yes have seen that happen MANY times and we agree on that part. However also have seen it not happen many times (and not as often as many fear) the bass that are there are like none other. The gizzards ahd are for the most part 9-12 inches with only an occasional one over 14 inches. One exampleis alke that they claim has had gizzard shad for over 20 years and not even well managed. BTW I like that last pic I think that was our fish we brought to you.
One example is the lake you came to for the PB GA meeting. Lake Sovereign was killed off. Before many fish were stocked gizzard shad found their way in via entry creek. That was 5 years ago and they are just now getting to average 12 inches and they have monster bass. This to me is a worst case study they got there before any bass much less like we recommend stocking them after the year 3-4 or high% of bass over 18 inches. In this case it is sad and the fishery will go down hill soon but in the mean time they enjoy the large bass and crappie and they norhtenr bass we stocked to help keep the GZ in check.