Thinks about this gent and his elephants. In the wild there are rainy and dry seasons. Wild elephants have good memories and they know where then need to go to find things like water, food, and mud which they need to survive. How will elephants which have lived in captivity, often for most of their lives, be able to know these things when they get released into the wild.
My fish pretty much all know when food is coming. They almost all (except plecos) assume their feeding positions when they believe it is. These fish have been in my tanks for years, some for closer to 18 years. If I released them into the wild I wonder if they would be able to find food. I doubt they would know what predators or situations to avoid.