Majority of the Winters in the system right now, have darkening pectoral fins, while every single 2-3 pound Steelhead I have hooked in riffles since Early March has had very clear fins. The shape, size, and color deviations are all a little different species to species, and with more experience you will be able to spot Summers huddled up to Winters in a pool. But the dead give away is the fight. Summers run at you, and then all over over the place. Winters fight like big trout. Aggressive, but lazy at the same time. Also Winters are generally a bit larger than Summers. But in the Clack, the mint bright, black, and white fish are Summers. The Winters are blushin out a hair, and have dark spots developing around their face, and fins.