I have also heard the rumors that the DNR removed adult fish to plant into other lake years ago. I heard that a few locals had gone as far as to threaten to dynamite the Pike River Dam if that practice did not stop! I have never heard any proof either way on that report.
I assume that fry are planted into lakes that they cannot reproduce in to give fishermen in the area of those lakes the chance to fish for walleyes. Most lakes that the walleyes can reproduce in naturally usually do not require yearly planting to maintain a fishable walleye population.
The DNR quit milking walleyes early because they had no demand for fry elsewhere in the state.
They very seldom try to fill all of the egg batteries in the hatchery anyway.