SEATTLE (AP) — UPDATE: Sick orca J50 has died, according to Ken Balcomb with the Center for Whale Research. More details to follow.
Teams searched Thursday for a sick, critically endangered orca in the waters of Washington state and Canada, but a scientist who closely tracks the population in the Pacific Northwest said he believes the whale known as J50 has died.
Experts have been preparing last-ditch efforts to save the nearly 4-year-old, emaciated whale — including the possibility of capturing and treating the orca.
Officials said they would intervene and rescue the orca if she became stranded or separated from the rest of her tightly knit group of whales. But she hasn't been seen in days.
Ken Balcomb, senior scientist with the Center for Whale Research, said he believes the whale "is gone."
Michael Milstein, a spokesman for NOAA Fisheries, said boats and planes in the U.S. and Canada are on the lookout for the whale and the network of people who respond when marine mammals wash ashore has been alerted.
J50 was last spotted Friday in extremely thin and in poor condition and has not been seen in recent days with her family.
Whale experts feared the orca was dead earlier this month when J50 lagged behind her family and went missing. But she later turned up and was seen with her family.
Balcomb said he thinks she's dead because searchers spotted her family multiple times in recent days and she was not with them. The whales travel closely in family units.
He said J50 has not been seen despite several days of favorable sighting conditions. "She's certainly not with her family," Balcomb said.
The distinctive black-and-white orcas, known as southern resident killer whales, have struggled since they were listed as an endangered species in the U.S. and Canada well over a decade ago.
The death of J50 would bring the population to just 74 animals, the lowest in more than three decades.
Another whale in the same pod, known as J35, triggered international sympathy this summer when she kept the body of her dead calf afloat in waters for more than two weeks.
The orcas are struggling because of lack of chinook salmon, the staple of their diet. They also face threats from toxic contamination and noise from vessels. The whales use clicks, calls and other sounds to navigate, communicate and forage and noise from vessels can interfere with that.
There hasn't been a successful birth in the population since 2015. Losing J50 would also mean losing her reproductive potential.
"We're watching a population marching toward extinction," Balcomb said. "Unless we do something about salmon recovery, we're just not going to have these whales in the future."
An international team of Canadian and U.S. whale experts has mounted an intensive effort to help the orca since concerns were raised in mid-July.
Response teams injected her with antibiotics and tried to give her medication to help with parasitic worms, which they believe she has based on fecal samples taken from her mother.
Teams also dropped live salmon from a boat as J50 and her pod swam behind — a test to see whether fish could be used as a means of delivering medication.
Drone images taken earlier this month showed J50 much thinner than she was last year. Her mother, J16, has also declined in condition in the past month.