Once hunted as notorious monsters of the sea, sperm whales are now considered an endangered species. One of those who wants to help protect them is Nino Pierantonio. In the Mediterranean he researches the behavior of the animals – and translates their unique songs
Squeezed between the desk and the wood-panelled wall, Nino Pierantonio listens to the sea. He squints at the monitor, listens to the sounds on his headphones and follows the audio track, which moves across the screen as a jagged green line. “At the moment I only hear the ferry, that’s this graph,” says Pierantonio and points to the monitor. In the belly of the sailing boat “Pelagos” he is waiting for another sound. Sometimes nothing happens all day. Then in the evening the measuring devices are packed up again and the boat is parked in the port of Sanremo without having achieved anything. To explain what he’s looking for, Pierantonio clicks his tongue three times, it sounds like a kind of click: he’s waiting for the sound of a singing sperm whale.
“Sperm whales are communicative animals, they make noises about eighty percent of the time,” says the researcher. The largest of all toothed whales can produce up to two hundred clicks per second, the closer it gets to its food, the more frequently it clicks. A short break means: It eats – especially squid, which it captures at great depths, but also cod, tuna, smaller sharks or larger crustaceans.
Since the beginning of the 19th century, sperm whales, which are at home in all oceans, have been hunted for their fat, meat and blubber. Particularly popular: ambergris, a substance from the intestines of whales, which was used to make perfumes, and from the head the substance spermaceti, also known as spermaceti, used for ointments, candles and cosmetics. Although commercial whaling was banned by the International Whaling Commission in 1986, sperm whales are still hunted by Japanese fishermen under the label of scientific whaling.
Once Hunted, Still Threatened: Sperm Whales are an endangered species
To date, the population has not recovered. The International Union for the Conservation of Nature (IUCN) lists the species as “vulnerable” on the endangerment scale, and in the Mediterranean since 2006 it has even been one step higher: “endangered”. Researchers estimate the population there at only around two hundred animals.
And there are other dangers: lost fishing nets floating in the sea – so-called ghost nets – in which whales can become entangled, undersea cables running along the seabed where sperm whales forage for food, collisions with ships and rising sea temperatures. Above all, however, the noise, which has been increasing for decades, disturbs the animals. The hum of more and more ships – the sound pollution along major shipping routes is estimated to be 32 times higher than it was fifty years ago -, the construction and operation of wind turbines, the beeping sonar of fisheries, military reconnaissance or the banging of sound cannons in the search for oil and gas deposits. Between 2005 and 2013, the use of the sound cannons, which can produce up to 260 decibels, increased by 20 percent to 27 percent of the surface. For comparison: A jackhammer generates about 100 decibels. All of this disturbs the whales, whose most important sense is hearing.
In 1953, the US Navy recorded a sperm whale for the first time. Sperm whales were not previously known to make sounds, Pierantonio says. The 42-year-old spends four months a year on a sailing boat in the Mediterranean and follows the click of the sperm whales. The biologist leads field research for the Italian NGO Tethys. The Tethys Research Institute was founded in 1986 and is dedicated to the research and protection of marine mammals in the Mediterranean Sea. 35 researchers are studying whales and dolphins, but also monk seals and sea turtles. Its goal is to contribute to the preservation of the marine environment by providing scientific knowledge.
Odontoceti, toothed whales, which include the sperm whale, are the most interesting cetaceans for Pierantonio. In contrast to melodically singing whales, their short, hard clicking noises fascinate him. The sounds work like a sonar, the echoes allow the whales to navigate, communicate and locate food. He wants to understand why the whales use the click, when and how they use it – so conclusions can be drawn about their age, size and behavior.
Unlike other whales, sperm whales do not use whistles for social interaction. Instead of using the larynx, they produce their sounds with their nose, right at the tip. To the right and left of the blowhole is a kind of lips through which they force air, which is how the whales send sounds out to sea. They recycle part of the energy required for this – this in turn travels in the form of a sound from the nose through the head, is thrown back by the concave bone that separates the head from the body and exits again at the front. If you measure the time it takes for the sound to traverse your head, you can precisely determine your body size. “Sperm whales are honest animals, they just can’t lie,” says Pierantonio: They can’t make themselves bigger than they are by singing, for example.
Noise pollution in the Mediterranean is becoming more and more of a problem for sperm whales
Waves rock the ship back and forth, the reflection of the sun dazzles even through the small porthole. The heat builds up below deck, beads of sweat have formed on Pierantonio’s forehead. Then, finally, there’s a sound, Pierantonio’s eyes widen. It clicks, about once a second. The noise is short, it sounds a little like the whale is using Morse code. The sperm whale gets louder, its song faster – then it falls silent: the sign that it is about to appear.
Everything is going fast on the sailboat now. Pierantonio pulls off his headphones, squeezes out of the seating area, grabs binoculars and camera and sprints onto deck. “The clicking has stopped,” he calls over the boat. His team of five prospective scientists, most of whom study biology and use the time on board for practical research, is getting ready. The crew scans the sea for a sign: a dorsal fin, a puff, a movement.
Once they saw a whole family of sperm whales, but more often you meet young bulls here. While females and their young form social groups of around twenty animals in warmer waters, males travel in small groups and, the older they get, can be found alone and even in the polar regions.
It takes a good six minutes for the whale to come to the surface from its half-hour dive at a depth of up to a thousand meters. Six minutes in which the researchers want to get as close as possible to the animal. “The whale comes up relatively straight, but it doesn’t make any noise in time. We can only guess where he shows up,” Pierantonio previously explained.
Shielding the sun with his hand, he now stands at the bow. “There!” he shouts, “30 degrees north-west!” A blown cloud, hundreds of meters away. The cloud of breath rises forward at a 45-degree angle. The skipper turns the boat and accelerates. The whale breathes again, this time the cloud is closer. Pierantonio follows them through binoculars, then motions for the skipper to slow down.
The Pelagos Sanctuary is designed to provide a safe haven for sperm whales and other animals
The boat just rocks, now the whale is so close that you think you can reach out to it. Pierantonio’s camera keeps clicking. The whale is apparently relaxed. He stays on the water surface for nine minutes; every movement is photographed, every exhalation noted. He takes a breath every twenty seconds, finally flashes his fluke and dives.
With a long net in hand, Pierantonio leans over the rail and fishes the remains left by the animal out of the water. Small black chunks end up in the net of the landing net. “The whale poo is as big as a basketball,” says Pierantonio, “but it disintegrates immediately.” The laboratory will later analyze what this sperm whale has eaten, and microplastics can also be detected in this way. Plastic is a problem for whales: While the millimeter-small particles break down into toxic components, large plastic parts are mistaken for squid or jellyfish. In 2019, a pregnant sperm whale stranded off Sardinia – 22 kilos of plastic in her stomach.
Lunch break at sea. There is pasta and salad in the shade of the awning. Since the early morning, the sailor has been cruising off the Italian-French coast on behalf of the Tethys Research Institute. It is the territory of the Pelagos Sanctuary, an 87,500 square kilometer marine reserve spanning the northern Mediterranean Sea between Monaco, northern Italy and Corsica and extending to the north coast of Sardinia. It is one of the most important feeding grounds in the Mediterranean, and the concentration of whales and dolphins is correspondingly high. Founded in 1999 at the initiative of Tethys, Greenpeace and the University of Barcelona, the protected area is now part of the United Nations Environment Program.
Before Pierantonio came to sperm whales, he oversaw a dolphin project off the west coast of Greece. “Dolphins sing at a high frequency,” says Pierantonio, whistling a few notes, “sperm whales sound similar.” Although sperm whales are very loud – 190 decibels have already been measured – they are inaudible to humans: they sing at a low frequency of the highest 24 kilohertz.
Pierantonio’s underwater ear is a nondescript gauge. The hydrophone hangs on a 200 meter long orange cable behind the boat in the sea, it converts the sound waves, which propagate faster under water than in the air, into audible signals and curves that can be read on the screen.
Below deck, Pierantonio types the dates of the whale encounter into the database. Geo and weather data, time, time the whale spent on the surface, gasps of breath, the sound recording of the animal. Linked to the photos taken by the team, you get a whale portrait with the fluke as a passport photo – it is something like a whale’s fingerprint, individual and unique. Indicators are color, bumps, injuries.
The research team has known some of the sperm whales for twenty years
Pierantonio estimates our whale to be a good twelve meters long, the head alone is four meters long. Because he is traveling alone: probably a male. How old? Hard to say. In the first ten years, both sexes are about the same size. However, while females are fully grown at the age of thirty (about twelve metres), it takes the bulls up to the age of 50 (20 metres); they can weigh up to fifty tons. Sperm whales in the Mediterranean are smaller than their counterparts in the Atlantic – why is an open question.
Tethys researchers have known some of the whales since the mid-1990s. Long-term data series help them understand the whales. For example, it has been found that Mediterranean sperm whales use a dialect that has not been detected in the Pacific. Its meaning is not yet known, says Pierantonio. Hiking routes and winter sites in the Mediterranean are also largely unexplored, and there is little money for such long-term projects. Tethys finances it largely through Citizen Science: Anyone can rent the research sailor for a week and look over Pierantonio’s shoulder.
Below deck, the researcher clicks through photos of past whale sightings – and finds our whale’s fluke in the database. This whale has been sighted before, multiple times, the first time twenty years ago. And: The light gray sperm whale is a female and is called Sabina. Pierantonio calls the news through the boat, which is now sailing west. The goal is an underwater canyon off the coast of Monaco, where the sea is particularly rich in nutrients due to its microclimate.
Pierantonio reaches for his headphones, the jagged green line wanders across the screen in front of him. He listens – very quietly another sperm whale has started clicking.
