Thick weeds can often be a major issue. If a vast area of your pond is covered in certain species of submerged aquatic vegetation that doesn't allow movement of predators access, it provides too much refuge for BG, BC, etc... Some species like hydrilla, elodea and some species of pondweed get very thick.
This is a description of what my pond was like when I purchased it. About 70% Elodea coverage. Only a strip in the middle of the pond was open. Skinny LMB and large GSF. The Elodea gets so thick it's almost impossible to paddle a kayak through let alone fish in it.
Did I ever mention before that I hate Elodea?
