rivrat-I have had great success in pinpointing staging areas for river walleyes, but have not been able to locate big females during prespawn on my local resevoir (Lake DuBay-Marathon Cty, WI). Any suggestions?

Look in the warmer bays for feeding purposes. At the appropriate water temperature, they will move to the staging area. There, they generally do not feed, until after they finish spawning. That does not mean that they refuse or won't feed, just that they feed little and may be a reason for the low catch of those big females.