If there’s one thing Tasmania should be known for, it’s Pacific oysters. In past years, 4 million dozen of them were grown annually, valued at $24 million.
But on 1 February 2016, everything changed.
Some oysters from Pitt Water, not far from Hobart, were tested and confirmed industry’s worst fears - they were positive for an extremely deadly and contagious virus, called Pacific Oyster Mortality Syndrome (or POMS).
In under a fortnight, the virus had spread to four major growing areas, Biosecurity Tasmania enforced a complete lock down of the industry, and farmers were faced with up to 90% of their oysters dying.
The only silver lining is that POMS doesn’t affect people at all, only oysters.
The bad news is that the virus is here to stay, and the virus can spread and take effect very quickly. POMS is probably one of the worst marine viruses that the aquaculture industry has had to deal with.
When POMS arrived in Tasmania, the threat was immediately recognised, and industry and government responded quickly. Part of this was supporting research through the CRC-P Future Oysters Program.
One project titled “Advancing the understanding of POMS to guide farm management decision in Tasmania” (Project 2016-804) was to help oyster farmers work out what they could do on their farm to reduce mortalities and the overall impact of the virus.
Christine Crawford and Sarah Ugalde from the Institute for Marine and Antarctic Studies (IMAS) have been spearheading this research, and have worked closely with industry to investigate issues such as:
When are oysters most vulnerable to POMS?
Are environmental conditions important and can the timing of outbreaks be predicted?
Is there a pattern in the way the virus spreads and takes effect on oysters?
Are handling regimes affecting mortalities, and what is the best stocking density?
Does oyster age and size influence POMS-associated mortalities?
How has POMS changed the business and management practices in industry?
To answer some of these questions and more, Christine and Sarah, in conjunction with Biosecurity Tasmania, conducted an industry survey to capture what industry has been through over the two summers since POMS arrived in Tasmania (2016/17 and 2017/18).
The results of the 2016/17 survey showed that in the first year, almost all farmers (95%) in POMS-affected areas drastically changed their farm management in response to POMS:
90% changed their handling regimes;
62% moved oysters only at specific times;
61% changed their stocking density, and;
52% changed the type of stock on their lease.
All these changes contributed to reducing the average mortality to 31%, compared with 59% when POMS was first detected. This reduction in mortality gave farmers confidence that their future business viability was strong (79%).
Things looked even better for the second year.
“The overall message from the recent POMS survey is that industry is feeling like they’re on top of things, despite some challenges.” Sarah said.
“The industry looks like it’s ready to get employment and production levels back to what it was before POMS arrived in Tasmania’’.
“Although half of the farmers in POMS-affected areas think the overall effect of POMS in Tasmania has been a major negative, 63% of them still think their future business viability is strong. The saving grace here is the increased market price, better genetics, and improved farm management”.
Sarah has been blown away by industry’s resilience.
“It has shocked me, in a very good way, how well our industry has dealt with this disease and they have done an amazing job at taking information and using it to find out what works for them. The industry as a whole has done so well in dealing with something that was described as ‘catastrophe’.”
When asked how industry had done this, she simply said, “People have been willing to learn. To be able to crack this, farmers needed to learn how to do research, and researchers needed to learn how to farm oysters. This research has been very much a partnership with industry where we design projects together, industry helps us collect information, we crunch numbers, and industry helps us interpret the results. When science and industry work well together, we see amazing progress.”
Christine and Sarah have spent the past 12 months working with growers to developing farm management strategies to reduce mortalities. They have developed a predictive model for POMS outbreaks based on water temperature, as mortalities due to POMS only occur when temperatures are high.
They have also shown that no handling during the summer POMS season can, in fact, result in increased mortalities, contrary to views held by some growers. However, adapting farm practices in POMS-infected areas is an ongoing process as we learn more about how the virus operates in the Tasmanian environment.
The next step is focusing on leaving a best practice guide for managing POMS, based on the information gathered so far. This should be valuable for farmers living in non-POMS affected areas.
For many of them, waiting for POMS to be detected in their growing bay is like the stress you would expect from playing Russian Roulette. It’s just a matter of time, and eventually, your turn could be up.
“This best practice guide will provide them with a decision-making tool for when it does arrive, and so industry is able to respond quickly. Obviously, every site is different but there are general principles of what works and what doesn’t”, Sarah said.
“At the end of the day, we hope that it’s a tool used for helping people, preserving families, increasing business and sustaining a multi-million-dollar Australian industry.”
For more information on this project, please visit: https://www.oystersaustralia.org/project-2016-804
The author acknowledges that the CRC Program supports industry-led collaboration between industry, researchers and the community. The Future Oysters CRC-P, which focuses on the production of ‘Better’, ‘Healthy’ and ‘More’ oysters, is led by Australian Seafood Industry Pty Ltd in partnership with Oyster Australia Ltd, Select Oyster Company Pty Ltd, Fisheries Research and Development Corporation, Department of Primary Industries and Regions (South Australian Research & Development Institute), University of Tasmania, The Flinders University of South Australia, The University of Newcastle, The University of Adelaide, Commonwealth Scientific and Industrial Research Organisation, University of Technology Sydney, University of Sunshine Coast, Macquarie University, Department of Skills and Regional Development (NSW), and The Yield Technology Solutions Pty Ltd.
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