I also agree coho jack -
Look at the lack of spots on the fish's dorsal fin, the larger/longer anal fin (result of salmon have more anal fin rays), the lack of spots on the forked tail, etc; expect that there was a bit of a button on the tip of the fish's snout. As an aside many of the coho jacks I have seen this year have been unusaually small - in that 11 to 14 inch range. Not sure what that means for next year except that the coho hitting the ocean this year did not find the expected/normal food supply.

To the question of steelhead/resident rainbows - typically the Puget sound wild steelhead pre-smolts in the fall are in the 5 to 6 inch range and migrating in the next spring as two year old fish (see a few one year and three fish) and rarely see winter steelhead smolts larger than 9 or 10 inches. It has also been the case that the O. mykiss populations in our rivers while mostly steelhead also included resident rainbows. Early in the resident rainbow life they show growth similar to the future smolts but decide to remain in the river. This fish usually mature at age 4 or 5 (just like steelhead) but of course are much smaller (typically in that 14 inch range at first spawning). However they do seem to survive spawning better than their anadromous cousins with some fish spawning as many as 5 or 6 times at ages as old as 10 or more.

Those resident rainbows have always been found in Puget Sound rivers and at times pretty low in the river systems. Have caught resident rainbows in the main Snohomish in the uypper end of tide water pushing 20 inches. Historically these fish were pretty common and developing information shows that they could be critically important to the over all O. mykiss populations, especailly during cycles of low marine survival.

Most of our rivers lost the majority of their resident rainbows due to harvest and release mortalities associated with the use of bait. There are a number of examples in the Puget Sound region where those potential resident rainbows are protected from those mortalities they have become significant portion of the river's over all O. mykiss spawning populations.

Tight lines
Curt