Both Sebastes serranoides - Olive Rockfish and S. flavidus - Yellowtail Rockfish can be very tough to distinguish without a good look. The main difference is that Olives don't have mottling on their scales below the lateral line, while Yellowtails do. Olives are purportedly sleeker with a sharper face, while Yellowtails have a broader body and face. In any case, I'm fairly sure I got it right for these pages...
adult |
juvy |
These Young Of the Year (YOY) on the right are S. flavidus or S. serranoides - Yellowtail or Olive Rockfish: light bodies with an obvious black spot on the dorsal, and yellow tails. Kelp, Gophers, Black and Yellow, and Copper (KGBC) Rockfishes are a different group that you can see here:
vimeo.com/97452851
For more info on rockfish recruitment and YOYs:
piscoweb.org/files/file/Kelp-Forest-Monitoring/classroom-materials/training-yoy-id.pdf
piscoweb.org/research/science-by-discipline/population-connectivity/recruitment/rockfish-recruitment-and-upwellin
vimeo.com/97452851
For more info on rockfish recruitment and YOYs:
piscoweb.org/files/file/Kelp-Forest-Monitoring/classroom-materials/training-yoy-id.pdf
piscoweb.org/research/science-by-discipline/population-connectivity/recruitment/rockfish-recruitment-and-upwellin