When we fished for pike using spin rods and baitcasters and lures we never used any special leaders and seldom lost and pike to bite offs. When we started using flies we thought we could do the same thing but found that about every third fish bit us off. We found as 'hap' says that longer shanked hooks make a difference but not enough for us. We currently use heavy fluorocarbon (50lb or heavier) for pike and up to 80lb for muskie. The difference we found was the fact that the retrieve on the flies was slower than with lures and the pike had more opportunity to inhale the whole fly exposing the leader to their teeth. I like to use the single hooks that guys use on spoons for downrigging salmon. I tie the head of the fly on these then add a tail tied to a treble hook. The treble hook with material tied to it will give the fly some added action.