You log onto an international forum, which means that half the people are either working or gone to bed, and you expect an answer within 15 minutes?
There are so many aspects to it that I have no clue what you already thought of and what not...
The pro's that you mentioned are multifaceted;
- Conservation
There's in-situ and ex-situ conservation. Many zoos raise money for projects abroad, and also raise awarenes for those projects in their zoos. Same animals are ambassadors for their species, and some species are just used to save the habitat of an impopular species. Many zoo's have breeding programmes set up for endangered species and there have been releases back into the wild in a few specific cases (Bongo and arabian Oryx spring to mind). There have even been species saved, just by keeping them in zoos (like some of the partula snail species ZSL hold).
- Education means learning that the animal exists in the first place, but also tries to teach people how their status is in the wild, what habitat they live in and how their habitat is doing. Usually they also show some of it's peculiar habits or weird foods.
The cons;
Keeping animals in confined spaces is animal cruelty. Many aspects have been covered; - Some social animals are not allowed to be kept in their normal social structure
- Some solitairy animals are kept together in a confined space.
- They are not usually not allowed their normal diet,
- given their normal roaming space (territory)
- and given their normal day pattern.
- They are sometimes held with other species or in close proximity to predators giving them stress.
Many breeding programmes are useless;
- Many times subspecies are mixed together, making it unwise to put them back into the wild because they are not pure-bred.
- Many programs are run for species who are not threatened and are not likely to be in the near future.
- When you reïntroduce them they might bring in a disease to an otherwise healthy population.
- The main reason species are in decline is because of habitat destruction, where are you ever going to release animals?
- Many programs are set up on a VERY small genetic base, making the captive-raised animals prone to genetic disease or vulnerable to other infections.
- For many species there isn't enough space in zoos to keep a genetically healthy population
Many animals, specifically reptiles and fish but also some birds are still bought by zoos keeping the trade in them alive.
ISIS restricts the movement of animals, UNLESS they are captive-born. That means that any zoo could sell their own bred animals to anyone that has a permit (which is not necessary in some countries/states) and many more shabby zoos have no hesitation to sell a lion or two, keeping that trade alive as well.
There's so much more i have forgotten, but theres a start...