The longer days(more daylight) draws them near into the staging areas, water temps of 40 to 45 at or near the surface as walleyes are broadcast spawner's and spawn on or near the surface, and the full moon will really set them off once the right temps are reached. If you get out shortly before daylight during the jig bite you will hear them breaking water and especially there is more spawning activity during the full moon but once it starts breaking day the spawning activity slows to almost a standstill until dark again.