The whole thing is absurd if you ask me. A guy can’t catch some small fish and throw them back in the water without ending up in the Supreme Court of the United States, Where one of the Justices bases her opinion on Dr. Seuss?
I can see a purpose for it being unlawful to catch and keep an undersized fish; but certainly not criminal.
When you have more than one undersized fish; I think that is a problem.