You can fix a LMB crowded pond by stocking. Its a #s game and can be expensive. It works far better if you reduce the LMB #s first ,during and afterward. If you stock 2-3 in. BG expect about 2 % survival to year 1. If you use 5 in. BG you can expect much higher survival around 25- 30 % to year 1. The best time to stock larger BG is now (just before they spawn) because you get the quick benefit of loading up the pond with their yoy. In that situation most of them ( 75 %)will survive long enough to spawn. If you can get the TShad in just before they spawn and have a plankton bloom that can work also. Electroshocking should work better than what you experienced.