Not saying I fish over redds but what is the difference in catching a fish on the way to the redd and knocking it over the head and one that gets pulled off a redd and bonked? Only thing I can see is that the one on the redd is possibly one of those "evil" hatchery origin fish contaminating the stream. Or it could be a true native fish which in my opinion shouldn't be targeted for any purpose at all.

I would imagine most fish on redds aren't worth bonking anyways.