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Listen: Elusive whales heard in pioneering underwater recording project in Cook Strait

Researchers eavesdropping on whale calls in Cook Strait believe they've detected a number of elusive species very little is known about.

The team from NIWA used underwater microphones which were deployed underwater for six months until they were retrieved in December.

NIWA marine ecologist Dr Kim Goetz, who led the programme, says more than half the world's whale and dolphin species are found in New Zealand waters, yet very little is known about their migration paths, their behaviour and where they go.

However, results from a preliminary investigation of the data revealed some exciting findings.

Among more common whale species, the acoustic devices recorded vocalisations from Antarctic blue whales, Antarctic minke whales and several different beaked whale species that are rarely seen due to their extensive diving behaviour. 

These are likely to be the first recordings of Gray's and strap-toothed beaked whales in New Zealand waters, Dr Goetz said.

The project looked at what sounds could be heard in the waters of Cook Strait, from the man-made noise from vessels and industry to natural noise such as weather events and biological contributors such as whales and dolphins.

The devices also picked up November's 7.8 earthquake centred off Kaikoura, the noise of the quake so loud it was outside the sensitivity range of the microphones.

Dr Goetz says the data so far shows Cook Strait may be segregating different whale populations, with Antarctic blues primarily heard on the east side. 

There is just nothing known about these animals - they are every elusive, deep diving animals which can spend over an hour on a single dive - NIWA marine ecologist Dr Kim Goetz

"We have also picked up Antarctic minkes - it matches the time minkes are known to go into Australian waters but they have never been acoustically recorded here before."

But it is the beaked whale sounds that Dr Goetz is most excited about.

There are 22 species of beaked whales, of which 13 can be found around New Zealand and the acoustic devices detected several beaked whale calls, including Cuviers, and possibly strapped-tooth and Gray's beaked whales.

"There is just nothing known about these animals - they are every elusive, deep diving animals which can spend over an hour on a single dive and surface for a very short time so they are not often documented," Dr Goetz said.

Cuvier's beaked whales were recorded at all mooring locations, even in Queen Charlotte Sound.

The devices also recorded the sounds made by large groups of fish communicating with each other, known as fish chorusing. These sounds play an important role in the behavioural functions of fish species.

Dr Goetz says the long term aim of her research is to assist the consent process for activities in the Cook Strait.

"Right now we don't know what's in the area and that uncertainty makes getting resource consent difficult. If we can determine what species are there and when, industry can operate in a manner that accommodates species presence, so it's a win-win in my eye."

NIWA used underwater microphones which were deployed underwater for six months. Source: 1 NEWS


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