Some whale songs can give scientists valuable information about the ocean’s geography, according to a study published Thursday in the journal Science. What’s more, their songs can be used as a form of seismic testing, which uses blasts of sound to map out the ocean floor. Forms of this technology can be harmful to whales and other marine life.
If we’d only listened more closely to whales, we may have not needed to develop certain practices that hurt them.
“I’m not entirely surprised about this study,” said Michael Jasny, director of the Marine Mammal Protection Project at NRDC. “And if you’d asked me to guess which animal this study used, I’d have said fin whales. Fin whale calls have been mistaken for some years as a regular geologic groaning… It took some time before oceanographers figured out this was actually an animal.”
Jasny, who was not involved in this study, noted that scientists and some industries reliant on seismic testing have been exploring for years how to substitute natural sounds, including geologic noises and sounds from animals, for human-made ones.
Fin whales can yell pretty loud, hydrologically speaking. Their calls can reach up to 189 decibels — louder than firecrackers or gunshots and comparable to noises made by large ships, the study explains. They’re also remarkably consistent: Fin whales string together individual calls into long, low-frequency songs that can last for hours, taking short breaks only to surface for air.
This consistent noise, the study found, has valuable information stored inside it. Researchers looked at six separate songs, ranging between 2.5 and 5 hours, from individual whales captured on ocean-bottom seismometer stations off the coast of Oregon, which were initially installed to monitor seismic activity along a fault zone.
“The powerful sound waves these songs produce reverberate and refract through the layers of rock beneath the station,” the study notes. The researchers were able to use these recordings to gather information about the sediment along the floor as well as the crust beneath it. “Our study demonstrates that animal vocalisations are useful not only for studying the animals themselves but also for investigating the environment that they inhabit,” the authors write.
It’s helpful to know what’s going on on the ocean floor for a variety of different reasons. Unfortunately, scouting for oil and gas reserves along the ocean floor has become one of the most common — and most disruptive — uses of the technology. To survey the seafloor, the fossil fuel industry employs seismic guns that fire off incredibly loud blasts, disturbing marine mammals that have evolved to use sound as their primary navigator underwater.
Seismic guns “are towed behind vessels on the surface of the water,” Jasny explained. “The sounds they generate have to go down through the water column, hundreds or thousands of metres, penetrate the seafloor, penetrate layers of sediment — 14, 15 km down to what the industry is interested in — and then the sound has to come back up and be received by the vessel to transmit information that’s worth millions or billions of dollars.”
“Air guns go off roughly every 10 seconds or so for weeks or months on end. It just rips at the fabric of ocean life,” he continued. “There have been studies indicating that it could mask whale songs, particularly fin whales and humpbacks, thousands of kilometres away from the source — so a single seismic survey could interfere with fin whale breeding.”
The study is quick to note that fin whale calls probably aren’t going to replace these types of high-powered seismic surveys. Fortunately, as the price of oil plummets worldwide and scouting for new offshore reserves becomes a riskier financial bet, the industry has suffered a series of blowbacks in its drive to find more oil, including national legislation to ban the practice in certain areas and concentrated local opposition.
Still, there are other uses for seismic technology that don’t serve fossil fuels and that could be helped by new research into using natural sounds. Offshore construction work, for example, including construction of offshore wind turbines and other renewables infrastructure, needs to build on data about what’s on the ocean floor in order to properly site projects.
“In general, there’s a lot of potential in using a whole host of sounds that are geologic as well as biologic…[this is] an exciting study,” Jasny said. “It provokes you to think about the sounds that animals make as another driver of human exploration. There’s so much we don’t know about the oceans.”