Lack of salmon may not be the problem after all for endangered orcas, report suggests
A key assumption about dwindling numbers of southern resident killer whales pins the blame on a lack of salmon, but a study out of the University of British Columbia has found they have twice the number of chinook available in summer as their much healthier cousins, the northern residents.
Researchers spent months tracking the two whale populations' preferred food in the Salish Sea and the waters of northern Vancouver Island and their findings have now been published in the peer-reviewed research journal PLOS One.
Andrew Trites, the report's co-author and the director of the marine mammal research unit at the university, said they didn't find what they expected.
"It was surprising,” Trites said of his first reaction to their discovery.
“When you find what you don't expect, then you look even harder at your data, and your first thought is, you must have done something wrong."
This month's latest census of the endangered southern residents found they number just 73, compared with the growing population of the northern residents at about 300.
Trites said they double and triple-checked the salmon numbers found during the summer of 2020.
“I guess I've learned over time that we have to be careful about jumping to quick conclusions,” he said.
The report found chinook were twice as prevalent in the southern residents' feeding areas compared to those of the northern residents.
"This implies that southern resident killer whales have greater access to chinook salmon compared to northern residents during summer — and that any food shortage southern residents may be encountering is occurring at other times of year, or elsewhere in their range," said the study published Oct. 10.
Trites said researchers collaborated with commercial and sport fishermen and whale-watching companies to identify the feeding areas from the entrance of Juan de Fuca Strait off southern Vancouver Island and the mouth of the Fraser River, up to waters off the northern end of Vancouver Island.
The widening population gap between the two groups of fish-eating whales has variously been attributed to ecological and biological differences between regions, such as salmon availability, competition, physical disturbance, underwater noise, contaminants and inbreeding.
"However, food availability likely plays the greatest role in limiting their carrying capacities," the study said of southern residents.
Trites said noise is more common in southern waters which prevents southern residents from catching prey.
“It’s a bit like going into a busy supermarket and you are shopping with somebody else, but you can’t tell each other what to get because it’s too noisy.
"It’s so hustling with so many people in it that you can’t hear each other, you can't talk about what you’re trying to get for dinner,” said Trites.
The study said vessel noise can "mask communication" between pod members and interfere with foraging and navigation — while the physical presence of vessels can also reduce foraging efforts.
"Killer whales are more likely to encounter greater numbers of vessels in the Salish Sea than in the north (Vancouver) Island waters, which could mean that salmon are less accessible to southern residents than to northern residents despite there being a higher abundance of chinook," the study said.
Trites said some may find it difficult to accept the results of the study, but it could make people rethink their assumptions.
“And I think if we really want to save southern resident killer whales, we need to think bigger and not assume that we've solved the problem because if we're wrong, we're dooming them to extinction," said Trites.
This report by The Canadian Press was first published Oct., 2024.
CTVNews.ca Top Stories
BREAKING Trump chooses anti-vaccine activist Robert F. Kennedy Jr. as health secretary
U.S. President-elect Donald Trump says he will nominate anti-vaccine activist Robert F. Kennedy Jr. to lead the Department of Health and Human Services, putting him in charge of a massive agency that oversees everything from drug, vaccine and food safety to medical research and the social safety net programs Medicare and Medicaid.
LIVE UPDATES Rogers Centre opens its doors to thousands of Taylor Swift fans for the first sold-out show
Taylor Swift is in Toronto to perform her first of six sold-out shows at the Rogers Centre tonight.
Police release bodycam video of officer-involved incident at Hindu temple protest in Brampton, Ont.
Police say an officer who forcefully removed a 'weapon' from a protester outside of a Hindu temple in Brampton was acting 'within the lawful execution of his duties' after bystander video of the incident circulated widely online.
New Pentagon report on UFOs includes hundreds of new incidents but no evidence of aliens
The Pentagon's latest report on UFOs has revealed hundreds of new reports of unidentified and unexplained aerial phenomena but no indications suggesting an extraterrestrial origin.
Here's how a potential Canada Post strike may affect Canadians
A disruption in Canada Post services would hit some Canadians harder than others. As the deadline approaches for a potential strike at midnight Friday, CTVNews.ca asked readers how it would affect them and how they are preparing.
'Countless lives were at risk:' 8 charged, including teen wanted in deadly home invasion, after West Queen West gun battle
A teenage boy arrested along with more than 20 others following a gun battle in Toronto’s West Queen West neighbourhood was wanted in connection with a deadly home invasion in Etobicoke back in April, Toronto police say.
Train derailment and spill in Longueuil leads to confinement and travel disruptions
A confinement measure with an 800-metre radius is currently in effect in part of Longueuil after a Canadian National Railway (CN) train derailed and spilt an unknown quantity of hydrogen peroxide on Thursday morning.
Jasper National Park to welcome campers back in 2025 at most campsites
Starting in January, people will be able to make online reservations for campsites for the 2025 season.
Everything is under US$20 at Amazon's newest store
Amazon is targeting retail rivals Shein, Temu and TikTok Shop with a new deeply discounted storefront that sells a wide array of products for US$20 or less.