I used photoshop to zoom in, color correct and sharpen the pic... and I say COHO all the way.

The eye pupil isn't small like that of a chinook, the inside of the mouth definitely has too much white and there aren't any spots on the lower lobe of the tail. It looks like the fish may have been mutilated a bit as a smolt in a concrete tank, causing it's nose to be shorter and it's maxillary to be deformed.