Government to help Hawkesbury oyster farmers

State government assistance will be offered to Hawkesbury oyster farmers after millions of oysters were wiped out last week following an outbreak of Pacific Oyster Mortality Syndrome.

It was confirmed earlier this week that the virus had spread to half of the area's stock, reports SMH, and many of its 15 growers are sceptical they'll have any produce remaining by the end of the year.

John Stubbs, chairman of the Broken Bay Oyster Association, told SMH, "The harvest for the end of the year has been wiped out.

"This year we had on order 10 million oysters, so basically you can wipe 50 percent off that straight away," he said.

The recent heatwave could have reduced the oysters' immunity to the virus, contributing to its  outbreak. It could also have spread naturally in ocean currents or via boat hulls or commercial ships' ballasts.