Does it say in the rule something about obeying state laws ? I just read the Dakota walleye classic rules and no where in their rules does is state it is against the rules to retrieving fish previously caught, so by your ethics this must be legal.
https://dakotawalleyeclassic.com/rules/
now it does state
ALL CURRENT STATE (ND GAME AND FISH DEPARTMENT) RULES MUST BE FOLLOWED. ( this is required by the G&F for all tournaments).
now I would be willing to bet that somewhere in the game and fish regulations it has a law against destruction of Property