White spot disease (WSD) is a highly contagious viral infection that affects crustaceans. The disease is caused by white spot syndrome virus (WSSV).

WSD is a highly contagious viral disease of prawns, however it does not pose a threat to human health or food safety.

Current situation

Photo showing prawns with White Spot Disease lesions
Photos courtesy of Queensland Department of Agriculture and Fisheries - White Spot Disease lesions

WSD has been detected in black tiger prawns (Penaeus monodon) at three prawn farms on the north coast of New South Wales on 14 February, 28 February and 21 April 2023.

NSW Department of Primary Industries (DPI) is working with each of the affected farms to complete decontamination, disinfection and discharging of waters from the ponds, which are now in the final stages.

The NSW Environmental Protection Authority (EPA) has provided technical advice to NSW DPI to ensure any water discharge from the affected farms meets strict environmental standards and protocols. The treated water has undergone rigorous ecotoxicology testing, which found the treated water does not pose a threat to river or aquatic life. The treated water is safe for people, aquatic life and livestock.

The NSW DPI will inform the community and stakeholders when this process is completed.

Wild prawns and other crustaceans collected in the Clarence River control zone and adjacent offshore areas have been sampled and tested for WSSV. Initial surveillance of wild caught prawns collected within the Clarence River control zone in February 2023 found trace levels of WSSV DNA in a small number of samples.

NSW DPI will be undertaking ongoing long-term surveillance for WSSV within the control zone and surrounding area, once a fallowing period (drying out of ponds) is completed for all affected farms.

Background of the current WSD outbreak in NSW

In August 2022, WSD was detected in broodstock prawns at a biosecure facility in northern NSW. This incident was quickly contained and eradicated. Genetic analysis indicated the virus was different from that detected in South East Queensland between 2016 and 2020 and was likely to be of separate origin.

Following extensive investigations, there was no conclusive evidence to determine the origin of the NSW WSSV detection in 2022.

On 12 February 2023, a producer reported dead prawns with white spots in a single grow-out pond. On 13 February, a small number of prawns across 4 grow-out ponds were observed to be sick or dead. On 24 February, a second farm in the vicinity reported lethargic prawns. The Australian Centre for Disease Preparedness (ACDP) confirmed positive test results for WSSV on both these farms on 14 and 28 February, respectively.

NSW DPI issued the two infected farms with formal Individual Biosecurity Directions. Accelerated harvesting and destruction of stock was completed on both farms and post-control surveillance activities are ongoing. The decontamination phase of the response is underway on these farms to finalise the on-farm eradication program.

On 11 to 13 April 2023, prawn samples were collected from the third farm within the control zone area as part of active surveillance during the WSD response carried out by NSW DPI. The sampled prawns showed no signs of disease. On 18 April, initial laboratory analysis of these samples by NSW Department of Primary Industries (DPI) detected WSSV in all the ponds sampled. On 19 April 2023, the samples from the third farm were then sent to ACDP, which confirmed all samples tested positive for WSSV on 21 April 2023.

On 3 May 2023, ACDP confirmed the WSSV strains at the three NSW prawn farms affected are strongly similar to the WSSV detected in NSW in August 2022. They are a different lineage to the Queensland strain detected in 2016-2020.

Extensive investigations and tracing were not able to determine the origin of the infection in NSW.

Response activities

On 13 February 2023, NSW DPI stood up an Incident Management Team (IMT) to coordinate disease investigation, surveillance and response activities.

Prawns from healthy ponds on affected farms were harvested and cooked under a biosecurity direction before leaving the affected farms. The remaining stock was destroyed and decontamination of farms is entering its final stages.

The IMT was communicating with industry stakeholders and providing support to affected properties during the destruction and decontamination processes. The IMT formally stood down on 30 June 2023 and the emergency response has now transitioned to management phase.

On 16 February, DPI issued a biosecurity control order for restrictions on the movement of raw, uncooked prawns and other decapod crustaceans (including crabs and lobsters), and polychaete worms out of the Clarence River Control Zone (see map below).

This control order has been extended for up to 2 years to minimise WSD risks in the Clarence River estuary. The control order supports risk management, surveillance and tracing activities to inform future management approaches.

NSW DPI is working closely with commercial fishers, the bait industry and prawn farmers to manage the impact of this order while investigations are underway.

NSW DPI has a long-term surveillance plan that will involve surveillance of wild crustaceans within and outside the existing control zone for up to two years. This will include the Clarence River, coastal and offshore areas.

National response arrangements are in place to respond to WSD through AQUAVETPLAN, which provides technical guidance on destruction, disposal and decontamination activities.

The national Aquatic Consultative Committee on Emergency Animal Diseases (Aquatic CCEAD) convenes regularly to provide technical assistance.

Temporary restrictions in northern NSW

Prawns and polychaete worms may only be moved out of the Clarence River Control Zone if they have been cooked. There are exemptions for certain uncooked decapod seafood species, such as crabs and lobsters, to be moved out of the Clarence River Control Zone for the purpose of human consumption only, which must be cooked as soon as possible upon arrival at the destination.

More information on the Control Order movement conditions and restrictions for crustaceans and polychaete worms in the state of New South Wales can be found on the NSW Department of Primary Industries website

If you find prawns with suspected signs of WSD, contact NSW DPI as soon as practicable by either calling the Emergency Animal Disease Hotline on 1800 675 888 or by emailing aquatic.biosecurity@dpi.nsw.gov.au

Clarence River Control Zone

Map of the Clarence River control area
& & Clarence River Control Zone

South East Queensland movement restrictions

Poster of man fishing at the beach warning people not to move prawns, yabbies or marine worms out of the white spot disease movement restriction area.
Photo courtesy of Queensland Department of Agriculture and Fisheries - White spot disease movement restrictions

Movement restrictions remain in place in South East Queensland.

The restrictions prohibit the movement of high-risk animals such as prawns, worms and yabbies out of the Movement Regulated Area that extends from Caloundra to the NSW border and west to Ipswich.

An exemption exists for low-risk species: spanner crabs, three spotted crabs, blue swimmer crabs, mud crabs, red champagne lobster, slipper lobster, tropical rock lobster, red claw and bugs.

These species can be moved out of the Movement Regulated Area raw, however anyone wishing to move these species out of Queensland must check the importation requirements of the destination state before doing so.

The movement restrictions do not apply to molluscs (oysters and mussels).

To find out more about the current movement restrictions in Queensland and to download the map, see the Department of Agriculture and Fisheries White spot information guide.

Restrictions in other states and territories

Before importing seafood product from the Movement Regulated Area to other states or territories, check for import restrictions.

History of the disease in Australia

Between December 2016 and February 2017, white spot disease was confirmed in 7 prawn farms on the Logan River in South East Queensland. In early 2017, the virus was detected in wild populations of crustaceans, such as prawns and crabs in the northern part of Moreton Bay.

Prawns on the infected farms were destroyed to eradicate the disease, and 5 farms resumed production in 2017.

A Movement Regulated Area (MRA) in South East Queensland is still in place to prevent the virus spreading to other parts of Queensland and other states and territories.

White spot syndrome virus has established in some populations of wild crustaceans within the MRA. A national surveillance program that commenced in 2017 demonstrated that all areas of Australia, outside of the MRA, have remained free from the virus.

Movement and fishing restrictions remain in place in the Queensland MRA.

In August 2022, WSSV was detected at a biosecure prawn hatchery in northern NSW. The incident was quickly contained and WSSV was eradicated from the facility.

Following extensive investigations, there was no conclusive evidence to determine the origin of the NSW WSSV detection in August 2022.

Recreational and commercial fishers

Keep Australia's fishing spots free from disease

Everyone who uses our waterways has a role in keeping them free from disease. Regardless of where you are in Australia you need to take some simple steps to prevent the spread of aquatic diseases or the transfer of marine pests.

Diseases and pests that affect aquatic animals can easily spread between waterways by the movement of contaminated bait and fishing equipment.

Disease outbreaks can cause major social and economic damage to Australia’s seafood industries.

Tips to keep your favourite fishing spot disease free

Fishing rod being cleaned with sponge
Photo courtesy of NSW DPI
  • When you are selecting your bait, use local and reputable bait shops or source your own bait from local waterways.
  • Do not use seafood meant for human consumption as bait.
  • Make sure you put all unwanted seafood in a rubbish bin, not in the ocean or waterways.
  • Keep your fishing gear, boat and trailer clean. Make sure that any bait, debris and seaweed is removed. Check wheel arches on trailers, boat propellers, fishing tackle and footwear.
  • Use soapy water to clean your boat and trailer, fishing rods and other equipment, and allow them to dry completely before using them at another location, even if it is on the same day.

See the NSW DPI fact sheet: Make ‘clean’ part of your routine

Queensland white spot disease movement restrictions video featuring fishing guru Scott Hillier

Marine pests website: recreation and community

Information for prawn farmers

The information below provides advice on how to prevent a disease incursion on your farm.

On-farm biosecurity

Prawn farmers need to ensure appropriate biosecurity measures are in place on their farm which includes sourcing disease free stock and animal feed.

Make sure livestock, water, visitors and staff, and equipment that are coming onto, and leaving the farm are clean. Equipment and footwear should be disinfected in addition to being cleaned.

The Department of Agriculture, Fisheries and Forestry (DAFF) offers a range of free resources to manage aquatic animal health, including:

  • National biosecurity plan guidelines for Australian:
    • prawn farms
    • land-based abalone farms
    • barramundi farms
    • oyster hatcheries
  • National policy guidelines for the translocation of live aquatic animals
  • National policy guidelines for the translocation of domestic bait and berley

Access the above listed resources on the DAFF website.

Disease reporting

If you suspect disease on your farm, phone the Emergency Animal Disease Hotline from anywhere in Australia on 1800 675 888.

About white spot disease

White spot disease is a highly contagious viral disease of decapod crustaceans including prawns, crabs, yabbies and lobsters. The disease is caused by white spot syndrome virus.

For more information download:

White spot disease - Aquatic Animal Diseases Significant to Australia: Identification Field Guide

How to identify white spot disease

Prawn with White Spot Disease lesions
Photo courtesy of the Queensland Department of Agriculture and Fisheries
Prawn with White Spot Disease lesions
Photo courtesy of the Queensland Department of Agriculture and Fisheries

Prawns with white spot disease may have a loose shell with numerous white spots (0.5-2.0 mm in diameter) on the inside surface of the shell and a pink to red discolouration.

More reliable signs to look for include:

  • unusual mortality
  • prawns coming to the edge or water surface of the pond
  • prawns demonstrating unusual swimming patterns or lethargy
  • reduced feeding and failure to thrive.

Important: Animals infected with the virus may show one or more of these distinctive signs, or they may not show these signs at all, and the virus may still be present.

If in any doubt about whether your prawns are sick, farmers and fishers are encouraged to seek advice via the Emergency Animal Disease Watch Hotline on 1800 675 888.

How the disease can spread

The disease is primarily spread through the movement of infected animals or contaminated water. Birds that feed on and move infected animals can spread the disease.

The disease effect on other species

Finfish are not affected by the disease and are not a carrier of the disease.

Decapod crustaceans including, but not limited to, prawns, lobsters and crabs are susceptible to the infection. Marine worms are also considered to be vectors of the disease.

The white spot disease detected in South East Queensland and NSW is not the same disease that can infect ornamental/aquarium fish. White spot in aquarium fish is a parasitic skin infection and not related to white spot disease of crustaceans.

Where white spot disease is found

White spot disease is widespread throughout prawn farming regions in Asia and the Americas where it has caused severe losses on prawn farms.

Food safety and information for consumers

Consumers should be aware that white spot disease does not pose a threat to human health or food safety.

White spot disease can only be diagnosed through appropriate laboratory testing. Infected prawns and yabbies may not display any symptoms and white spots may appear for a range of reasons including, salt crystallisation, freezer burn and bacterial or fungal infections.

The most common reason you may see white spots on prawns that you have purchased is due to the crystallisation of salt under the shell of the prawn. This is because prawns are frozen quickly in a concentrated saltwater immersion process, during which the prawns pass through a saline brine tank. Some salt is then absorbed by the prawns as they freeze. This salt can crystallise under the shell while the prawns are frozen which causes white mottling to appear under the shell of the prawn. This mottling can be found on the body and head and becomes more noticeable as the prawns defrost.

With white spot disease, prawns are likely to have a loose shell with white spots that are 0.5 to 2 millimetres in diameter on the inside surface of the shell and a pink to red discolouration.

The photos below show the difference between white spots caused by white spot disease and white mottling caused by salt crystallisation.

Photo showing prawns with White Spot Disease lesions
White Spot Disease lesions. Photo courtesy of Queensland Department of Agriculture and Fisheries
Prawn with salt crystallisation
Prawn with salt crystallisation. Photo courtesy of Queensland Department of Agriculture and Fisheries

Australia’s import conditions

The Australian Government Department of Agriculture Fisheries and Forestry (DAFF) continues to monitor and enforce stringent import conditions to manage the biosecurity risk associated with imported prawns and safeguard our valuable fisheries and aquaculture industries.

Measures to ensure Australia's import conditions are being met include pre-border and border disease testing, retail testing, and working with exporting countries.

DAFF released the final report for the Review of the biosecurity risks of prawns imported from all countries for human consumption (the Prawn Review) on 5 June 2023.

The final report proposed that prawns and prawn products can continue to be safely permitted import under the enhanced import conditions implemented in a staged approach since 2017, subject to compliance with additional strengthened biosecurity measures.

DAFF will now work with Australia’s trading partners and importers to implement the additional biosecurity measures.

DAFF continues to undertake a range of activities to verify that import conditions manage risk to a level which achieves Australia’s appropriate level or protection (ALOP).

Further information about the prawn review is at agriculture.gov.au/prawns

Enforcement action will continue to be taken against importers who are found to be deliberately non-compliant with import requirements.

DAFF will continue to manage market access where an exporting country or particular supply chain within them display systemic issues or non-compliances.

DAFF has notified the World Organisation for Animal Health (WOAH) of the current WSSV incident in NSW, which is consistent with our international obligations.

Further information is available at Review of Prawns and Prawn Products on the DAFF website.

Enforcement action will continue to be taken against importers who are found to be deliberately non-compliant with import requirements.

The department will continue to manage market access where an exporting country or particular supply chain within them display systemic issues or non-compliances.

DAFF has notified the World Organisation for Animal Health (WOAH) of the current WSSV incident in NSW, which is consistent with our international obligations.

More information

Find out about interstate movement conditions and other white spot disease information that relates to your state or territory: