Assuming you’ve never actually caught a big bass in your pond or had the pleasure of watching one leap through the air after a tasty insect, you’ll need to do some detective work to know for sure and to find out why they may be absent. Go out for a few days of fishing several times over a year, in different conditions, and with appropriate baits for a variety of fish and keep careful records of the size, weight and condition of everything you catch. If your rate of catch is high but your bass haul consists almost exclusively of specimens in the 8-12 inch range while bluegill and other prey fish are on the larger side, you have an overpopulation of small bass. You may notice that the fish you catch are thin as well. Ponds loaded with these stunted specimens will never grow large bass because available food is distributed among too many fish, allowing none to flourish and grow large. In this case, your most effective strategy is to remove as many small bass as possible. Harvest aggressively and discard all bass smaller than 12” so that more food is available for the population that remains. Given a few years, you’ll begin to see the big healthy catches you’re hoping for.
On the other hand, if there are zero bluegills in your haul, your pond has a significant food shortage and the situation requires immediate attention. Similarly, if you catch only small bass and large bluegills, you’re seeing a situation where the young bass are consuming 100% of the smaller bluegills. This removes competition for food among the bluegills, leaving the survivors to grow unchecked, while the bass are too small to eat them. This situation also demands attention since your bass cannot survive or grow without prey. Try introducing about 200 juvenile (at least 4 inches long) bluegills per acre in this situation and aggressively harvest the smaller bass to reduce population pressure, and allow the bluegills to grow undisturbed for at least 2 years. Avoid hybrid bluegills, which do not reproduce effectively. You want your bluegill to produce lots of fry and fingerlings for your bass to feast upon, while leaving enough to mature and reproduce. If you have an overpopulation of small bass, you have a lot of fishing in your future, but you’ll also need patience. It takes time for populations to adjust and for fish to grow. In fact, it may take several years to get the results you want, but the destination is surely worth the drive