Went back out today to try for another limit of perch. Went to same spot as Monday when the fishing was excellent, but today not much. We were between the intake and little cedar point in 18-20 fow. After not getting many bites while the screen was full of fish we started looking closer at the few we did catch......another mayfly hatch??? Yep some of the perch had their mouths full of mayflies and after carefull watching in the water we began to see very small amounts of mayflys coming to the surface. we even managed to catch a couple to confirm....Anyone else ever saw a mayfly hatch this late in the season? Now I know why we were getting so few bites and it also explains the black blobs of the depth finder.