The Maui's dolphin is one of the world's smallest, with a maximum length of 1.7 metres (5.5 feet), prompting conservationists to call it "the hobbit of the sea".
Found only in shallow waters off the North Island's west coast, it is listed as critically endangered with just 55 adults remaining amid fears it will disappear by 2030 unless urgent action is taken.
The International Whaling Commission's (IWC) scientific committee said it was extremely concerned about the dolphin's plight, adding: "The human-caused death of even one dolphin in such a small population would increase the extinction risk for this sub-species."
"Rather than seeking further scientific evidence, the priority should be given to immediate management actions that will lead to the elimination of bycatch of Maui's dolphins," it said.
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"This includes full closures of any fisheries within the range of Maui's dolphins that are known to pose a risk."
It noted that proposals for seabed mining, including seismic surveying, also represented a potential threat.
Barbara Maas, an endangered species specialist at Germany-based conservation group NABU who attended the meeting, said there could be no more stalling if New Zealand wanted to save the dolphin.
She told AFP today that the country was willing to spend tens of millions of dollars promoting itself as the home of "Middle Earth" and "clean and green" but needed to back up the marketing with action or risk tarnishing its image.
"We're looking at a species of dolphin going extinct in a country that advertises itself as 100 percent pure... It's all very well faffing around with a fictitious hobbit, but here you have the hobbit of the sea, the smallest dolphin in the world, that needs saving.