July 31 (UPI) -- A grieving orca whale mother in Seattle has begun to fall behind her pack as she carried the body of her dead calf through the water for the seventh straight day Tuesday, conservationists said.
The orca, known as J35 or Tahlequah, gave birth to the calf on July 24. It lived for about half an hour before dying.
She has since carried the corpse with a flipper, in her mouth or pushed it with her head.
Biologist Deborah Giles with the Center for Conservation Biology said the orca is aware the calf is dead, adding it is common for orca mothers to mourn the death of a calf.
Tahlequah has fallen behind her clan, J pod, traveling at a speed of about 6 knots after expending much of her energy carrying the calf and diving deep into the water to retrieve the corpse any time it slips from her grasp.
"She has to prime herself six, seven breaths to take a deep, long dive to go get that carcass," Giles told The Seattle Times. "What is killing me is when is it going to be the last time? And she has to make that decision not to go get it."
Tahlequah's clan has stayed with her despite her slowed pace and she was seen surrounded by her entire family Sunday.
Researchers have been concerned whether Tahlequah is getting enough to eat, but Taylor Shedd, who has been observing the orca from a Soundwatch boat, said she breached three times Saturday and "you could not see any ribs."
She is part of an endangered family of 75 southern-resident orca whales. Each birth and death, particularly for females, is critical to the clan's survival.
"I am so terrified for her well-being," Giles said. "She is a 20-year-old breeding-age female and we need her."
Ken Balcomb of the Center for Whale Research said the United States and Canada must "redouble efforts" to restore wild salmon populations throughout the waters of Washington state and British Columbia.
"Whales in this endangered population are dependent upon Chinook salmon for their primary food source," Balcomb said. "Unfortunately, Chinook salmon are also endangered."