That last part is VERY frustrating. I'd say the new generation of fisherman is much more wildlife conscious, myself included at 39. I'm hoping things continue to improve, and tournaments move away from weighing, I love the way MLF does it. I know their way is only practical for very small tournaments, but just off the top of my head I can think of ways to apply this method to larger tournaments.
40% mortality for fish that were caught by electrofishing, no trauma, means fish that are caught and weighed is a number less than that, extrapolating, much worse.
I apologize that my first post was somewhat off topic, OP I hope you figure out your problem soon, it's definitely an odd one. Is it possible they are going from such poorly oxygenated water you're shocking them?