Maui's dolphins: distribution

Results of aerial research surveys

A series of aerial surveys of the critically endangered Maui's dolphin have recently been completed off the west coast of the North Island, New Zealand, between Dargaville and New Plymouth.

The survey was undertaken to estimate the abundance and determine the distribution of the local population, in particular how far offshore they are found and whether this changes seasonally.

The results have shown that in summer and winter, Maui's dolphins are concentrated close to shore. In winter dolphins appear to be evenly distributed between the shoreline and about 4 nautical miles offshore, whereas in summer more of the sightings were much closer to shore. Given the current boundaries of areas closed to fishing activity, in both seasons dolphins are still at risk from capture in fishing nets.

The research team estimated the total population at 111 Maui's dolphins. As expected, most of the sightings were made between Manukau Harbour and Raglan Harbour.

Fishing bans need to be extended
The surveys highlight that Maui's dolphins are still at risk from fishing and the current fishing restrictions are insufficient. WWF now calls on the government to look at extension of the trawl and gill net bans to sufficiently protect the dolphin from further population decline.

Non-invasive vs. invasive research
"We are pleased that the aerial offshore survey has proven to be a successful non-invasive research method to deliver data on offshore distribution of Maui's dolphins. The results also show that non-invasive research methods are ideal for determining distribution of Maui's dolphins, unlike invasive research methods such as satellite tagging," says Chris Howe, WWF-New Zealand, Conservation Director.

The surveys are jointly funded by the Department of Conservation, The Ministry of Fisheries, and WWF-New Zealand.

For more information on aerial surveys see our project overview.