Caretakers at Chicago's Shedd Aquarium say they have euthanized a 13-year-old male California sea lion named Otis.
Aquarium officials say they made the decision after the sea lion showed a rapid decline in health due to progressive urogenital cancer. Otis came to the Shedd Aquarium in 2009 as part of a program to relocate sea lions from the Bonneville Dam in Washington state. Dozens of sea lions were endangering fish stocks in the Columbia River.
Veterinarians say Otis started losing his appetite and showing signs of lethargy a few weeks ago. He was euthanized last week. Shedd Aquarium animal care and training vice president Ken Ramirez said euthanizing the sea lion was a "difficult but necessary decision."
Shedd has two other male California sea lions named Biff and Tyler.