A grieving orca whale who carried the corpse of her dead calf for an unprecedented 17 days has finally let it go.

The killer whale, known as J35 to scientists monitoring the population in the Pacific Northwest, was spotted swimming without the infant balanced on her head for the first time since July.

“J35 frolicked past my window today with other J pod whales, and she looks vigorous and healthy,” Ken Balcomb, of the Centre for Whale Research, told The Seattle Times. “The ordeal of her carrying a dead calf for at least 17 days and 1,000 miles is now over, thank goodness.”

The 20-year-old whale, also known as Tahlequah, is an important member of the critically endangered southern resident orca population. Her relative youth age means she could have years of reproductive ability ahead of her.

But the death of her daughter triggered a grieving process that took longer than any other documented case among killer whales, with Tahlequah carrying her infant night and day, and diving deep underwater to bring the body back to the surface when it slipped off her head.

“She is alive and well and at least over that part of her grief,” Mr Balcomb added. “Today was the first day that I for sure saw her. It is no longer there.”

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It is not known if Tahlequah finally let the corpse go, or if the body simply began to fall apart – it was beginning to decompose when spotted earlier this week.

The mother’s grief has captured the attention of the world and helped to illustrate the existential threat facing Tahlequah’s pod.

The calf was the first in three years to be born into the dwindling population of southern resident killer whales, which number just 75.

Animal rescue teams have launched an unprecedented attempt to save another orca in the pod, called J50, who is dangerously thin due to a lack of the whales’ most common food source — Chinook salmon.

SeaWorld's killer whales Show all 10 1 / 10 SeaWorld's killer whales SeaWorld's killer whales Visitors are greeted by an Orca killer whale as they attend a show featuring the whales during a visit to the animal theme park SeaWorld in San Diego, California March 19, 2014. A California lawmaker introduced a bill to ban live performances and captive breeding of killer whales in the state, a measure that would force the SeaWorld San Diego marine theme park to end is popular "Shamu" shows. Mike Blake/Reuters SeaWorld's killer whales A trainer shows the crowd a killer whale during a show at the animal theme park SeaWorld in San Diego, California March 19, 2014. A California lawmaker introduced a bill to ban live performances and captive breeding of killer whales in the state, a measure that would force the SeaWorld San Diego marine theme park to end is popular "Shamu" shows. Mike Blake/Reuters SeaWorld's killer whales An Orca killer whale is seen underwater at the animal theme park SeaWorld in San Diego, California March 19, 2014. A California lawmaker introduced a bill to ban live performances and captive breeding of killer whales in the state, a measure that would force the SeaWorld San Diego marine theme park to end is popular "Shamu" shows. Mike Blake/Reuters SeaWorld's killer whales Visitors get a close-up view of an Orca killer whale during a visit to the animal theme park SeaWorld in San Diego, California March 19, 2014. A California lawmaker introduced a bill to ban live performances and captive breeding of killer whales in the state, a measure that would force the SeaWorld San Diego marine theme park to end is popular "Shamu" shows. Mike Blake/Reuters SeaWorld's killer whales Trainers have Orca killer whales perform for the crowd during a show at the animal theme park SeaWorld in San Diego, California March 19, 2014. A California lawmaker introduced a bill to ban live performances and captive breeding of killer whales in the state, a measure that would force the SeaWorld San Diego marine theme park to end is popular "Shamu" shows. Mike Blake/Reuters SeaWorld's killer whales Trainers have Orca killer whales perform for the crowd during a show at the animal theme park SeaWorld in San Diego, California March 19, 2014. A California lawmaker introduced a bill to ban live performances and captive breeding of killer whales in the state, a measure that would force the SeaWorld San Diego marine theme park to end is popular "Shamu" shows. Mike Blake/Reuters SeaWorld's killer whales Trainers have Orca killer whales perform for the crowd during a show at the animal theme park SeaWorld in San Diego, California March 19, 2014. A California lawmaker introduced a bill to ban live performances and captive breeding of killer whales in the state, a measure that would force the SeaWorld San Diego marine theme park to end is popular "Shamu" shows. Mike Blake/Reuters SeaWorld's killer whales Trainers have Orca killer whales perform for the crowd during a show at the animal theme park SeaWorld in San Diego, California March 19, 2014. A California lawmaker introduced a bill to ban live performances and captive breeding of killer whales in the state, a measure that would force the SeaWorld San Diego marine theme park to end is popular "Shamu" shows. Mike Blake/Reuters SeaWorld's killer whales Tillikum, a killer whale at SeaWorld amusement park, performs during the show "Believe" in Orlando, September 3, 2009. A killer whale at the SeaWorld amusement park in central Florida killed a trainer on February 24, 2010, police and company executives said. According to the Orlando Sentinel the orca involved in the incident, named Tillikum but popularly known as "Tilly," has a controversial past. Mathieu Belanger/Reuters SeaWorld's killer whales An unidentified trainer works with a killer whale during the "Believe" show at Sea World in Orlando, Florida, in this photograph taken on February 14, 2010. A killer whale at the SeaWorld amusement park in central Florida killed a trainer on February 24, 2010, police and company executives said. Picture taken February 14. Richard Baum/Reuters

On Friday, wildlife biologists loaded up two boats with live salmon and rushed to waters off Washington state’s San Juan Island, preparing if needed to test-feed the four-year-old whale.