Wellington Zoo has defended plans to have more African lions at some point in the future.
This morning, 20-year-old lioness sisters Djane and Zahra have been euthanised.
Djane's health was precarious - and it was decided Zahra couldn't be alone.
The pair have been at Wellington Zoo since 2002.
Wellington Zoo chief executive Karen Fifield told Heather du Plessis-Allan that they are all hurting after the decision.
On replacing the pair, she says they are part of the global breeding programme.
"Lion populations are in trouble, and they are regarded as vulnerable."
Fifield says that their lions will come from other zoos rather than being pulled from the wild.
She says that lions live longer in captivity, and get regular medical care.
"Lions live in the wild for 10-15 years, and our lions would have been 20-years-old."