Two endangered orcas in British Columbia are dangerously thin, and biologists fear that the whales could starve to death by summer.

The whales – a male and female – are members of two separate pods in the southern resident killer whale population. Losing two adults would be a major blow to the dwindling southern residents, which have lost seven adults since 2016.

Several pervasive threats face the orcas, including ship strikes, acoustic disturbances and water contaminants. But according to Jason Colby, an associate professor with the University of Victoria, the biggest problem is a lack of food -- namely, chinook salmon.

“You can talk about a lot of different causes in this decline, but ultimately, when animals don’t have enough to eat, they cannot survive,” Colby told CTV News.

Wild chinook salmon stocks are in steep decline. Of the 28 chinook populations in B.C., eight are considered endangered -- meaning they’re at risk of extinction -- with another four considered threatened, according to a recent report.

The two starving whales both show signs of “peanut-head,” which is when they lose fat around their heads due to malnourishment.

Lance Barrett-Lennard, director of the Vancouver Aquarium’s marine mammal research program, has monitored the pair of starving whales. He said that when whales lose this much weight, they have “a very small chance of recovering.”

Biologists expect both whales will die by the summer.

The ailing male orca is far too young to die, Barrett-Lennard said.

“He should be at prime of life right now, a young adult male,” he said.

The female orca is 42 years old. She is the matriarch of her pod, and losing her would be a serious blow to the group.

Her pod already suffered a loss in September when a young orca, known as J50, died from starvation despite efforts to give her life-saving medication.

In July, a different female orca was photographed trying to save her newborn calf, which died shortly after birth. The mother was seen pushing the dead calf to the surface for 17 days, apparently in an effort to resuscitate the newborn.

In the last three years, no new southern resident calves have survived.

Canada and the United States have launched efforts to boost the populations, including the designation of new protected habitats.

Chris Wilke, executive director of Puget Soundkeeper, a wildlife organization that aims to protect the waters of the Puget Sound, said preserving salmon populations is key to saving the whales.

“We need to protect the streams in rural areas to make sure that they’re hospitable for salmon, so we can have the abundant salmon resource we once had,” Wilke said.

Southern resident orcas are known for spending their summers in the busy waterway between B.C. and northern Washington state. They migrate along North America’s Pacific Coast, swimming as far north as Alaska and as south as central California.

Southern resident populations have wavered between 70 and 99 whales since 1976. Fisheries and Oceans Canada says the whales are “currently facing imminent threats to their survival and recovery.”

Unlike B.C.’s transient orca whales, which use echolocation to hunt warm-blooded mammals like seals, resident orcas rely on salmon stocks.