I'm with RA3, I'm having trouble remembering a steelhead that was hooked so bad it was bleeding. The one's that get hurt are the cutts - those buggers are eating, not just biting, and they tend to swallow everything. I use barbless hooks always, as they make releasing (and really even hooking) fish so much easier, but a 2/0 down the throat of a cutthroat is probably pretty much fatal, even if you cut the line. I'm pretty convinced that incidental hooking of cutthroat while steelhead or salmon fishing is hurting recovery of searun cutts .

I caught one hell of a lot of coho on the Columbia last year, releasing all the natives, and I also had a couple that were bleeding so bad that in spite of releasing them rapidly and having them swim off vigorously I'm sure they died, in fact one I saw die - it had a distinctive seal bite on it and it popped to the the surface belly up and bled out 5 minutes after I released it. But that was probably 1% of the fish I hooked, and 99% survived a whole lot better than if they were bonked. And no, I didn't take that fish home - it's illegal and I don't want my boat and gear confiscated. I just went home one short of a limit that day.

I also had an otherwise healthy 25lb chinook that I let go on the Columbia after they shut down chinook retention get nailed by a sea lion right after I released him - he was swimming away ok but he was worn out from the battle and was no match for Herschel But I guess that meant he wouldn't take the next one I caught right off my line as he was full.

Finally, I've caught a number of trout in lakes with broken off gill arches sticking out of their gill covers, exactly as smalma described. These were usually small fish that obviously had the power bait hook ripped from their gills by some high-grader, yet they survived to bite my fly somehow. So if you want to release it use barbless hooks, land it quickly, cut it off if it's hooked deep, and if it dies anyway, well, the rest of God's creatures got to eat too, so nothing is really wasted. Just take one less home that day if you kill one for the river livers.