Yes, there are fly only waters.
As far as killing fish, with the advancement of modern circle hooks the natural bait crowd is considerably better than it once was in many waters and a wide range of species. Even the half awake “3 rods on forked sticks” angler has no trouble NOT gullet hooking with circles. Circle popularity is not all a result of this low mortality functional attribute, the hooks themselves are just plain easier to remove. Good design which often appeals most to the worst offenders of the bunch.
As far as lethal habits of American fisherman, I’ll put the modern soft plastic lures pretty high on the list for deep ingestion especially when used with oversized/wide gap hooks. Not the silicone squirmees of the fly world, but more traditional offerings like tubes and Senkos on J-hooks or EWGs. They go down fast, often hang deep, and their popularity in the trout world has grown considerably over the years.
Treble hooks are another problem especially when time-out-of-water is considered for a successful C&R.
Methods aside, we have a lot of bad habits here in the States when it comes to the photo-op on more delicate species. The Keep ‘em Wet campaign is catching on, but when folks really want the hero shot on Facebook those gills will get dry.
Although our behaviors are probably worse here than where you are, we have a lot of water and a lot of fish so it’s hard to invoke much change in angler behavior. Some of the bad things are strongly industry driven and quite compelling in their effectiveness. Large hooks of any kind, while popular on many flies and lures, are really asking for it on serious wounding and time-out-of-water. The actual mortality rate from some popular methods here is likely a great deal higher than anyone suspects, we just don’t see the death happen.
Don’t know what to tell you on the overplaying of fish on fly tackle, especially the trout and salmon. American anglers can get really bad here when they pick-up a flyrod and never even come close to tapping into the power of it. On some species it doesn’t seem to matter much, others it likely gets into lethal territory on a regular basis.
Sometimes we scapegoat on various groups, but in reality the belly-up fish can have a diverse array of potential suspects. Most of it's involuntary and perpetrators themselves are often naive of of their own culpability.
I think the fly crowd is probably better overall relative most other groupings, but again, it's the terminal tackle which lends itself well to this. No one is D-haulin' two sets of #2 trebles.
