In brief: Looking for the blue whales

It's long been thought that blue whales only transit through New Zealand waters when migrating between the Antarctic and equatorial waters. But a ground-breaking NIWA study into their distribution patterns off the south Taranaki coast confounds this hypothesis.

NIWA's study of historical whaling data, opportunistic sightings of blue whales and seismic survey data since 1979 show that blue whales, occur more regularly and with greater densities in the South Taranaki Bight than expected.

NIWA Marine Ecologist Dr Leigh Torres linked the observed sighting patterns of blue whales with a prominent upwelling near the South Island's Farewell Spit to set out the hypothesis that blue whales are using the area as a foraging ground. The area is well known for high zooplankton biomass, including a known prey item of blue whales, as a function of the upwelling plumes that generate huge clouds of plankton that are transported into the South Taranaki Bight.

"We know they need to eat vast amounts of food to support theirenergy demands. So the south Taranaki coast could be a perfect place for them to feed.

"With just four confirmed blue whale foraging grounds in the Southern Hemisphere, these findings add considerably to human understanding of one of the world's most elusive creatures."

The new information may also prompt a rethink on how blue whales are classified in New Zealand. Currently, they're classified as a migrant under the New Zealand Threat Classification System. This means they are not given the same level of conservation protections as other whales that regularly use New Zealand coastal waters.

New Zealand Threat Classification System 

Full study and results: Evidence for an unrecognised blue whale foraging ground in New Zealand 

Research subject: Marine Mammals