"She has been thin for a while, so this may not be an acute illness, but her body condition is incredibly concerning".
The whale known as J35 was spotted in coastal waters near the border between British Columbia and Washington state Wednesday with the carcass of her calf that was born and died on July 24.
J50, the ailing 3 1/2-year-old orca, was seen along with her mother, J16.
The team led by the US agency lacks a permit to feed the whale, which is emaciated and possibly suffering an infection, in Canadian waters, though it had one for medical treatment.
An global team has been waiting for the chance to get close to the female killer whale to help her, including possibly giving her antibiotics or feeding her live salmon at sea.
Fearing that J50's fate will be the same if they don't intervene, scientists are considering multiple strategies created to save the starving whale, including feeding her live salmon dosed with medication at sea. "That is good news ... the pneumonia side of things is slipping down the list of why she is in the condition she is in". However, Dawn Noren, a research fisheries biologist with the National Oceanic and Atmospheric Administration (NOAA) Northwest Fisheries Science Center, said that a female killer whale could fast for a period of up to four weeks before it became detrimental to its health.
The Vancouver Aquarium's head veterinarian, Dr. Martin Haulena, was on the vessel assessing and treating the whale, according to statements from the aquarium and NOAA.
"She was breathing very well; her respiratory rate was normal", he said.
"It is very possible she has succumbed at this point and we may never see her again", Rowles said.
US and Canadian scientists said they were concerned about the mother's condition and would keep monitoring it but have no immediate plans to help it or remove the calf.
The fish-eating orcas that frequent the inland waters of Washington state are down to 75 animals, and there hasn't been a successful birth since 2015.
An worldwide team of experts is waiting to get close to the 3½-year-old killer whale known as J50 so they can carry out a step-by-step emergency plan that includes giving her antibiotics or feeding live salmon at sea.
"I certainly think the duration of carrying the calf is unprecedented", she said during a conference call with reporters on Thursday. What would be unique is giving the orca medication through live fish, Rowles said.
The last time scientists rescued a killer whale in the region was in 2002, when they rehabilitated an orca known as Springer who was found alone. Chinook salmon, their primary source of food, has been in a steep decline since the 1980s due to overfishing, habitat destruction and contaminated waters. She returned to her family of whales in Canada later that year and was seen with her calf in 2013.