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Oyster farms closed in Mahurangi Harbour

NZ NewswireNZ Newswire 10/06/2016

Oyster farmers in Mahurangi Harbour have stopped harvesting while a biotoxin warning is in place for the Whangaparaoa region.

On Friday the Ministry for Primary Industries extended the area of a warning it issued last weekend, saying people should not collect or consume shellfish in the area northwards from Toroa Point to Takatu Point, north of Auckland.

This includes Mahurangi Harbour, where there are commercial oyster farms, Kawau Island and other islands.

The commercial oyster farms in the Mahurangi Harbour are closed.

Danny Addison, chairman of the Mahurangi Oyster Farmers group, said the industry was taking a cautionary approach and consumer safety was its priority.

"We will not start harvesting again until tests show the algae has dissipated from the shellfish growing areas," he said.

Shellfish samples in the Whangaparaoa region found PSP levels of 0.1 mg/kg, above the safe limit of 0.65 mg/kg.

The PSP toxins detected are caused by an increase in algae of the species Alexandrium, which could be related to above-average ocean temperatures and warmer weather.

Shellfish store the toxin from the algae, he said.

"This is the first time in memory that PSP levels have been an issue in this harbour. We hope that this resolves quickly," he said.

In severe cases the toxin can cause paralysis and respiratory failure but people are most likely to present with numbness and a tingling around the mouth, face, and hands and feet, MPI said when first issuing the warning.

They may have difficulty swallowing or breathing. Other symptoms include dizziness, headaches, nausea, vomiting and diarrhoea.

Further testing will be carried out by MPI on Monday.

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