They aren’t being raised to be released though. They are being raised to be zoo animals. Bears raised in captivity probably aren’t well suited to surviving in the wild anyway.

>The AZA attempts to play matchmaker with polar bears by studying a number of factors, including genetics, of each one on a case-by-case basis. Through its species survival plan, the AZA is trying to stabilize the population of zoo-owned polar bears, which had plummeted to only 41 last fall after peaking out at 200 polar bears in 1995.

>There are now only 40 zoo-owned polar bears - 17 males and 23 females in the United States. They are spread out across 21 institutions, according to Allison Jungheim of the Como Park Zoo & Conservatory, who tracks captive polar bear trends for the AZA.

https://www.toledoblade.com/local/animals/2022/03/02/newest-member-of-toledo-zoo-s-arctic-encounter-exhibit-is-unveiled/stories/20220302054