I asked my licensed fish supplier about turtles and he confirmed Dave's statements that turtles don't do much harm, especially to risk a bad shot off the water. They do clean up the dead critters, which is good enough for me, and eliminate the weak and struggling. While I don't care for them in my pond, they are part of a natural habitat and food chain that doesn't hurt my efforts to have a good fishery. So, I'm leaving them alone....for now.