Oz pearl aqua-culture bug

Pearl farms hopeful as killer bug fades
2nd January 2007, 7:00 WST

WA pearl producers hope they have seen the back of a mystery disease which has killed oysters at 10 pearl farms in the North-West, where the lucrative pearl industry injects $150 million into the economy each year.


Oysters affected by the disease were quickly quarantined and isolated when the first outbreaks were detected in late October and although there have been no further mortalities, the pearling industry and the Department of Fisheries are nervously waiting for the results of scientific tests they hope will help them prevent future outbreaks.

Despite the mystery surrounding the cause of the oyster deaths in the Exmouth Gulf, Pearl Producers Association executive officer Brett McCallum was quick yesterday to hose down speculation that the WA pearl industry was in jeopardy.

"My concern is people saying "The pearling industry is threatened". Well, it's not. It was an isolated incident and we've got on with life," he said. "We have very strong protocols that have the farms at different distances apart from each other and that's all by law so we don't spread stuff.

"That's why it was isolated and nipped in the bud pretty quickly."

Mr McCallum could not say how many oysters had been wiped out or put a value on the impact of the oyster deaths until the end of the production process in two years time.

He said the first outbreak could have been caused by any number of factors … such as boats exchanging ballast water close to shore … and the first sick oysters could have passed on their affliction to others.

"Any sort of animal in the water is going to be subject to problems that might be floating around the water and pollution and ballast water is an issue," Mr McCallum said. "Water is a great vector - it transfers things very quickly."

Department of Fisheries principal fish pathologist Brian Jones said department researchers were working to find the cause of the oyster deaths.

"The department has restricted the movement of live pearl oysters and provided best practice advice on the washing down of workers and equipment as necessary mitigation measures while investigations are concluded," Dr Jones said. "Industry has since reported recovery of sick pearl oysters at some affected sites."

WA fishing company M.G. Kailis is one pearl producer reporting that oysters are returning to normal.

"Since early December, shell health appears to have stabilised," managing director Alex Kailis said, adding that the oyster deaths would have no impact on the quality and availability of finished pearls from their farms.

WA pearls are renowned worldwide for their quality and lustre which are attributed to their cultivation in the pristine waters off the Kimberley coast. More than 80 other pearl farms in WA have been unaffected by the disease.

DANIEL EMERSON