It says Cyprus had been doing well since his arrival, eating consistently and interacting with his trainers and animal care team, along with two other rescued belugas.
But it notes belugas can mask discomfort or underlying concerns that are not immediately visible, and it says a full necropsy will be conducted.
Marineland in Niagara Falls, Ont., had said it was running out of money and could no longer care for the last captive whales and dolphins in Canada, and 30 of its belugas and four dolphins were transferred to other facilities in a mass relocation effort.
SeaWorld San Diego says the other rescued belugas in its care are in stable health and remain under close monitoring as they continue to adjust to their surroundings.
"As we have indicated, this process will take a considerable amount of time. Our commitment to the health, well-being and care of these belugas, like every animal we rescue, continues," the facility said in its social media post on Sunday.
It said that after the necropsy is completed, the cause of Cyprus's death will be shared with the National Oceanic and Atmospheric Administration.
Less than two weeks ago, Shedd Aquarium in Chicago said Caspian, a 27-year-old female beluga that was relocated from Marineland, died despite efforts to save her.
Caspian had not been eating properly and blood samples showed abnormalities in her electrolyte levels, Shedd said.
Shedd said it performed necropsies on Peekachu and Rain, two other Marineland whales that died there, and concluded that they had chronic, pre-existing diseases.
A beluga named Jelly Bean and a dolphin named Echo also died at Oceanografic Valencia in Spain after the move.
This report by The Canadian Press was first published Oct. 18, 2026.
Copyright 2026, The Canadian Press. All rights reserved.
