What J-pod teaches us about noise

The Southern Gulf Islands have become a desirable destination for human recreation. One of the most exciting draws is the possibility of spotting orcas who share the Salish Sea with us year-round. Since 2023, Raincoast, in collaboration with Simon Fraser University and the Saturna Island Marine Research & Education Society (SIMRES), has been analyzing acoustic recordings from two underwater hydrophones to try to understand how underwater noise affects the endangered Southern Resident killer whale population. Southern Residents, like other whales, rely on sound to hunt, navigate, stay in touch with their family groups, and pass on cultural knowledge. But as the ocean gets noisier, it may become increasingly difficult for them to communicate.

Our study analyzed recordings from two sites in the Southern Gulf Islands to examine how one family of orcas, known as J pod, changes its vocal behaviour in response to underwater noise. Results showed that J pod called less often as background noise levels increased and appeared to prefer certain call types when conditions were quieter. Specifically, call rates dropped by about 2.4% for every 1dB (decibel) increase in noise, and by 21% for every 10 dB increase. 

While sound behaves differently underwater than in air, the following exercise helps show how even small increases in background noise can make it harder to communicate.  To put that into perspective, imagine you’re at home having a conversation with a friend or family member. While you’re talking, the refrigerator begins to hum.  It may cause a slight interruption, but it does not affect the conversation. This is a good example of a 1 dB increase in noise. Now imagine that someone decides that now is the best time to vacuum the kitchen floor. Suddenly, it is noticeably trickier to communicate. You may try to raise your voice over the noise, shorten the sentences and repeat certain words, or stop talking altogether. That’s what a 10 dB increase would feel like. 

Killer whales do something similar. Prior studies have demonstrated that they vocalize more loudly to communicate over the noise.  Our findings suggest they also call less, or even stop calling, when ambient noise becomes too loud. Between Pender and Saturna Island we observed noise levels ranging from 80 dB to 120 dB.   Although decibels underwater aren’t directly comparable to those in air, you can think of this range as similar to the difference between a busy street and a jet engine. You can imagine how difficult that makes having a conversation!

What’s more interesting is that J pod seemed to prefer specific call types in quieter conditions or locations. Although all call types analyzed in our study were used less with increasing noise, one stood out: the S04 call. The S04 is a short, almost grunt-like call, like blowing into a “Kazoo”. It’s an easy way to identify J pod and an easy call to remember. Congratulations, you now speak whale! This distinctive call was especially prominent around Saturna Island. 

Historically, J pod has been well known for their S01 call – an almost donkey-like “hee-yaaw” that usually dominates their call repertoire. We observed this typical calling behaviour around Pender Island, but as the orcas moved into the listening range of the Saturna Island hydrophone, the S04 became much more frequent. The reason for this shift in this location is unclear, but we can make some educated guesses.

Saturna Island was slightly quieter than Pender Island. While both locations are exposed to shipping traffic, Pender Island also lies near several ferry routes and likely sees more recreational vessels due to its central location and proximity to Swartz Bay. Perhaps the S04 is a call associated with lower energy states such as resting, or low-level socialization. Similar calls in Northern Resident orcas have been linked to resting or transitions between behavioural states. Another possibility is that the structural qualities of the S04 all make it more effective in quieter environments. The S04 is often quite short and lacks a high-pitched tone. Imagine you are at a concert: which would be easier to hear over the noise, the high-pitched scream of excitement or the lower-pitched voice beside you? We did not investigate the structural properties of the S04 further, but this could be an interesting avenue for future research.

Whatever the reason may be, these findings highlight the importance of maintaining and protecting quiet marine environments, not only for the benefit of Southern Residents, but for all the other species that share the same habitat A reduction in vocal output in response to elevated noise levels may signal broader changes in both behaviour and habitat use,  the implications of which remain poorly understood. 

It is an important reminder that when we enjoy these beautiful coastal environments, we often leave a footprint that may not be immediately obvious. Sound pollution is a real threat to marine environments. The next time you cover your ears when the ferry sounds its horn, keep in mind that orcas, and many other animals, don’t have that option. That doesn’t mean we should all stop taking ferries, but rather that we should be mindful of how our actions affect those around us. Slow down, observe quietly from a distance, or even better, enjoy a picnic and watch from shore! The best whale watching on earth can be found meters from the sea on the shores of the Gulf Islands.

As the world appears ever more centered on personal gain at the expense of others, it is important to think about and care for those around us– both on land, and in the sea. 

This study formed part of Dylan Smyth’s master’s thesis (PDF) at the Universidade do Algarve (Portugal), titled “Call type modification in Southern Resident killer whales (Orcinus orca) in response to variable ambient noise levels” which he successfully defended in November 2025.