Her dead calf resting on her nose, an orca has swum in mourning for more than three days in the Pacific Northwest.

The calf died on Tuesday morning, half an hour after it was born off the coast of Victoria, British Columbia, to a 20-year-old whale called J35. It was the first calf known to have been born to the local population, known as the Southern Resident killer whales, since 2015.

“I think she’s just grieving, unwilling at this point to let the calf go, like, ‘Why, why, why?'” said Ken Balcomb, founder and chief scientist for the San Juan Island-based Center for Whale Research, who has tracked the population for more than 40 years.

We are saddened to report that a baby Southern Resident killer whale (SRKW) died a short time after it was born near Victoria, British Columbia on July 24, 2018. The newborn whale was reported alive and swimming with its mother, J35 ... https://t.co/ql0kDBU9LL pic.twitter.com/GQteYuPsv4 — Whale Research (@CWROrcas) July 26, 2018

Southern Resident killer whales, which consist of three different pods, generally stay near British Columbia and Washington state, though some swim north to Alaska and south to California. Researchers fear the decline of the population, which has been besieged by a shrinking gene pool, dwindling food supply and environmental degradation.

Orcas have been shown to have complex social circles, use vocal communication, and exhibit emotions like grief. The whales do sometimes carry the bodies of their dead calves on the water’s surface — another whale was seen doing so in the Pacific Northwest for a few hours in 2010.

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But J35’s sad journey, which began near Victoria and has taken her some 150 miles around the San Juan Islands and Vancouver, has continued for an unusually long time, researchers said. It has become a devastating symbol, and an uncannily pointed one, for the whales’ plight.

“We know it happens, but this one is kind of on tour almost, like she’s just not letting go,” Balcomb said.

J35 was spotted again Friday morning near the southern end of the San Juan Islands, he said. She has largely been balancing the dead calf on her nose.

“Sometimes she bites the flipper and pulls it up,” he said. “The calf sinks because it doesn’t have enough of a blubber layer, and it goes down. She dives down and picks it back up and brings it to the surface.”

Balcomb’s team first started monitoring the area’s orca population in 1976. They numbered about 70 at the time after approximately 50 were removed from the wild to become attractions in marine parks.

The larger environmental question reflected in the J35 story is that both the USA and Canada MUST redouble efforts to restore wild salmon (particularly Chinook) throughout Washington State and British Columbia for a food supply for the SRKW in this region. - Ken Balcomb pic.twitter.com/mqQy83KxSe — Whale Research (@CWROrcas) July 27, 2018

About 20 years later, after federal protections were implemented, the number of whales in the population peaked at around 100. Then it started to decline again, and today, there are about 75 left.

Given that number, there should be about nine babies born each year, Balcomb said. Instead, no calves had been born since 2015.

“Once they stop reproducing, they may still swim around here for 50 more years, but there will be no babies,” he said. “Functionally, they will be extinct.”

The population decline, and the lack of new baby whales, has largely been attributed to their primary prey, the king salmon, or Chinook, dying off.

Jan Ohlberger, a research scientist at the University of Washington’s School of Aquatic and Fishery Sciences, said that the orcas prefer the larger Chinook salmon that are richer in energy, but that they have steadily declined over the last several decades.

He said it could be because of overfishing or climate. “We don’t really know,” he said. “There’s a lot of hypothesising about that.”

Whales do sometimes carry the bodies of their dead calves on the water’s surface, but J35’s sad journey, which has taken her 150 miles around the San Juan Islands, has continued for an unusually long time: https://t.co/EJmEQnBrP8 via @nytimes — Defenders of Wildlife (@Defenders) July 28, 2018

Conservationists have said the whale population has also declined because of inbreeding, noise pollution from ship traffic, and municipal and industrial waste and other chemicals being spilled into the water.

There are more potential threats on the horizon. A recent agreement to expand the Trans Mountain Pipeline, which carries oil from Alberta to British Columbia, would multiply tanker traffic through the orcas’ habitat and expose them to more noise and potential spills. Construction on that pipeline is expected to begin in August.

In May, Governor Jay Inslee of Washington convened the Southern Resident Orca Task Force, a group of state, tribal, provincial and federal officials, to help protect the region’s orcas.

“The loss of a newborn orca calf from our endangered southern resident killer whale population underscores what’s at stake as we work to protect these iconic, beautiful animals from vanishing completely,” Inslee tweeted this week.

Balcomb, who sits on the governor’s task force, said J35’s plight has become a rallying point for the efforts to protect the whales.

“Everybody is devastated,” he said. “This is very, very dramatic, saddening, disheartening.”