SBT are found throughout the southern hemisphere mainly in waters between 30 and 50 degrees south. The only known breeding area is in the Indian Ocean, south of Java, Indonesia. SBT can live for up to forty years, reach a weight of 200 kilograms, and measure more than 2 metres in length. They reach maturity at around eight years, when they are about 1.5 metres long.
Mature females can produce several million eggs in a single spawning period.
Breeding takes place from September to March in warm waters south of Java, Indonesia. The juveniles migrate south down the west coast of Australia towards New Zealand, and also west through the Indian Ocean towards South Africa. Origins of the Convention for the Conservation of Southern Bluefin Tuna SBT were heavily fished in the past, with catch reaching 80,000 tonnes in the early 1960s. Heavy catches resulted in numbers of mature fish dropping to a low level. In the mid 1980s it became apparent that SBT stock was at a level requiring rebuilding and that there was a need for a mechanism to limit catches.