31 Aug 2021

Oyster parasite Bonamia ostreae not in Foveaux Strait despite warning it was

6:16 pm on 31 August 2021

A deadly oyster parasite which was reportedly found in Foveaux Strait earlier this year was never there, the Ministry for Primary Industries (MPI) says.

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NIWA scientists tested more than 2000 oysters for Bonamia ostreae Photo: RNZ / Dom Thomas

In March, the Ministry for Primary Industries reported that three oysters had tested positive for Bonamia ostreae in Foveaux Strait.

There were concerns the parasite, which can kill whole populations of oysters, would risk the entire Bluff oyster trade.

In response a rāhui was put in place to stop the spread and Biosecurity New Zealand also put a controlled area notice in place in the 30 square kilometre zone of Foveaux Strait where the three infected oysters were found.

Scientists at Niwa tested more than 2000 oysters taken from 15 sites in the strait - all which came back negative.

But now Biosecurity New Zealand said the results were wrong and Bonamia ostreae was never in the strait.

Biosecurity New Zealand director of readiness and response John Walsh said a review of the March test results found they were reported incorrectly at the time. The testing returned inconclusive results for the three oysters.

"We have now done that additional testing through Australia's national laboratory, the Australian Centre for Disease Preparedness, which returned a negative result. We are now confident there is no evidence of Bonamia ostreae in Foveaux Strait.

"However, even with the inconclusive result, because of the importance of the wild 'Bluff' oyster fishery, we would have taken the action we did at the time while looking to further test the inconclusive find we had," Walsh said.

He said while this news will come as a relief to the affected communities, the original reporting of a positive result is likely to have caused great anxiety to mana tangata that hold mana moana over this area and those involved in the wild oyster industry, oyster farmers and the local community, and we apologise for that.

"We have reviewed the situation and put corrective actions in place to ensure this cannot happen again.

"An internal audit showed there was poor communication between laboratory and operational staff at Biosecurity New Zealand that contributed to the misreporting. We have now put measures in place to prevent this occurring again."

The audit also highlighted process improvements that could be made in the surveillance and testing programme for Bonamia ostreae, which is contracted to Niwa-Biosecurity New Zealand and Niwa are now working on an end-to-end process review.

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