A ban on taking or eating shellfish remains in place in the Marlborough Sounds after testing revealed high levels of toxic algae.
The toxin can cause paralytic shellfish poisoning and symptoms include numbness and tingling around the mouth or difficulty swallowing and breathing.
Nelson-Marlborough medical officer of health Ed Kiddle says people should not eat mussels, pipi, tuatua, oysters and cockles harvested from Queen Charlotte Sound and Tory Channel.
Dr Kiddle says cooking shellfish does not remove the toxin and warns people to completely remove the gut from all seafood including paua, crab, finfish and crayfish before eating it.