ive caught more turtles on trot lines then i can remember, Id say setup a trot line but use a bait that turtles will eat and fish dont like. the trick would be finding a bait that fish wont go after just the turtles. maybe chunks of chicken, but even that might attract a catfish or two. or set the trot line shallow enough so only the turtles can get to the bait. good luck.