work on the Chetco river on the SW Oregon Coast is a # 6 or #4 (non "x" hook) done with a black chen. body and a lime, or flo. green, hackle. Fished off a very heavy sink tip or full sinking line out of the "dory (or for you "Yanks," a pram) line."
Almost a social event for the fishermen at "Tide Rock" on the lower Chetco in the fall. Anchor is set/tied to a couple of empty bleach/gallon milk jugs then a short pop off loop to the dory. Cast out into the flow and let the line sink in front of the boat and your good to go.
Fish hits fly, you pop the loop to the floating bottles (these hold your "place in line") and Mr. King towes you around for awhile until you finally beach the thing or break off. And it's the "landing" part of this whole trip that's worth the beach watch.
Long rod, large fish, 8 foot pram, rod clampted between your knees, rowing like hell to get to the bar or someone below you in al like pram with a net ..... you get the picture.
The "Military Term" for this is Cluster F...