Here in the northwest this time of year I first look for weeds knowing bait will be there. I fish outside edge with fast baits, burn spinnerbait, crawfish pattern square bill. You will get bit or at least see sm chasing those baits. When you locate fish throw green pumpkin tubes or Z-man ned finesse TRD rigs.
So, no, it is not necessary to see fish on sonar before fishing them, but it is important to find structure on your electronics.