Seaborne

Boaties asked to help with Māui dolphin sightings as marine survey continues

Māui are the rarest and smallest dolphins and are often spotted between Manukau Harbor and Waikato Harbour.

Delwyn Dickey / Stuff

Māui are the rarest and smallest dolphins and are often spotted between Manukau Harbor and Waikato Harbour.

Boaters enjoying the ocean off the west coast of Waikato are urged to report sightings of the Māui dolphin, as a survey to determine the population of the rare mammals continues.

Māui dolphins are among the rarest dolphins in the world and their habitat is restricted to the waters of the Tasman Sea off the west coast of the North Island.

The Department of Conservation’s marine species officer, Ian Angus, said the survey is focused on estimating the number of Māui dolphins and obtaining vital information to help guide their protection.

“The last population estimate was completed in 2016 and indicated that there were only 63 dolphins over the age of one,” Angus said.

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WWF New Zealand

A conservation group wants to use a drone near Raglan to track endangered Māui dolphins.

“This is the third abundance estimate using this method, and from this we hope to get an indication of the population trend of this taonga species.”

The abundance estimation work is done over two consecutive summers. The 2021 work is the second year of this investigation.

The work is undertaken in late summer and early fall, when dolphins are known to be in the area, allowing direct comparison between years to estimate population size.

The investigation requires the removal of a small piece of skin and blubber from free-swimming dolphins off the coast.

Māui dolphins are most commonly seen between Manukau Harbor and Waikato Harbour.

Dominico Zapata / Stuff

Māui dolphins are most commonly seen between Manukau Harbor and Waikato Harbour.

“The sample size is only 2mm in diameter and 5mm long, and from what we have observed over a long period of time, the dolphins are not harmed.

He said the dolphins generally continued to interact with the DOC boat, “behaviour that one would not expect if it caused them distress.”

The DOC personnel conducting the survey will make 10 trips, basing themselves and their vessel out of Raglan Port and Manukau Port.

Angus said this year’s investigation was not without its challenges.

“Apart from the usual weather issues, the Covid-19 lockdowns have also caused disruption. However, we are still on track to complete these important investigations as planned. »

Samples obtained as part of the abundance estimate are analyzed to identify individual dolphins through their unique DNA, whether females are pregnant, the age structure of the population, and calculate the total number of dolphins.

Māui and Hector's dolphins have a uniquely shaped dorsal fin

STEVE DAWSON/Stuff

Māui and Hector’s dolphins have a uniquely shaped dorsal fin “much like Mickey Mouse’s ear”.

Staff involved in the investigation have already seen several calves, which is an encouraging sign.

Angus said boaters and surfers can help by reporting sightings.

The Hector’s Dolphin Sighting app is specially designed to allow the public to report sightings of Hectors and Māui dolphins in real time. App users can upload photos of the dolphins they see to help identify them.

If you see a dead Māui or Hector’s dolphin on the beach, urgency is critical, Angus said.

“We can get an enormous amount of vital information from a dead animal, potentially including the cause of death and identification of any illnesses the dolphin may have had.”

The DOC and the Ministry of Primary Industries recently completed a review of the Hector and Māui’s dolphin threat management plan. As part of this review, additional management measures were implemented in late 2020 to further protect Māui’s and Hector’s dolphins.

The Māui dolphin abundance survey work comes amid Seaweek, which urges New Zealanders to enjoy responsible leisure in the marine environment, to be safe and aware on and near the sea, and to respect the ocean.