Bluff oyster fishermen are demanding that all farmed oysters in a Stewart Island bay be pulled up out of the sea as soon as possible to keep a lethal parasite at bay.
They will be urging the Minister for Primary Industries to make that call today.
Graeme Wright of the Bluff Oyster Management Company said there was "no time to delay".
He heads into the meeting with the Ministry with a near-unanimous mandate he got at a meeting of about 100 people in Bluff last night over the threat posed by the Bonamia ostreae parasite, now that it has spread to the far south.
"So the science advice is quite clear, based on overseas experience, that if you want to reduce the risk of mortality in the Foveaux fishery you need to remove all the infected oysters from the infected farm sites, you could certainly severely reduce the risk."
But he said it was not possible to tell an infected oyster from one that was alright, so all the farmed oysters in Big Glory Bay would have to go.
It could mean the end of some oyster farms. "That's potentially what it means so there's some pretty serious outcomes, yeah," said Mr Wright.
One oyster farmer on Stewart Island, who did not wish to be named, said this would accomplish nothing apart from ruining livelihoods.
He said the parasite was almost certainly already in Bluff Harbour, and that increased surveillance would soon spot it there.
He said it probably arrived some time ago, carried in with oysters from Marlborough, where the infection first broke out and has been contained since 2015.
Fishing company Sanford has a joint-venture oyster farm in Big Glory Bay. That farm is infected, as is one other, among the three or four oyster farm permit holders in the bay.
Sanford chief operating officer Greg Johansson said pulling out just the infected oysters would mean thousands would go, while removing the whole farm would cull tens of thousands of oysters.
"We'll follow any advice from MPI as to what they believe the best course of action is, because we are also ... the second largest quota owner in the wild fishery, so we have very close interests on both sides."
Protecting the wild fishery must be the absolute top priority, said Mr Johansson, who held out hope farmers may be cushioned from the blow.
"There may well be some compensation provisions within the biosecurity regulations," though the ministry had not told him yet.
The Stewart Island farmer said the ministry appeared to be scrambling. He said it sent him a warning email last Thursday but had not given him any other information, even when he asked about the rules around sending oysters to shops.
Mr Wright was less damning of the time the ministry was taking, saying it had to be sure before it alerted the industry to the parasite last week.
"It's fair to say it's a big machine and the wheels take a while to turn. I'm not defending that at all, it's not ideal."
A related strain of the parasite took a heavy toll on oysters in Foveaux Strait in the 1990s and the early 2000s.