I guess it depends on how you think about it and how you go about releasing them.
For me, they go absolutely ballistic when they get near the boat. If you net them, then they get wrapped up in the net tangling hooks and prolonging the time out of the water. All the mean while they are beating their own scales off a tenderizing themselves at the same time.
We did release a few that seemed like they'd live cause they were relatively calm and didn't get wrapped up in the net and weren't out of the water long; but if we felt like there was any chance they'd die anyway, we kept. Seems like the right thing to do, IMHO.
It just doesn't make sense to let every fish go. For instance, let's say you catch a fish that is not big enough to be "legal" but is gill hooked and bleeding severely before you even pull it out of the water (I've had it happen several times). Does it make sense to throw that fish back? Not to me. But I do it because it is "the law". I still think it is wrong. Even for bass it doesn't make sense to me sometimes, regardless of the size restrictions. If it is clearly going to die anyway are you still supposed to throw it back? Doesn't make any sense to me.
So back to keeping small chinook. We through back as least as many as we kept, but throwing them all back isn't necessarily the right thing to do either. That's how I look at it, anyway.
Respectfully.