If the gut is not removed its contents could contaminate the meat during the cooking process.
If anyone becomes ill after eating shellfish from an area where a public health warning has been issued, phone Healthline for advice on 0800 61 11 16 or seek medical attention immediately.
Anyone who becomes ill is also advised to contact their nearest public health unit and keep any leftover shellfish in case it can be tested.
Monitoring of toxin levels will continue and any changes will be communicated accordingly. Commercially harvested shellfish - sold in shops and supermarkets, or exported - is subject to strict water and flesh monitoring programmes by the Ministry of Primary Industries to ensure they are safe to eat.
Symptoms typically appear between 10 minutes and three hours after ingestion and may include:
•numbness and a tingling (prickly feeling) around the mouth, face, and extremities (hands and feet)
•difficulty swallowing or breathing
•dizziness
•headache
•nausea
•vomiting
•diarrhoea
•paralysis and respiratory failure and in severe cases, death.