Now, concerns are growing about what sort of impact that may have.
A federally organized response team was able to administer antibiotics to the ailing, "very skinny" 3-year-old orca J50 in USA waters near San Juan Island on Thursday, NOAA announced Thursday night.
J35 has carried her dead calf on her head for at least 16 days.
Images of the mother clinging to the dead calf have struck an emotional chord across the world.
J50 was last spotted Wednesday alongside her mother. But this orca has left even scientists surprised. No babies have been born to this struggling orca pod in three years.
Ken Balcomb with the Center for Whale Research said the southern resident orca J35 was spotted Thursday in the Strait of Juan de Fuca off the south shore of Vancouver Island. We can operate in calm winds.
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 scientists will try to match the whales' course and speed, then cautiously move in without disturbing them.
Scientists are still not sure why the whale has lost so much weight and believe an infection could be one of the problems.
Tahlequah is part of the Southern Resident population which the NOAA Fisheries says is critically endangered.
DFO is working with the US -based NOAA to observe the whale and hopefully provide treatment.
The orca is thin and in poor body condition. However, this mother's actions have left scientists surprised as well.
A team of whale experts has injected an ailing killer whale with antibiotics in a rare emergency effort to save her. The experts now have authorization to intervene with medical treatment in both US and Canadian waters once the critically endangered orca shows up again in the inland waters of the Pacific Northwest.
The possibility of giving medicated fish to a free-swimming whale in the wild would be a first, officials said.