Decline in salmon populations means endangered BC killer whales are starving, researchers say

Killer whales are one of the largest ocean predators, but in the waters off the coast of British Columbia, researchers say hunters are starving.

According to a new study from the University of British Columbia, endangered southern resident killer whales are missing thousands of much-needed daily calories.

“They don’t get 28,716 calories, or about 17 percent of what they need on a daily basis,” said study lead author Fanny Couture. “If we’re talking about humans, we’ll say it’s the equivalent of missing one meal a day.”

Couture is a marine ecologist at UBC’s Institute for Oceans and Fisheries. She says orcas have been in an alarming and constant “energy deficit” since 2018.

“That means the whales used more energy than they consumed from food, and they are very large animals with large energy demands,” he said.

With fewer than 80 in the wild, the southern residents are the smallest orca population in the Pacific Northwest. Not only have they been an iconic fixture in BC, they are culturally significant to West Coast First Nations.

Together with her team, Couture reviewed data from 1979 to 2020 to analyze the abundance, age, and size of the different species of salmon that killer whales consume.

“Chinook salmon make up as much as 90 percent of their food source, and we know that their populations have also declined,” he said.

Wild chinook, also known as king salmon, are prized for their large size; however, their stocks are in steep decline.

According to the Pacific Salmon Commissionwhich is a joint regulatory body run by Canada and the United States, Chinook salmon populations “have declined 60 percent” since 1984.

Fisheries and Oceans of Canada cites a number of factors by a drop in the salmon population, including “habitat destruction, harvesting, and the effects of climate change.”

“There’s a real urgency to all of this because killer whales and Chinooks are so connected, and we need to really understand what’s going on with both the prey and the predator,” Couture said.

Scientists say killer whales are not a fasting species and, depending on their size, need to consume about 200,000 calories a day. With such high energy demands, food shortages can devastate a population.

“They share their food, almost compulsively, so the whole group tends to suffer and lose weight if there’s food depletion,” said Lance Barrett-Lennard, senior scientist at the Raincoast Conservation Foundation.

Barrett-Lennard has been studying killer whales for more than 30 years and is also a co-author of the UBC study.

“When they go through these periods of not having enough food and being in really bad shape, it can affect their ability to hunt, reproduce and grow in size.”

Barrett-Lennard says that young killer whales are often hit the hardest when food is scarce, adding that if they aren’t fed properly for the first three years of life, “they can be about three feet shorter by the time they’re fully developed.”

In 2019, the federal government announced a “enhanced recovery strategy” for southern resident whales that includes area-based fishing bans to increase the availability of Chinook salmon if killer whales feed in the areas.

In April, Ottawa implemented more measures to protect the whales in hopes of boosting their dwindling numbers, but many scientists say more needs to be done to address food shortages.

“There has been a lot of effort and money to try to save endangered southerners, but clearly more needs to be done because the population is not recovering,” Barrett-Lennard said. “They need safe places where they can feed, and we must continue to work to increase the salmon supply for them.”

As for the new study, Couture says he hopes it highlights that both killer whales and Chinook salmon are “important and iconic species for Canada’s west coast.”

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