I'll defer to our experts, but after reading the DNR report, it seems that productivity may be low. As it is not your personal lake, you probably can't dump money into it.
Do you own waterfront property? If so, check in to feeding the prey species, specifically bluegill, along your shoreline. In time, you'd attract plenty of fish. The sunfish and perch would show up for chow; some bass would follow. I don't know if this would be considered "chumming" in Wisconsin. Chumming is illegal out here in the wild west.
It amazed me that the fish were so small. That may reflect the sampling technique and timing.
Our experts can advise.
