(CNN) — The world lost one of its oldest penguins over the weekend at the Oregon Zoo. Mochica, known as Mo, was 31 years old. He was America's oldest male Humboldt penguin and lived his entire life at the zoo in Portland until he was euthanized Saturday because of old-age ailments.
"He had a mature cataract in one eye, old-age haze in the other, bilateral arthritis in his hips," said Travis Koons, who oversees the zoo's bird population. "He was just a very old bird. It was hard for him to see, and at times difficult for him to walk."
Hatched on July 6, 1990, Mo enjoyed spending time with people and often chose hanging out in the keepers' quarters over the companionship of his bird friends.
"It was pretty common to walk into the keeper kitchen area and find Mo 'helping' with the food prep or just hanging out with care staff there," Koons said.
Mo was the oldest male of his species in any North American zoo or aquarium and perhaps the whole world, Koons said.
His species, wild Humboldt, rarely live past the age of 20, the zoo said in a news release.
"It's an incredibly sad day for his care team and for everyone who spent time with this amazing bird," Koons said. "We've all had times in our lives where animals have left an indelible mark on our hearts. Mochica has done that for thousands of people. He inspired generations."
Humboldt penguins are native to South America and are protected by the U.S. Endangered Species Act. The overfishing of their prey as well as getting tangled in fishing nets threaten their population.
According to the zoo, the Humboldt species are the most vulnerable penguins, with an estimated population of 12,000 breeding pairs.
"Humboldt penguins live in a region that's greatly affected by human activity," Koons said. "They need healthy ocean habitats to thrive, and we can help make a difference -- even in simple ways like downloading the Seafood Watch app and choosing sustainable seafood."