5444, the forum is fixed, can you repost the picture from your post above?
The 'wake' you see in the pond is not a turtle. Concern you may have a predator already (LMB?) You should soak a minnow trap, or make your own, or try to set up a seine net in the shallows and catch some minnows. Put the biggest minnow under a bobber and catch that cruising predator and let us know what it is! IF you have LMB already then your plan for stocking crayfish may be able to change a bit early.