Anglers on a Scottish river face prosecution and fines of up to £2,500 unless they get an English licence.
Anglers on the Esk now require an English licence
Two-thirds of the River Esk is north of the Border, but England's Environment Agency (EA) has responsibility for the administration of the entire river.
Rod fishermen in England already pay £63.50 a year, but now fishing the Scottish stretch will also be charged.
The EA said managing the whole river was more effective. Opponents said it was "bureaucratic nonsense".
The Esk and its tributaries run through the Scottish Borders and Dumfries and Galloway to the Solway Firth.
Keith Kendal, the EA's fisheries team leader for North Cumbria, said: "This is being introduced because the Border Esk, as the name suggests, straddles the border. For fisheries management to be effective it needs to be treated as a whole catchment.
"The anglers on the English part of the Esk already pay a licence fee, so we need to treat the whole of the Esk the same and that is why we are now starting to enforce the legislation on the Scottish part of the Esk."
He said the management of salmon needed to be "more robust" than it was in the past.
Mr Kendal said all revenue raised through licence sales would be used to fund river works such as habitat improvements, removing obstacles to migration and increasing angling opportunities.
He said the Esk in Scotland had already benefited from the money taken from English licence fee payers.
Mark Oddy, chairman of the Esk and Liddel Improvement Association (Elia), said he supported much of the EA's management plan for the river.
But the rod licences were just "an English tax being imposed on Scotland".
Aeneas Nicolson of Elia took the matter to the Petitions Committee of the Scottish Parliament.
He said: "I think they see, as we see, that this is just bureaucratic nonsense.
"There is no requirement whatsoever for an English licence on this river."
Tory South of Scotland MSP David Mundell joined fishermen to protest over the licence fee on Friday.
He said: "I have been appalled by the arrogance of the Environment Agency and their determination to press ahead with the implementation of these charges without the support of the local community and before the Scottish Parliament's Petitions Committee has completed its consideration of the legal issues."