The mysterious deaths among dogs visiting the beaches of Auckland have now been solved; they were caused by tropical pufferfish.

Tropical pufferfish contains a highly potent toxin known as tetrodotoxin. They are considered a delicacy in Japan, but will be a deadly indulgence unless prepared by an expert pufferfish chef. Even just touching a pufferfish can be lethal.

Tests done by the Cawthron Institute found tetrodotoxin in the vomit of one of the dogs that died after visiting Narrow Neck beach, and the toxin was also present in a sea slug sample taken from the same beach. How the toxin got into the sea slug remains unknown.

If members of the public find unusually large numbers of fish and other dead animals they should report these to the MAF Biosecurity New Zealand emergency pest and disease hotline 0800-809-966.