A female polar bear cub has died at Sea World a fortnight after being born at the Gold Coast theme park.
The cub was one of two born to 16-year-old Liya last month, and died on Saturday just hours after staff had retrieved it from a den amid growing concerns about its health.
Staff monitoring the bears noticed on Thursday the smaller of the two cubs had stopped growing at a healthy rate while the mother bear began focusing her attention on the other cub.
Staff used night-vision goggles and tongs to retrieve the ailing cub on Saturday morning but it died later that evening.
Such behaviour is not uncommon for polar bear mothers, as more than 50 per cent of cubs born in captivity die within a month according to polar bear experts.
In 2013, Liya gave birth to twin bear cubs but only one, Henry, survived.
Sea World director of marine sciences Trevor Long says the bear's sex makes its death particularly tragic however.
"It was a little girl which is even more sad because that little girl could have contributed to the breeding program," Mr Long said.
While Sea World staff were "saddened" by the cub's death, Mr Long said the mother bear was showing positive maternal behaviours towards the second, larger cub.
"The team are continuing to carefully observe Liya and the cub 24 hours a day through state-of-the-art monitoring systems and we remain cautiously optimistic for the welfare of the cub during this extremely critical period," he said.
The cub's death has prompted criticism from animal welfare group PETA, who issued a statement calling for Sea World's captive breeding program to be abolished.
"Conservation is about preserving natural habitats and protecting species in nature, not breeding more animals to live in glass boxes," PETA's Ashley Fruno said.
"This should be a wake-up call to Sea World, which must make the humane decision to stop breeding polar bears for human profit."
