For B.C.’s whales, finally some quiet time
Fewer boats on the water means a big reduction in noise for these mammals
VANCOUVER— The waters off the coast of British Columbia are quiet these days. So quiet, the whales don’t have to shout to be heard over the loud hum of noise we humans make with our boats.
Due to coronavirus restrictions, yachts have been anchored at marinas, BC Ferries says trips are down by 80 per cent and whale watching businesses have closed.
It’s a rare opportunity that has scientists scrambling. For decades, they’ve asserted that a quieter ocean could help take the Salish Sea’s southern resident killer whales off the endangered species list. But they lacked enough data to quantify this theory — until now.
The Salish Sea off Canada’s West Coast is an inland sea dotted with islands that cargo ships must navigate in order to dock at the busy ports near Vancouver and Seattle. The Salish Sea is also home to the iconic orcas — and normally, it’s an incredibly noisy home.
Here, the low rumble of the ocean liners is constant. And motors from smaller vessels punctuate the soundscape as they whiz by.
Underwater, sounds travel incredibly well. Some baleen whales can call to each other from as far as tens of thousands of kilometres apart. But orcas communicate in closer quarters and at a higher register — around the same register as the sound small boats make.
“When we put that kind of noise into their environment, it can really impact the ability of these whales to effectively communicate with each other, and to detect the fish,” said Lauren McWhinnie, a marine biologist and coastal geographer who has been studying the effect of vessel noise on orcas for the past five years at the University of Victoria.
She compared it to trying to talk to a friend at a noisy pub. It’s difficult to hear because everyone is talking at about the same register, said McWhinnie, who is currently an assistant professor at Heriot-Watt University in Edinburgh, Scotland.
“We know from studies the whales have adapted over time to increase the energy in their calls, and they change the type of calls they are using,” she said. “The theory is they’re trying to talk over that background noise level.”
And how do scientists eavesdrop on the whales? With underwater microphones of course. A network of more than 50 hydrophones provide a soundscape of B.C.’s coastal waters that scientists use to analyze everything from the force of winter storms to orca conversations.
Fisheries and Oceans Canada operates about a dozen hydrophones while more are monitored by OrcaLab and other non profits. But the majority — about 25 — belong to Ocean Canada Networks, a research initiative based at the University of Victoria.
The Salish Sea is a particularly unique place, said Richard Dewey, associate director for science services at Ocean Networks Canada.
“There are few other places in the world where there is higher shipping,” he said, adding the area also has a steady stream of recreational boating in the summer.
And the resident orcas add to this noise. The fish-eating orcas are particularly chatty and spend much of their time talking with each other, said Dewey. The mammal-eating orcas, called transients, are quieter.
At times, the resident orcas’ calls and squeals — which almost sound like meows — are sometimes difficult to hear above the vessel noise.
But the human-made noises are more than just a nuisance.
Sound is for whales what sight is for humans, according to researchers. The more noise there is in the ocean, the harder it is for the orcas to use echolocation to find food and navigate.
“Making it noisy would be equivalent to us being blind,” said Dewey, adding that the orcas can adjust to their environment to a certain extent.
But research shows vessel noise impacts whales at a physiological level.
In 2012, biologists published a study that found right whales in the Bay of Fundy had lower stress levels in the aftermath of 9/11, when there was a substantial decrease in commercial shipping on the East Coast.
That same year, a paper by a group of Washington-based scientists found hungry southern resident orcas have higher levels of stress hormones when there are many boats around.
Deborah Giles, a scientist at University of Washington’s Center for Conservation Biology as well as the advocacy group Wild Orca, has studied the southern residents for more than 15 years. Her work centres around the analysis of stress and nutritional hormones in whale feces.
“In a nutshell, stress hormones were higher in times when there were high boat numbers and the whales were nutritionally stressed,” she said.
And the southern residents are always hungry.
The three pods in this distinct population — Jpod, Kpod and Lpod — traditionally spend nearly a third of the year in the Salish Sea, earning them the name “resident” killer whales.
The southern resident orcas used to spend nearly 100 days in the Salish Sea in the spring and summer, following the summer runs of Chinook salmon. Last year, they spent 20 days in the area, according to Taylor Shedd, program co-ordinator with Soundwatch, a non-profit that tracks the presence of boats near the orcas.
Researchers say a lack of prey, vessel noise and toxins in the water all threaten the critically endangered southern residents.
The demise of this particular group of whales has increased dramatically in recent years. Fewer than 30 are of breeding age, according to the Center for Whale Research, the organization responsible for conducting an annual whale census. There has also been a high percentage of miscarriages — 70 per cent, according to a 2017 paper — and several recent high-profile deaths.
These setbacks have meant the population is getting closer to the levels of the1970s, when dozens of orcas were captured for aquariums, leaving just 68 whales in the southern resident population. Eventually, it grew to 89 whales by 2006.
Today, there are 72 resident orcas left.
Scientists hope that the fragile population will have a reprieve this summer — a chance to forage and rest in the Salish Sea with fewer boats to disturb them.
And a small army of researchers are already using this unique situation to collect as much data as possible.
Between January and April this year, an offshore hydrophone station west of Vancouver Island recorded a 15 per cent — or 1.5 decibel — decrease in noise compared to the same time last year.
It’s a small but significant reduction and may hint at even larger decreases in the coming months, said David Barclay, an assistant professor of oceanography at Dalhousie University, who conducted the analysis.
Over the year, noise in that part of the ocean can change by as much as six to seven decibels, he said.
And in the busy Strait of Georgia — the body of water between Vancouver Island and the B.C. mainland — Barclay looked at the change in noise week over week, noting that not only was the ocean getting quieter, it was getting quieter at a faster rate.
“The hope is we seize this moment to make the measurements necessary to get a better understanding on what impacts we humans are having on the ocean,” said Barclay.
“We’re very good at modelling and predicting these things, but a little data can go a long way in being really convincing.”
The more noise there is in the ocean, the harder it is for the orcas to use echolocation to find food and navigate