Three strains of Sydney rock oysters, bred by the DPI at Port Stephens for increased disease resistance, are being trialled in the Richmond River at Ballina.
Three strains of Sydney rock oysters, bred by the DPI at Port Stephens for increased disease resistance, are being trialled in the Richmond River at Ballina.

Super oysters: If they can live in Ballina, they can survive anywhere

DEPARTMENT of Primary Industries researchers are trialling disease-resistant 'super oysters' on the Richmond River at Ballina - because if they can live there, they can survive anywhere.

The Gaelic word 'Ballina' is thought to have sounded like the Bundjalung word meaning "many oysters here” but declining water quality has meant that at no time in this century has a Ballina oyster reached old age, at around 10 years.

TRIAL RUN: Ian Cardow, of Richmond Oysters, installs hardware funded by Ballina mullet haulers to house oysters that may have a better chance of surviving in the low-quality Richmond River water at Ballina.
TRIAL RUN: Ian Cardow, of Richmond Oysters, installs hardware funded by Ballina mullet haulers to house oysters that may have a better chance of surviving in the low-quality Richmond River water at Ballina.

The main culprit is the QX disease parasite Marteilia, a single-celled organism that abounds in all coastal waterways each summer-autumn.

Low salinity, turbidity, poor oxygen levels and other factors influence an oyster's ability to fight off QX and other diseases. And acid runoff can actually eat holes in their thick shells.

Mismanaged farming practices, agricultural runoff and wetland drainage have all played a part in the Richmond River's water problems, to the extent that Ballina's remaining handful of commercial oyster farmers must get their stock from other waterways.

The DPI Oyster Research Division at Port Stephens, headed by Dr Michael Dove, has been working on disease-resistant families of Sydney rock oysters and was interested to see if they could survive in the toughest of conditions.

So the division teamed up with local growers Richmond Oysters and the Richmond River chapter of national angling conservation group OzFish Unlimited to provide volunteer help and monitoring of the three new strains under test.

Once comprising hectares of spat sticks, poles, slats, racks, trays and baskets, Ballina's oyster infrastructure is now at a low ebb, mainly because the oysters would die within the 2-3 years they took to reach market size.

But the new trial needed the latest hardware and farming methods and that cost money.

Ballina's sea mullet haul-netters came to the party, shelling out cash from their "future fund” to purchase the cages, trays and floats required.

"The Ballina sea mullet haulers recognise the ecological importance of oysters in a healthy estuary and are to be commended for making this project possible,” Ballina OzFish chair John Larsson said.

"Our efforts to improve water quality on the Richmond will continue unabated and parallel to the oyster project.

"If these oysters don't survive, it will be a damning indictment of the Richmond's water quality, providing us further powerful data to lobby government at all levels.”

Stay tuned.



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