There are two reasons why light line will produce more bites than heavier line. One reason is visibility. Water is usually clearer when the water gets cold so smaller diameter and low visibility is an advantage. More importantly, light line gives your baits more action.
“One thing that will help an average fisherman is to use small line,” says Al Linder. “Even in stained water, they will catch more fish on 4-pound test line. I’m positive of it. Especially with jigs that have movement. A small jig, like a 1/32-ounce, will move a little each time the line turns. That’s the whole reason for its success. Stiff line stops the jig from moving.”