The price of oysters is expected to increase after the spread of a virus which caused millions of dollars of damage to the Tasmanian industry last year.

Pacific Oyster Mortality Syndrome (POMS) was first found in the state's waters 12 months ago.

It started to reappear in farms near Hobart before Christmas and this week it has been found in several other prime growing areas in the state's south.

Oyster farmer Peter Dawson said the virus had emerged at his Pipe Clay Lagoon farm near Hobart.

"We have seen mortalities, certainly on our leases limited mortalities, a number of the other farms in the lagoon have seen sign higher mortalities," he said.

Mr Dawson is trying to move his oysters out of Pipe Clay Lagoon to save them from being killed by POMS.

He lost 70 per cent of his stock in the lagoon last year, costing him $1.5 million.

The virus is harmless to humans but kills oysters in days.

"The virus attacks the gills of the oyster and in layman's terms suffocates the oyster," he said.

"The oysters are open and quite clearly distressed, they are perfectly safe for human consumption but at that stage we wouldn't send that product to market."

The virus is triggered by warm water and was not a problem in Tasmania until last year.

Other states, such as New South Wales, have lost oysters to the disease before.

Oysters Tasmania executive officer Neil Stump said testing this week showed oysters in northern Tasmania had escaped the disease, but it was a different story in the south.

Full extent not known until March

POMS has been confirmed in Pittwater, Dunalley and Pipeclay Lagoon near Hobart.

"We're just entering the summer period now, where water temperatures are warming up in growing areas around the state," Mr Stump said.

"We really won't know how widespread the disease will be until mid-March."

Mr Dawson expects the price of the shellfish will increase.

"Clearly there will be a significantly less oysters in the market. Tasmania is around about 40 per cent of total Pacific oyster production in Australia," he said.

"Tasmanian output in the next 12 months will be significantly reduced."

Mr Stump said the Tasmanian industry was trying to breed disease-resistant oysters.

"Information we have to date, although very preliminary, is that the latest family lines are POMS resistant, are showing high survivability," he said.

Primary Industries Minister Jeremy Rockliff said the resistant oysters were at least two years away.

"We're probably another two to three years away from finding disease-resistant stock for Pacific Oyster Mortality Syndrome, and the sooner we find that disease-resistant stock, the better," he said.