Bluff oyster scare

FISHERMEN are being asked to report any sightings of sick, dying or dead oysters after the first wild oyster to test positive for the fatal Bonamia ostreae parasite was found in Stewart Island’s Big Glory Bay.

The diseased oyster was detected through Biosecurity New Zealand’s (BNZ) surveillance programme, in which 150 oysters were taken from the bay on September 18.

The Bonamia ostreae parasite infects flat oysters, such as the Bluff oyster, causing illness and death.

Bluff Oyster management company operation manager Graeme Wright said yesterday, ‘‘from a fisheries perspective it’s a real concern’’.

‘‘It’s now what happens from here. If we go on what has happened overseas, there has been devastation when it has spread into the wild population.’’

However, because it was one oyster found in a sparsely populated area, the risk of it spreading was lessened, he said.

The fishing industry had made a huge investment in

Bonamia detection tools, including DNA testing, separate to what the ministry was doing, with sustainability at the forefront of the research.

The BNZ surveillance programme was instigated in 2017 when infected oyster farms were removed from the bay to stop the parasite from spreading to wild areas.

BNZ’s director of response John Walsh said the find was not unexpected, and did not increase the risk of the parasite spreading to infect Bluff oysters fished from Foveaux Strait.

‘‘Even with the removal of oyster farms in 2017, we have been working under the assumption that Big Glory Bay would continue to contain low levels of Bonamia ostreae.

‘‘It is a relatively enclosed body of water and wild oyster populations there are very sparse, so there is a very low risk of any infection spread.’’

BNZ was not asking fishermen to take any further action at this stage, other than to report sightings of sick, dying or dead oysters.

‘‘There are already strict rules in place to manage any risk presented by relevant commercial fishing activities.

‘‘No shellfish products can be moved to or from Stewart Island unless under a specific permit.

‘‘Commercial fishermen with a permit are then required to notify MPI (Ministry for Primary Industries) of every shellfish movement.’’

The BNZ would continue surveillance, both in Stewart Island and Foveaux Strait waters, as well as in other key areas, including Marlborough Sounds, Tasman and the Chatham Islands.

The next surveillance round would take place in February.

❛ If we go on what has happened overseas, there has been devastation when it has spread into the wild population Bluff Oyster Management Company operation manager Graeme Wright