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
Most Americans believe abortion should be legal, at least in most circumstances, but it's still a flashpoint issue in JD Vance's home state
Abortion is a flashpoint in the upcoming American election, even as polls in the U.S. show most people support reproductive freedom. Abortion rights advocates tell CTV News that when candidates take a stance on that, it could influence a decision at the polling station– especially for women on who they want elected.
'2032 is not good enough': Kelly Craft says Canada has to spend faster on defence if Trump wins
A former U.S. ambassador says Canada needs to spend more on defence, and do so faster than the federal government's currently planning to, to meet the expectations of its NATO allies.
Weekend warriors have the same risk of mild dementia as more frequent exercisers, study suggests
People who only exercise on weekends have a similar risk of developing mild dementia to those who work out more frequently, a new study has found.
She got on a plane to find the guy she fell for at Oktoberfest. ‘I’m going to go and find my ginger’
Mandy Suess was so certain the red-haired man she met at Oktoberfest was special that she got on a plane to go and find him
Clocks fall back an hour as daylight time ends for much of Canada
Clocks turned back one hour across most of Canada this morning as daylight time came to an end.
They sent ballots from Canada. Now, Americans prepare to watch the election from afar
More than 600,000 people who are eligible to vote in the U.S. election live in Canada, according to the U.S. Federal Voting Assistance Program.
Harris appears on 'Saturday Night Live' as mirror image of Maya Rudolph with election looming
U.S. Vice-President Kamala Harris made a surprise appearance on 'Saturday Night Live' in the final days before the election, playing herself as the mirror-image double of Maya Rudolph’s version of her in the show's cold open.
Alberta Premier Smith gets 91 per cent support in leadership review
Alberta Premier Danielle Smith received a dominating 91.5 per cent vote of support from her United Conservative Party members in a scheduled leadership review vote on Saturday.
'It’s a dream come true': Holt, Liberal cabinet sworn-in to office
Susan Holt, the province's first female premier, and 18 cabinet ministers took the oath of office in the chamber of the legislative assembly Saturday.