while all that may be true herons fish in very shallow water and I have a hard time believing those areas 12" or less right at the bank are that full of trout. All things are possible, but that doesn't make them common or consistent.
Back in September we watched and eagle light on a small bar across from us, probably 100yds<>. He went a few feet out on a log and within a couple of minutes had a meal. Not sure what it was, but about 6" and probably not a trout. he ate it and then returned to his perch, but after a long wait he went back to the bar and then to the upper end and started his vigil all over. He stayed about and hour and then gave up and went up river. He replaced a heron that spent a could of hours in the area and went hungry.
For all whose waters have been decimated by herons, Taney, Bennett and the Niangua are still healthy and they're cooking more to replace them.