Study Discovers Southern Resident Killer Whale Has Insufficient Food, Causing Energy Deficiency

According to recent research, the critically endangered southern resident killer whale population is not eating enough and hasn't been since 2018.

For the past 40 years, on average, over spring, summer, and fall, the animals have been in an energy deficit, meaning that the energy they receive from food is less than what they spend.

According to the authors, the average energy differential is 28,716 calories, or nearly 17% of the daily energy needs of a typical adult killer whale. 

Not enough food for southern resident killer whale

(Photo : Hagen Hopkins/Getty Images)

According to the primary author Fanny Couture, a doctorate student at the Institute for the Oceans and Fisheries (IOF) and Ocean Wise, this sort of research is urgent given the low level of the southern resident population, as per ScienceDaily.

Killer whales are significant, iconic animals for the Canadian west coast, as are Chinook salmon, the primary prey of the southern resident.

Studying the population's decline might assist in finding remedies for the southern inhabitants and prospective future killer whale populations.

In contrast to the approximately 300 residents in the northern resident population, which is growing, there are 73 residents in the south that mostly consume Chinook salmon. 

Studies have shown that a scarcity of food may be impeding the expansion of the southern region's resident population.

From 1970 to 2020, for three seasons each year, the researchers looked at how variations in the abundance, size, and age of the Chinook, coho, and chum populations that the southern residents prey on in the Salish Sea and on the west coast of Vancouver Island affected the killer whales' daily food intake.

Scientists utilized the study's estimated losses in Chinook salmon quantity and size to demonstrate that a lack of these fish had probably led to killer whale energy deficiencies.

According to co-author Dr. Villy Christensen, professor at IOF, the years when southern inhabitants were in an energy shortage are also when other research revealed lower population growth rates and greater fatality rates for killer whales.

Previous studies have found links between Chinook salmon abundance and southern residents' fertility and survival rates.

According to Couture, there are a variety of explanations for the fall in Chinook salmon numbers, including the impacts of climate change, increased susceptibility to illness, and predation by other species.

Also Read: Killer Whales Bred for Captivity: China's First Orca Breeding Facility Highlights Country's Need for Animal Welfare Law

Critical habitat

In the years when Chinook salmon populations were low, the model predicted that people in the south would prefer chum salmon over Chinook, demonstrating that animals may move to other salmon species when the abundance of their main diet decreases, as per EPA.

Because it offers the characteristics, capabilities, and qualities necessary to sustain the species' existence or recovery, critical habitat is crucial to preserve.

Such an environment enables continuous foraging, eating, resting, interacting with others, reproducing, raising, and migrating.

Southern resident killer whales and their prey depend on coastal watersheds that are not officially listed as essential habitats.

In Canadian seas, the crucial habitat for southern resident killer whales increased in 2018. The National Oceanic and Atmospheric Administration recommended expanding the southern resident killer whale habitat in the United States beyond the Salish Sea.

Related article: Oldest Known Orca 'Granny' Now Considered Dead After Missing for 3 Months