WOW.... That was a lot of fish to stock into 3 1/2 acres. How many of the bream were hybrids? Have you harvested any of the bass?

The conditions you describe are almost textbook over crowded bream. If this diagnosis proves to be true, my favorite recommendation is to add more predators and let them clean up the bream for you. However, you stocked an awful lot of fish initially so I would be a bit concerned about going over the carrying capacity of the pond.