PROVINCETOWN, Mass. — Researchers off the coast of Provincetown said Saturday they’ll keep trying to free an endangered North Atlantic right whale from fishing line wrapped around her jaw.

The whale, dubbed “Kleenex,” is a great-grandmother to six calves that was first spotted in Cape Cod Bay in 1977. Researchers and scientists said they made progress removing the gear from the whale on Thursday in the Stellwagen Bank National Marine Sanctuary.

Female right whales like Kleenex are a focus of right whale conservation efforts because their ability to reproduce is critical to the survival of the species, which had dwindled to no more than 450 animals.

Kleenex is a “superstar” who is the mother, grandmother and great-grandmother of 5 percent of the North Atlantic right whale population, said Tony LaCasse, a spokesman for the New England Aquarium, in a statement. Right whales recorded no new births in this year’s calving season, making preserving reproductive females especially important, LaCasse said.

“For more than a half century, Kleenex has defied the odds of survival and been a pillar of the right whale’s modest recovery,” LaCasse said. “Let’s hope that she sheds the entangling gear.”

Kleenex hasn’t been seen since the disentanglement attempt, but that is typical of whale rescue efforts, said Cathrine Macort, a spokeswoman for the Center for Coastal Studies in Provincetown. Macort said rescuers will keep looking for her.

The whale has had the fishing line wrapped around her jaw for three years, the Cape Cod Times reported.