Some animals can be kept in captivity well. Dolphins no, but tigers, bears, zebra and the like can do very well. Work with animals in the wild. Learn the misery that is thier "natural" life before making some high-minded judgement about fences. See how many ticks live on a wild lion's face, what starvation means. Zoos are hard, very expensive, but can be ethical. They can give some animals a good life and by doing so fill a social purpose.
Be afraid of a world without zoos. Look at what happens to people who never see animals. Talk to anyone who grew up without dogs. They have all sorts of misconceptions. Zoo animals represent the wild. They manifest our nebulous ideas about wildlife and wild spaces. Without them our kids will too easily dismiss wild nature. To demonstate to kids that wild animals have the right to exist we need to first show them how they actually exist. Nothing does that so well as seeing the wild in the flesh.
Be afraid of a world without zoos. Look at what happens to people who never see animals. Talk to anyone who grew up without dogs. They have all sorts of misconceptions. Zoo animals represent the wild. They manifest our nebulous ideas about wildlife and wild spaces. Without them our kids will too easily dismiss wild nature. To demonstate to kids that wild animals have the right to exist we need to first show them how they actually exist. Nothing does that so well as seeing the wild in the flesh.