Four of the whales who died at Shedd had been moved from Marineland in Ontario. The fifth, Beethoven, was a resident whale. Among the rescued whales who died were Peekachu, 23, on Aug. 25; Rain, 20, on Sept. 2; Osiris, 26, on Sept. 21; and Caspian, 27, on Oct. 7. Rain had a poor appetite and a longstanding digestive inflammation, Shedd staff have said.

The deaths came after five aquariums agreed to take in 30 belugas from Marineland, which had threatened to euthanize the animals, saying it could no longer afford their care. Since the transfers, six Marineland whales have died: four at Shedd, one at SeaWorld San Diego and one at Oceanogràfic Valencia in Spain. Six of the rescued whales — Acadia, Gimli, Lillooet, Secord, Sierra and Yukon — remain at Shedd.

Coughlin said Shedd began assessing the situation in January, sending staff to Marineland to review records, observe the whales and work with the facility’s staff. She said the aquarium’s teams have made multiple visits and stayed in contact by phone and video calls. Shedd spokesperson Johnny Ford said the collaboration with Marineland veterinarians and animal-care workers lasted seven months before the rescue and continued after the whales arrived.

“We have been truly rescuing these animals since January,” Coughlin said. “So while to many it might have seemed recent, this has been a really diligent, multi-step process.”

Alysha Tullio, a former Marineland trainer who worked there for four years and led care for two whales now at Shedd, said the transfer and deaths have been devastating for former staff. She said she was especially concerned that Shedd did not seek advice from the people who had worked closely with the whales, including Rain’s care team.

“I knew Rain would have a harder time with being moved to a different facility because … she was very particular in who she chose as her people,” Tullio said. She learned of Rain’s death from her former supervisor, she said, and has not felt ready to look for another job.

Ford said Shedd contacted Marineland supervisors first when sharing news of the deaths, expecting them to inform former team members. He said the aquarium wanted to give those workers time and consideration because it knew the news would be painful.

Animal-rights advocates have questioned the decision to move the whales and argue that the deaths underscore the need to end captive whale breeding and phase out keeping whales in tanks. Coughlin said decisions about the animals’ future should be guided by ongoing science, while staff concentrate on their immediate care. She said Sierra is receiving eyedrops and Secord is being encouraged to eat a more varied diet.

Shedd says the six surviving rescued whales are making progress, including consistently eating their full daily diets. They remain mostly separate from the aquarium’s resident belugas, and Shedd has not set a date for when visitors will see the newcomers. The aquarium’s animal-behavior and training director, Charlie Jacobsma, said introductions would proceed at the whales’ pace and that staff were seeing promising signs.

The debate comes as Shedd undertakes a $300 million renovation expected to be completed in 2028. Asked whether whale deaths had unsettled donors, Coughlin said the concern she had heard was about staff and the six surviving rescued animals. Abbott Laboratories, whose name is on Shedd’s Oceanarium, declined to comment.