In South Australia and all other countries spionid polychaete (‘mudworm’) infestations are a major problem for oyster growers and have large financial impacts, it has been recorded by individual oyster growers to lose up to $50,000 in stock in one year. There are 150 licensed oyster growers in SA and if this loss caused by mudworm was calculated at 5% of the extreme cases at $2500 per licence holder the economic cost to industry would equate to $375,000 per annum. These losses may not be through mortality, but growers experiencing mudworm problems provide extra oysters when selling to their buyers to compensate for losses from mudworm infestations. In South Australia the species causing damage are not well known. It is for this reason that South Australian Oyster Research Council (SAORC) want to implement a survey to gain an understanding of mudworm species found in SA to assist industry with the management of this pest.

The industry views the need to understand and control mudworm infestations as the losses caused by these worms could potentially be reduced if known species are identified and management techniques can be put in place to reduce infestation rates. However, the farmer’s ad-hoc management approaches have failed to stop or reduce mudworm infestation rates, as farmers have reported that with even the best management practices they still experience mudworm infestations. Due to this, the South Australian Oyster Research Council has identified two experts in mudworm identification to work with SA scientists to survey mudworm species and suggest management practices to SA oyster growers to potentially reduce the problem. Mudworm surveys have been conducted in many other oyster growing areas and different species have been identified which have different life cycles, hence, different forms of management practices are required to reduce infestations.

If this project can achieve a 50% reduction in mudworm infestations or mortality after harmful species have been identified and farmers have implemented management techniques developed through the extension training workshop, the savings to growers will be approximately $187,500 dollars over the next year. The reduction in oyster growers production costs is a small component, the benefits will be seen in the future through increased consumer confidence, hence, increased sales of SA oysters.

In addition, minimising the impact of mudworm on the Pacific oyster aquaculture industry in SA will also strengthen the confidence of new growers and investors in this industry thereby encouraging its further development.

The South Australian oyster industry is recognised as a major economic contributor of seafood to the state. In the 2000/01 financial year the total value of the Pacific oyster production in SA was about 12 million dollars. The industry is expected to increase by 10% per annum over the next five years resulting in the production of Pacific oysters worth nearly 20 million dollars by 2006. However, since the mortality of oysters was first noted in SA about three years ago the industry has suffered 5 to 20% losses each year of their marketable stocks, which is equivalent to 0.726 to 2.9 million dollar losses in 2002/03 and 0.96-3.8 million dollar losses in 2006/07 if mortality is not controlled and remains at the same relative level. A less optimistic forecast is that epidemiological factors could result in a much greater and possibly catastrophic rate of increase in losses in the future.

The industry views the need to understand and control the reasons for these losses as a matter of great urgency. However, the farmer’s ad-hoc approaches have failed to identify any clear direction to address the present mortalities. Due to this, the South Australian Oyster Research Council has spent considerable time discussing the matter with various researchers and has decided to support a specific research project to systematically address the issue. This proposal outlines the approaches to be taken.

If this project can achieve a 50% reduction in mortality one year after its completion, the savings to growers will be approximately 0.455-1.9 million dollars in the first year of implementation in 2006/07. These savings are more than the total investment by FRDC to this project ($364,197) and equivalent to half of the entire project cost to all parties (1.144 million dollars).

In addition, minimising the impact of mortality on the Pacific oyster aquaculture industry in SA will also strengthen the confidence of new growers and investors in this industry thereby encouraging its further expansion.