Poison triggers new shellfish ban

By BRIDGET CARTER AND NZPA

A second warning not to eat shellfish from the Bay of Islands has been triggered by tests of a new poisonous algae bloom plaguing the area.

The alert also follows unconfirmed reports to Northland Health that a woman was sick after eating shellfish and that commercial oysters growing in the area could also be polluted.

The shellfish co-ordinator for Northland Health, Neil Silver, said the offending algae bloom was Alexandrium tamarense.

Mr Silver said the warning was issued for the coast from Cape Brett to the Waikare Inlet after tests on mussels taken off Tapeka Pt on Monday showed they contained 135 micrograms of toxin per 100 grams of flesh - 55 micrograms over the safety levels.

An April 17 ban on eating shellfish was lifted only weeks ago after dangerous levels of another type of shellfish-polluting algae bloom, Alexandrium catenella, invaded Northland's eastern coastline from Cape Brett to Houhora.

"This is a brand-new bloom and it is not the same one at all," Mr Silver said.

These two varieties of algae bloom and three others in New Zealand contained a cocktail of 22 chemicals that created paralytic shellfish poisoning toxin, Mr Silver said. People who ate shellfish with high levels of the toxin risked getting paralytic shellfish poisoning (PSP) - a potential killer without medical help.

A dizzy, numb or tingly face, inability to breath or swallow properly and double vision were all symptoms of this type of poisoning.

Mr Silver said a woman in Doubtless Bay may have been made ill by eating the shellfish, but that was yet to be confirmed.

He had been told some of the commercially grown oysters in places such as Orongo Bay and Kerikeri might contain the toxin, but he had not yet seen any test results ruling that the oysters were unsafe.

"We have recommended to industry that they are cautious about harvesting and have asked them to make sure that their sampling is on the dot," he said.

Mr Silver's main concern was that many visitors would be in the Bay of Islands for the long weekend.

"It is most unfortunate that the April warning came out on a long weekend and so has this one."

Shellfish elsewhere around the New Zealand coastline had been off-limits over the years after dangerous levels of the poisonous algae were detected.

It was difficult to tell how long the latest warning would last, because toxic blooms were affected by environmental conditions and the problems were cyclic.

A west coast ban several years ago lasted eight months, but in Northland warnings usually lasted only several weeks.

Meanwhile, Hawkes Bay health authorities have extended the area of a ban on shellfish collection because a potentially deadly toxin has spread.

The Hawkes Bay District Health Board ban now includes the coastline between Whareongaonga, 22km north of Mahia, and Paoanui Pt, 3km north of Pourere Beach in central Hawkes Bay.

Shellfish from Pania Reef, Napier, tested on Tuesday had levels of the paralytic shellfish poisoning toxin 2 1/2 times greater than the safe-health limit, the board said.

Because of those high levels, it had extended the shellfish ban. Tests of shellfish from the Porangahau region in the southern end of central Hawkes Bay have as yet shown no trace of the toxin.

The algae has caused closure of sections of the Hawkes Bay coastline during the past two winters.

Seafood safety

Not safe to eat in the Bay of Islands: Kina, mussels, toheroa, pipis, tuatua, oysters, cockles.

Safe after removal of the gut, where toxins can accumulate: Paua, crab, crayfish.

Safe to eat: Snapper, gurnard, terakihi.