‘Quieter ocean’ from COVID-19 could be a boon to endangered orcas, say researchers

One of B.C.’s most threatened species could be facing an unprecedented respite during the novel coronavirus pandemic.

The southern resident killer whales who spend their summers in the waters of the Salish Sea are listed as endangered with just 73 members left, and are facing a triple threat from pollution, a lack of food and marine noise caused by humans.

That third factor, however, has all but disappeared during the pandemic.

“What we are experiencing right now is actually an unprecedented opportunity of a quieter ocean,” said Prof. Richard Dewey, associate director of science with Ocean Networks Canada at the University of Victoria.

“What we are seeing right now is a significant shutdown, anywhere from 20 per cent for some deep-sea cargo vessels, all the way up to 100 per cent for some industry, tourism, cruise ships, whale watching.”

Researchers in British Columbia are now taking advantage of a network of submarine hydrophones that Dewey says is among the world’s most advanced cabled ocean observatories to listen in on that now-quiet ocean.

Lauren McWhinnie, an assistant professor of marine geography at Heriot-Watt Univesity in Edinburgh and an adjunct professor at UVic, studies the effects of human noise on marine mammals.

She says when the southern residents return to their summer feeding grounds, many of them will experience something completely new.

“Many of these whales in the southern resident community have never known a quiet Salish Sea,” she said, adding that marine noise has doubled every decade, globally, within the last 30 to 40 years.

Underwater noise is particularly damaging to the southern residents, because they rely on it to detect their prey and to communicate while stalking it.

“If we do anything to reduce their efficiency or their ability do detect prey or communicate with each other, it effects how they carry out their day-to-day life functions and it reduces their ability to hunt effectively,” McWhinney explained.

A reduction in noise will also allow hydrophones to be far more effective — allowing researchers to better detect and pinpoint the whales, as well as monitor their behaviour.

While the effects of a quieter ocean on the orca population have yet to be fully observed, both McWhinney and Dewey are optimistic.

“They will experience, I think, a quieter ocean and perhaps may be able to socialize, forage and hunt better than they have in the last few years,” said Dewey.