Impacts of underwater radiated noise may be underrated in the Juan de Fuca

We like to think that the ocean is a vast and silent world but over the past decades, human or anthropogenic underwater radiated noise (URN) generated by oil tankers, commercial shipping vessels, cruise ships and military exercises is on the rise. And now scientists are measuring its impacts on marine life.

Sound travels four times faster in water than it does through air. A recent study charting global underwater shipping noise, looking at ever-increasing traffic, warns that global shipping noise source energy emissions will double in a period of 11.5 years.

The Westshore newsletter often provides some information on the tankers and other ships that readers see anchored or moving slowly in the Strait of Juan De Fuca—off the coast of Colwood, Metchosin, Sooke and Port Renfrew. These vessels are commonly referred to as “convention vessels” and include tankers, container, bulk carrier, and general cargo ships. They look benign enough. But to Southern Resident Killer and migrating humpback whales and a host of other marine mammals that also inhabit the west shore of the Island, they represent an ongoing threat of contamination, ship strikes, and behaviour-modifying acoustic disturbance.

All night long and as we sleep, scores of giant ships make their way over to Washington, out to the Pacific en route to Asia, or travel up through the Salish Sea to Vancouver. The strait is the principal waterway by which international and regional commerce moves to and from the Washington State ports of Port Angeles, Bellingham, Everett, Seattle, Tacoma, Olympia; and the oil terminals at Anacortes and Ferndale.

The season of the highest rate of vessel traffic in the area is from May to September and yet, on a Sunday night, the Emerald Star (vehicles carrier), Glovis Star (vehicle carrier-Bahamas), Wonderful SW (cargo vessel-Panama), Lowlands Patrache (bulk carrier-Panama), Salvia Ace (vehicles carrier-Japan), Lavender (bulk carrier-Panama), Jag Maira (India), Grouse Arrow (cargo ship-Bahamas) were only a few of the huge, ocean-going vessels that moved through the dark waters through the strait in the space of a few hours.

Those who are interested can follow marine vessel traffic in the strait in real time online. A comprehensive list of vessels transiting Canadian waters and destined for Washington State ports is maintained by the BC Chamber of Shipping along with their status.

“The Strait of Juan de Fuca serves as the entrance to these US and Canadian ports and facilities and is transited by approximately 8,300 deep draft vessels annually, including arrivals and departures,” states a draft report of vessel traffic by the department of ecology in the state of Washington.

In fact, roughly three in every five tankers entering the Salish Sea through the Strait of Juan de Fuca will call at a port in the US. But it’s not just potential tanker spills that are of concern to residents like Gerry Fletcher who serves on the Board of Sea Change and Friends of Ecological Reserves. “The concern voiced by the municipal councils of Sooke and Metchosin,” says Fletcher, “is a testament to the shared sentiment among communities directly impacted by the passage of tankers through our waters.”

At a Sooke Council meeting on Oct. 18, 2023, Coun. Tony St. Pierre discussed a recommendation “that basically prevents or hopefully prevents tankers from traveling when there’s no opportunity to actually mitigate disasters.”

Council members voted in favour of supporting a July 18, 2023 letter, drafted by the District of Metchosin to George Heyman, the minister responsible for the environment and climate change strategy, demanding that he disallow tankers to travel through the Juan de Fuca Strait “when spill response teams are not permitted to respond to dangerous sea conditions and that the province should assist local governments to stockpile personal protection equipment and spill response equipment and develop shoreline and evacuation response plans.”

These concerns relate to serious one-off, potentially cataclysmic spill events. But they do not address the persistent impacts of tankers and other deep vessels on wildlife in the strait like underwater noise and ship strikes.

While you may not have heard any of them unless you’ve been snorkeling or scuba diving along the Sooke shoreline, a typical cargo vessel emits around 190 decibels of underwater noise.

Underwater sound gives marine mammals and fish the information they need to survive but underwater noise can also interfere with the way they receive and share acoustic information around social interaction, foraging, and navigation. Researchers have found that noise produced by large commercial vessels like tankers is at levels and within frequencies that warrant concern among wildlife managers regarding the ability of endangered killer whales to maintain acoustic contact.

Killer whales use echolocation to hunt and navigate. Whales and dolphins are also highly dependent on sound to communicate effectively and forage for food. Noise fog or “masking” from deep vessel propellers can scatter and interrupt the sounds they receive and emit, making doing these things difficult. And it’s not just larger mammals that suffer. Octopus and squid can suffer lethal hair-cell damage and fish and crab can experience noise stress that impacts feeding and reproductive behaviour.

Fisheries and Oceans Canada has funded a number of research projects in BC that delve into the impacts of underwater noise, mainly on orcas.

In the Gulf Islands, QENTOL, YEN / W̱SÁNEĆ Marine guardians installed hydrophones to capture whale calls and clicks, and the sounds of marine traffic. They created interim sanctuary zones for killer whales off Pender and Saturna Islands and at Swiftsure Bank (just outside of Pacific Rim National Park Reserve waters).

BC Department of Fisheries and Oceans Management measures to support Southern Resident Killer Whales only include temporary bans on recreational and commercial fishing for salmon around Port Renfrew (July 11 to Oct. 31 and around O’Brien Point between Aug.1 and Oct. 31). And while DFO specifically acknowledges acoustic and physical disturbance as a primary threat, vessel number speed or distance (400 metres) regulations under the Canada Shipping Act are limited to Campbell River and Ucluelet. None apply to the Juan de Fuca Strait.

White-sided dolphins, a common and year-round inhabitant of the Westshore, significantly alter their movement patterns in areas of high vessel traffic, altering what marine biologists call their “behavioural and energetic budgets.” This means they spend more time traveling away from vessels than resting or socializing. Humpback whales decrease the number of bottom-feeding events per dive and spend more time swimming at the surface. All of this means less food, less rest, and more stress.

There is some good news around solutions to these challenges.

The International Maritime Organization has issued guidelines to reduce noise impact from container ships, new propeller designs, re-routing and slowing down. Slowing down is a simple and effective way to reduce underwater noise. However, the guidelines are not mandatory and many shipping companies choose not to follow them. As part of its Oceans Protection Plan, the DFO is developing an Ocean Noise Strategy for Canada, which will inform what it calls “a whole-of-government approach to addressing underwater noise in our oceans.”

The question remains, should the DFO force shipping companies to comply with IMO guidelines for the sake of the health of marine life in the Strait?

Sidney Coles, Local Journalism Initiative Reporter, Capital Daily