Pacific Oyster Mortality Syndrome


Pacific Oyster Mortality Syndrome (POMS) is a disease that causes major production and economic losses in commercial oyster farms. It is caused by a virus that only affects the Pacific oyster species.

POMS has been confirmed in feral oysters in the Port River estuary in Adelaide, South Australia. This estuary is a shipping port - not a commercial oyster growing area. POMS has not been detected in South Australian oyster farming areas.

At this stage the disease is contained to the Port River estuary. The nearest commercial growing area is approximately 60 km away.

The Department of Primary Industries and Regions South Australia (PIRSA) is removing and destroying the feral oyster population in the harbour to reduce the risk of the virus spreading.

PIRSA has put in place a legal order under the Fisheries Management Act 2007 to restrict the removal of bivalve shellfish from the Port River estuary and harbour. Bivalves include oysters, mussels, cockles and razorfish.

PIRSA has also put in place a legal order under the Livestock Act 1997 to restrict oysters for grow-out from being moved between growing areas in South Australia, and spat cannot be moved out of any hatchery in the state without the written consent of the Chief Inspector. Commercially grown oysters can move within a growing area.

These are precautionary measures to keep the virus out of growing areas. It is important that people comply with these restrictions to protect South Australia’s oyster industry.

Recreational and commercial vessel owners who use the Port River estuary have been provided with information on how to reduce the risk of spreading the virus.

The Aquatic Consultative Committee on Emergency Animal Diseases has met in response to this outbreak. The committee is providing technical advice and support to PIRSA which is the lead agency for this incident.

It is important that consumers are aware that this virus poses no threat to food safety or human health. In this incident, the affected oysters are feral, and not in commercial leases.

More information including maps showing the restricted areas are available on PIRSA’s website.

Biosecurity and reporting

Oyster farmers

Good farm biosecurity measures are vital in preventing pest and disease outbreaks in your stock.

Oysters Tasmania has a best practice guide on biosecurity and disease preparedness, with a focus on this virus. Growers are encouraged to download a copy from

Boat owners and fishers

Recreational boaters and fishers can also play a role by keeping their boats, trailers and fishing equipment clean. Keeping vessels and aquatic equipment free of biofouling is important in preventing any water-borne virus spreading to new waterways.

Report a POMS outbreak

If you find a number of dead oysters in your stock or in feral populations, report it to the Emergency Animal Disease Watch Hotline on 1800 675 888.

Previous POMS outbreaks

There have been previous POMS outbreaks in Australia. From 2010 to 2013 it was found to be the cause of massive mortalities of farmed Pacific Oysters in the Georges River and the Hawkesbury River in the Sydney region. The virus that causes POMS is also known to have impacted wild populations in Sydney’s Parramatta River and Brisbane Water on the Central Coast (north of Sydney).

An oyster lease

In 2016 POMS caused major economic and social damage to Tasmania’s oyster industry when it infected commercial growing areas in the south east of the state, including Upper Pitt Water, Pipe Clay Lagoon, Blackman Bay, Island Inlet and Little Swanport. Wild Pacific oysters from the Derwent River estuary were also impacted.

Movement restrictions on live oysters and oyster equipment remain in place in both NSW and Tasmania to reduce the risk of spread to other areas.

About the disease

POMS is a disease that causes major production and economic losses. It is caused by a virus that only affects Pacific oyster species (Crassostrea spp.), not other oyster species.

This virus is often not detected until oysters start dying in large numbers. In Australia, mass mortalities have been observed at seawater temperatures of 21oC to 25oC.

The precise trigger for mass mortality events is still not well understood but may be linked to other environmental factors.

Oyster mortalities occur quickly once infected with the virus, and losses can be up to 100 percent of stock.

POMS is generally spread through movement of live oysters, bivalve products or equipment that has been in contact with infected animals.

The virus is not known to affect other oyster species including Sydney Rock oysters, however, they can be contaminated with the virus.

More information

Below are links to information about the disease and the response undertaken in each of the affected states: