DUTCH HARBOR, ALASKA — America's biggest catch lands here and at nearby ports every year: more than 2 billion pounds of Alaskan pollock to feed a global appetite for fish sticks, fast-food sandwiches and imitation crabmeat.
The tightly managed Alaskan pollock fishery has been a rare success story in the U.S., which has seen the collapse of species such as New England cod and now imports 80% of its seafood.
Yet the careful management that helped make Alaskan pollock a billion-dollar industry could unravel as the planet warms. Pollock and other fish in the Bering Sea are moving to higher latitudes as winter ice retreats and water temperatures rise.
Alaskan pollock are becoming Russian pollock, swimming across an international boundary in search of food and setting off what could become a geopolitical dispute.
Andrew Rosenberg, former deputy director of the National Marine Fisheries Service, expects the pollock to be a test case in an emerging pattern of fish driven by climate change across jurisdictional boundaries.
"It will be a food security issue and has an enormous potential for political upheaval," said Rosenberg, now a professor at the University of New Hampshire. "We aren't getting along that well with the Russians now."
A warming trend in the Bering Sea has forced fishermen like Jim Summers to motor 360 miles in his 191-foot trawler, the Aurora, to reach profitable fishing grounds. Docked here recently, he gingerly worked a hydraulic lever, unleashing 30,000 pounds of the mottled, pale-bellied pollock onto the deck.
"It feels like every year we're going farther and farther north," Summers said. "It used to be that most of our trips found fish near Dutch Harbor, with an occasional run up toward Russia. Now it has flipped."
While Summers repositioned the net, a pair of 12-inch-diameter hoses vacuumed more than 1 million pounds of fish from the hold of the ship into a dockside processing plant. Once there, the fish coursed through a labyrinth of tanks, conveyor belts, and automated slicing, dicing and washing machines that turned the fish into fillets or fish paste.
This flow of white flesh was then frozen in blocks and stacked in containers on freighters, destined to be breaded and fried at McDonald's and other fast-food restaurants, or shipped to Europe for fish-and-chips platters or to Japan for surimi, the fake crab at the heart of California rolls in sushi bars.
At a fueling dock nearby, Steve Olsen, captain of a stern trawler, pored over the GPS tracks of his trawls in recent years. The lines on the screen moved ever closer to Russian waters. "When you are towing [the net] and you stop finding fish, you typically turn northwest and you'll find them again," Olsen said.
His finger traced the squiggling line of a successful trawl that took his 112-foot ship, the Western Dawn, next to the border. "We could see the Russian guys fishing the other side," he said. "We see them right on the line. If we see them right on the line, we'll check it too."
Pollock spawn each winter near the Aleutian Islands and then follow their food north as waters warm in the spring. But the food has shifted farther north with receding sea ice, and now pollock, which follow the northwesterly contour of the continental shelf, are shifting their range ever closer to Russian waters.
Scientists who help manage the fishery are confirming what fishermen report: The fish disappear from the Aleutians area each summer and can mostly be found near Russia.
Every June and July, federal scientists trawl a grid pattern in the Bering Sea in an area about the size of California. Counting the fish caught in these trawls and matching them against sonar readings, they estimate the size of fish stocks. These assessments help set limits on the next year's catch to safeguard spawning stock.
An analysis of 25 years of surveys showed that the ranges of most fish are shifting north as the ice and cool water have retreated, said Franz J. Mueter, a fisheries oceanographer at the University of Alaska.
"What we found confirmed the obvious," Mueter said. "As waters warm, a lot of fish on the eastern Bering Sea shelf are moving north."
Not all scientists agree. Some suggest that other factors need further study, including different migration patterns of older and younger fish, whether trawl data provide a complete picture of fish populations, and whether these waters are becoming overfished despite the Marine Stewardship Council's eco-label certifying that the pollock fishery is managed sustainably.
Federal scientists pointed out last week that their sampling showed the Bering waters were colder the last three summers. And yet pollock continue to appear mostly at the northwestern edge of their range.