I'm not surprised at the size of that fish. Its small but well within the range of what you would expect a 2 year old coho to look like. Jacks and Jills that return one year earlier than their cohorts (year class) come back for one reason.... to spawn. But to spawn and 'want to spawn' are two entirely different matters. Most Jacks and Jills that come back are able to spawn successfully or at least are able to, if given the chance by the dominant age class. There are others though that have returned simply on the urge to do so with no real sexual maturity to back up that urge. From the look of that fish, I would think it is very sexually immature and has more of the 'urge' rather than the 'stuff'. Reminds me of when I was younger, hogging the bathroom and my mom would say "what are you doing?" To which I summoned all my fisheries knowledge and not wanting to lie to mommie said, with all seriousness.... "just spawning...be out soon".