London - Britain plans a vast marine reserve around the remote Pitcairn Islands in the South Pacific as part of global efforts to halt over-fishing, the government said on Wednesday.The reserve would cover 834 334 square km - an area bigger than Texas - around the British overseas territory, home to about 50 people as well as at least 1 249 species of fish, seabirds and marine mammals."The government intends to proceed with designation of a marine protected area around Pitcairn," according to the budget presented to parliament by Chancellor George Osborne. It would be one of the biggest protected areas in the world.The Pew Charitable Trusts and the National Geographic Society, which have worked for the reserve and surveyed life off the islands, welcomed the plan that is also backed by the islanders."These marine reserves provide an incredible treasure trove," said Jo Royle, manager for Pew's Global Ocean Legacy campaign. Tuna are among commercial stocks off the islands.Seas off Pitcairn are extremely clear. The survey found the deepest living marine plant - a type of algae at a depth of 382 metres, far beyond depths usually reached by sunlight.Royle told Reuters Pew aimed to help the British government with satellite monitoring for five years - any vessels that zig-zag rather than travel in straight lines, for instance, trigger an alert indicating they may be fishing.By some estimates, one in five fish are landed illegally worldwide despite government pledges to crack down. A study in 2009 estimated that illegal fishing was worth between $10bn and $23.5bn a year.The inhabitants of Pitcairn are descendants of British sailors, who mutinied on the royal navy ship HMS Bounty in 1798, and Tahitian women who settled with them.Enric Sala, of National Geographic, said the plan "will protect the true bounty of the Pitcairn Islands - the array of unique marine life in the surrounding pristine seas."