Is it safe to eat farmed oysters?
Oysters sold through retail outlets remain safe to eat. Advice from interstate authorities where the disease also exists say there is no risk to human health from POMS.
What is POMS?
POMS is a disease caused by a virus that only affects Pacific Oysters (Crassostrea gigas). This virus has not affected other oyster species, such as the Sydney Rock Oyster.
When was the disease detected?
On Thursday 28/1/16 a lease holder in Pitt Water reported unusually high mortality rates within their oyster stocks. Samples from the oysters were taken and tested.
Laboratory results on 1/2/16 confirmed the presence of Pacific Oyster Mortality Syndrome (POMS).
Further surveillance and testing determined that the POMS virus is present in a number of areas around Tasmania. All oyster growing regions of the State have since been assesed and categorised for the purpose of movement restrictions relating to oysters and oyster growing equipment. More information about Area Classifications can be found here.
The POMS virus was first detected in Tasmania when it caused a high level of mortalities at an oyster lease in late January 2016, however tests on stored frozen oysters indicated that the virus has been present in the State since at least mid-December 2015. POMS can be present in a dormant state having no adverse effect on the animal until triggered by environmental factors such as rising water temperature in summer. These frozen oysters had been retained from samples collected under a routine surveillance program conducted by Biosecurity Tasmania for food safety purposes.
How does POMS kill Pacific oysters?
The triggers for POMS are unknown but a range of environmental factors, including seasonal rises in water temperatures, may trigger the development of the disease in oysters already infected with the virus.
Where did the virus come from?
Oyster viruses have previously been identified in Australian waters in bivalve molluscs but until now have not been reported in Tasmania.
Are other animals affected?
No, POMS is specific to oysters and will not affect other marine animals.
What is Biosecurity Tasmania doing to limit the spread of the disease?
Current activities are aimed at restricting further spread of the disease.
The original declaration of Control Area, established under the Animal Health Act 1995, has now been adopted in its entirety as a Control Order under the Biosecurity Regulations 2022. The risk-based movement permit system continues to operate limiting the movement of oysters (and animal materials and conveyances used in the production of oysters) to areas of similar or higher risk.
Movement of oysters for human consumption within Tasmania is not restricted as POMS does not affect humans.
Oysters Tasmania has been very proactive in assisting with communicating with their members and supporting control measures.
Biosecurity Tasmania contributes to ongoing disease management by:
- Having established the disease risk status of various areas through a structured testing program.
- Working with industry to maintain restrictions on the movement of oysters (other than for human consumption) and associated equipment.
- Issuing permits to allow low risk movements.
- Investigating cases of suspect disease including confirming the diagnosis.
- Contributing to a better understanding of POMS risk factors.
- Notifying other states and supporting negotiations for maintaining or regaining interstate market access.
Can Tasmanian producers harvest and move stock within the state?
Yes, the initial response to POMS in Tasmania included restrictions on the movement of oysters onto oyster farms while a structured testing program was undertaken to determine where the virus was present in the State. This testing program made it possible to assess oyster movements that could occur between farms without spreading the virus. Based on the information from the POMS testing program, three (3) areas of differing disease risk have been determined as a basis for issuing movement permits: Infected, Intermediate and POMS free areas.
For general stock and equipment movements (excluding movements of stock from hatcheries) Biosecurity Tasmania has issued a Group Permit to Tasmanian oyster producers which details specific conditions for those movements to occur. The Group Permit can be found here
Further information on Movement Permit Applications can be found on the POMS - Declaration of Control Area
page of this website, the application form is also available here:
What can you do to prevent the spread of POMS to other oyster growing regions?
Familiarise yourself with the POMS risk status of the areas you are visiting to boat or fish in. If they are infected or intermediate risk areas (see Area Classification) and you intend to move to another estuary, to ensure that fishing gear or other equipment are free of any oysters, sediment or biofouling:
- Drain all water from your boat and gear;
- Use car/truck wash to rinse gear and equipment, boats (inside and out) and trailers and then air dry; and
- Flush outboard engines.
What you can do to help
Biosecurity Tasmania encourages all community members to report all suspected aquatic disease events so they can be investigated. Improved vigilance in recreational boat cleaning helps reduce the spread of aquatic diseases and pests.
Help protect Tasmania from introduced aquatic threats by CHECK, CLEAN, DRAIN and DRY all boating, fishing and diving gear before coming to Tasmania, and after every trip in Tasmanian waters.
Reporting oyster mortalities
Any unexplained and significant mortality of oysters (greater than 5%) should be reported to: