With the faint parr marks extending above and below the lateral line with wide spacing and the dark caudal edge, I'd say coho smolt.
*EDIT*
I'll leave my original answer unedited, but I can't see the dorsal or the adipose, which would help greatly with ID...I'm also unsure if what I'm seeing are faded parr marks or just light artifacts. Good chance it could be a Sockeye smolt as well, I don't know at what age the Baker Sox outmigrate.