The hulking, white mammal, which at approximately 46 was the oldest of the aquarium's three whales, died a day earlier after several weeks of declining health.
Aquarium veterinarian Dr. Martin Haulena said a necropsy uncovered a series of lesions and tumours. Some were benign and others were more serious and acute, likely the result of a recent and quickly spreading cancer, he said.
"Right now, the lesions are most consistent with a cancer, and that is unfortunately a disease we associate with age," Haulena told reporters Tuesday morning, standing in front of the aquarium's beluga tank.
"So we're looking at a great life for a great whale who had almost nothing wrong with her."
Further testing was planned to rule out other potential causes such as bacteria and fungi that can mimic cancer.
Haulena noted beluga whales typically live 25 to 30 years in the wild. Staff at the aquarium believe the animal was at least 46 years old and possibly closer to 50.
Kavna was captured in the wild off Churchill, Man., and became the Vancouver Aquarium's first whale in 1976. The whale was pregnant at the time and gave birth to a calf, Tuaq, which died several months later.
In the years since, the aquarium estimates more than 30 million people have seen Kavna. Among them was children's singer Raffi Cavoukian, more commonly referred to simply as Raffi.
It was a meeting with Kavna in 1979 that inspired Cavoukian's popular song "Baby Beluga," which tells the story of an imaginary beluga's life in the deep blue sea.
"It was my first time at the aquarium, and I was very fortunate that I got to be taken poolside and the trainer helped me play with Kavna," Cavoukian told The Canadian Press in an interview Tuesday.
"She was just so beautiful. She was so playful and she had a very pure spirit and you could swear she smiled at you."
Cavoukian released "Baby Beluga" the following year, with its catchy tune and whimsical lyrics etching themselves into the minds of generations of young listeners.
He last visited Kavna several years ago when he and the whale "had our second kiss." A photo taken during that visit, posted on Cavoukian's Facebook page, shows the whale lifting its nose up to the singer's face.
Cavoukian said news of Kavna's death was difficult to hear.
"I felt sad and I also felt a lot of joy for the privilege of having gotten to know her and the fact that she stirred me to write that song," he said.
Kavna was also featured on a Canadian postage stamp in 2006 to mark the aquarium's 50th anniversary.
The aquarium currently has two remaining whales in its beluga tank. Aurora, a female, was caught off Churchill, Man., in the summer of 1990. In July 1995, Aurora gave birth to female calf, Qila.
There have been three other whale deaths at the aquarium in recent years.
Last September, Tiqa, a three-year-old calf that was born at the aquarium, died of pneumonia.
In June 2010, a one-year-old calf named Nala died of an apparent infection. An examination later found a pocket in the whale's larynx contained two stones and a penny.
And in 2005, a three-year-old whale named Tuvaq died.
The aquarium also has whales on loan to other facilities. General manager Clint Wright said the aquarium plans to bring a male back to Vancouver for breeding purposes, likely after a series of renovations are complete in 2016.
Wright said keeping animals such as whales gives the public a rare opportunity to appreciate and understand the creatures.
"For many people, the Arctic is just somewhere up there, people don't really know a lot about it, and I think Kavna really brought home what the Arctic is about," said Wright.
"We believe that it's only by bringing these animals, talking about them, having great interpretation, talking about the issues that we make people aware of it. Otherwise, it's just another animal out there that people kind of know about."