 2012)
- Burnie, D. [Ed.] (2001) Animal. Dorling Kindersley, London.
Fisheries Global Information System (August, 2002)
Commission for the Conservation of Southern Bluefin Tuna (August, 2002)
Greenpeace, Australia Pacific (August, 2002)
Fishbase (August, 2002)