There is a strong case for further investigating a cluster of dolphin deaths in the Auckland Region, according to a marine ecologist.
Karen Stockin, from Massey University, says it is not clear whether the deaths of eight dolphins in a three-week period are linked to the deaths of at least four dogs along the coastline.
Scientists have discovered sea slugs containing deadly tetrodotoxin, which they believed to be responsible for the deaths of the dogs.
Dr Stockin says she initially understood the Auckland Regional Council would be testing the stomach contents of the dolphins, but now it appears the testing will not go ahead.
She says the deaths are not normal and are not because of natural causes or starvation.
Auckland Regional Council was not available for comment.