You can safely release salmon and trout with good judgment. When you're popping them off the back with pliers and not netting them when lip hooked, no problem. If fish are slamming and burying hooks in the gills and you're going to be throwing back bleeders with their gills ripped out, or the surface is 78 degrees and the kings you're dropping are going belly up, you should probably take your limit and quit fishing that day. If someone was in a tourney and doing it, than that's sad and says a lot of bad about them. Ethical sportsman make the right decision based on the circumstances above.