In the case of crappies, they are the first fish to find warming water in structure areas which they prefer. Small bays will often offer the first crappie fishing after the ice leaves the lake. Bays on the north side of the lake would heat up first because of the angle of the sun. Any shallow, black-bottomed bay with wood structure and good exposure to the sun would be a sure early season bet. The next choice would be the rocky faces of the dam.
Rocks act like giant radiators.
The sun warms them and they in turn, warm the water which is washing against them. As main lake water begins to warm, main lake shoreline with wood structure becomes important crappie territory. Water draining into a lake will also be warmer at this time of year and, in lakes which have such inlets, the finest crappie fishing of the year may be found here at this time if the runoff water isn't muddy. Crappies are sight feeders so, if they have a choice, they will move to the cleanest water in the lake. Submerged shoreline brush and trees or limbs hanging into the water will attract crappies.