Shedd Beluga Dies from Blood-Borne Bacteria

Immiayuk, the beluga whale who last year became the first captive member of her species to give birth successfully, died at the Shedd Aquarium in Chicago on Dec. 26. She was almost 10 years old.

Following the whale's death, aquarium officials confirmed that the whale died from acute septicemic (blood-borne) bacterial infection. The disease, erysipelas (AIR-eh-SIP-el-us), is caused by a bacterium that occurs in fish, mammals and birds and affects whales and dolphins both in the ocean and in zoos and aquariums.

According to Vice President of Research and Veterinary Services Jeff Boehm, the bacteria that cause the disease grows so quickly, that Immiayuk's death occurred less than a day after trainers noted the first subtle changes in her behavior. The result, Boehm said, was a sense of shock among trainers and veterinarians who knew the whale well.

"It was especially difficult for our staff because of its sudden onset," said Boehm. "The course of this disease is so swift and the symptoms typically are not visible until the animal is near death, making it difficult to detect in time to treat effectively."

Boehm said that the bacteria that causes erysipelas is naturally found in healthy fish, so it is probable that the infection came from fish Immiayuk ate. He added that this because this bacterium survives freezing, and, because it does not affect the fish themselves, no visible evidence can be seen of its presence.

Ken Ramirez, the aquarium's director of husbandry and training, said his employer uses only restaurant-quality fish with high nutritional value. Ramirez says that trainers inspected every fish several times for damage or physical defects before the whales and dolphins eat it. These trainers prepare food for the Aquarium's animals in an immaculate area that is cleaned and disinfected several times daily.

Since Immiayuk's death, trainers have been extra-careful in inspecting the fish they use to feed their animals. This disease is not contagious from one whale to another, and all of the animals continue to receive regular medical exams. So far, none of the other animals have showed signs of contracting the disease.

"While this is a very sad time for us, we are encouraged that all the whales are interacting and behaving normally," Ramirez said, adding that Kayavak, Immiayuk's six-month-old calf, is progressing well. "Through study, and interactions with scientists at other aquariums around the world, we hope to understand why whales and dolphins are so susceptible to this deadly disease, and develop tools to help us prevent or control its occurrences."

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