Short of stabbing one in the gills, trout are a lot more durable than most experts give them credit. The C&R craze has set aside most common sense practices. If listen to them, don't touch them, don't pick them up, don't net them , and don't take a picture because you might expose them to UV rays. If you really want to get serious you might as well use a hookless fly and just count coup. I have touched them, netted them, pictured them and abused them. Turn them loose and caught them again the following week. I might add that I have boga gripped them as well.