Britain's North Sea oil and gas sector has shed more than 5,000 jobs since late last year, the new Oil and Gas Authority said today, putting an official figure on job losses resulting from a year-long decline in oil prices. North Sea oil companies have been particularly hard hit by the near 55% decline in Brent crude prices since June 2014, as they were already facing some of the industry's highest operating costs in one of the world's most mature basins.