Southern Bluefin Tuna

Commercial tuna farming is a relatively new industry as it is only 20 years old but the progress of the industry has been very exciting and certainly impressive.

All Southern Bluefin Tuna ranching occurs in a small region offshore of Port Lincoln, South Australia. This industry was initiated in 1991 and has now developed to be the largest farmed seafood sector in Australia.

Tuna farming began as a result of a declining wild fishery. Australian catch peaked in 1982 at 21,500 tonnes. In response to increasing concerns about sustainability, Australia, Japan and New Zealand formed the International Commission for the Conservation of Southern Bluefin Tuna (CCSBT) in 1984, to limit and manage the total allowable catch (the Australian share has been 5,265 tonnes since 1990). As a result, the Australian tuna fishers investigated the potential for value-adding their catch through aquaculture.

The tuna are mainly caught from December to March when they are present along the continental shelf in the Great Australian Bight region. The schools are found, seined and transferred through underwater panels between nets to specialised tow pontoons, and then towed back at about 1 knot to the farm areas adjacent to Port Lincoln. The total process takes several weeks.

On arrival at the farm sites, the tuna are swum from the tow pontoons into 40-50m diameter farm pontoons. They are then fed bait fish six days per week, twice a day. This is done by feeding fresh local Sardines or placing frozen blocks of bait fish in a mesh cage within each pontoon.

The exciting advances in the industry are reflected in the recovering Southern Bluefin Tuna wildstock, and an increased export of farmed Southern Bluefin Tuna. The conclusion of the scientists indicated that the Southern Bluefin Tuna global catch was at about "replacement yield". This provided a more positive conclusion built partly on the data from the spawning ground that large numbers of young spawners, as young as seven years, were now entering the spawning stock. Exports in 2002 exceeded $A300 million for the first time.

In 2003, the Japanese tuna market was destabilised by a big increase in supply of Northern Bluefin Tuna from Europe and Mexico. This, plus the strong Australian dollar, reduced Australian export income, despite a further increase in tonnage.

The Japanese market was stronger in 2004/2005, but still below 2002 levels. The Australian industry is adjusting to the new market situation, but retains its commitment to continuous improvement through research and training.

Southern Bluefin Tuna has medium flavoured flesh, which is in demand for sashimi and sushi.

This information was supplied by Brian Jeffries from the Australian Tuna Boat Owners Association and the Aquafin Cooperative Research Centre

For more information visit www.aquafincrc.com.au or www.cleanseastuna.com.au