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.