A shellfish toxin that has forced a ban on people taking the seafood from much of Northland's west coast could spread and take shellfish off the menu for the whole region over the busy festive holiday period.
The Northland, Auckland, Taranaki and Waikato District Health Boards (DHBs) have issued a public health warning advising the public not to collect or consume shellfish harvested from Mohakatino north to Maunganui Bluff. The warning includes the Kaipara, Manukau, Kawhia, Aotea and Raglan Harbours.
Tests on shellfish from the areas have shown high levels of Paralytic Shellfish Poisoning (PSP), well above the Ministry for Primary Industry's safe limit.
Anybody eating the toxic shellfish is potentially at risk of illness, with kina, mussels, toheroa, pipis, tuatua, oysters, cockles and scallops all off the menu as cooking shellfish does not remove the toxin. Paua, crab and crayfish may be eaten if the gut has been completely removed prior to cooking. If the gut is not removed its contents could contaminate the meat during the cooking process.
Northland DHB medical officer of health Clair Mills said the warning not to take shellfish from Northland's west coast would probably continue for at least three weeks with at least two clear samples needed before the resource could be reopened.
Dr Mills said there was no guarantee the closure wouldn't extend up the whole of the west coast or round to the east coast, before Christmas. It has already spread to parts of the Bay of Plenty on the east coast.
She said the health warning may be frustrating for some people gathering shellfish ahead of the festive season.
Dr Mill said shellfish PSP is caused by any of three different algae in New Zealand and could be particularly nasty.
"The symptoms - numbness and tingling around the mouth, face or extremities, difficulties in swallowing or breathing, dizziness, double vision - occur within 12 hours," she said.
Anyone who becomes ill after eating shellfish should contact a doctor immediately, advise their local Health Protection Unit and keep any leftover shellfish.
As well as the PSP scare, people should not eat shellfish in the Hokianga Harbour due to microcystin toxins above safe levels in shellfish.
Shellfish in the Hokianga Harbour were tested for microcystins after a bloom of toxic Cyanobacteria occurred in Lake Omapere which drains into the Hokianga Harbour.
High levels of microcystins are thought to cause liver damage in humans.
Further information is available at: www.foodsmart.govt.nz/food-safety/hunting-collecting-fishing/seafood-gatherers/.