Snipe- That�s incredible that such old bass could be so small, and also all die at the same time. I once heard Bob Lusk say that every bass has a limited number of heartbeats, so it makes sense they could all die at the same time if they�re the same age.
Mike- I would definitely find it strange if the �new guy� was able to conquer the prime feeding spot from the established fish. Since you caught all 3 earlier this year, it is possible that the bass are simply avoiding you, since they associate you with a hook to the mouth. My bass have definitely become much more wary of human presence since getting caught. My main concern would be the possibility of other humans having caught and taken your bass, if your pond is somewhat �unsecure� However, the only way to really know is to see or catch them again, but obviously you don�t want to stress and kill the very fish you are worried about (especially since you have already named them) One option might be removing the hooks from a crankbait and seeing if you get a bite. But if you have much aquatic vegation, It will be hard to discern that from a bite since the fish will spit or have the bait yanked. A topwater frog or popper with the hooks removed would be a good way, as long as #4 doesn�t just hit it repeatedly. Obviously you still won�t kbow the fish aren�t there if you don�t get a bite, but you will know if you do get a bite. Might be worth trying, I know I am constantly worrying about my fish when I shouldn�t.