Across the remote, nearly 1 million square miles of water stretching north and south of the Arctic boundary between the U.S. and Russia, a monumental ecological shift powered by rising water temperatures is today underway, the results visible in dying seabirds and bounties of salmon.
The birds have perished by the thousands in the Bering and Chukchi seas, according to the National Park Service, while sockeye salmon returned to Bristol Bay at the southern end of the Bering in record numbers, and pink salmon populations boomed along both the U.S. and Russian coasts, according to Russian fish processors and residents of remote Alaska.
Some of the changes – dead and dying whales, walruses, seals, shearwaters, murres, puffins – sound almost apocalyptic when strung together. The accounts of carcasses washing up on beaches tend to make the Bering and Chukchi sound like areas hit by an oil spill without the oil.
But then humans have a tendency to focus on what they view as negative and sometimes overlook the positive. And what is going on in the region runs two ways.
If you are commercial fishermen in Bristol Bay or a grizzly bear almost anywhere along the western coast of Alaska, these are the good times. If you’re a subsistence hunter on St. Lawerence Island, where changing sea conditions have altered the behavior of whales and walruses, and disappearing sea ice has interfered with traditional hunting, these are scary times.
“These conditions we find ourselves in now are so out of historic context we’re sort of scrambling,” Alan Springer, a University of Alaska scientist with long experience in the region, said Tuesday. “It is mindboggling. It is all new ground.”
Whether the changes are relatively short term and destined to roll back or the beginning of some new norm, no one can say. Likewise, there are only guesses as to what fish and wildlife will emerge as winners and which as losers in the future because there are no real precedents on which to base predictions.
Their investigations followed a crash in western Alaska salmon populations that began in the late 1990s. The scientists eventually tied that to a stutter in what has been a trend of steadily warming waters.
“Climate-induced variation in ocean conditions affects the carrying capacity of juvenile salmon in the eastern Bering Sea,” they wrote. “Cold spring temperatures in 1999 might have reduced carrying capacity in the eastern Bering Sea, resulting in poorer than expected returns per spawner in subsequent years.”
The cooling didn’t last long. By the middle of this decade, warmer waters were powering their way back into the northern seas and by the start of this year, speculation was growing that the Bering, which seasonally has frozen in large part since almost forever, could soon become an ice-free sea.
A researcher with 30 years of experience in the region – biological oceanographer Jacqueline Grebmeier with the University of Maryland’s Center for Environmental Science – in March told Science News that there isn’t enough data to predict what is going to happen, but admitted to a gut feeling.
“I think it’s the beginning of change,” she said.
If the Bering Sea does go ice free, there is no telling how events play out because of the ripples throughout the ecosystem. Though the attention to warming water tends to focus on big changes near the top of the food chain – “Warmer Arctic waters attract surprising visitors: Clams, fish and whales,” the Washington Post headlined last fall – the profound changes come at the bottom where water temperatures influence both the productivity and kinds of plant and animal plankton on which all other life depends.
Those changes work upward. Opportunistic species, those evolved to live on a variety of foods like humans, usually thrive while species evolutionarily linked to a particular food normally found in abundance suffer.
Maine puffins, for instance, suffered mightily early in this decade when warmer Atlantic Ocean waters pushed herring and hake to the north. The puffins shifted their diet to butterfish, the shape of which made them difficult or impossible for young puffins to digest. Sixty-nine percent of the young birds died.
When one of the chicks – a bird named Petey – suffered and eventually died in front of a “Puffin Cam,” Mother Jones magazine labeled him “the new poster child for climate change.” The birds have since made a comeback, but largely only because cooling waters have brought hake and herring back to the waters off their rookeries.
A variety of Alaska seabirds now face the same environmental hurdles as the Maine puffins as waters warm. But not all species suffer.
Warmer Alaska ocean and freshwaters, the latter in part a product of warmer nearby seas, are giving the region’s economically valuable sockeye salmon a jump start on life, University of Washington (UW) researchers concluded in a paper published in “Nature, Ecology & Evolution” in May, although upon going to sea the fish do find they must compete for survival on increasingly competitive pastures.
That’s because other species of salmon and fish in general are also flourishing.
Scientists generally agree warming has made the northern ocean more productive. The metabolic theory, which links total resource biomass to temperature and decrees production should go up as temperature increases, is holding. But no one can know for how long.
“With climate change, is there a limit to how productive the ocean will become?” Daniel Schindler, one of the authors of the UW report told Science Daily this summer. “We just don’t know where there’s a tipping point, especially as we fill the ocean with hatchery competitors.”
Springer and Gus B. van Vliet, an independent Juneau-based scientist, in 2014 authored a paper suggesting salmon, particularly pinks, have now become so plentiful in the North Pacific and Bering Sea they can trigger top-down, “trophic cascades” when the competition for food diminishes the ability of seabirds to feed their young and thus reproduce. They further suggested in a 2018 paper that large numbers of migrant seabirds dying of starvation in years of high pink salmon abundance was no accident.
“Several lines of evidence indicate that pink salmon themselves are having a large top-down influence on other salmon species, other upper trophic level pelagic species, plankton standing stocks, and by inference, the functioning of the open-ocean ecosystem in the sub-Arctic North Pacific Ocean/Bering Sea,” they wrote.
The NOAA scientists studying the Bering in the 2000s noted the consumptive power of the smallest and fastest growing of the Pacific salmon. In even-numbered years when adult pink salmon are historically less abundant than odd-numbered years, they wrote, “total stomach content weight and proportions of euphausiids, copepods, fish, and squid increase in sockeye and pink salmon, and the proportion of euphausiids and other crustaceans increase in chum salmon stomach contents.”
It is the opposite in odd-numbered years, such as this one, when sockeye and chum salmon along with the seabirds must compete with lots and lots of pinks for food. Still, Springer and van Vliet’s linking of lost production among sea birds to pink salmon numbers has been roundly criticized by Bill Templin, the chief fisheries scientists for the Alaska Department of Fish and Game, who likes to repeat the old, scientific cliche that “correlation is not causation.”
That’s fine, Springer said, but if Templin has a better hypothesis for what is driving what have become regular, regional die-offs of seabirds and marine mammals due to starvation, he should pull together some data and get the theory in the discussion because the even year-odd year pattern of reproductive failures and die-offs so closely follows the boom cycles of pinks it is hard to ignore.
Pacific-wide, scientists Greg Ruggerone and James Irvine have calculated pink salmon are on average 37 percent more abundant in odd-numbered years than even-numbered years. The odd-year and even-year fish have been found to be genetically distinct, though they look and behave as if identical – spawning in the late summer or early fall with their young going immediately to sea the following spring or early summer. There they spend about 18 months before themselves returning.
Though the large volumes of these hungry predators – the northern pike of the sea as one Kenai River fisherman called them – appear to be causing ecosystem wide impacts, the root cause of most of the change now is driven by events that might be linked to man – rising seawater temperatures as a result of global warming – or is directly linked to man – the exceptional growth in abundance pinks thanks to large hatchery production in Alaska and better management everywhere.
Pacific-wide, pink-salmon harvests – the easiest measure of abundance – generally ranged from 75 million (to a maximum of 258 million from 1925 to 1965. Since 1990, harvests have ranged from 149 million to more than 400 million. Alaska alone produced a record 213 million pinks in 2013.
There was a time when fisheries biologists questioned whether the Pacific could support as many salmon as it now does, but the warming of the water appears to have significantly increased carrying capacity.
“The thing that ties this all together is how hot the ocean has been, Springer said. “The last several summers have been way above average….there’s an out of control climate warming in the Bering Sea.”
A NOAA survey in the summer, the results of which are due out later this fall, found bottom water temperatures in much of the Bering 5 to a staggering 14 degrees above what researchers have come to expect.
Overcoats to t-shirts
Areas once near freezing were “in the forties,” NOAA trawl supervisor Lyle Britt told KNOM radio during a stop in Nome in August. “The crabs and whatnot, they went from needing an overcoat, to needing t-shirts.”
The Seattle-based, nearly $1 billion Bering Sea pollock fishery is now anxiously awaiting NOAA’s assessment of what the water temperatures meant for the white-fleshed fish that support the nation’s biggest offshore fishery. The winter fishery was this year allowed a total allowable catch (BAC) of almost 1.4 million metric tons. There are fears that could shift downward although fish stocks in general have all been trending upward.
“Pink salmon in particular have been just increasing, and they haven’t quit,” Springer said. “They’ve just been going gangbusters.”
Subsistence fishermen in the “top of the world” community of Barrow were this summer complaining they couldn’t keep pinks, which they didn’t really want, from swarming their nets.
Short-tailed shearwaters have been at the other end of the spectrum. The Park Service and the U.S. Fish and Wildlife Service are asking residents of the region to report dead and dying ones to try to get an estimate of the death toll.
Early in summer, “thousands of short-tailed Shearwaters were reported dead and washing up on beaches in the Bristol Bay region, or observed weak and attempting to feed from salmon gillnets in inland waters,” a Park Service statement said. “By mid-August, the shearwater die-off had extended north, in smaller numbers but widespread locations, into the northern Bering and Chukchi seas along the coasts of Alaska and the Chukotka Peninsula of Russia. Puffins, murres, and auklets are also being reported, but at much lower numbers than shearwaters.
“Additionally, live short-tailed Shearwaters have been observed in large numbers this August in the Gulf of Alaska, along the coasts of Glacier Bay and Kenai Fjords national parks, and bays of Kodiak Island. It is unusual to see this species in high abundance in these areas, as it is typically offshore and comes from the southern hemisphere to forage in the Bering and Chukchi seas during the summer and fall.”
It is expected most of those birds will not make it home to their Australian breeding grounds.
Big seabird die-offs along the Alaska coast are not unprecedented, Springer said, but this appears to be the biggest since 1997 for shearwaters. Shearwaters have been most affected this year. There have, however, been a lot of smaller die-offs scattered across the years between then and now, including a massive, 2015-16 die-off of murres in the Gulf of Alaska
“It’s been episodes now for the last several years in a row,” he said with shearwaters, kittiwakes, puffins and murres involved. It is clear the Bering Sea is an ecosystem in flux trying to find some sort of new equilibrium between the many species of fish and wildlife that co-exist there.
Sadly that can make for a painful adjustment to witness even for rural Alaskans used to regularly killing birds and wildlife for food. Driven as much by death as by life, nature seldom kills peacefully.
Update: This story differs from the original. It was updated to reflect the effects pink salmon appear to have on the reproductive success of seabirds and to include further data on the numbers of pink salmon in the Pacific.