When Silence Fell Over the Sea: Whale Stress as it Relates to Ship Noise

Series inspired by Jane Goodall: “If one wants to change attitudes, you have to reach the heart. You can reach the heart by telling stories, not by arguing with people’s intellects”

Beneath the sea’s surface, there’s a kind of quiet, but it’s not silence. It’s a softer soundscape that echoes through your whole body, gently rattling into the deepest folds of your mind like a tuning fork. A melody of faint crackles of life, pops of rising bubbles, the deep thump of swell as it releases its energy into sand. If you are in precisely the right place at the right time, you may even catch the low, rhythmic moan of a baleen whale. A song that can travel across entire ocean basins.

These giants, members of the group Mysticeti, speak in low-frequency long wavelength tones, rolling notes that can be heard hundreds of kilometers away. It’s like listening to the ocean’s deep rhythmic classical orchestra made of complex notes that click and buzz in stanzas, repeating on nature’s own metronome. However, these songs now share the same frequency range as something far less sacred. The constant drone of ship engines. What was once a vast underwater symphony has become a room clouded with static. Sound for whales is how they make sense of their world, and our ship noise is turning off the lights. To imagine the implications of this, how would you feel if your world went dark? These whales have to scream, strain and repeat to do what was once met with ease. Finding food, communicating with their young and evading predators becomes stressful.

Everyone remembers where they were on September 11th, 2001. A day of immense human tragedy that left a wake of shattered normalcy. With shockwaves sent through every corner of the world including the Bay of Fundy, Canada. Here, a team of scientists found themselves at the crux of what would become an important discovery in the North Atlantic right whales physiological response to anthropogenic (human-caused) noise.

As the world stopped, as planes were grounded, freeways emptied, and ships rested in their harbors, the ceaseless hum of our machines was finally paused.

For the first time in modern history, the hum of industrial noise faded from the sea. In those rare days of stillness the western North Atlantic right whale, part of the baleen suborder and one of the most endangered whales on Earth, finally experienced what a quiet ocean might feel like.

In those days before and after 9/11, researchers measured what the pause of industrial stimulus looked like under the surface. They recorded the background sounds of the Bay of Fundy and noticed underwater noise had dropped by about six decibels, especially in the low frequencies that overlap with whale communication. Ship traffic, usually constant, had almost vanished. The scientists also measured the whales’ stress levels. They did this by collecting floating fecal samples (often found with the help of trained detection dogs), and analyzed the samples for hormones that indicate physiological stress. What they found was when the ocean quieted, the whales’ stress hormones dropped too.

For the first time, we had measurable evidence that human noise, the hum of ships, the underwater reach of our industry, can cause chronic stress in whales. When our engines stopped, the North Atlantic right whale, was able to feel calm again. Mother whales were able to feed and nurse their calves in a peace that only their ancestors have known. Not having to shout over the low rumble of ships allowed a healing silence.

Scientists have long known that stress hormones like glucocorticoids rise in animals facing threats like predators, starvation, drought, even traffic noise in terrestrial species. A short spike in these hormones can be useful in mobilizing energy to flee danger. But when stress becomes chronic like when the noise never stops, it can weaken the immune system, disrupt reproduction, and reduce survival. For right whales, already battling ship strikes, entanglements, and dwindling food, this invisible stressor may be pushing them toward the brink.

The Bay of Fundy wasn’t unique. Across the ocean, from the Stellwagen Bank to the Gulf of Maine, shipping noise has been shown to shrink the “communication space” of right whales by over 80%. Imagine trying to comfort your child, speak, or call for help but your voice stops short. This is the soundscape we’ve created for some of our most enchanted creatures.

The events of 9/11 marked one of humanity’s darkest days. Yet in the deep quiet that followed, we are given a brief glimpse of what a quieter ocean could mean for the creatures who call it home.

As of 2024, NOAA Fisheries estimates just 372 North Atlantic right whales remain.

A number of students that fits easily within a single college classroom.

If we don’t know what swims beside us, how will we ever learn to protect it?

If we don’t know what hurts them, how can we hope to stop the harm?

And once we do know how can we advocate for its end?

Based on a true story:
Rolland, R.M. et al. (2012). Evidence that ship noise increases stress in right whales. Proceedings of the Royal Society B: Biological Sciences, 279(1737), 2363–2368. doi:10.1098/rspb.2011.2429

Written by: Kalia Chalom

Featured image by: David Trinks on Unsplash

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About the Author

Kalia Chalom is a marine biology graduate from UCSD’s Scripps Institution of Oceanography, dedicated to bridging science and storytelling.