Veterinarians are seeking a new home for Astro, the young sea lion who crashed a walk-a-thon last week and completed one lap in the elementary school fundraiser.
But caregivers fear it will be tough to find a zoo or aquarium to accept the 11-month-old, 165-pound marine mammal, who has been bottle-fed for most of his life and keeps returning to civilization despite attempts to set him free.
Astro is expected to grow into a territorial, 11-foot long, 2,500-pound bull. Few zoos and aquariums are equipped to keep endangered Steller sea lions.
Astro was swimming in the shallow San Francisco Bay on Friday and apparently noticed children doing laps around a course at the Marin Country Day School in Corte Madera, about 15 miles north of San Francisco. He waddled ashore, completed a lap and starred in the school's photos and videos.
Since then he's been at the Marin Mammal Center in the Marin Headlands, but he hasn't eaten and has lost as much as 20 pounds.
"He's swung backward a little bit in health," Jim Oswald, spokesman for the Marine Mammal Center, said Tuesday.
The center is keeping Astro in secluded outdoor pens and pools, away from humans. Only his vets may visit.
In June, Astro's mother abandoned him at Ano Nuevo Island off the San Mateo County coast, the Steller's southernmost range. The species extends north to the coast of Russia and Alaska.
Stellers are near the top of the marine food chain, and it's unclear whether the mother died or orphaned the 39-pound pup. Astro still had his umbilical cord attached when biologists spotted him and took him to the Marine Mammal Center.
After months of bottle feeding, Astro practiced catching fish in a big pool. But he would only track trout — not herring, a Steller staple in the wild.
Back in time for the walk-a-thon
The Marine Mammal Center released the adolescent April 25 with a radio tag. He greeted elephant seals and meandered between Point Reyes and the Farallon Islands, 27 miles from San Francisco.
About a week ago he returned, swimming under the Golden Gate Bridge to the shores of Corte Madera. The Marine Mammal Center again picked him up and released him in the Farallons.
He returned again Friday, just in time for the walk-a-thon. The center has given up on the idea of Astro living in the wild.
"We just want him to get back to a somewhat normal state and a normal feeding schedule before they send him to the zoo," Oswald said.