A toxic algae has sparked a warning over eating shellfish gathered on Northland's west coast.
Those that eat them run the risk of poisoning due to the presence of toxins in the shellfish.
Paralytic shellfish poisoning can cause death if sick people do not get medical help quickly enough, says the Ministry of Primary Industries.
Toxins have been detected at more than double the safe limit.
The affected area stretches between Omapere on the Hokianga harbour, southwards to Pouto at the entrance to Kaipara harbour. The harbours are not included in the warning.
The ministry says cooking does not remove the toxin from the shellfish affected, which are mussels, oysters, tuatua, pipi, toheroa, cockles, scallops, catseyes, kina (sea urchin) and all other bivalve shellfish.
Another warning has been in place since last month in Bay of Plenty and Coromandel stretching from the southern end of Whangamata beach to Pukehina beach.