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
Quebec nurse had to clean up after husband's death in Montreal hospital
On a night she should have been mourning, a nurse from Quebec's Laurentians region says she was forced to clean up her husband after he died at a hospital in Montreal.
Northern Ont. lawyer who abandoned clients in child protection cases disbarred
A North Bay, Ont., lawyer who abandoned 15 clients – many of them child protection cases – has lost his licence to practise law.
Bank of Canada officials split on when to start cutting interest rates
Members of the Bank of Canada's governing council were split on how long the central bank should wait before it starts cutting interest rates when they met earlier this month.
Maple Leafs fall to Bruins in Game 3, trail series 2-1
Brad Marchand scored twice, including the winner in the third period, and added an assist as the Boston Bruins downed the Toronto Maple Leafs 4-2 to take a 2-1 lead in their first-round playoff series Wednesday
Cuban government apologizes to Montreal-area family after delivering wrong body
Cuba's foreign affairs minister has apologized to a Montreal-area family after they were sent the wrong body following the death of a loved one.
'It was instant karma': Viral video captures failed theft attempt in Nanaimo, B.C.
Mounties in Nanaimo, B.C., say two late-night revellers are lucky their allegedly drunken antics weren't reported to police after security cameras captured the men trying to steal a heavy sign from a downtown business.
What is changing about Canada's capital gains tax and how does it impact me?
The federal government's proposed change to capital gains taxation is expected to increase taxes on investments and mainly affect wealthy Canadians and businesses. Here's what you need to know about the move.
New Indigenous loan guarantee program a 'really big deal,' Freeland says at Toronto conference
Canada's Deputy Prime Minister Chrystia Freeland was among the 1,700 delegates attending the two-day First Nations Major Projects Coalition (FNMPC) conference that concluded Tuesday in Toronto.
'Life was not fair to him': Daughter of N.B. man exonerated of murder remembers him as a kind soul
The daughter of a New Brunswick man recently exonerated from murder, is remembering her father as somebody who, despite a wrongful conviction, never became bitter or angry.