ABERDEEN, Scotland — For the oil industry, the decline of the North Sea fields is part of a global challenge.

But for Britain, it is also a political problem.

The British government, which has long treated the oil industry as a cash cow, was forced to confront the threat to jobs and taxes during the run-up to last year’s referendum on independence for Scotland, which claims a big portion of waters where the North Sea oil and natural gas are.

The Scottish National Party, which supported independence in the referendum, accused the central government in London of mismanaging Britain’s oil and gas resources. Oil officials including Bob Dudley, BP’s chief executive, said during the referendum campaign that the uncertainty and legal problems a Scottish victory would bring could discourage future investment in the North Sea.

The government of Prime Minister David Cameron responded to falling production, industry warnings and its own review by setting up a new agency — the Oil and Gas Authority — with a mandate to avert oil field shutdowns and stimulate investment in exploration and production.