Collecting them from the wild is exactly why the Box Turtles and several of people's favorite tortoises went into decline. So santoury is actually right. The decline would impact them if everyone collect turtles like you do, which a lot of people do. This is why in Canada, most of the provinces banned collecting wild herptiles without a research permit, we don't want to repeat the mistake of what Americans did to their turtle species.
The whole concept of captive-bred is to reduce the impact on the wildlife by making them avaliable in the pet trade by breeding them so people won't have to harvest them. Do you think if we didn't breed Bearded Dragons, they would be so cheap or have to rely on the export of Australian herptiles, which is illegal? Smuggled Australian herptiles cost a lot of money -- sometimes up to the several thousands and million ranges.
Reptiles are adapted species; they have survived for millions of years. They really don't need our help, and what they really need is less human intervention. If they really thought their environment is not for them, they would had up and migrate to another area. Read up on the concept of microenvironment and microclimate and how animals choose and move toward those zones before deciding to rescue animals.
Either way, even though I would like to tell you put it back where you found it... I cannot actually force you to do it, only shun you. So I hope you will make the right decision, if not -- the best luck to turtles.