Eavesdropping on the elusive blue whale

Mike holds the tall silver canister that houses the sonobuoy with a red float at the top.
Mike Double explains how the sonobuoys are used to find whales (Photo: Glenn Jacobson)
Three men stand smiling at the camera with a banner of a blue whale behind themBlue whale spotters aboard the Eastern Voyager January 2012Blue whaleMarine mammal acoustician, Dr Brian Miller, deploying sonobuoyBlue whaleDr Brian Miller deploying acoustic mooring

4th October 2012

Australian Antarctic scientists have successfully tested new acoustic technology to track and locate scores of blue whales hundreds of kilometres away by eavesdropping on the resonating song of these rare and elusive animals.

By using sound rather than sight to initially detect the whales, the scientists significantly improved the likelihood of finding and counting whales in the vast Southern Ocean.

The research is a core part of an Australian-led international project to estimate the abundance, distribution and behaviour of the species which was decimated in the early 1900s when industrial whaling killed approximately 250,000 animals.

To test the technology, the team of Australian Antarctic Division scientists deployed directional sonobuoys in northern Bass Strait in January and March this year.

Environment Minister Tony Burke, who was given a demonstration of the science in Hobart today, said he applauded the innovation and dedication of Australian scientists towards finding out more about this magnificent creature.

“Blue whales are under threat of extinction and improved scientific knowledge will help in the conservation and recovery of the species,” he said.

“This research reinforces Australia’s commitment to non-lethal research of whales.

“This contrasts with Japan's so-called ‘scientific whaling’ where the alleged research begins with a harpoon.

“This breakthrough project again shows you don’t have to kill a whale to study it.”

Leader of the Australian Marine Mammals Centre Dr Mike Double said that over 20 days on the voyage there were 103 sightings of blue whales over a 10,000 km2 area.

“While blue whales are the largest animals on earth, growing up to 31 metres long, they’re still very difficult to find in a vast ocean and we know very little about them,” Dr Double said.

“The real-time passive acoustic tracking system was highly effective at picking up their low frequency calls from hundreds of kilometres of away, thus maximising our chance of locating them.”

The sonobuoys allowed researchers to record more than 500 hours of audio including more than 20,000 blue whale vocalisations.

“During the voyages 32 vocalising blue whales were detected via acoustic tracking and of these 29 sightings located one or more whales. That’s a 90% success rate!” Dr Double said.

Once the whales were located they were photographed and biopsied for further identification.

A prototype moored acoustic recorder was also trialled, with the equipment deployed for three days in a fixed position.

While the results from this recorder are still being analysed, the fixed moorings could be used to listen for whale song for up to 15 months.

Mr Burke said the acoustic technology will now be used in the Antarctic Blue Whale Project, which will estimate their abundance and migration patterns, in January next year.

“The Blue Whale Project is an initiative of international Southern Ocean Research Partnership involving nine other countries,” he said.

“The Blue Whale is the largest creature in the history of our planet; no dinosaur was ever as large as a Blue Whale.

“When Australia attends the International Whaling Commission and some countries talk about so-called ‘scientific whaling’ we pursue programs like this.”

More information

[Video]

Tracking blue whales

Video transcript

Marine mammal acoustician Dr Brian Miller

Antarctic blue whales were hunted to the brink of extinction during industrial whaling. There are very few whales in a large ocean, so in order to continue to monitor the recovery of Antarctic blue whales we need to develop new ways of finding whales over larger ranges. The reason that we use acoustic tracking is that whale sounds can be heard over ranges much further than whales can be seen.

We conducted two voyages this year - a voyage in January and a voyage in March. We are looking and listening for pygmy blue whales and we are developing and testing new methods for real time acoustic tracking.

We had a total of 20 days of good weather across the two voyages and during that time we covered a 100 kilometre area along the Bonney Upwelling. There’s a strong upwelling which is an oceanographic process that brings nutrient-rich foods to the surface. There’s lots of food for whales there at that time of year and it’s a perfect place to test out new tracking methods because we know the whales are going to be there.

We used directional sonobuoys to locate the whales in real time. So the sonobuoy has a hydrophone which is deployed to a depth of either 30, 100 or 300 metres. The hydrophone transmits sound back to the ship via a VHF radio link. So we receive the sound on the ship and then we are able to process the sound in order to get direction to the whales. If we deploy more than one sonobuoy, then we can use the two bearings to the whales to triangulate their precise position, in order to photograph and take genetic samples of the whales.

We had over 100 sightings of whales and we photographed 49 different individual whales - 25 in January, 25 in March and one whale was sighted both in January and March. We were very pleased with the result. The real time tracking worked incredibly well and we are now ready to take those methods down to the Southern Ocean in order to track Antarctic blue whales.

[Video]

Launch of the Antarctic Blue Whales Project

Video transcript

Environment Minister – Tony Burke

A couple of years ago at the International Whaling Commission, Australia, and I was Australia’s Environment Minister, launched the Southern Ocean Research Partnership. It was there to make sure that we started turning the corner, not merely on conservation, but on the science that could be drawn from conservation. It was also an opportunity for the conservation nations of the world to show up in lights that if you want to conduct scientific research into whales you don’t need to harpoon them, chop them up and sell them for food. If you want to conduct scientific research on whales then you can do it through ordinary scientific methods. The flagship part of that work was to launch the first of the programs that Australia would lead under the Southern Ocean Research Partnership would be research into the Blue whale.

The blue whale wins every test that you could possibly put on whether or not a species is going to be iconic. In terms of its total numbers and the threat that it has been under it has been right to the brink. During the whaling years blue whales generally in the order of about 340,000 were slaughtered. The Antarctic blue whale in the Southern Ocean in the order of about 200,000 of them were lost during those whaling years up until the mid 80’s. It was believed that their numbers got right down to probably in the order of about 500 individual blue whales.

As an iconic species, we are talking about the largest mammal, the largest animal in the history of the planet. There was never a dinosaur as large as the blue whale. But then when there’s only 500 in a place as large as the ocean, how do you actually do the most basic scientific research like finding them, counting the numbers. The work that will begin, and you’ve got 11 nations, 10 of the other conservation nations involved in this work, over the next summer period is quite ground breaking in what’s now possible in finding and counting blue whales.

Australian Antarctic Division Chief Scientist – Dr Nick Gales

The scale of removal was immense and it is probably one of the most spectacular examples of badly managed human behavior in extracting resources. What we know now is very little. We have had since 1979, the IWC conducted about 25 years of sighting surveys around the Southern Ocean around Antarctica mainly looking for minke whales but they did encounter blue whales. The dots on that map on the left show where those blue whales were encountered, but the numbers are really small and our level of knowledge on exactly how many of them there are remains really poor. So that gives rise to the Antarctic Blue Whale Project, which is, as the Minister said, the flagship project Southern Ocean Research Partnership in the IWC.

It’s really ambitious and we couldn’t do this on our own and we couldn’t do it without the advancements we have been able to make in molecular sciences, in survey sciences with statistics with micro-processors and tagging techniques to track these animals. This project represents bringing all of these non-lethal sophisticated scientific tools together to address these questions.

Then with the help of all these other nations come up with an abundance estimate of how many whales there are, understand the genetics around how these populations around Antarctic interact and then we can start learning about how they feed, where they feed. And their vulnerabilities to changes in the Southern Ocean and their vulnerabilities to practices conducted by humans. So it’s really important work.

Head of Australian Marine Mammals Centre – Dr Mike Double

I just wanted to show you this piece of kit here. This is a sonar buoy. IT is originally developed by navy to track submarines, to locate and track submarines. This part at the bottom here is a hydrophone and then there’s up to 300 metres of cable within here and this part floats at the surface and transmits a VHF signal back to the vessel. So you deploy this, the hydrophone drops close to the bottom of the ocean and then it will listen to the whales, it will eavesdrop on the whales.

So we had to trial these before we could deploy them in the Antarctic. And we did that on two voyages in the Bonny Upwelling of Bass Strait in January and March this year. So we spent 20 days at sea and we heard some 7000 blue whale calls and we did a total of 32 active follows, where we could repeatedly put out sonar buoys and follow these whales. Of the 32 follows that we did, we actually found whales 29 times, which is over a 90% success rate. Often when you find one whale, you find other whales, so although we did 29 successful follows we actually saw 49 different whales.

So given the success of these voyages it really does stand us in good stead for the forthcoming Antarctic Blue Whale voyage.

This page was last modified on 4 October 2012.