I'm with Hamsih and Sandy on this one. Make the code compulsory.
As for the trouters pulling them in and not returning them, I must have been fishing the wrong river all this time asI have not seen that. Better turn myself in to which every fishery board I need to as I'm sure it was the Don I was fishing!
I guess if salmon fishers do not return the fish to spawn and the runs are already poor it could go the same way as some of the East Coast US rivers and a blanket ban on Atlantic Salmon fishing could be enforced until the stocks recover. Drastic but it has helped a few rivers over there. Saying that, the rod caught fish are a small number and other issues such as offshore netting, river water quality, forestation and its effects on run-off etc all need to be answered if the salmon runs are to be improved substantially.