The Port Stephens Fisheries Institute was originally slated to receive an extra 50 research and other staff after the closure of the state government's fisheries centre at Cronulla as partof a decentralisation strategy.

However the Examiner understands that less than 20 staff may now be coming to Port Stephens.

According to Public Service Association (PSA) assistant secretary Shane O'Brien the drop is due to staff refusal to leave Sydney.

"They've realised they won't be able to retain staff and that some things need to be kept in Sydney," he said.

"Most of the research staff are going to Mosman, which isn't exactly decentralised."

While the most recent departmental figures show around 20 staff, Mr O'Brien said that the final number would be lower.

"Some of the names that are here (in Sydney) are long-term scientists and they're just not going," he said.

Port Stephens oyster farmer Geoff Diemar said that he did not believe the downgrade would have a negative affect on Port Stephens research capabilities.

"I don't think it'll make any difference to the area," he said.

"We've got the best people in the area ... the research staff know the farmers and the farmers know them."

The Minister for Primary Industries, Katrina Hodgkinson, said she expected 80 percent of Cronulla staff would be relocated to regional centres but could not comment specifically on Port Stephens.