A top marine biology chemist says people who risk eating toxic shellfish from Northland's west coast could "end up with more than just the poos and spews".
Tim Harwood, from the Cawthron Institute in Nelson, said people around the world die every year from paralytic shellfish poisoning (PSP), which has been found in shellfish off Northland's west coast.
Northland District Health Board posted warnings on Tuesday that people should not take or eat filter-feeding shellfish from between the Kaipara and Hokianga harbours, after routine testing by the Ministry of Primary Industries found PSP toxins above the regulatory level. New Zealand has a reputation for having many types of toxins that cause conditions like PSP, although there are few cases of people becoming seriously ill from them. But eating shellfish from affected areas is a risk people should not take, say health authorities.
Dr Harwood said PSP occurs when certain micro-algae accumulate and release toxins in shellfish that have eaten them. He said micro-algae and associated marine toxins typically occurred more often on New Zealand's west coast.
But scientists are still unsure what conditions cause some algae to become toxic and not others. About two weeks after the affected algae cells die off the shellfish will also lose the toxins and become safe to eat again.
