I believe the measuring method most commonly used is TL. Tip of mouth/snout to end tip of tail. That's what biologists and majority of state enforcements use anyways. I personally always drop an inch or two down when mentioning the length of my fishes. But I Personally think that the most correct method to use is the TL method. I don't think one should count streamers but if one happens to include the length of the streamers they shoul mention that. That's my take on it anyways.