polarized sunglasses are designed to reduce the glare caused by the reflection of sunrays to give you a better view , particularly from the horizontal planes like water, snow, flat road and car hood.They have been popular for years with boaters,fisherman and help the participant in these activities to see more clearly, allowing for the avoidance of potential hazards, but this has nothing to do with the UV protection. Regular sunglasses are only used for blocking UV rays and decoration.
Polarized sunglasses will reduce the glare reflected from the surface of the water. I do not know whether you have such an experience or not. You can not see the water directly while fishing. However, if you wear polarized sunglasses, you can see the surface of the water directly and you will not feel uncomfortable. However, regular sunglasses does not have this kind of function.