Australian Bluefin Tuna
Found in the Southern hemisphere, southern bluefin tuna are a large and fast-swimming open ocean fish. They exist largely in the world's southern oceans and congregate in the coastal waters off Australia.
They spawn between September and April each year in the only known spawning grounds in the Indian Ocean, between the northwest coast of Australia and Indonesia. The eggs are estimated to hatch within two to three days.
After only twenty days, the southern bluefin tuna larvae become fingerlings, which feast on a wide range of food--including fish larvae and juvenile fish. They continue to grow to 15 kilograms over the next two years and this size is the principal wild catch of the bluefin tuna industry.
The population has decreased over the past 50 years due to the increasing demand from overseas markets. Improved refrigeration techniques in the mid-1960's paved the way for the transportation of fresh bluefin tuna across the world.
The world southern bluefin tuna catch was approximately 80,000 tons per year in the early 1960's -- and by the mid-1960's it had plummeted to 60,000 tons. During 1980, the catch had declined even futher to 40,000 tons per year. Japan, Australia and New Zealand soon recognized this sharp decline and a voluntary catch quota was enforced. Despite these protective measures, numbers still continued to decline and in 1989 the three countries reduced the quotas even further to their current levels of 11,750 tons between them.
Clean Seas Tuna Limited is a company that has been working over the past number of years in delivering their stated goal of "growing out southern bluefin tuna fingerlings produced from their own brood stock to sizes required by the rapidly expanding world seafood markets, enabling year round production of southern bluefin tuna and lowering the overall cost of production."
Their breeding breakthrough should give Clean Seas the ability to at least duplicate Australia's southern bluefin tuna annual quota within the next few years and to dramatically grow the aquaculture industry in Australia without impacting on wild tuna stocks.
Until the fingerlings are mature enough for harvesting, Clean Seas will continue to provide tuna as they have for a number of years--the tuna are captured wild, then fattened up with natural feed on a "ranch" before being harvested. Since there are no brood-stock or hatchlings as yet, they are labelled wild. However, from a global perspective, successfully recreating the natural breeding cycle of one of the world's premier pelagic (open ocean) fish species is a key step towards ensuring sustainability of this species at a time when wild stocks are under significant pressure. Hopefully, that will translate to a better quality fish that costs less and that will contine to thrive for years to come.