The head of the Vancouver Aquarium says the sudden illness and death of two of its beluga whales over the past two weeks remains a mystery.
John Nightingale says that the cause of death could be anything from food poisoning to intentional sabotage and the staff aren't ruling anything out.
The aquarium announced the death of Aurora on Friday evening, days after she began exhibiting the same symptoms as her 21-year-old offspring Qila, who died nine days earlier.
Necropsies performed on both whales have failed to shed any light on the reason behind the deaths.
Nightingale says the aquarium has five other belugas housed at facilities across the United States but that none will be brought back until Aurora and Qila's deaths are understood.
He says plans to begin construction on expanding the beluga tank will also be put on hold.