“So the Norwegian government can simply say: catch all you want. No license required.”
Your solution makes perfect sense. The fly in the ointment is the word in the first sentence: “government”. Picture the USA with the same problem and all of the agencies, bureaus, administrations and various governmental organizations this would have to be approved by, then all of the whacko special interest groups like Greenpeace, the Sierra Club, etc. not to mention PETA and ELF, who are the constituents of the whacko officials like Pelosi, Waxman, McDermot, Reid and the like, then throw in the unbalanced malcontents like Nader and Gore. It would be easier to reverse the rotation of the earth. Regardless of the cost to wildlife, the economy, the environment and mankind itself, it would never happen.
Actually I believe that in the cases of a couple of nuisance fish, No limit and no size restriction are actually the case (E.g. Snake heads in MD, Rainbow trout in Yellowstone)