Hmmm. We don't encounter a whole lot of success turning young animals loose into the wild. They need a certain amount of tutoring to be succesful.
Also, have you ever watched that old show that used to come on in the States with Marlin Perkins? He used to send Jim out with the natives to catch this or that species. It didn't look easy. Sometimes, it would take Jim, plus four or five natives to wrestle one snake into submission. How long do you figure it would take Noah with his three sons to round up all those animals.
And complicating this problem- from your own explanation- is the fact that Noah would not only be rounding up animals per se, but taking lion cubs away from their families, bear cubs away from their mums, wolf puppies away from their packs etc. You see what I mean? You go out and try to take a Grizzly cub away from its mother and see what happens. Noah didn't even have a tranquilizer gun (as far as I can tell).
Him and his boys were obviously some hard core animal herders. Able to trek thousands of miles to get the animals they needed and bring them back. I'd reckon if we set whole nations of people doing it today with tranquilizers, planes and what not- this whole operation would take years and years and years. Something just doesn't add up there somehow. Maybe it's just me...