NZ's rarest dolphin nearing extinction

Maui's dolphins. Photo / Supplied

New Zealanders are being warned the country's shrinking Maui's dolphin population is "staring down the barrel of extinction" and we could end up following in China's footsteps if more is not done to protect the rare species.

Five years ago an international group of marine scientists scoured the 1669km Yangtze River in China for the waterway's highly endangered freshwater dolphin, the Baiji.

They planned to move the last living specimens of the dolphin to a haven and rebuild the population.

But not a single Yangtze River dolphin, or Baiji, was found.

It was declared extinct, and China earned the dubious honour of the first recorded disappearance of a cetacean through human influence.

The extinction of the Baiji meant the rarest dolphin in the world was now the Maui's dolphin, found only on the west coast of New Zealand's North Island.

The dolphin's coastal habitat is a contrast to the Yangtze River, which became near-opaque with industrial waste.

But despite the Maui's cleaner waters, it contends with the gillnets and trawl nets used by commercial and recreational fishers.

A report released last week says only 55 Maui's remain.

The previous survey of the dolphin in 2004 found 111 individuals, down from 1000 in the 1970s.

University of Auckland marine biologist Rochelle Constantine said: "We are staring down the barrel of extinction of this sub-species."

Asked whether the tiny surviving population meant any protection attempts would be futile, Dr Constantine said there were still reasons for optimism.

Marine mammals had recovered from this level of depletion before.

Co-researcher Scott Baker said the population had retained an equal balance of females and males, and the individuals had reasonable genetic diversity.

The dolphins stayed mostly within a region between Kaipara and Raglan, which prevented the population from fragmenting.

But their survival will depend on how free from human interference their habitat is.

The coastline from Dargaville to Taranaki has a set net ban and sanctuary status.

Conservation Minister Kate Wilkinson responded to last week's report by proposing that the ban and the marine sanctuary be extended further south than Taranaki to Hawera. A review of the sub-species has also been brought forward.

Zoologist Liz Slooten, from the University of Otago, said the the protected area did not extend far enough south, and did not include harbours, where the Maui's dolphin were known to swim. There was also no proposed protection for an important region between the North and South Islands, and a possible corridor which could connect the population of Maui's dolphins to their South Island relatives, the Hector's dolphin.

Public and stakeholders can make submissions on the Government's proposals until April 11, and a decision is due at the end of May.

This two-month window of time has conservationists nervous.

World Wildlife Fund and Forest & Bird have called on ministers to use their emergency powers to ban gillnets and trawl nets immediately.

Dr Constantine said it would be devastating - and embarrassing - for New Zealand if a natural and cultural treasure went the way of the Baiji because of failed interventions.

"This is a big question that New Zealand needs to ask itself: do we want to have Maui's dolphins?"

MAUI'S DOLPHIN

Size: Females grow to 1.7m; males are smaller.
Weight: Females up to 50kg.
Markings: Grey, white and black, with short snout and black, rounded dorsal fin.
Population: 55 "critically endangered".
Region: West Coast of North Island.
Reproduction: One calf every 2 to 4 years.
Life expectancy: 20 to 30 years.