The only one of those rivers I have heard of is the Spey, I wonder why ? What is the salmon season over there ?
By the way I do not know of any rivers in the US where you have to pay to fish the water. There are some private trout lakes and with maybe a few streams on them, but overall everything here is open to the public. Some rivers though the land is private and you must float it and stay in the water while fishing in these sections.
I would not mind paying for some of these quality waters if the number of fisherman could be mitigated though.