The Georgia Aquarium has released the results of a necropsy performed on Ralph, one of its resident whale sharks. The giant fish died on Jan. 12 after several days of not eating.
"Findings show that Ralph's stomach appeared abnormal, because it was thin-walled and perforated. This likely caused peritonitis, which led to Ralph's death," said Jeff Swanagan, the aquarium's executive director, in a news release. Peritonitis is an inflammation of an abdominal membrane.
Swanagan noted that physical examinations on the aquarium's other male whale shark, Norton, have not revealed the same condition.
The release pointed to a series of treatments conducted last year on the animals' enclosure to suppress an external parasite, a leech often found on aquatic animals.
"This treatment has been commonly used in both professional and home aquariums for many years," Swanagan said. Scientists noticed, after several treatments in the Ocean Voyager exhibit where the whale sharks are kept in Atlanta, that the appetites of Ralph and Norton were on the decline, and that they eventually stopped eating.
Alice and Trixie, the aquarium's two female whale sharks, were not exposed to the same number of treatments and have not shown the same behavior.
"There is no evidence that anything in the Ocean Voyager's environment led to Ralph's death," said Swanagan. He added that environmental conditions in the aquarium's exhibits are closely monitored and the Georgia Aquarium is engineered to support the collection as it grows and matures.
The whale shark is the world's largest fish, sometimes reaching up to 50 feet in length and weighing several tons. Since the aquarium opened in November 2005, more than 4 million U.S. and international guests have viewed the whale sharks, increasing the public's awareness of and appreciation for these animals, about which very little is known.