...Keep 'Em Wet.
It makes sense that fish that are played longer and held out of water longer will experience more stress, and the more stress experienced by a fish the more likely it is to die when released. To reduce stress, scientists have recommended some general guidelines for catch-and-release angling
1) Minimize angling duration (the time a fish is played and handled for hook removal) .
2) Minimize air exposure (15-20 sec) by removing hooks with the fish in water and photographing fish quickly.
3) Use barbless hooks and artificial lures/flies.
4) Use rubber nets void of knots that protect fish scales and mucous 5) avoid angling during extremes in water temperature
Many of these guidelines are already practiced by educated anglers that retrieve fish quickly, leave them in water during hook removal, use barbless hooks, and photograph fish quickly before releasing them, ultimately keeping fish out of the water for no more than 15-20 seconds.
Anglers should also limit fishing during warm summer periods when trout are stressed (management agencies sometimes close fisheries during these warm periods).
These behaviors by educated anglers have helped substantially to reduce fish stress from catch-and-release fishing, thus increasing the chance those fish will live to be caught again.