well, cultured pearls are still based off a captive population of oysters/mussels collected from the wild.
They are given a safe haven to live and breed, with an irritant inserted that does not affect any biological functions. As a pearl takes ages to grow to marketable size, a lot of them live longer than they would in the wild, and all of them wouldn't even know the difference. Also, meat/shells are reuseable. Shells go into the production of lime, and meat is sold as food/animal feed.
So, its debatable as to wild or cultured is more cruel. How do they determine if a wild oyster has a peal in it anyway?