Scarlet is the youngest southern resident killer whale among a group of 75 that feed in the waters off of Alaska and northern California, but when scientists were last able to evaluate her condition, she was underweight and had an infection, Rowles said during the press call.
The teams were, however, racing out to sea to help another ailing young killer whale in the same critically endangered pod.
Scientists on both sides of the border have been working together on an emergency rescue plan for a young female orca known as J50, that appears emaciated but continues to swim alongside her mother.
Brad Hanson, a wildlife biologist with the National Oceanic and Atmospheric Association in the United States, said removing the calf, in order to encourage the whale to forage, is not an option. The team of experts who followed the whale on the water for about six hours Thursday got a breath sample to analyze whether she might have bacteria or fungus in her airway.
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 changed in late July, when a female member of the group - known as J35, or Tahlequah - gave birth to a calf, but the baby whale only lived for 30 minutes.
The tweet says the next step is to decide if trial feeding of J50 should proceed, although it says that will depend on the location of the pod, as well as water and weather conditions. They are waiting for her to show up again in Washington state waters so they can zip out on a boat to do a health assessment, said Teri Rowles, marine mammal health and stranding coordinator for NOAA Fisheries.More news: Everything Samsung announced at its Unpacked event
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The orca was given a dose of antibiotics from a dart Thursday, and Marty Haulena, head veterinarian at Vancouver Aquarium, who got a close look at J50.
"She was breathing very well; her respiratory rate was normal", he said.
U.S. and Canadian scientists said they were concerned about the mother's condition and would keep monitoring her but have no plans to help her or remove the calf.
An global team of experts has been waiting for an opportunity to get close to the female killer whale so they can carry out an emergency plan that includes giving it antibiotics or feeding it live salmon at sea. The fish could be a vehicle to deliver medication to her that can't be administered any other way. She returned to her family of whales in Canada later that year and was seen with her calf in 2013.
They face nutritional stress over a lack of their preferred food source, Chinook salmon, as well as threats from toxic contamination and vessel noise and disturbances that disrupt their ability to communicate and forage.
Rowles said injections of antibiotics or sedatives have been given to other free-swimming whales or dolphins that were injured or entangled but it hasn't been done for free-swimming whales in this area. The Center for Whale Researchers confirmed that she was still seen pushing the now-deteriorating corpse of her newborn calf.
The Puget Sound calf was the first in three years to be born to the dwindling population of endangered southern resident killer whales.
University of Washington scientist Deborah Giles said she was heartbroken for what is happening with the mom and child.