I didn't want to bog the article down with too many stats but:

Research by Cornell University indicates that 15 times as many bluegills as bass can and should be harvested. Here's a synopsis of some stats. The average bass/bluegill pond can support annual harvests of only about eleven adult bass per acre. Bass and bluegill are predators and cannibalistic. Large fish eat smaller fish; females and the smallest fish consume eggs. Bass eat bluegill. If they eat most of the bluegill before they reach 2 to 4 inches in length there is not enough food for the medium-sized bass and they can’t grow to larger sizes. Then the only bluegill present are the newly hatched fish that have not been eaten yet and a few large adults that have somehow escaped the bass and reached a size too large for the bass to eat comfortably. Waterbodies that are bass crowded have large numbers of small (12 inches or less) and thin bass and a small population of large bluegill. In a healthy fishing water, the catch will consist of bluegill and other panfish averaging 6 inches in length and bass averaging about 1 to 2 pounds. An overabundance of panfish is indicated by numerous 3 to 5 inch fish and few bass that average about 2 pounds or larger. Bass averaging less than 1.0 pound and large panfish averaging ? pound and above indicates an overabundance of bass. An overabundance of intermediate-sized 3 to 5 inch pan fish is an indication of predator-prey imbalance. A good balance would be 3 pounds of panfish for every pound of bass, or 10 panfish per bass.