Quiet Seas: How a global pandemic provided an opportunity to study whale behaviour

This year many of us have lived quieter lives, keeping each other safe by distancing during the COVID-19 pandemic.  With restrictions in travel across the globe, a phenomenon occurred during the pandemic lockdowns that is unlikely to happen again anytime soon; a quieter ocean.

Over the last few decades, it has become increasingly apparent to scientists and ocean stewards that marine noise pollution is a great threat to marine organisms³.  With new technology and an increased understanding of underwater communities, scientists have observed the harmful effects of noise pollution on marine animals, especially cetaceans such as whales and dolphins.

Having evolved in a dark underwater world where hearing is better than vision, cetaceans take advantage of the fact that water transfers sound much faster and farther than air.  All cetaceans and many other marine mammals use sound to communicate, hunt and navigate¹. This finely honed sense of hearing is critical to their survival, and a loss of hearing spells certain death. The short-term impact of very powerful noises such as sonar or underwater detonations are known to cause the death of cetaceans². However, the long-term impact of low-level noise are more difficult to figure out. Some researchers think increases in ambient noise level are making it harder for them to hunt. With fewer salmon in the sea, the noise may make it particularly hard for Southern Resident Killer Whales to get enough to eat, and could be why some of them appear to be starving.

Our underwater world is increasingly noisy due to various sources including vessel traffic and seismic exploration. Around the globe, cetaceans are affected by noise impacts, some receiving actual physical damage to their hearing and ears⁴, and other effects like stress or disruption of behaviours like hunting and migration⁵.

This is probably the most important year ever for us to be listening to these whales. We have the ability to collect something that never would have happened before.” – Janie Wray (lead researcher, BC Whales)

So why has this summer been so important? Not only has the reduction in shipping and cruise ship traffic given cetaceans a break from the heavy noise, it has allowed researchers to compare the behaviour of whales observed on our coast in a quieter versus louder environment. This year’s opportunity to listen to whales off the coast of British Columbia could not have come sooner. Some of our local populations are in decline or threatened, like the Southern Resident Killer Whales, and change is necessary to conserve and protect these species.

 A better understanding of how shipping noise affects our local species is an important part of figuring out how we can improve the ocean environment so these marine mammals can thrive. The BC Coast Hydrophone Network is a collaboration of the following organizations monitoring whale acoustics, including our neighbours on Saturna Island: the Saturna Island Marine Research & Education Society (SIMRES), North Coast Cetaceans Society, the Pacific Orca Society (OrcaLab) and BC Whales. Hydrophones are highly sensitive underwater microphones that collect acoustic data from the ocean. By having a network of hydrophones along the coast, we can compare behaviour between whale populations with different vessel traffic levels.

To learn more about the hydrophone research being done in BC, watch “It’s Time to Listen,” a short movie created by Hakai Magazine and the Pacific Orca Society.

“If we can prove that whales prefer quiet oceans, and the absence of noise, government regulators should pay attention and change the way in which they manage the oceans, and particularly shipping on the oceans” Paul Spong (Founder and Co-director of OrcaLab)

Further Reading:

ClearSeas: Underwater Noise and Marine Mammals

Georgia Strait Alliance Issue: Orcas are Drowning in Noise

References

1. Brownell Jr, R. L., Nowacek, D. P., & Ralls, K. (2008). Hunting cetaceans with sound: a worldwide review.
2. Fisheries and Oceans Canada. 2018. Recovery Strategy for the Northern and Southern Resident Killer Whales (Orcinus orca) in Canada [Proposed]. Species at Risk Act Recovery Strategy Series, Fisheries & Oceans Canada, Ottawa, x + 84 pp.
3. Hildebrand, J. A. (2009). Anthropogenic and natural sources of ambient noise in the ocean. Marine Ecology Progress Series, 395, 5-20.
4. Simmonds, M. P., Dolman, S. J., Jasny, M., Parsons, E. C. M., Weilgart, L., Wright, A. J., & Leaper, R. (2014). Marine noise pollution-increasing recognition but need for more practical action.
5. Weilgart, L. (2007). The impacts of anthropogenic ocean noise on cetaceans and implications for management. Canadian Journal of Zoology, 85(11), 1091-1116.