A young Māui dolphin has been found dead on an Auckland beach.
The dolphin, which is endangered, was discovered on Wednesday by a member of the public at Karioitahi Beach on Auckland's west coast.
It was reported to the Department of Conservation (DoC), who say the dolphin was badly decomposed when it was found, making it difficult to determine how it died.
DoC marine species and threats manager Ian Angus said on Thursday a necropsy on the body will be carried out by Massey University.
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"If confirmed, it will be the third Māui dolphin death to be reported to DoC this year," said Mr Angus.
"The previous two were found to have died from natural causes."
WWF-New Zealand CEO Livia Esterhazy said many people have been working hard for a long time to turn the situation around for "these precious taonga".
"To lose another one now, when the population is so small, would be a devastating blow," she said.
"The Māui dolphin Threat Management Plan is currently under review and so the time is right to do everything in our power to remove all human threats from their habitat.
"Of course, wild animals will always die of natural causes, but removing human threats will give them the best chance to thrive again."
With less than 100 left, Māui dolphins are critically endangered and are only found on the west coast of the North Island.
"It's tragic to have another juvenile dolphin die," said Mr Angus, reflecting on the death of a pregnant Māui dolphin found in in October near Te Akau, north of Raglan.
"We are hoping an examination may help us better understand why this has happened."
The body of another Māui dolphin was discovered earlier this year at Port Waikato, and was found to be a victim of a shark attack.
DoC has urged the public to report any sightings or deaths of Māui dolphins as soon as possible.
"Every dead dolphin that can't be necropsied is a lost opportunity to understand what is threatening the dolphins," said Mr Angus.
Māui dolphins are easy to spot as they have a rounded ('Mickey Mouse') dorsal fin rather than a triangular or sickle-shaped fin like most dolphins.
Māui dolphins and Hector's dolphins are subspecies of the New Zealand dolphin Cephalorhynchus hectori.
In February, five Hector's dolphins were killed after they were trapped in a commercial set net off the Banks Peninsula.
It prompted the Government to review the use of set nets.
The Government faced backlash, however, after it signed off on a mining exploration permit in July inside a Māui dolphin sanctuary off the coast of New Plymouth.
The DoC is calling on the public to photograph and report any sightings of a Māui or Hector's dolphins to the emergency hotline 0800 DOC HOT (0800 362 468).