Coast toxic algal bloom worse

An ongoing toxic shellfish warning covering the East Coast from Cape Runaway south to Blackhead Point in Hawke’s Bay remains in place.Image supplied

A two month-long safety warning about poisonous shellfish here remains in place as toxin levels continue to worsen.

New Zealand Food Safety deputy director-general Vincent Arbuckle yesterday said their  advice to not collect shellfish in affected areas remains in place.

“Our website on biotoxin alerts is updated as soon as there is a new or altered warning, and when any warning is lifted.

“The most recent test results show biotoxins have risen to eight times the safe limit in Hicks Bay Beach (the safe limit is 0.8mg/kg) and 12 times the safe limit in Tolaga Bay.

“Unfortunately, there is no ETA on when the warning will be lifted. These blooms can last several months.

“We will keep monitoring sites along the coastline and reduce the size of the warning as soon as we know the bloom has gone and the toxin levels are below the safe limit.”

The warning was put in place around Tolaga Bay in October but has since spread to include the whole of the East Coast from Cape Runaway all the way south to Blackhead Point, just north of Pōrangahau.

The issue is caused by a microscopic phytoplankton, or algae floating in the sea, called Alexandrium pacificum, which produces the dangerous paralytic shellfish toxins.

If the conditions are right, they can multiply to high levels.

“This is a natural phenomenon. We often see algal blooms in the spring and autumn as the seasons change,” Mr Arbuckle said.

“Phytoplankton are photosynthetic. Like plants, they use the sunshine to grow, and like plants, they also need nutrients to grow.

“There’s been a lot of flooding in the region, which may have introduced a lot of nutrients into the water to help these blooms thrive.

“When shellfish filter-feed they can accumulate the algae and the toxins they produce in their gut and flesh, which makes them unsafe to eat.

“Generally the higher the numbers of toxic algae in the water, the more toxic the shellfish will get.

“These toxins can cause serious illness or even be life-threatening, so people should avoid gathering and eating shellfish from the affected areas,

“This includes bivalve shellfish such as mussels, oysters, tuatua, pipi, toheroa, cockles and scallops, as well as pūpū (cat’s eyes), Cook’s turban and kina (sea urchin).

“It’s also important to know that cooking the shellfish does not remove the toxin.

“Pāua, crab and crayfish may still be eaten if the gut has been completely removed prior to cooking, as toxins accumulate in the gut.

“If the gut is not removed, its contents could contaminate the meat during the cooking process.

“Finfish are not affected by this public health warning but we advise gutting the fish and discarding the liver before cooking.”

For biotoxin updates on the New Zealand Food Safety website, go to tinyurl.com/2p8xdy8d