Toxin halts harvest of oysters at 26 farms

By TONY GEE

Oyster harvesting has been stopped at 26 commercial farms in the Bay of Islands after mussels from a trigger site registered more than 10 times the safe limit for Paralytic Shellfish Poison toxin.

The Ministry of Health safe-health limit for the toxin is no more than 80 micrograms of PSP for 100 grams of shellfish flesh.

The sampling result led to the harvest closure of 22 oyster farm leases in Orongo Bay, three in upper Waikare Harbour and one in Paroa Bay.

Northland Health shellfish co-ordinator Neil Silver said yesterday that restaurants and retailers who had received oysters from farms in those areas since June 9 should return them to suppliers or call Northland Health for advice.

"It's the local restaurants or eating places we're concerned about, and people who may be holding oysters from these areas," he said.

MAF had cleared major supplies to export packhouses, but product, especially that sold locally, was being recalled from after the last clear sampling date, June 8.

Mr Silver said the affected oyster-lease owners had co-operated with authorities and adopted a responsible attitude.

They did not want to see their product responsible for an outbreak of illness.

Although the ban on harvesting so far applies only to leases in the three areas, Mr Silver said any change in wind patterns could drive the toxic algal bloom, Alexandrium catenella, up the Kerikeri Inlet.

The sample of the mussels, taken on June 16 from Tapeka Pt, near Russell, showed an increase in toxin levels to 825mg/100g of flesh - more than 10 times the regulatory safe- health limit.

Meanwhile, signs at Te Haumi, near Paihia, warning people not to collect or eat shellfish have been unlawfully removed. "This puts the health of the public at risk and we're asking whoever is removing the signs to stop doing so," Mr Silver said.

PSP toxin in shellfish is potentially fatal. Severely poisoned victims can suffer respiratory arrest and die if medical treatment is not immediately available.

Symptoms include numbness and tingling around the mouth, face or fingers, difficulty swallowing and breathing, dizziness, double vision and paralysis.

Mr Silver said anyone becoming ill after eating mussels, pipi, tuatua, oysters, cockles or kina from the Bay of Islands area should see a doctor urgently.

Cooking shellfish would not remove the toxin, he said.

Paua, crab and crayfish could be eaten if the gut was completely taken out before cooking.

Fish such as snapper and tarakihi were safe to eat.