Winter disease in farmed silver perch (Bidyanus bidyanus) in New South Wales, Australia
Non Technical Summary
'Winter Disease' is an emerging disease within the silver perch aquaculture industry. The condition can be responsible for mass mortality events in grow-out ponds. Prior to this project nothing was known about the causes of this condition or appropriate preventative and treatment strategies.
This project is just over half way to completion and has already identified the single water borne fungus involved. The association of water quality, skin and gill parasites and pond management with disease events is under continuing analysis. In particular, a single species of gill parasite has been implicated as a potential predisposing factor to outbreaks of winter disease. Experiments to examine the lifecycle of this parasite have been undertaken which will aid in the development of effective control measures.
Outbreaks occur in cool water temperatures below 16 oC. Outbreaks are often worse when there is a sudden temperature drop. Abrasion to the skin from handling has also preceded some outbreaks. Occurrence does not appear to be correlated with a range of water quality parameters, like oxygen levels.
The project has relied heavily on the active participation of industry members throughout the State to record data from their ponds and report disease events. Their efforts have greatly assisted the research work into developing a comprehensive health management strategy that will minimise losses due to disease in silver perch farms throughout Australia.