One fall my fishing buddy and i found the same thing where one small area was productive. The area was near near a stump and tag alders laying in the water . We hit it from every angle but only one 5 inch area between two limbs brought crappie. There had to be a substantial pocket under there although it was not evident from the surface because we caught 14 crappies out of it. at the end of the crappies we also caught 2 nice sized bass and a catfish who where undoubtely drawn to the area by all of the commotion