It's funny you wrote that. I've actually wondered if we have a "turtle problem" in this state, or at least in Union County. So many of the little ponds I fish are just simply infested with them. The majority of them are the red-ear and yellow-belly sliders, which although abundant in NJ, are not native. They're the "China Town" turtles that I'm sure people keep for a few months and let go. If you go to Meisel Ave. park in late June or July the place is literally filled with them. They have no natural predators, and if they keep reproducing and people keep letting them go, then there is really nothing to control the population.
http://www.nj.gov/dep/fgw/ensp/pdf/s...red_slider.pdf