Yesterday morning out of Muskegon at first light I had big arcs on bottom out from 50 to 70 fow constantly. I got a helix 9, and am very familiar with it. When I have big red arcs on bottom it's always fish. It seemed like too many fish for too long. I sent my down rigger right to it and never had a hit. Usually it seems like I don't mark alot on lake Michigan. I didn't notice it later in the morning. Any ideas on what I was marking?