I try and be a versatile angler who can switch from casting/jigging to trolling to maximize my fishing outings. One of the major tools I use to decide which presentaiton I use is to look for baitfish behaviour on my Raymarine Hybrid Touch using the C-MAP High Res Bathy charts, and the CHIRP DownVision clarity not only to mark baitfish, but to understand what they are doing and how deep they are.
When I’m fishing a shoreline and casting to shallow water and I start to spot a tight school of baitfish suspened below the boat it’s a sign that they are not feeding and “bunched-up”. This is a defensive behaviour in all likelyhood due to predator fish nearby. This means I should either be casting/fishing deeper, or change from casting to trolling and fishing lures that will swim between 15-20′ down.
If the baifish are in loose-schools, they are probably feeding in the water column and are not threatened by predator fish. That’s when I still to fishing the shallower structure looking for feeding gamefish.