A polar bear died at Sea World theme park, Queensland, Australia, on Saturday night.

The exact reason for Liya's, the 19-year-old polar bear, death was not known. The female polar bear was born in Russia and was transported to Sea World as part of an international breeding program back in 2001. She was also a mother of two cubs named Mishka and Henry.

In a Facebook post, Sea World management said they "were deeply saddened by the death of the much-loved polar bear." They also added that the animals at the park were like family to them and that Liya would be greatly missed.

“Liya lived a long and enriched life at Sea World and her legacy to the ongoing conservation and education efforts of Polar Bears will continue through her cubs, Mishka, who lives on the Gold Coast and Henry, who lives in Canada. In her 18 years at Sea World, she has helped generations of park guests gain a better appreciation for polar bears and the marine environment,” the post read.

The head of marine sciences at the park, Wayne Phillips, said Liya was coping fine and her death was unexpected.

"We're proud that Liya lived a full and enriched life here at Sea World and that her public awareness that she gave to millions and millions of visitors over the years is a legacy that we'd like to continue," Phillips said adding that the theme park does not plan on replacing Liya yet as they currently have three other polar bears.

Liya was the first polar bear to give birth in Australia and had been at the Sea World theme park for nearly two decades. She was also one of the only four polar bears in the country.

Polar bears can reportedly live up to the age of 20 to 30 years. However, only a small percentage of them live past the age of 15 to 18.

A polar bear tests the strength of thin sea ice. Mario Hoppmann/imaggeo.egu.eu