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
More than 115 cases of eye damage reported in Ontario after solar eclipse
More than 115 people who viewed the solar eclipse in Ontario earlier this month experienced eye damage after the event, according to eye doctors in the province.
Toxic testing standoff: Family leaves house over air quality
A Sherwood Park family says their new house is uninhabitable. The McNaughton's say they were forced to leave the house after living there for only a week because contaminants inside made it difficult to breathe.
Decoy bear used to catch man who illegally killed a grizzly, B.C. conservation officers say
A man has been handed a lengthy hunting ban and fined thousands of dollars for illegally killing a grizzly bear, B.C. conservation officers say.
B.C. seeks ban on public drug use, dialing back decriminalization
The B.C. NDP has asked the federal government to recriminalize public drug use, marking a major shift in the province's approach to addressing the deadly overdose crisis.
OPP responds to apparent video of officer supporting anti-Trudeau government protestors
The Ontario Provincial Police (OPP) says it's investigating an interaction between a uniformed officer and anti-Trudeau government protestors after a video circulated on social media.
An emergency slide falls off a Delta Air Lines plane, forcing pilots to return to JFK in New York
An emergency slide fell off a Delta Air Lines jetliner shortly after takeoff Friday from New York, and pilots who felt a vibration in the plane circled back to land safely at JFK Airport.
Sophie Gregoire Trudeau on navigating post-political life, co-parenting and freedom
Sophie Gregoire Trudeau says there is 'still so much love' between her and Prime Minister Justin Trudeau, as they navigate their post-separation relationship co-parenting their three children.
Last letters of pioneering climber who died on Everest reveal dark side of mountaineering
George Mallory is renowned for being one of the first British mountaineers to attempt to scale the dizzying heights of Mount Everest during the 1920s. Nearly a century later, newly digitized letters shed light on Mallory’s hopes and fears about ascending Everest.
Loud boom in Hamilton caused by propane tank, police say
A loud explosion was heard across Hamilton on Friday after a propane tank was accidentally destroyed and detonated at a local scrap metal yard, police say.