Traplines don't have to be registered. Wish that was so. Anyone with a trapping license can trap virtually anywhere. Even on private land if the land is not peppered with No Trespassing signs (see: http://www.adn.com/alaska-news/article/wildlife-trooper-traps-private-land-sued-trespass/2013/12/15/).  S/he doesn't have to post any signs that traps are in the area, they can set their trap one foot  from popular trails and they don't have to tag their traps with any kind of ID.

And if my dog is maimed or killed in a trap, as I extract him, I am breaking the law by tampering with the trapper's set.