White Spot Disease

About the disease

White spot disease is a highly contagious disease caused by white spot syndrome virus (WSSV).

White spot disease affects crustaceans like prawns, crabs, yabbies and lobsters, but not fish or other marine animals.

White spot disease does not pose a threat to human health. Prawns are safe to eat.

This disease is not the same as white spot found in aquarium fish.

White spot disease was first detected in Australia in 2016, on prawn farms in the Logan River region of Southeast Queensland. WSSV was subsequently detected in wild-caught prawns and crabs in surrounding waterways, including Moreton Bay and the Redcliffe Peninsula.

More recently, there have been WSSV detections at prawn facilities and in wild populations of school prawns in Northern NSW. While affected prawn farms have been decontaminated and disinfected, to prevent further spread of WSSV there are restrictions on the movement of uncooked prawns and other crustaceans from the Clarence River, Richmond River and Evans Head control zones.

Why is this disease a problem

• White spot disease has the potential to significantly impact Australia’s prawn aquaculture industry, affect commercial trawler operations and disrupt trade.
• Infected farmed prawns die quickly and in large numbers.
• Wild crustaceans can carry white spot but are rarely affected.

How it spreads

The disease is spread mainly through:

• Movement of infected animals, including prawns, freshwater crayfish, crabs and polychaete worms
• contaminated water and equipment
• birds feeding on and moving infected animals.

What to look for

Prawns with white spot disease may have a loose shell with many white spots (0.5-3.0 mm in diameter) on the inside surface.

Signs of white spot disease in farmed prawns include:

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

Prawns may appear to have white spots for other reasons including from freezing. Salt crystals under the prawn’s shell appear as white marks and are easier to see as the prawn thaws.

Prevent the spread

• Never use prawns meant for human consumption as bait
• Buy bait from trusted sources
• Dispose of bait responsibly - in bins not waterways

Practice good biosecurity - Wash your equipment before moving to another location

Report sightings