Ethics is about how you act, not about what happens. There are too many people who react to every situation and jump to the conclusion that a particular situation was unethical to begin with or ended up being unethical just because there was not a perfect outcome. Every situation is different and there are very few perfectly efficient hunters. Yes it is harsh to say it, but good hunters sometimes lose animals - it happens, it is terribly unfortunate, but it happens.
If I wound an animal and I give it my best effort to find it within a reasonable time period - and my best effort is pretty good, and the time period is extensive - then I will conclude that I did not mortally wound the animal and will continue my hunt. I WILL NOT "punch my tag" until I can physically attach it to the carcass of a harvested animal, AFTER I HAVE DONE ALL I CAN DO to retrieve it.
Now that doesn't mean that I will walk up on a downed deer or elk that is smaller than I first thought it would be and leave it lay there, that is the real problem here. There are too many idiots who do just that and I have seen it with my own eyes. This is exactly how and why the Bookcliffs was destroyed in the early 90's. In one season, (RIFLE) I personally witnessed over 23 dead two point bucks (the area was then a 3 pt. or better area) in about a 10 square mile radius. I have also personally witnessed many slob archery hunters fling arrows, pursue for 100 or so yards, not find the deer, get back in the truck and continue hunting. In 5 of these situations I have found their arrows and in 2 I found the wounded deer, (the other 3 had no blood on the arrows) one of which I was able to track down and make them claim their "trophy" (nice big Nomad buck with milk still dripping off his lip - Daddy showing off for the kids was none too happy he had to end his hunt at 8AM on opening morning!)Those are the individuals on whom our outrage should be focused - those that are either not skilled enough to finish what they started or who don't care enough to even try. That is what threads like these are really all about.
To me, there are no absolutes in this question. There is no cut and dried black and white - but the gray area is very thin. Hell even the very best predators don't have a perfect kill ratio. I consider myself a predator and part of the food chain. Yes I possess the abilities to reason and quantify that some of those predators do not and as such I have an obligation to hunt harder, but I don't feel I have an obligation to quit hunting if the situation is no longer within my control.
I have never lost any animal I have wounded, nor have I even ever failed to kill any animal that I have fired upon with a gun that I am familiar with. (I have missed one or two altogether, but that was with a borrowed rifle that wasn't sighted in as I was told it would be - an ethical and practical error I will never make again).
HOOK 'EM!