Snow Cone, the North Atlantic right whale, seen suffering from yet another severe entanglement

Hsu, who had previously photographed Snow Cone after she experienced another entanglement in 2021, was shocked by the precipitous decline in the whale’s health.

“It was like a punch in the gut,” Hsu said.

The 17-year-old mother, named for a callosity near her blowhole that looks like a snow cone, no longer had the same girth or the dark black skin of a healthy right whale. Instead, she was pale, thin, and swimming slowly, likely dragging submerged fishing gear at the end of the long ropes she was trailing. When she dove to feed, it was more like she was just sinking below the surface.

Most concerning, and the clearest sign of her dire fate, was that she was covered in orange cyamids, or whale lice.

“She was very obviously suffering,” Hsu said. “Unfortunately, there is no longer hope for her survival.”

Snow Cone’s latest entanglement is at least her fifth, according to scientists at the New England Aquarium who track the whales, and the most recent ones involve hundreds of feet of rope wrapped around her upper jaw and lodged in her baleen.

“Her condition has declined significantly from July,” when she was last seen, said Heather Pettis, a research scientist at the aquarium’s Anderson Cabot Center for Ocean Life. “Snow Cone is so compromised by these last two entanglements that she is likely not to survive to see 18.”

Pettis noted that right whales, without human interference, should live for 70 years or longer.

She and others described Snow Cone as emblematic of a species that has seen its population plummet by at least 30 percent over the past decade, most of them dying as a result of entanglements in fishing gear or from vessel strikes.

Last year, scientists estimated that the population of North Atlantic right whales had fallen to just 336 — the lowest in nearly 20 years. Previously, the population had been on a rebound, after the species nearly went extinct as a result of hunting.

For Pettis and other scientists, many of whom have spent their careers trying to protect right whales, the apparent demise of Snow Cone is hard to bear.

Born in 2005 off Florida, her lineage has suffered greatly. Her mother was killed while suckling another calf in 2011, which also died. Snow Cone’s first calf, born in late 2019, was wounded by a vessel’s propeller a few months later, and shortly afterward, the calf’s tale was severed by another propeller, killing him. She had a second calf in December 2021, but that calf, too, is now feared dead, as it hasn’t been seen since last spring.

In 44 years since Snow Cone’s grandmother was first spotted in 1978, 12 of her relatives are known or thought to be dead, said Michael Moore, director of the Marine Mammal Center at the Woods Hole Oceanographic Institution. Of those with known causes of death, three suffered entanglements and four were hit by vessels, he said.

Moore, a veterinarian, described Snow Cone’s chances of survival as “very low.”

“Her clock is running out,” he said. “She is succumbing to entanglement. This is a typical story for North Atlantic right whales.”

Moore and other scientists have called on the federal government to do more to protect right whales, urging officials to impose mandatory speed limits on vessels and reduce the amount of vertical buoy lines — ropes that extend from traps on the seafloor to buoys on the surface — in waters frequented by the whales.

The government has already taken some of those steps, or is considering them, and federal courts have recently ruled that the government must do more to protect right whales.

Those measures and rulings have caused growing concerns in the lobster industry, which may be required to change the equipment they have long used to fish and use so-called ropeless traps that don’t rely on buoy lines.

“In honor of Snow Cone, we should do everything in our power to bring entanglement solutions to fruition,” said Erica Fuller , a senior attorney at the Conservation Law Foundation, which has sued the National Marine Fisheries Service repeatedly over recent years to protect the whales. “We know that the only long-term solution to entanglements is ropeless fishing where right whales are at risk. Now we need to fund it and embrace it.”

In the coming months, a federal judge is expected to rule on what the National Marine Fisheries Service must do to accelerate its plans to protect the whales.

For now, the scientists are watching with horror as more breeding females — those critical to enabling the species to avoid extinction — perish.

“Bearing witness to the pain and suffering of this whale is gut-wrenching,” said Philip Hamilton, a senior scientist at the aquarium.

He noted that a reproductive female has the potential to produce as many as 30 future right whales, including grandcalves and great-grandcalves.

“The impacts of the loss of a single reproductive female gets amplified through time,” he said.

David Abel can be reached at david.abel@globe.com. Follow him @davabel.