We won't likely get a definitive answer to ST's question, but I would like the coho voters to consider the following when viewing the picture.....That little doe has a blunt head, with what appears to be white gums. She also has a little bit of an overbite on the upper jaw, which is common in spawned steelhead or kelts. Her mouth does not appear to go past the eye, as most coho do, and the eyes are down. We cannot clearly see the spots on the dorsal fin and tail, nor the shape of the tail, which would be a dead giveaway..Squaretail or a V?.........
The comment on the ventral fin and thickness of the tail do not hold water with me, as a spawned steelhead can have a very large ventral fin and often has white tips on it.....as this fish does.....Most of the steelhead caught locally are in the 5-15 lb. range and they DO have a rather thick diameter, just in front of the tail. Howewer, when the steelhead is returning to the ocean, they are very thin in the belly and in the tail as the fat reserves are quite depleted and they will bite almost anything (they are not fussy), just hungry!
The colouring on steelhead is so variable, that I think it is not a valid tool for species identification......Because the steelhead is semeiparous species(they don't die after spawning) and may return 3 or 4 times to their home river, their coloring is very variable depending on where they are in their journey...Was this a hatchery or wild fish?.Either way, I am glad you released this little guy, cause she's either back in the ocean or made a nice snack for one of those magnificent bald eagles along the river............Ortho