Keepers tend to aging marine mammal's complex needs as he nears his 27th birthday
Eye drops twice a day, meds concealed inside fishy treats, Adequan injections to ease an arthritic shoulder — it's all routine stuff for Gus, the Oregon Zoo's ultra-geriatric Steller sea lion, who at nearly 27 may be the oldest male of his species on the planet.
In the wild, male sea lions seldom live past the age of 18, according to marine biologists — and Gus, just one week shy of his 27th birthday, is noticeably slowing down.
"Gus is the oldest male Steller sea lion in any North American zoo or aquarium, and he could be the oldest in the world," said animal curator Amy Cutting, who oversees the zoo's North America and marine life sections. "It's not surprising that he's less active now. His remarkable age says a lot about how tough he is and the quality of care he's received."
Gus was born Aug. 11, 1987, and came to Portland from Connecticut's Mystic Aquarium in 2000, when the zoo opened its Steller Cove marine-life habitat. Animal-care staff have been monitoring him closely for several years and treating him for a variety of age-related ailments.
"He has an arthritic shoulder joint, which is probably getting more uncomfortable as he ages," Cutting said. "It's also molting season right now for Stellers, where they shed and replace their entire coat, so that can make a body pretty cranky as well."
To help ease arthritis discomfort, Gus's target weight has been lowered by about 40 pounds, making it easier for him to hoist his 1,000-pound body out of the water — especially during molting season, when pinnipeds typically are less motivated to work.
In 2012, Gus was included in an Oregonian article about elderly Oregon Zoo inhabitants that highlighted ways keepers and veterinary staff care for animals approaching the end of life. And over the past 15 months, the zoo's animal-care staff and management have had three meetings about Gus's quality of life.
"We are closely monitoring Gus's condition and hoping he perks up when his molt is complete this fall," Cutting said. "But with such an elderly animal we are realistic in our expectations. We will see him through this and do our best to make decisions regarding his welfare that are in his best interest. It is not an easy time for staff, but they see quality-of-life management as an important part of the lifelong care they provide to animals at the zoo."
For now, Cutting says, Gus is running the show: letting his keepers know what he wants to do — and what he doesn't.
"As Gus has aged, his activity level has decreased, and certain behaviors have become less easy or less comfortable for him," said Nicole Nicassio-Hiskey, the zoo's senior marine life keeper, who has worked with Gus for more than 12 years. "It is very important that he continues to move and use his muscles daily. He is still doing a great job of removing most of the fish from enrichment devices. His comfort is our first priority."