The Calgary Zoo’s oldest animal has died.

Foggy, a 47-year-old river hippopotamus, was put down by staff Wednesday because of struggles associated with his age.

"Foggy was extremely old for a hippo and his health has been in gradual decline for several years," said area curator Jamie Dorgan.

"For years we treated his ailments to make him comfortable and continually monitored his quality of life. Sadly, the time had come when there was nothing more we could do to mitigate his many age-related ailments and we felt that his quality of life was simply not acceptable anymore."

The average life of hippos in captivity is 35 years, and even less when they live in the wild.

Foggy was born on Sept. 17, 1965, at the Houston Zoo. He arrived in Calgary on May 19, 1966. He was named "Foggy" because of the loud bellows he made, which many say sounded like a fog horn.

Foggy sired seven surviving offspring with three different mates. Three of the calves were with Sparky, the zoo’s resident female hippopotamus.

Ambassador for hippo conservation

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Foggy was put down Wednesday after staff determined his quality of life was too low because of his old age. (Calgary Zoo)

Foggy was part of the zoo’s flagship conservation outreach project called the Wechiau Community Hippo Sanctuary, which is in Ghana in West Africa.

The Calgary Zoo supported the community-based conservation initiative since it was created in 1999.

It protects the hippos and ecosystem in the area and also provides the Wechiau-area inhabitants with a source of revenue and improved quality of life.

The hippo population along a stretch of river in the area is one of two remaining hippo populations in Ghana.

The Calgary Zoo is now working to bring in another hippo.

People interested in dropping off cards and gifts for Foggy can do so at the zoo's guest relations desk. The zoo is also encouraging people to upload their photos of Foggy on its Facebook page.