My guess is that somebody took out way too many bass, letting the bluegill, green sunfish, and crappie get out of control. Especially the crappie, but to a certain extent, the green sunfish, are probably taking out the year-of-young bass.
You probably have a couple of choices. None are quick.
One is to completely kill the pond and start over.
The second is to add a lot of large bass, but they may not be able to overcome large populations of crappie and green sunfish.
In your part of the country, is there any chance you could plant a small number of hybrid (tiger) musky? They won't reproduce, but they can do a pretty good job of cleanup on what is in the pond. You would just have to have a plan to get them out of the pond, or they will become the top predator, and you still won't have bass.
Definitely give Bob a call. I believe he can make some good suggestions on getting your fish population under control.
