As a fly fisherman at heart, this issue comes up in discussions quite a bit.... Do I kill fish? Yep, every once and again. Mostly bass or Crappie... Enough for Fish Tacos once and again. Do I go out at times specifically hoping to find a few fish to throw in the cooler? Yep, again, fish tacos.... Most, probably 90%+ of the fish I catch get released. More than anything, I fish for the enjoyment of the pursuit, the challenge and the time in nature. I spent a summer on a Charter Halibut boat and after that summer, I just don't really enjoy eating fish any more (other than fish tacos and a couple pieces of salmon a year).
When it comes to catch and release fishing, here is what really bothers me (especially with trout). Watching people (no matter how they fish, fly, spin, bait.....) who treat fish poorly that they are going to release. The guy who lets a fish flop around in the bottom of the boat for 30 seconds before he just throws it back in the river. The guys who squeeze a fish so hard in a picture that it's eyes are close to popping out then haphazardly tosses the fish back in the water with little care for what happens next. Just in general people who don't respect the fish that they are going to release. If you aren't going to respect a fish enough to handle it with a bit of care so that it can be released unharmed back into the water, you should keep that fish. Lastly, not every fish is built the same way. Know your fish and how to handle it, some fish need more care than others. Not every fish needs the same level of care. Bass can survive several minutes out of water, and if you toss a bass back, the impact with the water can help them to come back to their senses. Trout have great difficulty surviving if their gills aren't wet, and if you toss them back into the water the impact is far more likely to stun and disorientate them.
Does Catch and release work??? Yep.


These two pics were taken 7 days apart. I took the first pic, because you don't see many trout with that sort of wound. It's about a 13" brown that I caught out of the Bitterroot. First pic was 4/25/15 Second was 5/2/15. Caught it in the same run, within about 15' each time. One of only two times that I can say with any certainty that I have caught the same fish twice. But in my current home river I catch fish just about every time I'm out with hook marks in their mouth, or on their side from being foul hooked. Catch and release works. Studies have been done on survival rates with Catch and Release on Steelhead, and from what I remember it's about 1-3% mortality rate on Steelhead. I'm not sure what the rates are like for other fish, but it's safe to say that there are fish that die after being released, but most survive.
Long story short, it bothers me more to see people mistreat fish they release than kill fish to take home and eat (or even keep a fish to have it mounted...).