Warmer seas a challenge for tracking whales

NIWA megafauna expert and marine ecologist Kim Goetz led an expedition recently hoping to tag up to eight blue whales to help understand their foraging and migration patterns. The tags transmit location data via satellite.
The original plan was to locate and tag the whales in Cook Strait and off the coast of south Taranaki.

“Usually when whales are found off Taranaki, there’s a lot of upwelling going on and the waters are around 13-16°C. But we had water temperatures of 20-22°C and we are currently in a La Niña weather pattern which is not conducive to upwelling of nutrients in the Cook Strait region,” Dr Goetz said.

Upwellings occur when deep cold water rises to the surface. This water is rich in nutrients and plays an important role in the productivity of the ecosystem, which ultimately influences the movement of marine animals.

“We spent the first couple of days searching the area off Taranaki where we suspected the blue whales would be but came up empty.

While sheltering from bad weather in Westport, Dr Goetz and her team spoke to tuna fishermen who confirmed that the whales were 20 to 30 nautical miles offshore from Westport.

“The whales were feeding at depth – staying down for up to 10 minutes at a time.

“We were able to attach tracking devices to two whales which, on reflection was really good. The tracking devices, which should last for four to six months, show both whales are now heading north.

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

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