Maybe they were just shut mouthed. Including my skiff there were four boats on the lake, and 4-inch perch were biting now and then (when they could get their mouth open wide enough to get around a size 8 or so hook).
Swedish pimples with a perch eye were the popular lures, and I also tried both a crawler chunk as well as a bit of perch meat. Tiny nibbles tickled the rod tip on all the baits.
Fish showed up in the lower half of the water column in about 40 feet of water; surface temp was 36 degrees.
The light breeze created enough of a wind chill that after a couple of hours we called it quits, and went fishing for a good radio station. in the truck. where it was warm!