by New research into how baleen whales lower vibrational sounds is also showing the serious dangers these animals face from ocean noise pollution.
These mouth-watering animals include some of the world’s most recognizable species, including blue whales, humpbacks and bowheads, among others.
“They make sounds of very low frequencies very close to the surface,” said Coen Elemans, study author and professor of bioacoustics at the University of Southern Denmark.
“And that’s exactly where we make boating noise, in the same frequency range and also on the surface.”
Low but not deep
Compared to their toothed cousins like orcas or belugas, baleen whales use a new method to make these rumbling baritones, essentially taking their vocal organ and rotating it to vibrate against an “pad” inside, researchers say. .
“It makes Harley-Davidson sound like a child’s toy,” said Tecumseh Fitch, co-author and professor of cognitive biology at the University of Vienna.
The study, published in the journal Nature, focuses on low-frequency sounds made by these animals – around the 10 to 30 hertz range. Researchers suggest that these sounds cannot be made for long periods of time in deeper parts of the ocean. because of the physiology of whales. Further down, the air is too compressed for their vocal organs to use effectively.
“In other words, they can’t escape the surface noise created by ships, by human noise, by going down,” Fitch told CBC News from Sanibel Island, Fla.
“It would be like if you are in a very crowded bar and you need to sing to reach your friend while everyone else is making all this noise.”
Noise pollution strategies required
Beyond mating, ship noise has long been known to affect whales — both baleen and toothed — and their ability to orient themselves, find prey and avoid danger.
“These animals detect danger by hearing,” said Hussein Alidina, lead marine conservation specialist with WWF Canada. “So if that aspect is being hidden or interfered with, that puts them at risk.”
His organization recently called for the federal government’s Ocean Noise Strategy, which was supposed to come out in 2021 but has yet to be drafted, to be delayed. Alidina hopes a comprehensive strategy will coordinate what he refers to as the current “piecemeal and geographically fragmented” approach to underwater noise.
How to sing a whale
Alidina says it is important that the paper highlights the limitations of the whales’ bodies to make these sounds.
But just as researchers realized what Fitch describes as the “ugly business” of whale research: cutting out the vocal organs of dead whales.
“The whales, they’re beached. They’re dying,” Fitch said. “The whale basically starts to decompose.”
All three whales used for the study died, but it took more than speed to get the samples on ice.
“We were that lucky,” Elemans recalled of two of the samples in the study – a humpback and a sei whale. They were found nearby, with cold conditions helping to preserve the tissue from rapid decomposition.
Fitch described these operations as involving “big cranes and chainsaws” due to the size of the whales – a challenge for him and Elemans, who usually work on the vocal organs of small animals.
Their next challenge: figuring out how to recreate noise through the larynx of dead whales.
“The principle is always the same. You need to get a large volume of air. You need to attach it to the lungs,” Fitch said. “And then basically use your hands and manipulate it to do what the animal in real life would do with its muscles.”
New technology can help with ocean noise
Since 2014, the Canadian shipping industry association has been trying to educate international ships about the dangers of ocean noise pollution since 2014.
“Ocean-going ships spend a fraction of their time in Canada or in Canadian waters,” said Miako Ushio, director of environmental affairs for the Canadian Shipping Federation. “It is not necessary that there is already a high level of knowledge.”
Outside of education, the only measures currently in place, according to Ushio, are to move ships or slow down their speed to make less noise. Such measures have been used to help southern killer whales in the Salish Sea off the west coast of Canada.
Both Alidina and Ushio agree that newer technology can also help.
“Really, it’s the biggest thing that industry and governments can do to facilitate the movement towards quieter technologies and quieter ships,” said Alidina.
Ushio added that this could include quieter propellers or new hull coatings.
