Non classé, Leg 2

The man who listens to whales…

French below

Brian Miller and his wife Elanor are on the Akademik Treshnikov to listen to the whales in the Southern Ocean. Bastien Confino (RTS) interviewed Brian, a researcher at the Australian Antarctic Division.

– Brian, we are standing on the helipad at the back of the ship as the helicopter prepares to go and drop a buoy in the water. Can you explain what’s happening?

That’s a sonar – an underwater listening device that transmits the sounds of the ocean back to the boat via a radio link. When we’re under way, we can drop them directly from the ship. But now, we’re stationary. So if we dropped the sonar from here, we’d really only hear the motor and propeller. By using the helicopter, we can drop the buoy a few miles away. At that distance we won’t hear the noise made by the boat, and we can listen to the ocean. We hope to pick up the sounds of mink whales, blue whales, fin whales and others.

– Are there a lot of whales here in the Mertz Glacier polynya?

We only picked up five whales yesterday. Most of them were outside the ice-free waters of the polynya, on the other side of the ice pack. But our system still records their calls. The ice changes the sound a little, but it still reaches our sonar. That lets us know their location in the area.

– The water here is almost -2°C. The whales don’t seem bothered.

That’s because they have a thick layer of insulating fat. But they don’t come to this area near the ice pack because it’s cold. They come because it’s full of krill, which is what they eat. That’s why they migrate here in the summer from tropical areas.

– Have you been studying whales for a long time?

I started 12 years ago, in 2005. My research focuses on the sounds given off by whales and on anthropic noise that can disturb marine mammals.

– Can you draw any conclusions about the disruptive sounds caused by humans?

Not yet. Studying whales is very difficult. They live in an environment that is completely unfamiliar to us, spending most of their time under water. We only catch sight of them when they surface, so we directly observe just a very small fraction of their behavior. Whales use sounds to communicate with each other and to search for prey. Their sense of hearing is thus critical. By listening to them, we can learn more about their underwater behavior, and this adds to what we are able to observe visually.

Brian and Eleanor Miller, whale watching. / Brian et Eleanor Miller, observant les baleines. ©Noé Sardet, Parafilms/EPFL

– What are your goals during your time with the ACE expedition?

Our aim is to record whale sounds along the expedition’s route through the subantarctic region. That’s why we’re dropping sonars into the water at regular intervals. This will enable us to map out the distribution of certain species. The ones we can hear at least. Our main focus during this expedition is the Antarctic blue whale. It’s the most interesting species to listen to, since you can hear it from hundreds and even thousands of miles away.

– How big are they?

Antarctic blue whales can be up to 32 meters long. It’s the largest animal that has ever lived on earth.

– Can you hear a lot of them?

Yes. We started detecting them when we crossed the Antarctic polar front. So far we have recorded more than 1,000 sounds made by Antarctic blue whales, although some sounds surely come from the same whale. They give off a very deep sound that is barely audible. The volume can reach 180 decibels. But volume under water is not necessarily comparable to volume in the air.