Boat Noise Pollution
When we think of pollution, we often picture trash debris, chemical runoff, and oil spills. But there are other, less obvious forms of pollution. Light pollution, for example, disrupts nesting sea turtles that rely on moonlight for navigation. Today, I want to talk about another kind—noise pollution.
I spent two months in remote British Columbia studying orca acoustics. At OrcaLab , part of my job was to listen to hydrophones and record what I heard. OrcaLab monitors the ocean soundscape day and night, rain or shine. We have speakers throughout camp that remain on at all times, and we even livestream on Youtube 24/7. Our eight hydrophones cover a vast area around the lab, and while I was on shift, I carefully documented every sound I heard from the songs of humpback whales to the calls of the Northern Resident orcas. Something I did not expect to hear so much was boat noise.
A fast boat zips by and from the outside looking in, I have the power to turn down the gain so as to not blow out my eardrums or get a headache. But what about orcas and other marine mammals that are extremely acoustically sensitive? They cannot turn down the volume.
Whale-watching boats often surround orcas without shutting off their engines completely. Massive cruise ships, coming in threes, pass through Blackney Pass in front of the lab every day. Tugboats hauling entire forests of trees move slowly through the water, their deep rumble lingering for hours after they come into range.
If these boats head south, they enter Johnstone Strait which is a wide, relatively straight waterway with few obstructions. The hydrophones there can pick up sounds for miles. A slow-moving tugboat traveling through the strait can dominate our recordings all night. The range is so expansive that we are often completely overwhelmed with boat noise.
I recall listening intently over the roar of passing vessels, I cannot turn down the volume too much or I will not hear if a family of orcas come into range. It is my one job.
So what? I put up with it for a while, but I still got to hear the beautiful calls of Northern Resident orcas and the deep, resonant sounds of migrating male humpbacks. Not so bad, right?
But what about the orcas? How bad is it for them?
Odontocetes (toothed whales) rely on biosonar (also called echolocation) to navigate and hunt. They start out emitting broadband, high-intensity clicks, and the returning echoes provide information about the size, distance, and movement of objects. Once prey is detected, they switch to rapid burst buzzes as they close in for the catch. Sometimes they even participate in a ritual known to researchers as food sharing. Imagine trying to hunt in total darkness or poor visibility, relying only on sound but your surroundings are drowning in noise. If vessel noise is loud enough to mask those returning echoes, an entire family of orcas may go hungry.
A recent study by Tennessen et al. (2024) highlights how vessel noise is a global threat to marine ecosystems. As global shipping increases and ocean conditions change due to warming and acidification, the intensity of boat noise is also rising.
Environmental conditions mediate how an organism is able to meet basic survival requirements. Acquiring energy is a basic need for survival. For Odonocetes, this means successful foraging in their environment. Individuals that don’t consume enough energy may delay or even skip reproduction, and if they do reproduce, their offspring may not be viable. This could be the reason for the Southern Resident orcas’ critically endangered status.
Reducing the acoustic space available for orcas to hunt is a form of habitat destruction, just like cutting down forests. If we take a glass half full approach—trees take hundreds of years to grow, but it only takes a second to power off a noisy boat engine.
Worldwide shipping is the #1 most widespread anthropogenic (human-caused) noise stressor in marine ecosystems; this is why shopping locally can also help mitigate the habitat destruction of marine mammals—it isn’t just about reducing carbon emissions and supporting the local economy. Your choices matter. You matter. They matter.
References
Tennessen, J. B., Holt, M. M., Wright, B. M., Hanson, M. B., Emmons, C. K., Giles, D. A., Hogan, J. T., Thornton, S. J., & Deecke, V. B. (2024). Males miss and females forgo: Auditory masking from vessel noise impairs foraging efficiency and success in killer whales. Global Change Biology, 30(9), 6187–6200. https://doi.org/10.1111/gcb.17490
Resources
OrcaLab. Retrieved from https://orcalab.org
OrcaLab YouTube Livestream. Retrieved from https://www.youtube.com/watch?v=_M2WVpSzgCI
Endangered Species Coalition. Southern Resident Orcas. Retrieved from https://www.endangered.org/campaigns/southern-resident-orcas/
