While there are some late spawning coho (through March) in north Sound rivers with the rare exception they are all in the rivers at this time of year.
The steelhead fishery along the west side of Whidbey used to be in late December. In their migration to the rivers the fish travel along the shorelines typically in 5 to 8 feet of water suspended 3 or 4 feet below the surface. Typically travel in small pods and can be active showing themselves as they move down the shoreline. While they could be caught at any tide, the last of the incoming tide seemed to have been the most consistent.
As mentioned, the lure of choice for the gear angler was a large hoochie behind a large spin glow on a long leader behind a large piece of pencil lead. A popular colors included chartreuse, flame orange, white, red etc. The most common combination was a chartreuse and flame orange spin glow in from of a chartreuse hoochie over a double hook mooching leader. The rigged was casted out and reeled back to the angler's feet with most strikes happening in maybe in 2 feet of water. The fish would follow the lure to the shore gabbing it at the last second. The theory was the fish were attempting to grab the critter before it escaped.
A fly angler might try to mimic the gear angler's approach with a larger fly whose materials provide lots a movement and maybe some flash. Because the fish are suspended you probably want to present your fly above their traveling levels than below. Clearly the fish are reacting mor out of curiosity than hungry so an actively retrieved fly would more likely trigger a strike than on fished on the swing even though the water maybe moving like a river. To take advantage of the fish tendency to follow your fly as it nears the shallows changing both the speed and direction as the fly travels may trigger more strikes. In most such fishing situation I have good luck swing the fly parallel to the shore by sweeping the rod up current.
Good luck.
Curt
