Having read a number of these studies I gotta say the data is not really that great. Many of the situations created in the studies are not at all what occurs on a actual river. For instance in the above study the fish were near maximally exercised for 10 minutes. How many of you have actually taken 10 minutes to land a fish? And what fish swim full speed against your line for 10 minutes also? And who keeps a fish out of the water for 60 seconds that is using barbless hooks? It's a real stretch applying this data to actual fisheries. That being said, proper handling fish is just common sense I think. Grabbing by the gills, or dragging them on the rocks is pretty ridiculous if you are going to release it.