The Ministry for Primary Industries (MPI) has today confirmed it will be working with flat oyster farmers to urgently remove all flat oyster stocks from marine farms in Big Glory Bay on Stewart Island. This is due to the recent detection of Bonamia ostreae in 2 of the marine farms.
"Science has strongly guided our decision. The epidemiology of Bonamia ostreae, and the proximity of the 2 affected marine farms to others, means there is a strong risk of spread to those farms, and increasing the threat to the wild population. Removing all of the flat oyster stocks from the marine farms in Big Glory Bay significantly reduces this risk," says MPI Director Readiness and Response Services Geoff Gwyn.
"We acknowledge the strong feeling among locals to act quickly, however, our main consideration has been establishing the best process for the removal of the oysters. The last thing the community and industry needs is a rushed removal process that causes more harm than good.
"We're confident that the movement controls already in place have given us the time to get this next stage right. We will be working closely with the marine farmers to outline the plan for the removal of the oysters.
"While we appreciate enthusiasm from the local community and offers of help, the removal of the affected oysters without causing further spread is a very particular process and will require expert direction."
MPI will also be working with Marlborough marine farms to remove all flat oyster stocks to remove disease pressure in New Zealand.
Sampling to date has found no evidence of Bonamia ostreae in Bluff oysters in Foveaux Strait, however, MPI is continuing its sampling and surveillance.
There is no food safety issue from eating oysters with Bonamia ostreae. Fresh, good quality New Zealand oysters continue to be safe to eat.
"We have been in contact with the affected Big Glory Bay and Marlborough marine farmers. We appreciate this isn't positive news for these farmers. We would like to thank them for their input and cooperation to date," says Mr Gwyn.
If the flat oysters in the marine farms are at harvest age, they can be harvested for consumption, however, this will need to be decided by individual farmers.
Compensation under the Biosecurity Act, including the process for applying, is a matter MPI will be discussing with the affected Big Glory Bay and Marlborough farmers.
While flat oysters are farmed in Big Glory Bay and Marlborough, mussels form the bulk of the marine farming operations in those areas.
Seafood such as Greenshell mussels and Pacific (rock) oysters aren't affected by Bonamia ostreae, but they can carry and transmit it to flat oysters. However, this seafood also expels Bonamia ostreae and, once expelled, the Bonamia ostreae generally dies within 24 hours, so the risk of spread is low.
A Controlled Area Notice remains in place legally restricting movements of some shellfish species, including their spat, into and out of Nelson, Marlborough Sounds and Stewart Island. It also legally restricts movements of farm equipment and vessels associated with shellfish within and out of Stewart Island to limit further spread.