North Atlantic right whales are stocky, dark grey animals with distinct, mottled, bumpy white patches near the top of their heads. Their other distinguishing characteristic? They're a species on the precipice of extinction, dying faster than they can reproduce.
Scientists have identified many potential culprits for the population decline — ship collisions, vertical lines, lobster traps and gill nets, to name a few.
But what about sound pollution? How do the sounds created by ship traffic, navy sonar and seismic explosions affect different whale species?
Simone Cominelli is a PhD candidate at Memorial University, studying how noisy Newfoundland's Placentia Bay has become due to ship traffic and other human activities.
"Our primary sense is sight, but a whale experiences life through sound. It's their way of moving through the world, and the world has become much noisier over the past century," he said.
Cominelli's thesis mainly revolves around humpback whales, and he spends much of his time listening to undersea recordings.
"You can hear dolphins whistling, sperm whales using echolocation to find prey, the occasional North Atlantic right whale, and a variety of sounds made by humpback whales," he said.
The recordings demonstrate that human-made noises are a constant presence in these waters, and the impact of this exposure, Cominelli said, can have many consequences.
"Like us, whales can lose their hearing if exposed to sounds that are too loud, and in extreme cases, may never recover their full hearing capabilities. This can happen when animals are too close to active sonar, the air guns used in seismic surveys, or ships."
Cominelli is also concerned about the effect of everyday noise on whales.
"It's harder to know how constant noise exposure impacts a species over the long term, but research shows that the constant humming of ship engines in North Atlantic right whales' habitat is linked to increased stress in these animals," he said.
Fortunately, some whales have tools to protect themselves from deafening noises.
"Large whales like the blue whale or the sperm whale hear with their entire head," he said. "Their ear bones are not directly connected to their skull, and a thick layer of wax blocks their ears. These adaptations are thought to prevent whales from deafening themselves when using their powerful voices."
For whales that echolocate, like dolphins or orcas, noise from ships impacts their ability to find prey. Whales are also social animals, so temporary or permanent hearing loss can affect their ability to communicate with each other. Interruptions from human noises can take a toll too.
"Male humpback and blue whales sing convoluted songs to contact females," said Cominelli. "These songs are designed to be long-range communications that travel hundreds and hundreds of miles, but human-made noises interfere, and the reach of whale songs gets smaller and smaller. In the long term, this could affect the reproductive success of large whales."
Cominelli has been comparing the sounds of Placentia Bay with the sounds of the Flemish Pass. He began the work by operating under the assumption that Placentia Bay would be a much louder and more confusing space for marine mammals. After all, Placentia Bay is full of tankers, freight ships, and fishing boats. It's an active port, a hub of activity. The Flemish Pass is the open sea, far from land and the business of human activity.
"I found the opposite to be true," he said. "At times, the Flemish Pass has much higher noise levels. Seismic surveys cause loud blasts that can be heard from thousands of miles away. The blasts occur every few seconds, 24 hours a day, and a survey can last for weeks. Seismic noise overlaps with the sound frequencies used by whales — for a whale, each blast may reduce its chance of effectively delivering an important message to another whale."
Plenty of fish?
Is it possible for whales to experience loneliness? If their attempts at communication are constantly interrupted by human noise, can that affect their well-being or sense of community?
Cominelli says it's not unreasonable to think whales can experience trauma. He argues the consequences of a ship strike or an entanglement event can mark an individual for the rest of its life.
"Many species of whales have long lifespans," he said. "Some of the individuals we see today may have experienced more than one of these traumatic events."
"Of course, there needs to be more research done in this direction, but we know that whales are social animals with individual identities, complex sets of vocalizations, and a strong need to interact with others through sound. This need to communicate is particularly important for North Atlantic right whales, as their communication space has shrunk by more than 60 per cent compared to pre-industrial times."
Cominelli said right whales are so named because whalers found them to be the "right whales" to hunt. They were curious creatures, eager to approach vessels and investigate, making them an easy mark for harpooners. The North Atlantic right whale also had the unfortunate habit of floating after their deaths, making their bodies easy to retrieve.
Although hunting the animals in Canada has been illegal for decades, the species is more threatened than ever. There are only 340 North Atlantic right whales left, and most of them have been entangled in fishing gear or bear scars from a ship strike.
"If you think about how the consequences of an accident can affect our lives, it's not too big a leap to presume that each or most of these North Atlantic right whales carry trauma with them," said Cominelli.
Cominelli, like many who study marine mammals, doesn't work in a bubble.
"I'm not just studying a whale species," he said. "I end up observing how commerce affects humans, the role people's livelihoods play, how humans relate to other species, other mammals. On the whole, here in Newfoundland, I've found that people are fairly quick to report whale sightings and entanglements, which is good because for a species like the North Atlantic right whale, every whale counts."
Cominelli would like more investigations into how noise pollution affects marine species and more consideration for sensory pollution in general.
"Populations can decrease because of noise pollution. Sensory pollution tremendously impacts how we and other species read the world. It's something I've become more and more aware of as my research progresses."