i don't know enough about Taronga, so I won't speak about it, but I will stand up for Zoos Victoria here:
Firstly, (as has been said previously on this thread), Zoos Victoria are the entity with the power to undertake conservation programs (not Melbourne Zoo, or WORZ - they are just branches of the larger organization).
Zoos Victoria are actively trying to protect 27 different Australian native species - here they are:
1. Alpine She-oak Skink
2. Baw Baw Frog
3. Brush Tailed Rock Wallaby
4. Eastern Barred Bandicoot
5. Giant Burrowing Frog
6. Golden Rayed Blue Butterfly
7. Grassland Earless Dragon
8. Guthega Skink
9. Helmeted Honeyeater
10. Key's Matchstick Grasshopper
11. Large Brown Tree Frog
12. Leadbeaters Possum
13. Lord Howe Stick Insect
14. Mallee Emu Wren
15. Mountain Pygmy Possum
16. Northern Corroboree Frog
17. Orange Bellied Parrot
18. Plains Wanderer
19. New Holland Mouse
20. Regent Honeyeater
21. Smoky Mouse
22. Southern Bent Wing Bat
23. Southern Corroboree Frog
24. Spotted Tree Frog
25. Southern Barred Frog
26. Swift Parrot
27. Tasmanian Devil
Here is a link about this on the ZV website too:
Local threatened species (zoo.org.au)
When I went to look this list up, I had thought there were 20 species on it - as there were around 10 years ago, but now that list is at 27.... (that's 7 more than 10 years ago).
On top of that, you can throw in the breeding work they are doing with:
28. Oryx
29. Prezwalski Horse
30. Asian Elephant
31. White Rhino
32. Snow Leopard
33. Gorilla
(just to name a few that I can think of off the top of my head)
Add in the conservation campaigns over the years ("They're calling on you", "Don't palm us off", "Beads for Wildlife" to name a few).
What more does Zoos Victoria have to do??? Rewild the entire world? Plant 2 billion trees? Breed 1000 white rhinos and put them back into the wild?
I understand that people on here don't like the fact that Melbourne Zoo display less species than they did 30, 20 or even 10 years ago - but MZ are not about displaying a lot of species - they are NOT a traditional zoo in that sense: Zoos Victoria is a "Zoo based CONSERVATION ORGANISATION" - this is how this organization see themselves and define themselves. Their moto is "Fighting Extinction" - this is what they are about.
If you don't like this approach, then fair enough - they aren't the zoo(s) for you. However, to suggest that this organization doesn't do much for conservation is simply a ridiculous suggestion.