I know people that fish to eat and take all until they get what they want. I have seen fishermen "feed the racoons" to cull fish out of their way, panfish usually in both cases, but with the undersized gamefish also. I have fished with, usually only once, fly fishermen that belittle others from a high pulpit for not returning everything - except they need a picture taken with "their" fish and equipment and have found that we as fly fishers are usually the most righteous and critical.
In my life I have and probably will continue to kill fish (less now than my youth). White & yellow perch, hornpout, trout, salters, strippers, cod, salmon, shad, sunfish and eaten them. I didn't carry a priest, many where gutted and bled to put in the creel or the cooler, many more thrown on the ice around the tip ups, ethical ?Is buying your fish more ethical, or just easier to let someone else do it.
My pet peeve is not how you dispatch (hopefully quickly) or return your catch as long as you use it or revive it. Or the boaters, I don't paddle on weekends anymore. Or the sportsman on his pulpit, I like my solitude. The only thing that gets my goat is the trash. Want the best spot follow the path to the garbage pile. Here in the east it ranges from bottles & cans to lunch wrappers, fishing trash, condom wrappers, etc. so it is not all fishermen (hopefully) just my rant and my $.02