Here is an accidental anecdotal experience with adding gizzards to a 3 acre lbm/BG/crappie pond.
This pond was on our farm when we bought it, and had been stocked with the above fish by the previous owner. Mud bottom, pretty shallow, in the middle of row crop land. Lots of skinny 10-14" bass, small crappies, poor bluegill population, just as one would expect. I did not try to manage it in any way, and the fishing didn't change for several years. Although it is 40 feet above the Duck river, it flooded in 2010--introducing a large number of gizzards. Now, 7 years later, it still has lots of crappies with some nice ones to 14", what appears to be a healthy gizzard population, and really nice LMB--we frequently catch 4-5# fish, and they look healthy. I have caught several nice bass with gizzard tails coming out of their throats, especially on warm days in the very early spring. The water stays quite muddy, and I have wondered if this is helpful to the bass in their predation of the gizzards.
It is certainly possible that the fishing will fall off as more biomass gets concentrated in very large gizzards, but hasn't happened yet; this has been the best fishing year we've had so far.
I am absolutely not suggesting to anyone that they add gizzards to any body of water, large or small, and would never have put the gizzards in this pond myself. But is has been interesting, and fun, to see how they've done, and it certainly has made a huge difference in the fishing.
