<figure class="wp-block-image aligncenter size-full"><figcaption class="wp-element-caption">“We do believe that there is a food shortage facing Southern Resident Killer Whales (SRKW), we just don’t see the shortage occurring in the summer and fall,” says Dr. Andrew Trites, director of the Marine Mammal Research Unit at the University of British Columbia. His three-year study of chinook abundance in the Salish Sea suggests that endangered SRKW have more access to salmon than their northern counterparts, whose population is growing. (photo/NOAA Fisheries)</figcaption></figure><figure class="wp-block-audio"></figure>

King salmon, or chinook, are a critical part of the diet of Southern Resident Killer Whales (SRKW). The population of Southern Residents has been dangerously low for decades, at around 75 members.

Research into this problem focuses on the habitat, and especially the availability of chinook. There is a preponderance of evidence correlating, for example, low birth rates among Southern Residents to years of low abundance of chinook. There are also statistical models that point to the same conclusion: Southern Residents aren’t getting enough of what they need to thrive.

But no one has ever gone out and counted the chinook in the Southern Resident habitat – until now.

“And what we found was the opposite of what we expected, what was predicted,” said Dr. Andrew Trites, “the prevalence of chinook was double in the Southern Resident Killer Whale habitat.” 

Trites is the director of the Marine Mammal Research Unit at the University of British Columbia. He expected his research to confirm the premise that Southern Residents lacked a readily available supply of chinook – not upend it.

“I think it undermines the premises for a lot of that research,” said Trites, “and I think it undermines how quickly some people have jumped to conclusions. They’ve connected dots that should not be connected, and they’ve had huge leaps of faith in doing that.”

Trites’s study was conducted over three years (2018-2020), and was funded by Fisheries and Oceans Canada (DFO), the Canadian equivalent of the US National Marine Fisheries Service. His credibility, or the integrity of his project, isn’t in question. But in science, one study is never definitive. Misty MacDuffee is the Director of Salmon for the Raincoast Conservation Foundation, who specializes in chinook. She considers Trites’s paper a valuable contribution to understanding the availability of chinook in a particular area in summer and fall, but she doesn’t think the study solves the entire puzzle, when it’s only just a piece.

“I think the concerns start with extrapolating that (Trites’s paper) means that Southern Resident killer whales aren’t prey-limited,” she said.

Because there is no baseline study of the availability of chinook in the Salish Sea (as the waters between Washington state and Vancouver Island are known), Trites decided to compare the numbers of fish in the southern part of the Salish, with numbers in the northern part, where the killer whale population is actually growing. MacDuffee, however, believes the study misses the big picture.

“(To capture) the level of abundance that Northern Residents have access to in that time period in the Salish might be adequate for Southern Residents – but that the study wasn’t set up to answer that question,” said MacDuffee, “and so extrapolating that from what the study methods were and the study design were, is just too much of a stretch.”

MacDuffee was one of many scientists whose research supported a lawsuit brought in 2020 by the Wild Fish Conservancy, a Washington state conservation organization, against the National Marine Fisheries Service. NMFS carefully regulates certain commercial fisheries, like the Southeast Alaska chinook troll fishery, when they have an impact on endangered species.

The lawsuit nearly brought an end to chinook trolling, which has been the backbone of the Southeast Alaska economy for a century.

“Yeah, we feel vindicated,” said Matt Donohoe, former president of the Alaska Trollers Association, which filed a brief in support of NMFS. Donohoe feels Trites’s paper is confirmation of his industry’s position: the problem for Southern Residents is not in Alaska.

“The fish that don’t come up here, that are vital to killer whales,” he said, “the troll fishery was responsible for those killer whales’ decline? I mean it (the premise of the suit) was absurd on the face, even if the nutrition issues were correct.”

Donohoe believes the lawsuit was a fundraising tactic, and deflected attention from the genuine threat of marine contaminants in Puget Sound. 

Andrew Trites is aware that his work doesn’t unravel the problem of why Southern Residents seem to be at capacity, when their Northern neighbors are growing. If anything, his study suggests that more answers about the health of Southern Residents may lie outside of Puget Sound and the Salish Sea, and along their likely winter range on the Oregon and California coasts.

“Part of our message from this paper is that we want people to, yes, protect your backyard, but you need to also consider protecting the other areas that the whales use when you don’t see them,” said Trites. “And almost no research attention or management attention is being given to what they need when they’re not in the Salish Sea.”

Trites uses an analogy of a bird feeder in Alaska: If one summer you notice that you have far fewer birds returning to your feeder, he says “do you assume that there’s something wrong with your backyard?”

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