A NIWA expedition in the Cook Strait and South Taranaki coast has managed to put trackers on only two whales, due to warmer waters changing the mammal's movements.

The two-week expedition to tag blue whales in New Zealand waters for the first time almost came up empty due to warmer sea temperatures causing the animals to change their behaviour.

NIWA megafauna expert and marine ecologist Kim Goetz led the expedition hoping to tag up to eight blue whales to help understand their foraging and migration patterns.

The original plan was to locate and tag the whales in Cook Strait and off the coast of South Taranaki but when no whales were spotted, the expedition moved to the West Coast where a pod of 20 were spotted.

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An 18-metre female blue whale surfaces in the ocean of lower Northland in 2010. Photo/Ingrid Visser
An 18-metre female blue whale surfaces in the ocean of lower Northland in 2010. Photo/Ingrid Visser

"Despite it being really difficult to get near them, we were able to attach tracking devices to two whales which, on reflection was really good. We thought at first we weren't going to get any instruments deployed at all," Ms Goetz said.

The tracking devices, which should last for four to six months, show both whales are now heading north, with one bypassing the Taranaki region.

"We have no idea where these animals are heading but the tags are transmitting well and it has all been worth it," Dr Goetz said.

"This will give us novel information as it is the first movement data for this species in New Zealand waters which is very exciting."

The NIWA research expedition was also supported by OMV, University of Auckland, the Australian Antarctic Division, Western Work Boats, Oregon State University and the Pew Charitable Trust.

- NZN