@Laughing Dove: I suppose you are not completely against animals in captivity. So why are cetaceans an exception for you? Why is it okay to keep migratory birds in zoos (and cut some of them their feathers, so they are not able to fly)? Or tropical fishes, amphibians or reptiles under artifical light only? Why is it okay that cats and dogs are kept in an appartement, although most of them would be able to survive outside and with no human help?
In my opinion, every kind of animal CAN be kept in captivity. The point is the quality of the exhibit and the quality how they ar kept (means: giving them as many of their needs as possible). In this case, good surrogates should be allowed, also when you think that in the wild many animals show adaption skills of changing environmental conditions.