More than music
By Michael Bhardwaj

Whale music: It’s a well-flogged title often reserved for new-age soundtracks where the pops, clicks and moans of these graceful mammals are underscored with the hollow notes of a synthesizer.

Marine mammals rely on sound to communicate in the murky depths of the world's oceans. (Artist: Bob Hines, US Fish and Wildlife Service)

But underneath the whines of whale song is a legacy of scientific research probing beyond the music to find the meaning.

For many years, researchers studied songs that fall within the spectrum of human hearing, approximately 20 to 20, 000 Hertz. These songs are the now familiar though haunting lilts produced by popular whales, such as humpbacks and orcas.

But the universe of sound outside the human sensory experience had not even been imagined or considered. After all, scientists could, and often would, measure only that which they could experience.

Underwater spies

It wasn’t until the 1950s when the Cold War was in full swing that the possibility of tuning into the invisible songs of whale present itself. By then, the paranoia fueling two world powers caused them to sink enormous amounts of money into complex spy technology capable of monitoring sea, sky and earth.

Thinking a Russian submarine attack was immanent, the American Navy developed a series of underwater microphones capable of detecting low-frequency sounds below 20 Hertz. This secret net of hydrophones, called the Sound Surveillance System (SOSUS), was cast throughout the Atlantic and Pacific oceans where they could pick up the low beeps and clunks of subs and ships that would otherwise have gone unnoticed.

It wasn’t until long after the Cold War that whale researchers tapped into this antiquated spy technology. In 1993, Dr. Christopher Clark and a team of scientists from Cornell University’s Bioacoustics Research Program were granted permission by the Navy to use their vast network of underwater microphones. They wanted to use these hydrophones to listen in on the secret conversation of whales at frequencies below human hearing.

With a simple flick of a switch, the hydrophones began to pick up sounds never before heard by the scientists. In one afternoon, Clark and his colleagues approached a "Eureka!" moment when they realized they were listening to the songs of more blue whales than had ever been recorded.

Some of these were calling from a few hundred kilometres away while others were estimated to be singing from distances of 3,000 kilometres. Imagine a choir singing in Montreal’s Notre Dame Cathedral being heard by a congregation standing along the waterfront in Vancouver. That’s how far these whale songs travel.

Deep listening

Over the past decade, Clark’s team of researchers continued to work alongside the Navy, using more sophisticated hydrophone arrays to record and decipher the full spectrum of sounds from several whale species.

Stretching across the late winter and early spring of 1999 and 2000, a new team of whale researchers and sound engineers led by Clark tracked a pod of 43 fin whales through the Sea of Cortez off the west coast of Mexico. At the time, the purpose of the study was to test newly developed instruments which allowed researchers to detect these whales remotely and in real time. With these new acoustic instruments in place, they were hoping to simply locate, track and monitor individuals within the fin pod.

The research team gathered a wealth of information about the acoustic behaviour of specific whales, and correlated this information with sightings from several angles, diving patterns of distinct whales and the gender of each individual.

Because males and females look identical, the researchers also had to run a genetic test for each of the fin whales to determine gender. To get at the genes, they had to first collect a blood sample from each individual. They did this by shooting a tiny needle into the hide of each whale as it surfaced, which, when retracted had a caught a small pool of whale blood in the sliver.

Returning to the lab, a genetic analysis revealed the pod was evenly divided among the sexes; 21 males and 22 females.

Sweet serenades

When they combined this gender information with their notes on song, Clark and his team realized only the males were singing.

Realizing the long low-frequency song of the fin was actually a serenade from Romeo to Juliet shaped a new understanding of these mysterious mammals. Previously, it was widely believed that all fin whales sang, regardless of gender. From their study, however, the research team concluded the long low-frequency songs of fin males are likely used to attract females from great distances to sumptuous patches of krill. The ensuing feeding frenzy eventually turns into a predictable mating frenzy.

These results led to the understanding that song in fin whales was directly linked to the propagation of the species. Unlike their close blue whale and humpback cousins who congregate in the tropics during the breeding season, fins are primarily solitary. If a male happens to come across a wealth of food, he will begin singing in an attempt to attract females. He also attracts other males who will compete for the chance to breed.

The fin whale song is composed of a series of pulses that last anywhere from half a second to just over one second. Because of their low frequency, these songs are barely audible to humans. What one hears is more a feeling than a sound. It’s like having a moth fluttering for a moment in your ear canal.

The purpose of having such a low frequency or infrasound is that it can echo across the vast empty stretches of ocean.

“Infrasound travels even further [in water],” says Linda Weilgart, a whale researcher at Dalhousie University. "It looses very little energy as it travels so it can go much further.”

A singular sense of sound

Since they are solitary creatures, says Weilgart, fin whales evolved the ability to communicate using infrasound so they could sing to others located thousands of kilometres away. They are one among many whale species, such as blue whales, whose vocal range extends into the subsonic for the sake of signaling others.

According to Weilgart, sound is the most important sense to most, if not all whales.

“Everything that a whale does has to do with sound,” says Weilgart. “They use sound to find their prey and to escape predators. They communicate to each other by sound. They find their mates by sound. They also use sound to have contact with their young as well as to navigate through the ocean. So you name it, I think just about everything they do is based on sound.”

There are many forms of communication in the animal world used for a variety of reasons. Colour such as the bright oranges, burning reds and electric blues of many male bird species are used to attract females during the mating season. Smells secreted by many nocturnal moths form a invisible olfactory map of who’s who in darkened forests. And size, such as the many branched antlers of an alpha-buck signal a hierarchy within herds of elk.

But, because so little light penetrates the murky depths of the underwater environment and the oceans themselves are seemingly boundless, colour, smell and size are completely ineffective as forms of communication. Instead, whales must rely solely on song to sense their surroundings.

So, the next time you find yourself in a high-priced nature shop browsing through the synthesized soundtracks of the living earth, remember there is more to whale song than a slow waltz to dreamland. This is music that becomes a whale’s eyes, ears, voice and heart.