Commercial fishing doesn’t bother much with the Arctic Ocean. Ice covers a third of it even in the summer. It’s remote and has few lucrative fish. Horrendous storms and icebergs lurk. But the Arctic is warming twice as fast as the global average. The ocean’s cap of sea ice, just 40 years ago as big as Australia, is shrinking fast.

Henry Huntington, lead author of the recent paper, “Evidence Suggests Potential Transformation of the Pacific Arctic Ecosystem is Underway,” says these changes are reshaping the ecology of the Arctic ocean and waters just to its south, making fishing there increasingly attractive. “This is not your parent’s Bering sea or your childhood Bering sea anymore. This is something else,” said Huntington in a phone call.

Fisheries scientists anticipate that valuable fish fleeing warming waters in the Bering Sea and north Atlantic could find new habitats to the north, in the Arctic Ocean. Some fish species not recently seen so far north have moved to the Arctic Ocean already.

Someday, fishing fleets might follow them. When they do, the five countries that border the Arctic Ocean – the United States, Canada, Russia, Norway and Denmark (which oversees Greenland’s foreign policy) – probably will regulate Arctic Ocean fishing in their territorial waters. The U.S. and Canada have already banned commercial fishing in their parts of the Arctic Ocean. But what of the Central Arctic Ocean, the Mediterranean-Sea-size region of “high seas,” not under the exclusive control of any nation?

Pending final ratification, an international accord that also bans fishing in the Central Arctic Ocean will likely take effect later this year. A decade since negotiations began, the treaty – the Central Arctic Ocean Fishing Agreement – may give scientists breathing space to study the rapidly-evolving conditions in the world’s least-trafficked ocean. Fisheries experts hope that if fishing is eventually permitted, it will be managed rationally and sustainably. A disastrous frenzy of unregulated fishing in the 1980s that ruined an adjacent productive fishery, in the Bering Sea, gave ammunition to the agreement’s supporters. The new treaty is a rare international action to “‘prevent the fire’ rather than to ‘extinguish the fire,'” in the words of a recent paper in Marine Policy.

In 1986 Kevin Bailey, a fisheries scientist aboard the R/V Miller Freeman, an oceanographic research ship operated by the National Oceanic and Atmospheric Administration (NOAA), navigated to a location in the central Bering Sea known as the Donut Hole. The Donut Hole is a New-York-State-size territory of high seas and part of the region regulated by no country. Russia is 200 miles to the west, and Alaska 200 miles to the east.

Scientists generally had considered the Donut Hole too deep and nutrient-poor to support a sizable fish population. But industrial fishing operations had recently discovered otherwise. And they’d started scooping up huge loads of Alaska pollock, a cod-like fish with the mild white flesh that – battered, and fried – is transmuted into hundreds of millions of Burger King Big Fish, McDonalds Filet-O-Fish, and Arby’s Crispy Fish sandwiches and other similar products.

From a distance, Bailey spotted 60 huge trawlers from five countries waiting for their turn lowering tackle 1,000-feet, then towing it through the fish schools. He’d seen up close such gear harvest pollock in American waters. The nets’ cavernous mouths had a cross section the width and length of a football field. When winches hoisted them in, “endless loads of fish,” tumbled onto the decks, enough to fill an Olympic-size swimming pool.

Researchers could see that the take, at peak more than 10 percent of the Donut Hole’s biomass per year, was unsustainable. The U.S. fishing industry proposed a treaty regulating the Donut Hole. In the early 1990s, the two bordering countries (the U.S. and Russia) and four more-distant countries that had sent trawlers (China, Japan, Poland, and South Korea) met for discussions. They agreed to a fishing moratorium. But the trawlers had already scooped up most of the pollock. The Donut Hole had a biomass of 13-million tons of pollock in 1982, two fish apiece for everyone on Earth. By 1992 only 6 percent, 750,000 tons of fish, remained. It was “probably the largest fisheries collapse in the Northern Hemisphere,” says Kevin Bailey, who wrote about overfishing the Donut Hole in Billion-Dollar Fish: The Untold Story of Alaska Pollock.

The Central Arctic Ocean, across the Bering Strait from the Bering Sea, has no known major fish populations. But the increasingly warmer waters might someday make the waters more habitable for fish. “There is the prospect that there might be enough fish to support a commercial fishery in this area someday,” says Ambassador David Balton, the Deputy Assistant Secretary for Oceans and Fisheries in the U.S. Department of State in the Obama administration.

In 2008, the U.S. Congress passed a joint resolution calling for diplomatic efforts to protect the Central Arctic Ocean from over-harvesting, just in case. Negotiators from the five countries bordering the Arctic Ocean began meeting several years later. The fate of the Donut Hole 30 years earlier was “an important precedent,” says Balton, who represented the U.S. in the early treaty negotiations. “They didn’t want a repeat of that story,” he said in a recent phone call. Troubling changes in the Arctic Ocean, predicted by climate scientists, convinced negotiators that the region is destined for a far-reaching metamorphosis.

Ever since NOAA and NASA began monitoring the Arctic Ocean with daily satellite observations in 1979, researchers have found a steady decline in the Arctic sea-ice cap. In the last 40 years, the annual minimum size of the ice cap, in late summer, has shrunk by 13 percent per decade. The maximum size of ice cap, in winter, also is declining, though not as rapidly.)

The Central Arctic Ocean, the body of deep water roughly centered on the North Pole and extending hundreds of miles in every direction, had probably never been ice-free for hundreds – and possibly thousands – of years until the summer of 1998, when space-based sensors detected that 5 percent of it was open water. Parts of the Central Arctic Ocean have thawed out every summer since 2002, including the summer of 2012, when 40% of its ice melted. Researchers predict that the entire Arctic Ocean will be virtually ice-free in summers within the next several decades.

Big flora, fauna changes observed on ocean fringes

The Central Arctic Ocean’s snow-covered lid of sea ice blocks light that algae and other phytoplankton at the base of the food chain need to grow. The ice prevents waves and wind from stirring up nutrients that fertilize them. The recession of the ice sheet could boost productivity of these single-celled organisms. Everything they nourish, including bottom-feeding crabs, whales, seals and fish, could blossom. But the mix of species living in the revved up ecosystem may differ from today’s residents.

For instance, biologists are already observing unprecedented changes in flora and fauna on the fringes of the Arctic Ocean that could soon affect all the ocean’s waters. Henry Huntington’s paper, coauthored with nearly two dozen experts in an assortment of Arctic specialties, catalogues many unexpected appearances, disappearances, and behavior changes on both sides of the Bering Strait, in the Bering, Chukchi, and Beaufort seas. Walruses are hauling out on land rather than on sea ice. Killer whales are staying longer in the Arctic Ocean rather than moving to warmer waters to the south. Where black-legged kittiwakes and murres once preyed on fish, crested auklets and short-tailed shearwaters now graze plankton.

Researchers have reported similar incidents elsewhere in and near the Arctic Ocean, he said.

The changes in the Arctic Ocean’s biology have followed the combination of increased water temperature – both to the south and in the Arctic Ocean itself – and ice recession. Sea ice strongly influences the biology, chemistry, and physics of the Arctic. Marine mammals, such as seals and walruses, rest on it and hunt from it. Algae, the base of the food chain at melting ice edges in the spring, grows on its underside. Sea ice regulates regional temperature, moisture, and salinity. As sea water cools and freezes, waters nearby become saltier. When sea ice melts, nearby waters become less salty.

In shallow waters of the continental shelf just south of the Bering Strait, sea ice used to create a layer of intensely frigid saline water every year called the Bering Sea Cold Pool. Researchers believe that the Cold Pool, located near the bottom, blocks Bering Sea fish, such as salmon and Alaska pollock, from migrating into the Arctic Ocean. But in 2018 and 2019, the Cold Pool vanished, probably because of an unprecedented lack of sea ice in the Bering Sea. It may have recovered partially in 2020 (limited monitoring during the pandemic prevent definitive conclusions). But Seth Danielson, a physical oceanographer who has studied the effects of warming in the Bering Sea, says that the Cold Pool is bound to be a casualty of global warming. “It does appear to be a waning feature of the Bering Shelf.” The commercially valuable fish once constrained to the south are already sighted more often in the Chukchi Sea.

Expanded number of countries involved in talks

After two years of meetings on how to protect the Central Arctic Ocean – and a year’s pause after Russia invaded Crimea in 2014 – the five negotiating parties signed a declaration not to allow their commercial fleets to fish in the thawing international waters. But the agreement had no teeth. They’d determined that to reach an enforceable agreement they needed to invite the other nations with fishing fleets that might brave the Central Arctic Ocean: Iceland, China, the Republic of Korea, Japan, and the European Union (representing its member states) joined further meetings.

In 2017, all 10 parties signed an agreement to forgo fishing in the Central Arctic Ocean. The moratorium can be extended for increments of five years after the initial period is over. All signatories except China have since ratified the treaty. Balton, now a senior fellow at the Wilson Center International Center for Scholars in Washington D.C., says, “I don’t think there’s any serious doubt that China will move forward,” probably later this year.

Observers and participants laud the agreement for applying “the precautionary principle” – that it’s prudent to anticipate and prevent a problem rather than respond to it. It’s “the best example of it in action I’ve ever encountered,” says Balton. It succeeded because there was no organized lobby to oppose it, says Oran Young, a political scientist who specializes in Arctic governance and co-author of a paper on appraising the agreement. “It’s easier to put something in place before a strong interest develops to oppose it.”