I got to fish Beaver Dam reservoir VA. in January. I caught 20 plus fish and most were nice size crappie in the upper creek area. The weather prior that week was in the 50s plus so the fish were there in numbers, however so were the fishermen. I had to travel back to Va. a week or so later and the weather turn back closer to winter and I could not get a bite and had the whole area to myself. This has held true on Lake Marburg in South central PA also in years past. There is no doubt that water temperatures dictates spring crappie and other fish movement.