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.
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.
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.
'Anything to win': Trudeau says as Poilievre defends meeting protesters
Prime Minister Justin Trudeau is accusing Conservative Leader Pierre Poilievre of welcoming 'the support of conspiracy theorists and extremists,' after the Conservative leader was photographed meeting with protesters, which his office has defended.
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.
'One of the single most terrifying things ever': Ontario couple among passengers on sinking tour boat in Dominican Republic
A Toronto couple are speaking out about their 'extremely dangerous' experience on board a sinking tour boat in the Dominican Republic last week.
Boeing's financial woes continue, while families of crash victims urge U.S. to prosecute the company
Boeing said Wednesday that it lost US$355 million on falling revenue in the first quarter, another sign of the crisis gripping the aircraft manufacturer as it faces increasing scrutiny over the safety of its planes and accusations of shoddy work from a growing number of whistleblowers.
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.
Fair in Ontario, flurries in Labrador: Weather systems make for an erratic spring
It's no secret that spring can be a tumultuous time for Canadian weather, and as an unseasonably mild El Nino winter gives way to summer, there's bound to be a few swings in temperature that seem out of the ordinary. From Ontario to the Atlantic, though, this week is about to feel a little erratic.