I don't see nearly the number of turtles that I used to. Could trapping be the reason? I haven't encounter any turtle traps on my local lakes, but I'm not sure what they look like. It's evidently done in a good part of the US as the below link suggests.

http://usatoday30.usatoday.com/news/nation/environment/2009-07-19-turtle-hunt_N.htm