"We have obvious concerns about the displacement of her behaviour away from foraging and feeding towards carrying her calf, and concerns over the length of time this behaviour continues", said Department of Fisheries and Oceans (DFO) killer whale researcher Sheila Thornton.
J-50 is part of a family group known as J-pod, which also includes the mother orca who has gained worldwide attention for carrying her dead newborn calf for more than two weeks, in an apparent display of mourning. For instance, we've all personally experienced some form of loss and the pain that comes with it, so when we see someone else grappling with the loss of a loved one, we understand, we relate, we feel their pain.
Killer whale Tahlequah was first spotted carrying her daughter's body on her back near Vancouver Island on July 24.
Canada has received and is granting a permit for scientists to assess and treat the young orca, a female, in Canadian waters.More news: Magic, Bulls, Jazz to play in Mexico City
A federally organized response team was able to administer antibiotics to the ailing, "very skinny" 3-year-old orca J50 in US waters near San Juan Island on Thursday, NOAA announced Thursday night.
Killer whales, though they have a reputation for being ruthless predators, are some of the most socially sophisticated animals in the world.
"I certainly think the duration of carrying the calf is unprecedented", she said during a conference call with reporters on Thursday. It's now been 16 days and the orca mother still doesn't want to say goodbye.
"We've seen mother whales carry dead babies briefly, for parts of a day".More news: Ryanair pilot strike leaves 55,000 travellers stranded across Europe
The orca is thin and in poor body condition.
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.
J50 is one of just 75 remaining southern resident killer whales that swim the coastal waters between British Columbia and California, and the tweet describes her as "skinny and small", but keeping up with her mother and siblings. It's made up of three pods, all of which have been listed as endangered in both the USA and Canada.
From the Center for Whale Research. Chinook salmon, their primary source of food, has been in a steep decline since the 1980s due to overfishing, habitat destruction and contaminated waters.More news: Liverpool boss Klopp: Big spending always going to happen
With high winds predicted to be moving into the Strait of Juan de Fuca over the next several days, there was little time to waste to come to the whale's aid - if they come into range, and the conditions are right. "But this sets a record", Centre for Whale Research senior scientist Ken Balcomb told the BBC. "Functionally, they will be extinct".