- Thanks to acoustic drones, the team of bioacoustician Hervé Glotin managed to observe an impressive hunting party involving half a dozen sperm whales.
- These cetaceans, which form a matriarchal society, communicate with each other to train young people to hunt.
Hit clicks. Seabed enthusiasts know that sperm whales hunt as a team, communicating through a sort of three-tone walrus: clicks, codas and clangs. Researchers at the computer science and systems laboratory at the University of Toulon now have proof of this. Exclusively for 20 Minutes , they unveil this Thursday a video illustrating the results of their Sphyrna Odysseu mission, conducted between September and May between Toulon and Monaco. "It's a world first," says the team's scientific director, Hervé Glotin.
"We guessed that sperm whales hunted in a matriarchal group because we observed them on the surface," traces the bioacoustician, member of the computer and systems laboratory at the University of Toulon (CNRS). However, to date, beyond the first 50 meters, only observations have been made with cameras placed by suction cups on the back of the animal. "This process, used in particular by the British Marine Conservation Research , is ineffective according to Hervé Glotin:" We can better understand the underwater scene by listening to the intelligent sounds emitted by cetaceans. "
"Yes, they are there!" "
Their most beautiful "catch", carried out thanks to acoustic drones, is a hunting scene gathering half a dozen sperm whales, off Monaco. Hervé Glotin thinks he has observed elderly individuals guiding younger ones:
Either the juveniles follow the movements of their aunt or their mother, or they benefit from their observations to better see, by sound, the echoes that their prey reflect. So they hunt with them. "
Antoine Thébaud, boss of Sea Proven, the company that manufactured autonomous vessels, remembers the "hysteria" that took hold of the team that day: "From a distance, we very quickly understood the importance of this sequence! On board, it was downright "effervescence". Pauline Cottaz, who is preparing a documentary film on the mission, will long remember this January afternoon on a sea of oil. "When we see sperm whales rise to the surface, I drop a" yes, they are there ", when I intended not to speak," smiles the director.
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Blue and white dolphins | Travel companions | A whole world that I discovered since mid-September 2019 while working for the Sphyrna Odyssey mission. A unique scientific mission which aims to study the behavior of large cetaceans that hunt in the abyss (sperm whale, Risso's dolphin, Cuvier's whale, Globalephalus) and the impact of anthropophony on these animals. For this, the team of Professor Hervé Glotin of the University of Toulon, uses antennas of several hydrophones which, thanks to triangulation, allow the modeling of the trajectory of each individual. These antennas are attached to autonomous vessels, the Sphyrna 55 and 70. The goal is not to see cetaceans and approach them but to listen to them on a surface of up to 400 square kilometers and 2,000 meters deep . For more mission pictures: @seaproven #dauphin #dolphin #animals #wildlife #sphyrnaodyssey #nature #naturephotography #marinemammals #expedition #scientific #bioacoustic #deepsea #anthropophony #adventure #mediteranean
A post shared by Pauline Cottaz (@pcottaz) on Jan 17, 2020 at 1:20 am PST
We can guess that she admires the work of scientists. The bioacousticians (Paul Best, Maxence Ferrari, Hervé Glotin, Marina Oger, Marion Poupard and Sara Viera) took turns 24 hours a day to monitor the spectrograms. “The main purpose was to hear the animals, not to see them. But inevitably, when we learned that they were under the boat, we all went up on the bridge. Except Marion, who had to continue listening to the recordings, ”says Pauline Cottaz. She had never been on a ship before eight months of shipping - and confinement in 200 square meters with five co-workers.
Boats should slow to save sperm whales
The mission, which began in September, ended on May 10, the day before the deconfinement plan came into force. The last 18 days of observation have been particularly profitable for this scientific project, funded by the Prince Albert II of Monaco Foundation, Explorations de Monaco and Accobams. The reduction in maritime traffic led to a drop of 10 decibels in the bass sounds. "The communication distances between cetaceans were therefore multiplied by three or even six", appreciates Hervé Glotin.
Our file on the Mediterranean Sea
If it had been prolonged, this silence could have facilitated the reproduction of the 500 to 800 sperm whales that live off the French and Italian coasts. "Noise is one of the great disturbances on the megafauna of our seas," plague the researcher. He pleads for a reduction of 15 to 20% in the speed of ships in the Mediterranean Sea.
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