Scientist helps Cook Strait whales find a voice

Earlier this year, white humpback Migaloo was spotted in the Cook Strait (DOC Cook Strait Whale Survey)
Earlier this year, white humpback Migaloo was spotted in the Cook Strait (DOC Cook Strait Whale Survey)

The sound of whales and dolphins will be recorded for the first time in New Zealand's Cook Strait by a NIWA scientist.

More than half the world's whales and dolphins are found in New Zealand waters yet very little is known about their migration paths, their behaviour and where they go.

Marine ecologist Dr Kim Goetz is leading the project on NIWA's flagship research vessel Tangaroa. They will use six acoustic moorings, made up of a string of hydrophones anchored to the sea floor, in Cook Strait, which will record the sounds of marine mammals for the next six months.

"This research has never been done this way in New Zealand, and for me, as a biologist, it's exciting to be able to answer some of these really basic questions," Dr Goetz says.

"Cook Strait is one of the most dynamic tidal cycles on the planet and a busy area for fishing vessels and ferries," she says. "There are a few other places in the world that are this noisy that also have large numbers of marine mammals."

The moorings, four of which will be placed in deep water, and two in water less than 250m deep, will record the low frequencies of baleen whales and other migratory whales, as well as the high frequencies of the beaked whales and any dolphin or porpoise sounds.

"It will be interesting to see if this Cook Strait region acts as some sort of dividing line -- is one population of whales going through the Strait and going up the west coast while others go up the east coast?"

"We just don't know," she says.

The Cook Strait is known for its many deepwater canyons close to shore -- an underwater terrain similar to Monterey Bay, California, where researchers have found a lot of different species gathering to take advantage of a bounty of food there because of the strong currents.

"Cook Strait could be a hot spot for congregating lots of different species."

Dr Goetz is particularly interested in being able to identify the sounds of beaked whales, which New Zealand has about 13 species of. Not much is known about them, she says.

"Just to be able to hear them using this new equipment is the most exciting part for me."

The moorings will be retrieved after six months when the data will be downloaded and then put back out to sea for a further six months.