(CNN) A female orca whale is still apparently grieving her dead calf and still swimming with its body after more than two weeks, authorities say.

"It's heartbreaking to watch," said Michael Milstein of the National Oceanic and Atmospheric Administration's West Coast Region. "This kind of behavior is like a period of mourning and has been seen before. What's extraordinary about this is the length of time."

The adult -- Tahlequah, or J35 as the whale has come to be known by researchers -- and corpse were last seen definitively Thursday afternoon, 17 days after the baby's birth. The female calf died after a few hours.

The mother, preventing the body from sinking to the ocean floor, has been carrying it and nudging it toward the surface of the Pacific off the coast of Canada and the northwestern US.

Orcas, also called killer whales, are highly social, and this pod was spotted Friday afternoon near Vancouver, British Columbia.

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