The orca who was spotted Thursday off British Columbia is thin and in poor health.
Scientists are also anxious about another member of the endangered orcas.
Scientists are reporting progress in the race to help an emaciated and endangered West Coast killer whale in the waters of the Salish Sea.
Live chinook salmon aboard the King County Research Vessel SoundGardian are released into waters off San Juan Island, Wash, as a young female orca called J50 was not in the area on Friday Aug. 10, 2018.
The team led by the USA 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 of experts has successfully administered antibiotics to ailing young orca J50 in an emergency effort to save her life, an apparent first for an orca in the wild.
If things go well, she said, the team could move ahead with feeding the orca live salmon from a boat. Researchers spotted the 20-year-old whale and the calf off of Washington's Olympic Peninsula on Wednesday, the station says.
No intervention is planned, she said, but they will monitor her condition.
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Michael Milstein with NOAA Fisheries says experts plan to do a health assessment of the young whale if conditions allow. "That is very good news", he said.
"Removing the calf would be a very, very hard decision, and obviously we would have to take many factors into consideration, so that's now not on the table", she said.
US and Canadian officials acknowledged Thursday that they're concerned that J35's apparent grieving process could prevent her from foraging, but they have no plans to intervene at this point to remove the dead calf.
A team of whale experts injected an ailing Southern Resident orca with antibiotics Thursday in a rare emergency effort to save her.
One of the problems affecting whales is the lack of salmon, their main source of food due to overfishing for commercial consumption.
Experts have been watching the young whale lose weight since June and they took the novel action in an effort to prevent the loss of more reproductive potential within the population. The orca would initially get just a few fish to see whether it takes it and how it and members of its pod respond before deciding whether to give it salmon dosed with medication, officials have said.
The last time scientists rescued a killer whale in the region was in 2002 when a northern resident killer whale known as Springer was found swimming alone in Puget Sound.
Because Tahlequah was pregnant, it is possible she began carrying her deceased calf with an extra boost of lipids in her blubber that could be helping her now, said Dawn Noren, research fishery biologist at NOAA's Northwest Center in Seattle.
By the time the whale entered her third day of mourning, Dr Balcomb, said he had never observed a whale mourn for such a long time.