We've had multiple requests for information on how to properly handle fish for catch & release while doing the least amount of damage to the fish. There are many things that can be done to improve the survival rate of your fish.

Gear
Your gear, line weight and hook type, should be specific to the species you are trying to catch. Try to bring the fish in steadily, to reduce stress from coming up from deep water too quickly, as well as reducing the fish's fatique from a long drawn out fight.

Hooks
Use of barbless or hooks with barbs crushed in by pliers makes it easier to reduce the damage of hook removal. If the hook cannot be removed without causing stress to the fish (swallowed, etc.) cut the line and leave the hook. Swallowed hooks can be decayed by the fish's stomach acids, if the hooks are not stainless.
Circle hooks have become increasingly popular over the last few years, due to the reduction in hook swallowing.

Handling
Try to handle the fish as little as possible, while preventing it from battering itself against hard surfaces. If you can, perform release using pliers or a hookout to remove the hook while the fish is still in the water.
Avoid netting/gaffing if you must land the fish to remove the hook. If a landing net is necessary, try to use poly/neoprene netting rather than twine or cord, so that less of the fish's natural mucas coating is removed. Do not use a gaff if you intend to catch and release!
Pulling the fish into the boat by it's jaws causes major stress, and some species cannot survive even that much handling. A wet towel over the fish's eyes may subdue it, much like you would do to lead a horse out of a burning stable.
Avoid putting your fingers in the fish's gills. If you must handle the fish out of the water, wear wet gloves, or use a wet towel. This reduces the amount of removal of the fish's slimy mucas coating (a dry towel can remove so much of that natural protection that the fish will be extremely vunerable to infections and parasites).
Release as close to the water as possible, head first and in the water before you let go if you can manage it. If the fish is worn out, hold it in the current if possible, or swim it around a bit, to help revive it.

LINKS: www.tu.org Trout Unlimited

www.catchandreleasefound.org Catch & Release Foundation