Shellfish and seawater samples are taken every week from popular shellfish gathering sites around New Zealand and are tested for the presence of toxic algae. Photo: Supplied.

Toxic shellfish alert for Pelorus

A public health warning has been issued after a potentially life-threatening toxin was discovered in shellfish in the Pelorus Sound.

The Ministry for Primary Industries (MPI) has alerted the public after routine tests found unsafe levels of paralytic shellfish poisoning.

Staff are warning that anyone eating shellfish from Nydia Bay could be at risk.

The move comes after MPI lifted the warning from the Marlborough Sounds at the end of May.

MPI bosses said levels above the safe limit of 0.8mg/kg were found during routine testing.

Possible symptoms of the illness include numbness and tingling, difficulties breathing and swallowing and, in extreme cases respiratory failure.

The toxin can also cause headaches and diarrhoea, with inset of symptoms flaring up between 10 minutes and three hours after the infected food being eaten.

Mussels, oysters, tuatua, pipi, toheroa, cockles, scallops, catseyes, kina (sea urchin) and all other bivalve shellfish should not be eaten from the areas effected.

“Cooking 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”, the spokesperson warned.

Shellfish and seawater samples are taken every week from popular shellfish gathering sites around New Zealand and are tested for the presence of toxic algae.

Algal blooms occur when there is a rapid increase in the number of algae in water.

Blooms may show as large red or brown patches in the sea but sometimes can’t be seen.

An MPI spokesperson advised that anyone falling ill after eating shellfish from a warning zone area should seek immediate medical help.

“Call Healthline for advice on 0800 61 11 16 or seek medical attention immediately.

“You are also advised to contact your nearest public health unit and keep any leftover shellfish in case it can be tested.”.

Toxin levels will continue to be monitored.

Commercially harvested shellfish are not affected as they are subjected to regular rigorous testing.

Pest invasion threat

Biosecurity bosses are battling to contain a pest that could prove catastrophic to Marlborough’s multimillion-dollar aquaculture industry.

Marlborough District Council’s biosecurity unit were called in following the discovery of hundreds of invasive pest species.

The worst case of Mediterranean fanworm ever found in Marlborough was uncovered on a boat moored at Waikawa Marina.

While the pest species was immediately destroyed, staff now face an arduous task as more were found on the seabed.

Mediterranean fanworm will readily settle on mussel grow-out lines and may reduce mussel growth by altering water flow around the lines and competing with mussels for suspended food.

Council biosecurity manager Jono Underwood says the find poses a serious threat to both the region’s salmon and mussel industries.

“It can colonise any structure in the water and has a massive filtering factor.

“Not only will it compete for space, it will filter food before it gets to the mussels,” he says.

The sea scourge has only ever been found in Marlborough in low number.

Only a dozen had previously been discovered, says Jono.

But hundreds were found after a boat, which had been in Auckland, was taken out of the water for cleaning.

“It was right up there in density,” he says.

Initially found in Auckland in 2008, the species has been trying to make its way to other parts of New Zealand, Jono says.

“It’s a bit of a nasty one and has high reproductive rates.

“Our whole goal is to try and make sure it’s not established here in Marlborough.

“We want to make sure that more and more people know about it.

“Vessel owners and operators need to play their part, know the rules, and keep their vessels clean, especially when moving around.”

“Everyone needs to be especially vigilant moving boats from northern hubs such as Auckland and Whangarei, where the fanworm is well-established and can easily establish itself on to a vessel.

“If you’re moving something south, a lift and clean immediately prior to departure is your best chance of avoiding an unwanted passenger.”

The owner was unaware of the fouling, which was probably smaller in size when the vessel came south six months ago.

Any findings must be reported by law. Worried boaties should contact  Marlborough District Council or Ministry for Primary Industries.