Regarding the effects of the regulation on fly fishing, I wouldn't worry about it. Fly fishermen fishing with a sinking or sink tip fly line usually use a leader between 3 and 4' anyway, so that's no big deal. Sure, there are exceptions to using leaders longer than 4' on sinking lines, but see the part about this being no big deal. If a fly fisherman wants to participate in this fishery, then they can suffer the "hardship" of a 48" leader. When fly fishing with a floating line, leaders of 9' or longer are the norm. .