"We got 30 minutes!" It was 1:30 P.M., half an hour before the start of the commercial salmon-fishing season in Bristol Bay, Alaska, and I was sitting on the flying bridge of the F/V Erika Leigh with Lindsey Bloom, 29, one of perhaps a dozen female captains out of the 1,500 or so who convene here every June to chase one of the largest sockeye salmon runs in the world. Bloom, five foot two, her curly red hair pulled back into a ponytail, was hustling her three-man crew through final preparations. "How you guys doing down there?" she shouted to the back deck. It seemed less like a question than an order to keep moving.

Around us bobbed hundreds of similar 32-foot boats, each guarding its own small patch of gray-brown water, with two or three crewmen busily readying themselves to do battle with the fish. The captains eyed one another and jockeyed for position, a coiled-spring pregame tension hanging over it all. "Barely managed chaos is the only way to describe it," one of Bloom's crewmen said.

At the center of this, Bloom was focused, her mouth set in a slight scowl, but obviously enjoying herself. It was her sixth season at the helm of the Erika Leigh, but she'd been fishing the bay for 13 years, learning the ropes from her father, Art, who has worked these waters for nearly two decades. "I've gained some confidence knowing I can hang with the big boys," she said. But the start of the season is always a nervy time. She was scanning the nearby swells for signs of the 40 million salmon that manage to find their way from the Pacific back to this corner of southwest Alaska every year, where they return to their natal streams to spawn and die.

"Check the net and the reel!" Bloom yelled, and two of her crewmen spun the large wheel amidships, smoothly spooling a 900-foot net to insure it would pay out cleanly when the time came.

Fluttering above us on a radio antenna was a white pennant printed with the words PEBBLE MINE crossed through by a bright-red X, a reference to the Pebble prospect, a massive lode of copper, gold, and molybdenum ore worth hundreds of billions of dollars. In a potentially unfortunate coincidence for the salmon of Bristol Bay and the small constellation of people who rely on them for their livelihood, the proposed mine sits at the headwaters of the two main river systems—the Nushagak and the Kvichak—that feed into the bay and provide the spawning habitat and fish nursery. The hundred miles of open tundra between where we floated and where the copper and gold sit in the ground is perhaps the largest intact salmon habitat left in the world, supporting five species of the fish, as well as a remarkable ecosystem full of moose and caribou, brown bears and grizzlies, eagles and wolverines, and trophy rainbow trout. The 40,000-square-mile watershed encompasses two national parks—Lake Clark and Katmai—and is home to two dozen native communities, many of which still rely on subsistence fishing and hunting for a large part of their diet.

"Southwest Alaska," as a fisherman told me, "is one of the last undeveloped, pristine places left in our country."