Q&A Pacific Oyster Mortality Syndrome

Is this a food safety related incident?

No.  The NSW Food Authority and NSW Health have confirmed there are no food safety or human health issues related to this event. 

Where have Pacific oysters died?

Reports indicate that  a large percentage of wild Pacific oysters have died in the upper reaches of both Botany Bay and Port Jackson.  Most of the Pacific oysters that are farmed in the Georges River have died.

When did the Pacific oysters die?

In late November 2010 oyster farmers in the Georges River, Botany Bay,  reported to I&I NSW that they had experienced a large mortality event in their Pacific oyster crop and also noted that wild Pacific oysters had died too.  There were reports of Pacific oysters dying in the upper reaches of Port Jackson in late February 2011.

Why have the Pacific oysters died?

The Pacific Oyster Mortality Syndrome was noted after significant rainfall which resulted in a plume of discoloured water entering the Georges River and there was also an algal bloom in the area.

Samples of water from the Georges River were examined by NSW DECCW for pollutants that may have killed the oysters.  NSW DECCW has reported that no significant pollutants were found in the water that may explain the oyster mortality.

Samples of Georges River oysters were sent to an I&I NSW veterinary laboratory for examination.  The laboratory confirms that a virus is associated with the death of Pacific oysters.  This is also the case for the Pacific oysters tested from the Parramatta River, Port Jackson.

The trigger for the current Pacific Oyster Mortality Syndrome is unknown but may be due to a range of environmental factors.

Where did the virus come from?

Oyster viruses have previously been indentified in Australian waters in bivalve molluscs but until now have not been associated with significant mortalities of oysters. 

Similar viruses have been regularly detected in France since 1991 and in addition to European waters have been found in America, Asia and most recently New Zealand.

Have other oysters and molluscs died?

No. Sydney rock oysters and other molluscs appear unaffected by the event.

Are other estuaries in NSW affected?

I&I NSW has received no other reports of significant oyster mortalities in any other NSW  estuary.

What is I&I NSW doing to limit the spread of the disease?

There is a total ban on recreational fishers taking oysters from the Georges River, Botany Bay and Port Jackson.

Educational material will be developed to help boat owners better understand the risks of boating movement, and translocation of fouling organisms and bilge water from Botany Bay and Port Jackson to other waterways.

Movement controls for farmed Georges River oysters, oyster farming infrastructure and equipment to any other oyster growing estuary in NSW are in place. 

I&I NSW will also undertake a surveillance program to test oysters in other estuaries and consider impacts on other native species.

Can I catch the virus if I eat oysters?

No.  NSW Health has confirmed that the virus only affects molluscs and cannot be transmitted to humans.

Is it safe to eat oysters?

Yes.  Commercial shellfish are grown under a strict food safety program administered by the NSW Food Authority.