While wildlife officials continue to search for J50, a 3-year-old emaciated killer whale off the coast of Washington, some researchers have said she is likely dead after being absent from her family group for multiple days.

“J50 is missing and now presumed dead,” a Thursday press release from the Center for Whale Research states. The Washington-based nonprofit has had a vessel on the water searching for the female orca for three days, and has seen all the other members of her family.

J50 was last seen on September 7, according to NOAA.

While the situation is dire, officials say they have not given up hope, and have plans to rescue and administer medical treatment to the whale if found. The Coast Guard, NOAA’s Marine Mammal Stranding Network and nonprofit groups have been activated. NOAA has asked airlines flying in and out of the San Juan Islands to keep a lookout as well.

“We certainly have not determined at this point that we are giving up,” NOAA spokesman Michael Milstein told the Seattle Times.

But J50’s condition, noticed as early as May 2017, has been deteriorating in recent weeks. A depletion of fat reserves has caused what’s called “peanut head” — a dimpled area around the blowhole —that is a sign of extreme emaciation. Joe Gaydos, a veterinarian with UC Davis and one of the last to see J50, said she was the “thinnest killer whale” he’d ever seen, and that in the region, 11 out of 13 whales exhibiting similar symptoms had not survived.

The Center for Whale Research says J50’s deterioration “is what extinction looks like when survival is threatened for all by food deprivation and lack of reproduction.”

Declining Chinook salmon stocks have been cited as a stressor on southern resident killer whale populations, however the specific cause of J50’s illness is not known.

The critically endangered whales live in the Salish Sea between Washington and British Columbia. They number just 75 animals.

The loss of J50 would be the second death of southern resident killer whale in two months. In July, a newborn of female J35 after being alive only 30 minutes. A video that went viral showed J35 carrying her dead calf through the Salish Sea for 17 days, an epimeletic behavior that Gaydos called a form of mourning.