Death of Māui dolphin on Auckland beach a 'huge loss' to future of species

Monday, 7 February 2022

WWF NZ researcher Amanda Leathers explains why Hector's and Māui dolphin are on the brink of extinction. (First published May 9, 2019)

The death of a critically endangered dolphin that washed up on a West Auckland beach could have implications for the species’ survival, an expert says.

The Māui dolphin was found decomposing on Muriwai beach by a member of the public on Christmas Day, according to a recently released Department of Conservation incident report.

Because it was so badly decomposed and scavenged, neither a cause of death nor the animal’s sex could be determined.

But no matter how the creature died, WWF-New Zealand marine species programme manager Dr Krista van der Linde said it was a blow for the species, because there were “only 50-odd” left.

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Māui dolphins, swimming between Port Waikato and the entrance to the Manukau harbour.

The loss of any breeding-age females would set the breeding stock back years, she said.

About one-third of the remaining Māui dolphins were male, one-third female, and one-third juvenile, so there were only about 15 breeding-age females at any time, she said.

Because of the small population size, van der Linde said there was conjecture about whether the gene pool was even big enough to sustain a viable population.

“It’s a huge loss and every single one is critical at this stage.”

The Māui dolphin is a sub-species of the Hector's dolphin. It is the most endangered marine dolphin in the world.

The most recent death comes after a similar one in February 2021, when a female Māui dolphin was also found washed up on Muriwai.

It was in better condition and was found to have a “poor body condition which suggests an illness prior to death”, according to the report.

It also noted what appeared to be a shark bite that measured 28cm on the left side of the dolphin and 34cm on the right.

But while sharks were a possible threat, van der Linde said the biggest threats to the dolphins were boat entanglement or toxoplasmosis – a disease that comes from cat poo being washed out to sea.

Van der Linde said the more that could be learned about how far the dolphins ranged from the coast, the more could be done to help them.

Fishing with gill nets, which posed a great threat, had been banned in parts of the species’ habitat, but WWF wanted it banned throughout the Māui dolphin’s range.

The Department of Conservation has been approached for comment.