New whale sounds recorded in Niwa-led Cook Strait study

The new clicks potentially came from a Gray's beaked whale.
DEPARTMENT OF CONSERVATION
The new clicks potentially came from a Gray's beaked whale.

A research team has discovered two new types of whale clicks, or signals, in Cook Strait.

The signals belong to the beaked whale family, but with only seven of the 22 beaked whales ever recorded, the new sounds need further study to match clicks to species. 

Niwa marine mammal expert Dr Giacomo Giorli suspected the signals belonged to the Gray's and strap-toothed beaked whales. 

A map showing the location of the three acoustic moorings.
JASCO APPLIED SCIENCES
A map showing the location of the three acoustic moorings.

"The only way that we can prove it, is to do a dedicated study out at sea. We would try to find the whale and record it, so we can match a visual identification with an acoustic identification."

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But the Niwa-led team did not have the money to carry out such a dedicated study, Giorli said.

Stock
Humpback whale vocals recorded by Niwa.

Niwa published the study earlier this year, which described the two distinct whale echolocation signals, recorded in 2016.

The signals were captured by analysing underwater acoustic data collected during two six-month deployments of six passive acoustic moorings in the Cook Strait region. 

In the first project of its kind in New Zealand waters, the moorings recorded the entire underwater sound-scape of the region, including sounds produced by marine mammals. One of the aims of the project was to learn more about the presence and distribution of whales and dolphins in the region.

Niwa marine mammal expert Dr Giacomo Giorli says there is much to learn about the deep sea mammals.
DAVE ALLEN
Niwa marine mammal expert Dr Giacomo Giorli says there is much to learn about the deep sea mammals.

Giorli said the new signals did not mean a new species of whale.

They knew the signals belonged to beaked whales because they used the same type of frequency echolocation, he said. 

"But we don't know which whale produced them."

Unidentified beaked whale detections from Cook Strait.
JASCO APPLIED SCIENCES
Unidentified beaked whale detections from Cook Strait.

There were 15 species of beaked whale whose echolocation signals were unknown. 

"We expect that they're going to be similar to other beaked whales because they're in the same family, but in reality they've never been recorded."

But funding limited the work they could do, a struggle felt by many researchers, Giorli said.

A mature male Cuvier's beaked whale stranded north of Kaikōura in 2016.
JODY WEIR
A mature male Cuvier's beaked whale stranded north of Kaikōura in 2016.

"There is pretty much nothing known about these animals but we're struggling to get some detailed work done because we don't actually have the funding to do it." 

However, they were looking into other more cost-efficient ways to analyse their data including the development of a passive acoustic monitoring system based on Artificial Intelligence, he said. 

"The problem is that we collect so much data and to analyse it takes a long time, and time costs money in research institutions. 

ANTHONY POWELL
Antarctic minke whale vocals recorded by Niwa.

"We're trying to develop a system where we can train a computer to actually identify different sounds in large data sets."

In the past, some species of beaked whales had been impacted by anthropogenic, human-generated noise, Giorli said. 

"In particular military sonar activity," he said. "It was striking to me that there is no information about the distribution of these animals in New Zealand."

Niwa scientist Dr Kim Goetz with one of the moorings before it was deployed.
DAVE ALLEN
Niwa scientist Dr Kim Goetz with one of the moorings before it was deployed.

Beaked whales used deep ocean canyons as their habitat, diving to depths of 1000 to 2000 metres to hunt for prey, he said.  

"All these canyons are around here, in the Cook Strait and on the east coast, they are potential habitats for these animals, but there's really no information out there."

"We don't know what other human activity might have an impact on them. There's a very large fishing industry in this country. There's a lot of human activity at sea. 

A rare Shepherd's beaked whale spotted from a University of Otago research boat In late June.
University of Otago
A rare Shepherd's beaked whale spotted from a University of Otago research boat In late June.

"If we want to know if there's some impact, we need to know what the baseline of the population is."

The whole ecosystem of canyons relied on the food chain, he said. 

"These animals are top predators so they really have an important role in balancing the food chain. 

Deploying the acoustic moorings.
HAMISH MCCORMICK
Deploying the acoustic moorings.

"If you remove the top predator from the food chain, you might have all those cascading affects."

The Marlborough Express