The tuna industry in Australia is limited by catch quota. Increased competitiveness through production
efficiency is the main way to improve the value of the industry. Improved performance can be achieved through stress reduction and minimising mortalities. These issues will also be crucial for longer term holding, when the initial size of tuna will be smaller and the fish will be farmed for a longer time, increasing health risks to the tuna.

Tuna are hardy under current husbandry practices, and the industry experiences low mortality
The wild capture of immunocompetent 3 – 5 yr old fish is the main reason, however the short growout
time and advances in farming technology have been significant factors. Despite its newness,
the industry enjoyed healthy returns for the first 10 years.

Since 2002 there has been a significant fall in revenue (prices down over 50% and strengthening of
the Australian dollar). The worsening financial parameters, combined with the intrinsic high ‘value’ of
each fish, have placed a greater focus on all aspects of the industry and particularly stress impacts
limiting production. Mortality is an obvious area and the current level is no longer acceptable. Possibly
more important, stress may cause economic costs to the tuna industry in lost growth and condition. There is a potential for increased productivity through stress reduction.

The quota places a limit to what biomass can be farmed each year. Rather than merely growing out for
3-6 months, the option of longer-term holding is a priority to increase productivity. Then the role of stress and the influence of husbandry practices on fish health and production are even more important.

As each individual fish has high commercial value, there is a need to develop non-lethal indices for SBT
monitoring. Predictive indices will be valuable for planning production and harvesting.