Native oyster, Ostrea angasi. (Photo Credit: Natural History Museum Rotterdam/CC BY-NC-SA 3.0)

Native oyster comeback expected to boost SA aquaculture industry

The revival of the native oyster (Ostrea angasi) in South Australian waters is adding a delicious aquaculture product to the State’s premium seafood selection, states the South Australian Research and Development Institute (SARDI).

Local oyster producers have this month snapped up the latest batch of more than one million native oyster spat produced by the State Government’s research provider, SARDI, in response to the rising demand for the large, tasty delicacy from niche markets, such as high-end restaurants.

SARDI’s Aquaculture Science Program Leader, Professor Xiaoxu Li, said the spat was the result of the research team refining hatchery techniques for native oyster spat production over the past three years.

“The reintroduction of the native oyster to local oyster leases would boost the viability of the State’s AUD 40 million [USD 37.4 million] (2011-12 Econsearch report) oyster aquaculture sector,” Professor Li said.

“This appetite for South Australian seafood paves the way for the return of the local native oyster to our plates, and SARDI’s innovation has made this possible.

“It is also a smart step forward for oyster growers who want to diversify and expand their business.”

More than three million native oyster spat have been produced at the SARDI hatchery over the past three years to help growers build the new industry with growers on Kangaroo Island and the Eyre Peninsula using the spat to assess the best farming methods to grow the oysters and to explore market potential.

Native oysters are sold at a size similar to Pacific oysters, but can fetch twice the price of the popular and introduced Pacific oyster. The native oyster fishery was the State’s first dating back to the 1860s, but the industry collapsed in the early 1900s as a result of overfishing.

Professor Li said producing native oyster spat under hatchery conditions was more difficult than for Pacific oysters because there was not a robust technique to control their spawning and to culture newly fertilised eggs.

“Unlike Pacific oyster eggs which are spawned into the environment directly, newly fertilised native oyster eggs rely on their broodstock to look after them in their first eight to ten days before they are released into the environment,” Professor Li said.

“Also, we cannot tell visually which broodstock are pregnant and on average a broodstock normally produces about one million early-shelled larvae at each spawning, which is at least five times less than what will be spawned by the Pacific oyster of the similar size.

“So we have to collect or condition many more broodstock than we will be able to use as a larvae source.”

SARDI researchers have been collecting the progenies of different ages, from a few hours to a week old, from the females directly, and then rearing them in 2000 litre round tanks. They are fed a mixture of four microalgae species produced in SARDI’s algal culture system.

With a 70 per cent survival rate, SARDI is now investigating reproductive strategies and further optimising spat production techniques to enable the native oyster sector to expand while containing and where possible reducing input costs.

SARDI’s native oyster work has been supported by Marine Innovation Southern Australia (MISA), along with the SA Oyster Research Council, SA Oyster Growers Association and Pristine Oyster Farm, Eyre Peninsula.

MISA is a partnership of the Government of SA, SARDI, Flinders University, University of Adelaide, South Australian Museum and the seafood industry.

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