By Gio Braidotti
When infectious disease devastates human health, the world has sophisticated healthcare strategies on stand-by. But what happens when crops and animals in our food-producing farms are struck down by disease outbreaks that threaten entire sectors?
The Pacific Oyster (Crassostrea gigas) industry has faced that question since the arrival in New South Wales in late 2010 of Pacific Oyster Mortality Syndrome (POMS). The same disease has previously devastated oyster industries as it spread from France in 2008 to the UK, the Netherlands and New Zealand.
In NSW, the Georges River, Botany Bay, Port Jackson, Parramatta River and the Hawkesbury River were badly affected. Local research found that POMS reduced oyster survival to just one per cent when water temperature and environmental stresses conspired to assist the disease. At best, survival peaked at 40 per cent.
Some NSW operators have now left the oyster industry, unable to survive the dramatic economic impact of disease – first they were hit by QX disease, which affected Sydney Rock Oyster (Saccostrea glomerata) production, and then by POMS, which decimated the triploid Pacific Oysters used to rebuild some of those farms.
Research to find a solution to this devastating issue is happening all around the country and across the Tasman, with the University of Sydney, CSIRO, the NSW Department of Primary Industries, Hornsby Council (NSW), Tasmanian hatchery Shellfish Culture, Aglign Consulting and two groups in New Zealand working on POMS.
Tasmanian and South Australian growers – while currently unaffected by POMS – are facing a ticking bomb. It is generally accepted that the arrival of POMS in these areas is a matter of ‘when’ not ‘if’.
Rather than present a sitting target, growers are acting pre-emptively to safeguard their farms. This includes agreeing to a specific research levy to support a program to breed POMS-resistant oysters. The program will be conducted by the industry-owned company Australian Seafood Industries Pty Ltd (ASI).
Created in 2000, ASI has developed an applied breeding program for Pacific Oysters that has focused on breeding oysters with a balanced range of traits to improve productivity and marketability. These include gain in growth rate, shell width index, time to reach market condition, survivability and uniformity.
In the past, a premium has applied to spat produced from ASI’s advanced broodstock, for those growers who chose to buy it. However, the significance of POMS to the industry as a whole – and the importance of breeding POMS-resistant stock – has resulted in a new approach.
With support from growers and the Australian Seafood Cooperative Research Centre (Seafood CRC), a compulsory levy of $2.80 per 1000 spat has been introduced on all hatchery-produced Pacific Oyster spat sold in Australia, whether it is produced from ASI broodstock or not.
The levy will be collected by ASI from growers and invested in an accelerated POMS-resistance breeding program. The levy was approved by the Australian Competition and Consumer Commission in late 2014 and will apply for the next decade, with industry to review progress after three and seven years, providing opportunity for “go/no-go” continuation of the levy.
ASI director Ian Duthie says the POMS resistance program is based on testing genetically diverse oyster families in which all pedigrees are known. The families are exposed to POMS in NSW (or in laboratory tests that correlate with field findings and better ensure exposure to POMS). Back in Tasmania, relatives of the best-performing families are bred.
“None of the ASI families possessed complete resistance to POMS,” Ian Duthie says. “Some had none but others possessed various levels of partial immunity. With CSIRO assistance, we were able to devise crosses that will allow us to gradually increase resistance to commercially viable levels.”
The program’s goal is to achieve 70 per cent resistance to POMS in five years and the most recent trials in 2014 show the program is on track to achieve this.
This approach to POMS was adopted following a review of POMS’ impact internationally and the efficacy of various disease-control strategies.
ASI general manager Matt Cunningham says two broad strategies exist. In France and New Zealand growers buy three to four times more spat than needed and harvest whatever POMS spares. This approach is not economically viable in Australia where spat prices are considerably higher.
Globally, the consensus is that breeding for resistance to POMS is the only practical solution. In response, ASI adapted its longstanding breeding program to include selection for disease resistance.
Ian Duthie explains that selection for one trait can inadvertently force unwanted changes in other desirable traits the ASI program has been focusing on, such as meat to shell ratio.This is true in all agricultural breeding programs, be it in crops, livestock, timber or fisheries.
He says this proved the case with the QX-resistance work in Sydney Rock Oyster and in ASI’s earliest attempts to accelerate growth rates in Pacific Oyster. Today, ASI uses economically weighted values that balance productivity and marketability traits.
“The beauty of this strategy is that it achieves resistance without sacrificing gains made over many years in traits that improve farm-gate profitability,” Ian Duthie says. The other advantage for growers is the cost.
“If each hatchery was to pursue applied breeding independently it would cost industry more overall and disadvantage the customers of smaller hatcheries,” Matt Cunningham says.
Individual hatcheries have estimated that POMS-related breeding would result in costs of $5 per 1000 spat, compared with the $2.80 per 1000 spat for the industry-wide levy.
“That’s a clear case of costs to growers being minimised,” Matt Cunningham says. For a farm achieving 80 per cent recovery to sale, the levy represents less than one per cent of the oysters’ farm-gate sales price (4.2 cents per dozen oyster sold).
Peter Kosmeyer, general manager of Southern Cross Marine Culture, manages the purchase of more than 15 million Pacific Oyster spat a year for farming in Tasmania, South Australia and NSW. He says that achieving POMS resistance is vitally important to industry and hatcheries.
“The consequences of not having something in place are too horrible to think about,” he says. “Ditto SAMS [South Australian Mortality Syndrome] and whatever is next.”
ASI’s breeding model is being adopted by other nations, including New Zealand. But since Australia started accruing resistance earlier, ASI’s program is leading the world.
“This approach is measurable, reproducible and, most importantly, can achieve genetic gains for POMS resistance,” Matt Cunningham says.
Families most recently underwent a juvenile field challenge in late 2014 in the POMS-affected Georges River region, in NSW. As with previous trials, high levels of genetic variation in POMS resistance were observed.
“The results suggest that resistance is accumulating with successive generations of selection and we can remain confident that we will achieve our expected levels of resistance in the time frames predicted,” Matt Cunningham says.
“The fundamentals and science we are using is held up as the model for other oyster breeding programs around the world, in the US, New Zealand and France.”
The levy provides greater stability for ASI’s research program, but other changes to the business are also being made to further improve the sustainability of its operations. While the levy funds the POMS resistance program, other ASI projects are funded independently of this.
Since its inception as an industry-owned company, ASI has relied on dedicated volunteers as directors and a small, tightly focused budget. As the technical and business environment became more challenging, ASI recognised that this governance model needed to change.
Following a strategic review, ASI’s new business plan incorporates an expansion of the board, with remuneration for directors. It will include an independent chair, two independent directors and two shareholder-nominated directors.
Managing director of the Seafood CRC Len Stephens has been appointed as the new independent chair of the ASI board, and the process of appointing the other directors is being finalised.
FRDC Research Codes: 2012-032, 2014-040
Ian Duthie, 0409 411 322,