aerial view of a pod of killer whales swimming together

Southern Resident Killer Whales are not getting enough to eat, study says

A new UBC study found that the endangered Southern Resident Killer Whale population isn’t getting enough to eat.

As lead author Fanny Couture explained, “The study goes from 1979 to 2020. We were trying to understand whether the Southern Resident Killer Whale population had enough food to eat to sustain their energy needs. So a human needs 2,000 calories a day, a killer whale will need about 170,000 calories a day. What we found is that they were in energy deficits for six of the last 40 years. Some of them are spread out throughout the study period, but three of the last years (in the study), 2018 to 2020, they were in full energy deficits. They did not have enough food in the spring, the summer and the fall.”

L121 with fish – Photo courtesy NOAA, Ocean Wise

This study is important to the Discovery Islands because we are close to the boundry between Northern and Southern Resident Killer Whales, which is just south of Cortes Island. Many Southern resident killer whales swim through our area, as does one of the major Chinook salmon runs they feed on. 

Couture added that they would like to apply the same methodology to the Northern Resident Killer Whale population. 

L85, a robust male – Photo courtesy NOAA, Ocean Wise
L94, mother of L1212 – Photo courtesy NOAA, Ocean Wise

“There are evidences that they are also getting skinnier,  that they are also potentially lacking food. It’s possible that the different population trends that we observe for the Northern Residents and Southern Residents come from other seasons that we know less about, such as the winter,” said Couture.

“We need to understand the causes for the decline of those food resources.  There are several hypothesis, several factors that might impact those food resources and the salmon population. One of which could be predation from other marine mammals, including Stellar Sea Lions, but there are other factors to look at as well, such as climate change, prevalence to diseases for those salmon populations. More research is needed and there is an urgency to try to understand what’s happening to those Chinook populations.”

LBL 0324 – Photo courtesy NOAA, Ocean Wise

Links of Interest: 

Top image credit: Aerial view of southern resident whales swimming together – Photo credit NOAA, Ocean Wise

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