President Obama on Tuesday declared a large swath of southwest Alaska’s coast off-limits to oil and gas drilling, saying energy development in the region could endanger an environmentally sensitive waterway and imperil vital fisheries.

Obama announced the drilling ban for Alaska’s Bristol Bay in a video statement recorded in the Oval Office, calling the nearly pristine, 250-mile-long stretch of coastline “one of America’s greatest natural resources.”

“It is a beautiful natural wonder and it is something that is too precious to just put out to the highest bidder,” Obama said.

The decision means federal waters of the bay will remain permanently off-limits for oil and gas exploration, continuing a de facto policy that has been in effect for several years. While expected, the president’s announcement was a vindication for a coalition of commercial and recreational fishermen, environmentalists and some native Alaskan groups that have long opposed energy development in the area.

One of the world’s most productive fisheries, the bay supports more than 40 percent of the world’s wild sockeye salmon.

“This action ensures Bristol Bay will remain America’s fish basket for generations to come, unspoiled by additional industrial activity and safeguarded for the benefit of Alaskans and all Americans,” said Michael Conathan, director of ocean policy for the ­Center for American Progress, a Washington think tank.

The decision does not directly affect the Obama administration’s pending decision on whether to allow mining in an uninhabited inland region near the bay. The EPA is considering whether to preemptively ban mineral extraction in the region, potentially striking a fatal blow of the proposed Pebble Mine. If developed, it would be one of world’s biggest mines for gold, copper and molybdenum.

Environmentalists and outdoorsmen have pressed the administration to outlaw both mining as well as energy development, saying the risk to salmon and other wildlife would be unacceptable. The proposed mine would be near the headwaters of several streams where salmon spawn.

Chris Wood, president of Trout Unlimited, praised the White House for moving to protect an important fishery that is fundamental to the region’s economy, noting that salmon alone account for about $1.2 billion in economic output for the region each year, as well as more than 14,000 jobs. He called the ban on oil drilling “the first step in what should be a two-step process.”

“Now it’s time to resolve the outstanding litigation and finish the job of protecting the headwaters of the world’s most prolific salmon fishery,” he said.

Sen. Lisa Murkowski ­(R-Alaska), a staunch supporter of energy development in Alaska, said she would not object to the White House’s decision “at this time.”

“I think we all recognize that these are some of our state’s richest fishing waters,” Murkowski said in a statement released by her office. “What I do not understand is why this decision could not be made within the context of the administration’s upcoming plan for offshore leasing — or at least announced at the same time.

“We are not asking to produce [oil and gas] everywhere — but right now, we are not being allowed to produce anywhere,” she said.