What is a southern bluefin tuna?
The southern bluefin tuna is a large, fast ocean fish that migrates across the Southern Ocean and Indian Ocean. It is caught off southern Australia and farmed near Port Lincoln.
Southern bluefin tuna can grow to over two metres long and weigh more than 200 kilograms. They are warm-blooded compared with most fish, keeping their muscles warmer than the surrounding water, which helps them swim fast in cold seas.
The only known spawning ground is in the Indian Ocean south of Java. Young tuna then travel along Western Australia and into the Great Australian Bight.
Farming in Port Lincoln
Fishers catch young tuna in the Great Australian Bight and tow them in large pens to Port Lincoln, where they are fattened for several months. Most are exported to Japan for sashimi.
Overfishing in the twentieth century caused a major decline in the spawning population. Australia, Japan, New Zealand and other nations now manage the catch through the Commission for the Conservation of Southern Bluefin Tuna, which sets quotas.
The species has shown signs of recovery under these limits, and recreational anglers now chase bluefin off Victoria, Tasmania and South Australia, where they arrive in autumn and winter. Strict bag limits apply to recreational catches.
Did You Know?
Southern bluefin tuna can live for about 40 years.