Endangered orcas suffered calorie deficit in recent years: UBC study
A new study released by the University of British Columbia found that southern resident killer whales (SRKW) did not have enough to eat in recent years, which correlates to higher mortality and lower fertility rates.
The study tracked the critically endangered SRKWs over the past 40 years, and found that they did not get enough to eat in six of those 40 years – three of which occurred in the most recent years of the study, from 2018 to 2020.
On average, adult killer whales were about 28,716 calories short in their diet in the six years that deficits were recorded, or about 17 per cent of their average daily energy requirements, according to the study.
"With the southern resident population at such a low level, there’s a sense of urgency to this kind of research," said lead author Fanny Couture, a doctoral student at the Institute for the Oceans and Fisheries (IOF) and Ocean Wise, in a release Monday.
As of October 2021, the SRKW population numbered about 73 orcas.
CHINOOK SALMON DECLINES
The southern residents feed mostly on Chinook salmon, and when Chinook salmon populations declined, the orcas were affected, the study found.
"The years where southern residents were in an energy deficit are also years where other studies report lower population growth rate and higher mortality rates for the killer whales," said Dr. Villy Christensen, professor at IOF and co-author of the study.
Researchers are uncertain why Chinook salmon populations are declining, though there are several factors, including climate change, disease, and predation by other animals.
Commercial fishing also plays a role, though researchers say Chinook salmon harvesting was reduced in Canada in the late 1990s, and that salmon declines have continued over the past two decades.
"Those declines have continued despite severe fisheries reductions, and one very likely candidate for causing them is the massive increase in abundance of Steller sea lions since the mid-1980s; those sea lions now consume more fish than all the B.C. commercial fisheries for all species, combined," said Dr. Carl Walters, senior author of the study and retired professor at IOF.
MORE FISHING RESTRICTIONS MAY BE NEEDED
Researchers found that when Chinook salmon populations were particularly low, southern resident killer whales would feed on other types of salmon, such as chum. However, their energy deficits would still occur.
Study co-authors say more restrictions on Chinook salmon fishing may still be required to protect both the fish and the orcas, as well as further research into underwater noise pollution.
"Both killer whales and Chinook salmon, the southern resident’s main prey, are important, iconic species for the west coast of Canada," said Couture
"Studying what is happening to the population may help offer solutions, both for the southern residents and potentially other killer whale populations in the future."
CTVNews.ca Top Stories
Bodies found by U.S. authorities searching for missing B.C. kayakers
United States authorities who have been searching for a pair of missing kayakers from British Columbia since the weekend have recovered two bodies in the nearby San Juan Islands of Washington state.
'It's discriminatory': Individuals refused entry to Ontario legislature for wearing keffiyeh
Individuals being barred from entering Ontario’s legislature while wearing a keffiyeh say the garment is part of their cultural identity— and the only ones making it political are the politicians banning it.
Tom Mulcair: Park littered with trash after 'pilot project' is perfect symbol of Trudeau governance
Former NDP leader Tom Mulcair says that what's happening now in a trash-littered federal park in Quebec is a perfect metaphor for how the Trudeau government runs things.
Saskatchewan households will continue to receive carbon tax rebate: Trudeau
Households in Saskatchewan will continue to receive Canada Carbon Rebate payments, despite the province refusing to remit natural gas levies to the federal government, Prime Minister Justin Trudeau said Tuesday.
'It's just so hard to let it go': Umar Zameer filled with relief and grief following acquittal in death of Toronto police officer
'We hoped for this day, but we were scared that it would not never ever come because it took so long.' That’s what Umar Zameer, the man recently acquitted in the death of a Toronto police officer, told CTV News Toronto in a sit-down interview on Tuesday.
Senate expenses climbed to $7.2 million in 2023, up nearly 30%
Senators in Canada claimed $7.2 million in expenses in 2023, a nearly 30 per cent increase over the previous year.
Canucks goalie Thatcher Demko won't play in Game 2
The Vancouver Canucks will be without all-star goalie Thatcher Demko when they face the Nashville Predators in Game 2 of their first-round playoff series.
Pedestrian, baby injured after stroller struck and dragged by vehicle in Squamish, B.C.
Police say a baby and a pedestrian suffered non-life-threatening injuries after a vehicle struck a baby stroller and dragged it for two blocks before stopping in Squamish, B.C.
North Bay doctor accused of assaulting patient, threatening another
A North Bay doctor is facing charges after allegedly assaulting a patient with a weapon and threatening another person at the hospital, police say.