The introduced species is a declared pest with oyster growers and environmental groups doing all they can to limit its impact on the native Sydney rock oysters and the Wagonga inlet ecosystem.

This is small consolation to oyster grower Pat Murtagh who says his business was potentially ruined with recent hot weather slowly killing the oysters piled up next to his shed on Riverview Drive.

And as he used the traditional method of growing the oysters on sticks it was not that simple as removing the Pacific oysters and placing his stock back on racks or in baskets.

He said he had appealed the order to remove the oysters to the department all the way to former minister Ian McDonald saying rough weather and a delay in receiving the order meant he only had a few days to remove all his oysters.

"There is no way they can remove all the Pacific oysters from the estuary," he said.

"What about in the marine park and along the rock walls? Are they going to remove the rock walls?"

Fisheries officers said it was vital to tackle the Pacific oysters as they were about to spawn with each large adult potentially putting out 20 to 30 million spat or juvenile oysters.

Oyster grower David Maidment remains committed to the Pacific oyster control program being funded by the Southern Rivers Catchment Management Authority with work contracted out to the indigenous rangers from the Wagonga Local Aboriginal Lands Council.

Mr Maidment said the Pacific oysters needed to be controlled and the program was about to enter its third year with good progress made along the shoreline where the rangers "pricked" and killed all the large introduced oysters they could find.

"We can make an impact, the area we need tackle is relatively small compared to other systems," he said.

It was vital that the growers also did their part with most of the estuary's 16 or 17 growers moving toward new technology such as baskets that were easier to maintain and keep free of the Pacific or "Gigas" oysters, he said.