J-50 is almost four years old and part of the critically endangered southern residents, a population of killer whales with only about 75 individuals.
In Canada, where the whales were last seen, the fisheries department does not yet have the legal ability to treat the whale, said marine mammal coordinator Paul Cottrell.
Scientists on both sides of the border say the southern resident killer whale, identified as J-50, may only have days to live and veterinarians are prepared to administer experimental antibiotics in American waters.
The 4-year-old was part of the southern resident "baby boom" that occurred when eleven calves were born between 2014-2016.
Bangladesh floats death penalty for road deaths in bid to quell protests
The protests started after two students were killed by speeding buses. "The police just stood there". "We are panicked. "The remand order has violated Shahidul Alam's constitutional and human rights", he said .
But no one has seen J-50 or her pod since Friday off Vancouver Island, said NOAA and Fisheries and Oceans Canada in an update Tuesday. Her pod recently drew an worldwide spotlight when another whale, J35, was spotted pushing the body of her dead calf through the water for more than a week.
"We are hopeful that there's still a chance that we will be able to assist her", Rowles said. NOAA fears J50's condition is worsening as the days pass.
"If then things are going well and the behavior of the group and her responses to the (medication) is going okay, then they could move forward with the fish feeding trial", Rowles said. Cottrell says Canadian vessels are out on the waters off south west Vancouver Island but heavy fog is making the search hard. She was the first orca to be rescued, rehabilitated and successfully released back into the wild.