I have to say I raised ducks for years and observed the same behavior . The ducks are smarter than folks give them credit for . I would bet there is snappers in the pond set some jugs with with 6-10 ' of block line and hooks with chicken necks ( they stay on good ) . Those critters love cloudy water because they can sneak up on their prey . There's two different kinds regular snappers that can grow very large and Alligator snappers . I don't know off hand what, or both types are in your area . I have trapped many in my day in fact where I live I have to clean 6 - 10 of them out every year . I just got one yesterday . When they lay eggs, they lay many . Good luck ! Good turtle fishing . As soon as you catch them out, don't ask me how, but the ducks will return to the pond . 
