The ailing calf - dubbed J50 - was a member of an endangered population of orcas found south of Vancouver island, and hasn't been seen since Friday.
Appearing emaciated and lethargic, scientists have been tracking the whale and concerned for her wellbeing for a number of months and, unable to find her, are now operating under the assumption that she's died.
The rare superpod is suspected to have come together as a result of the youngster's death.
Speaking to Global News,Robb Krehbiel of Defenders of Wildlife said: "The fact that this gathering occurred and J50 wasn’t there means to us she is gone and her family is trying to deal with it."
This development follows the death of another orca in the endangered group, J35 - the deceased calf who, after death, was famously carried by the pod for over two weeks in what appeared to be a display of grief.
Salmon shortages in the area have kept the population from raising a calf to maturity for more than three years.
Scientists will continue the search for J50, or her body, over the course of the weekend.