I had the same problem in my 10acre pond this year. No one fishes it but me, but yesterday I was having trouble getting them to bite anything. Switched to drop-shotting and put on a 4" Watermelon Seed Lizard and they started going nuts. I was about 3' off the bottom of a 15' at the deepest point pond. I usually throw the largest spinnerbait I can find a few times and then start drop-shotting or texas riggin.