I find that changing bait speed often brings a strike. Last night we were trolling herring and had just began to pull up one downrigger to check the bait when a silver hit, handed the rod to my son and began reeling in the short line behind the boat and voila, a double!! Also, I experiment with depth, some days very shallow, other days as deep as 45 feet. Last saturday we got a limit of silvers very shallow and had several that hit the herrring when setting up the downrigger with the dodger still "surfing" behind the boat and the herring spinning just under the surface. Sunday, another limit but all the fish were taken between 25 and 35 feet!