I believe they found on the Skagit that there are one year smolts among the summer Chinook at about the same rate as the spring Chinook. Roughly 5% as I recall, but we know my recollection of fisheries statistics has been off a time or two lately. It used to be the conventional wisdom that Skagit springers were one year smolts, and the summers were sub-yearling. If I'm not mistaken (again) Russ Orell included that statistic in his report on Skagit Chinook in the 70s. And perhaps the springers were at one time predominately yearling smolts, and the changes going on in the environment and possibly the fisheries combined to favor the sub-yearling smolt variety. I think the same thing was found with Nooksack spring Chinook as well.

With the main Chinook stock in the Skagit being summers, it's certainly possible that their life history strategy would be a blend of what we "thought" spring and fall Chinook were supposed to be like. By finding yearling smolts among the summer Chinook stock, I think what the fish are telling us is that they will adopt life history strategies that are most successful for them in their respective watershed. And the yearling strategy hasn't played out so well in recent decades.