Gary,
Question: What kind of shallows does this pond have? Do you walk the entire bank of this 4 1/2-acre pond looking for evidence of bass? Do you fish the entire lake from the bank or from a boat? Are there shallow underwater islands in the middle of this lake where spawning may happen unnoticed?
Another thought that has not come up is: Hire someone to survey your pond. They will come in and Electro shock and let you know what you've got going.
Be sure to get into a Johnboat and tool around and fish a wider area.
Also, If you�re in hill country, it�s likely you have a lot of contour in your 4 1/2-acre lake. Get a depth finder and survey points and ridges that are underwater. Bass orientated in shallows close to deeper water. So underwater ridges, points, etc are good fishing locations. Think about building a dock out into the lake. Bass love to vertically orientate on pilings.
Do you have large trees growing at the bank's edge? If so, consider cutting several down so as to fall into the water. The sumerged tops are prime bass habitat. If you don�t have any big bank tree, try sinking a lot of Xmas trees in a spot you can cast too from the bank. This may bring the sows in closer. It will certainly be a hotel for the small fry, minnows, and juvenile fish.
I personally think you�ve got bass and big ones to boot. I just think that 100 to start where too few and the forage is so good that by daylight 00:30, these ole boys have had breakfast and are lounging.
So, let us know more about your fishing techniques. This is an interesting issue!!!