I don't agree with any fisherman trying to police each other. if you see a violation by all means call tip. that's what its for but no non law enforcement has any right to measure out another mans catch. I guarantee that wouldn't end well.
I'll bet you're not a big fan of the citizen's arrest then because that's exactly what it was designed for years ago. BTW, it's alive and well.
Every law enforcement officer I know says not to take the law into your own hands. I think citizens arrest is callling law enforcement if you see a violation. There will always be cheaters and thiefs.