How vessel noise affects killer whales

By slowing down just 3 knots, ships can reduce their noise pollution by half. Any reduction in man-made sounds in the Salish Sea can potentially help the struggling Southern resident killer whales to survive.

Marine conservationist and Oceans Initiative cofounder Rob Williams, who has a Ph.D. in biology, spoke to a room of more than 40 people at Emmanuel Parish Hall on Jan. 9 about quieting the killer whales’ habitat. The presentation was part of the SeaDoc Society and YMCA Camp Orkila’s marine lecture series.

“As ship noise increases, it’s literally – not metaphorically – it’s literally shrinking the whales’ world,” he said. “ It’s shrinking the range over which their calls are audible, which means it’s shrinking the range at which the whales can stay in contact, coordinate their movements, share their prey. So if salmon are scarce – and they are – these extraordinary families, these tight-knit social units, need all the help they can get to share information about where they’re finding fish and how to share it. And ship noise is masking the ability of the whales to share that information.”

Williams and his wife Erin Ashe, who has a Ph.D., founded Oceans Initiative, a charitable organization in both Canada and the U.S., to study marine life in the Pacific Ocean. The group is a registered nonprofit in both countries.

“We’re a team of scientists on a mission to protect marine wildlife … We work in a transboundary (international) way because the animals that we study are transboundary,” Williams said. “We were really inspired by Teddy Roosevelt’s line: ‘Do what you can, with what you’ve got, where you are’ … And I think that’s really how we approach all the science we do.”

Northern resident killer whales are 16 orca pods located off the shores of northern Vancouver Island and the mainland British Columbia coast up to southeast Alaska.

The Southern resident killer whales are comprised of three orca pods that live in the Salish Sea. The population of Southern resident killer whales dropped to 76 in late 2017.

Williams began studying Northern resident killer whales from the shores of Canada in 1995. He began observing the Southern residents in 2003.

“We try to identify their habitat, which in many ways is acoustic habitat, because sound, as you know, is as important to them as vision is to us,” he said. “We try to identify how much space they need; what else they need in their habitat – namely how much salmon they need in that habitat. And what they don’t need in their habitat, like contaminants and noise.”

In his early studies, Williams employed the use of a theodolite – a tool commonly used by surveyors – to measure the whales’ movement speed and breathing. The benefit of working from shore, Williams explained, was that he could observe how the whales reacted in the absence of a boat.

He would then introduce one or several boats, to see how the whales’ behavior changed. Whale watching companies in Johnstone Strait off the north end of Vancouver Island, where Williams worked, offered to help him with his research.

“It’s a wonderful place to work as a community and over the years we’ve learned a lot: about how whales change their behavior in the presence of boats and how they don’t always change their behavior in the presence of boats,” he said. “That now represents more than 20 years of systematically collected data on Northern resident killer whales in a variety of conditions.”

With the information gathered Williams could begin to determin how much energy a whale uses to avoid boats.

“You see that if a whale is around boats, they tend to spend more time traveling and they spend a little less time feeding,” Williams said.

Williams’ research found that Northern resident killer whales are tolerant of boats when traveling but not when feeding. He said scientists have observed about an 18 percent reduction in the time spent feeding when boats are present. More recent studies on Southern residents, he added, showed much of the same.

The problem, Williams explained, is that orcas are not consistent in their reactions to vessel traffic.

“You’d actually do better with a coin toss than with all our math because behavior is that variable,” he said. “This is real, biological variability because these are very clever predators making decisions in a very complex habitat. This is not a problem that’s going to go away with more data … this is not something that’s going to go away with a bigger sample size. This just is the real variability that we see.”

Williams’ team’s goal is to identify and seek protection for quiet pockets around Puget Sound for the whales to take shelter from the noise.

“I think we’re going to lose those areas if we don’t identify them and set them aside,” Williams said. “That’s really one of the things we’re working on as one of our main program areas: to identify these quiet areas and to keep them quiet and to identify the noisy areas and to work collaboratively to try to make them a little quieter.”

Williams said it’s just as important to preserve the areas that are currently quieter as it is to reduce noise in already busy areas.

Because orcas communicate via vocalizations and find food with echolocation, the noise caused by vessels is impacting their lives substantially, Williams explained. The vessels aren’t limited to the large ships that pass through the whales’ habitats multiple times a day – though container ships appear to have the most impact – but pertains to any outboard motor operated vessel that is running at a fast speed for an extended period of time near a pod of orcas.

“This is not animal rights; this is not an animal welfare argument. I can use solid science to estimate how much smaller is a whale’s world under noisy conditions than it would have been under quiet conditions,” Williams said. “Southern resident killer whales – on a good day – they’re losing 62 percent of their opportunities to communicate.”

Williams added that vessel traffic rises, orcas lose 96 percent of their ability to communicate.

Combined with information collected by other scientists, like the Center for Whale Research’s Ken Balcomb, there is now 40 years worth of data to draw from which their conclusions. They are able to see how the whales survived through years of Chinook abundance and scarcity.

“If you could reduce noise but do nothing about the salmon, you could get the population growing at 1 or 2 percent more, per year, than it is right now,” Williams said. “If you could somehow get us a little bit more Chinook and a little less noise – taken together – the whole is greater than the sum of its parts … This is up to us. We have some control over this decision.”

Salmon react to boat noise just as they would a predator, explained Williams.

“When we introduce noise into an acoustic predator pathway, we don’t actually know if the noise is going to mask the ability of the fish to hear the predator or the predator to hear the fish,” Williams said.

It takes years of research and data, he explained, for science to illicit policy change.

The Southern resident killer whales don’t have years to wait for studies to be done, with several proposed projects potentially adding even more vessel traffic the Salish Sea.

“We want to be asking the questions that have a chance of leading to policy action. … And that’s really important to us,” Williams said. “If you can’t protect the whole habitat, let’s preferentially protect their feeding hot spots because that’s where the food is – of course – but that’s also where they’re most vulnerable to disturbance.”

Read all of Oceans Initiative’s scientific studies at oceansinitiative.org/publications.