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Vera Alexander

What Vitus Bering Started, and How the Bering Sea Replied

I don't give a damn if I never see any more scenery.

My story begins in Dutch Harbor/Unalaska, the logistic gateway to the Bering Sea. I first came to Dutch Harbor 27 years ago, to join a research cruise. The first ocean-ecosystem research in the region was just beginning. The town differed then from the remote but modern community, which the Harriman Expedition Retraced participants visited in August 2001. In 1974, it was a primitive settlement that probably was more like its condition in 1899 than how it is today. There was no bridge between Unalaska and Dutch Harbor, and the magnificent Russian Orthodox Church had fallen into disrepair, just one symptom of decay among many. The bars were lively, though.

When the Harriman Expedition arrived in 1899, the town was a transportation hub for gold miners; the Pacific cod fishery was probably underway at the time as well. The harvest of sea otters, the original focus for the town, was over; the Bering Sea northern fur seal industry was still alive. Today, the port serves the pollock, crab, and other fisheries. The Harriman Retraced members also noted several large foreign vessels in port for repair or being held for fisheries violations.

Yes, Dutch Harbor has served as a transportation hub and military base (remnants of World War II military installations could be seen on the mountainsides when I first came to the town, and are there still), and the surrounding grasslands have been used for grazing cattle. Yet, regardless of the transitory importance of these functions, the town has always reverted to the commercial harvesting of the sea's resources as the primary economic basis for its existence. When the Clipper Odyssey arrived, it was leaders in the fishing industry who accompanied the mayor in welcoming us, and with whom we had a stimulating panel discussion onboard.

Throughout its history, Dutch Harbor/Unalaska has played an important role in supporting the harvest of the rich biological resources of the Bering Sea and northern Gulf of Alaska. Only days before the Clipper Odyssey approached Dutch Harbor on August 6, 2001, our first stop in the Bering Sea, the National Marine Fisheries Service had rated the port as number one in fish catches for the previous year for the entire United States. Along with New Bedford, Massachusetts, and Kodiak, it was also among the top three fishing ports in dollar value of the catch landed. Its strategic location at the base of the Aleutian Chain and its protected harbor have produced a prosperous community central to a variety of activities, fulfilling the prediction expressed by John Muir in his report of the cruise of the Corwin, as he described his arrival at Unalaska in May, 1881: By virtue of its geographical position, it is likely to remain for a long time the business center of Western Alaska.

At the same time, the fishing industry all the way from Kodiak to Dutch Harbor has been under constraints imposed by the plight of the western stock of the Steller sea lion (Eumetopus jubatus). The stock has been declining precipitously for three decades and is now classified as endangered under the Marine Mammal Protection Act. A controversial biological opinion released by the National Marine Fisheries Service in 2000 has resulted in closure to commercial fishing of numerous areas near rookeries or haul-outs.

The first Russian explorers of the area opened the gates to ruthless harvesting over the decades to come. Arriving in 1759, they were the first Europeans to report the existence of what is now known as Unalaska, which subsequently became the first permanent Russian settlement in Russian America. In 1776, Gregory Pribilof had discovered the islands that are named after him, and much of the hunting pressure became focused there[1].

By the time the Harriman expedition visited in 1899, the fur trade had wreaked havoc with the sea otter and northern fur seal (Callorhinus ursinus) populations. The stocks had been nearly wiped out by the Russian fur trade; after Alaska became the property of the United States, the renewed fur harvesting completed the devastation. Even by 1830, less than 100 years after Bering's voyage, sea otters had become so rare that Baron von Wrangell of the Russian American Company persuaded his government to forbid the use of firearms and to protect the remaining animals by rigid conservation measures. This near-extermination was followed by intensive and lucrative whaling, later accompanied by intensive fishing.

Our more modern exploitation presents a grim picture as well. When I first came to Dutch Harbor as a junior oceanographer, the king crab fishery was still in its prime. By the late 1970s, however, the king crab population had crashed, probably as a result of overharvesting and climate change. The pollock populations had increased dramatically, and the pollock fishery was underway. First an international fishery, today it is solely a United States fishery, with split allocations between shore-base processors and the large factory trawlers that both catch and process the fish at sea. The total catch accounts for more than half the total United States fish catch in a year. There are many wealthy fishing captains in Dutch Harbor, and processing plants produce large amounts of frozen fish and surimi, a purified fish product used for making analogs such as artificial crab legs. The Bristol Bay sockeye salmon fishery is another major component, as has been the snow crab fishery.

Contemporary paradigms hold that historical overfishing can have long-term effects, showing up decades, even centuries later[2]. Perhaps the history of the Bering Sea provides a good case study for this, for without a doubt man's activities over the years have had a large impact on its ecosystem, albeit we still do not know to what extent natural cycles control the ups and downs of the populations of the various species. Yet, the Bering Sea remains one of the most productive marine areas in the world. The region includes the world's most extensive eelgrass beds; at least 450 species of fish, crustaceans and mollusks; 50 species of seabirds; and 23 species of marine mammals.

Lying between the Arctic Ocean and the North Pacific Ocean, the world's third-largest semi-enclosed sea, the Bering Sea has properties of each and is influenced by both. It is neither truly polar nor typically north temperate in character. Most of its wide eastern shelf is extremely shallow, in many places less than 60 meters in depth, whereas the basin exceeds 3,000 meters in depth. About half of the Bering Sea is underlain by continental shelf, and the other half is a deep basin. Several huge undersea canyons run up from the basin onto the shelf.

What factors account for the high productivity and species diversity of the Bering Sea? A look at the world's fish catches, historical and contemporary, shows that the richest and most productive fishing grounds usually are found in hostile subarctic or northern temperate areas, where the weather is invariably unpredictable and nasty. The Bering Sea is no exception, except that arguably it is the most productive of them. Fishing under these conditions is hazardous, and in these waters disasters are inevitable. Members of the original Harriman Expedition spent a great deal of time suffering from the seasickness that is inevitable under these conditions, albeit this is a relatively minor problem when compared with the frequent loss of vessels and life.

Why are highly productive areas so inhospitablecold and stormyor, to reverse the question, why are cold, stormy seas highly productive? The Harriman Expedition had no oceanographers onboard. Oceanography had not yet become a science, and the concept of ecosystems had not yet arisen either. While the inclement conditions were noted, their significance was not recognized.

Today, we have some understanding of the forces that drive marine productivity, but even more important, we have marvelous new tools to study them, including satellite technology. If you look at a satellite ocean color-scan image of the distribution of plants in the oceans in spring throughout the northern hemisphere, you notice immediately that there is no other region as rich as the Bering Sea. Why? The answer lies in cold northern water meeting water moving up from the south. In the Bering Sea, some of the water that moves up onto the shelf is from the deep Pacific Ocean and carries a very high nutrient content. This produces the green belt, a zone of high plant growth along the outer Bering Sea shelf. A major driving force for all of this is the northward passage of water through the Bering Strait over the Chukchi Sea shelf and into the Arctic Ocean. Ultimately, this water moves into the North Atlantic Ocean via the East Greenland Current. This flow is driven by a difference in height between the Pacific and Atlantic Oceans.

To explore the Bering Sea part in a little more detail, water flowing along the coast of the Gulf of Alaska passes through Unimak Pass as well as other passes west through the Aleutian Chain and then north and west up onto the shelf, bathing the Pribilof Islands and the outer portions of the shelf with nutrient-rich water that supports the diverse and abundant biota in the area. This flow, prior to moving into the Bering Sea, also supports the fishery resources in Shelikof Strait and the Kodiak area.

In the Bering Sea, nutrient-rich water is transported onto the shelf through eddies and tidal action as well, and via canyons that transect the edge of the shelf. The Pribilof Islands lie in the path of, and are influenced by, this nutrient-rich flux. The islands also benefit from the trapping of materials in the surrounding shallow waters through tidal action.

After leaving Dutch Harbor, as we approached Bogoslof Island, the Harriman Retraced participants observed large numbers of Steller sea lions and northern fur seals on the rookeries. This island lies over deep water at the edge of the shelf. Compared to its appearance in photographs taken by Harriman photographer Edward S. Curtis, the modern island shows major erosional changes. What we couldn't see from our Zodiacs was that deep below us was one of the most important spawning areas for walleye pollock. The juvenile pollock move up onto the shelf to grow, making use of the rich food sources and reducing the danger of cannibalism by the older fish. Today, though, they face a new hazard. In the past decade, the populations of a large jellyfish, Chrysaora melanaster, have increased tenfold over the Bering Sea continental shelf. These jellyfish compete for food with the young pollock, and they also prey on them. The impact on the pollock population is as yet not known. They may also be affecting the salmon, which have been showing variable and often disastrously low returns in the Bering Sea.

The Steller sea lion population of the region has been declining for several decades, having undergone more than an eighty percent reduction since 1965. In 1997 the population was classified as endangered under the Endangered Species Act. As a result, in 2001 a federal judge banned pollock fishing in critical habitat adjacent to about 40 rookeries and 82 haul-outs in the Bering Sea and western Gulf of Alaska. In truth the effects of fishing and the removal of large numbers of pollock on the sea lions is not well understood, and therefore a precautionary approach has been adopted.

Steller sea lions are not the only species that have shown big changes in the Bering Sea. Northern fur seals, sea otters, and several sea birds have experienced either steady or episodic declines. Salmon returns have been very low along the Bering Sea coast. Small runs of sockeye salmon in Bristol Bay and of king salmon in the Yukon River have created considerable hardship for both commercial and subsistence fishers since 1997. Historical exploitation could be the cause of these declines, but most likely dramatic climate shifts have played a role as well. One major shift occurred in the late 1970s, with an accompanying increase in temperature and a significant decline in seasonal sea ice cover. The latter is important, because the sea ice, as it retreats in spring, creates an early plant bloom that provides a large input into the ecosystem. The warmer waters with reduced sea ice grew warmer still in response to the 1997-98 El Niño, and there was a reduction in nutrient input from the south. Evidence points to lower overall productivity, not just in the southeast shelf region, but all the way up to the Bering Strait, although a change in timing and distribution is more likely, bringing about changes in the food chain. Another unusual occurrence was a massive invasion of exotic calcium-bearing algae, coccolithophorids, in 1997. These turned the water into a milky white fluid over four summer seasons; traces have been noted in 2001 as well.

As Harriman Retraced moved northward and across the international dateline into Russian waters, the abundance of large mammals, including walrus (Odobenus rosmarus) and gray whales (Eschrichtius robustus), increased, tallying with our understanding of the distribution of primary production (plant production) in the Bering Sea. The rich Anadyr Water, which originates from the westward flow mentioned earlier, moves north toward the Bering Strait, hugging the coast of the Chukchi Peninsula. While there are very rich places in the U.S. side of the northern shelf, such as the Chirikov Basin and the southern Chukchi Sea, the entire Russian portion is highly fertile. There, subsistence-based communities have enjoyed the biotic wealth.

The northern Bering Sea is able to support very large mammals such as resident walrus and migratory gray whales (as well as large sea bird populations) because of the rich organic deposits lain over the sea bottom by sinking planktonic plant material over this shallow shelf. It is primarily a bottom or benthic-based ecological community; pelagic fishes are relatively unimportant here as a resource. The biota which grow on the bottom, clams and tube-dwelling crustaceans, present a stable food source, accessible to walrus in winter from the ice surface and to gray whales, which migrate from Baja California to feed on the copious amphipods[3] (small crustaceans) in the summer. That it is worthwhile, in a biological sense, for the whales to migrate such vast distances to feed here attests to the wealth of the available food. All this richness is driven by the northern extension of the green belt, driven by flow north through the Bering Strait.

Harriman Retraced members visited villages on the United States side of the Bering Strait that were almost entirely dependent on a subsistence hunting-based economy. Both the historic and contemporary villages on the Chukchi Peninsula also showed evidence of the important role played by whales and walrus in their lives. This region is unique, a place where Asia and North America meet. The peoples who straddle the region, too, have a close relationship.

The ecosystem of the Bering Sea has changed markedly during the last three decades, and it is likely that change has characterized this region for centuries. Scientists studying the region point to evidence that the changes that have been noted over the last two decades or so have been unusually dramatic and attribute them at least in part to climatic events, rather than to the short-term influence of harvesting. The regime shift of the late 1970s, followed by the huge El Niño of 1997-1998, may have produced conditions that cannot easily reverse themselves. Still, it is hard to believe that the amount of harvesting, from whales to crab to pollock, has not had some influence, as proposed by a National Research Council study of the Bering Sea ecosystem[4].

Prediction about how the ecosystem may change in the future remains confounded because the weather patterns are controlled by multiple factors: Arctic, Aleutian, North Pacific, and Siberian. We can ask, for example, whether the decline in populations of several marine mammal species, the increases in jellyfish, the unreliable salmon returns, and the shifting productivity regime are symptoms of a unique event, or does it recur on an as-yet unrecognized time scale? Exciting research is being done on what once lived in the oceans, and new techniques are being developed to investigate the past. It is difficult, though, to look back to the days of the Steller sea cow and deduce what the kelp forests would have looked like then. Furthermore, residents of the region were affecting the stocks well before the white explorers came, and it is impossible to define a pristine condition.

Not all the Harriman Retraced members may have realized how extremely fortunate they were the Bering Sea put on a calm mantle and allowed a careful and considered look at the mammals and birds and coastal communities and sites. From the glassy passage through Unimak Pass, the sunny visit to Unalaska, and on north, we enjoyed balmy, calm conditions. It is hard to imagine a more beautiful scene than the tundra heath of St. Matthews Island vanishing up the hills into the haze, or the jagged rocks at the ends of the beach, or the old rusty shipwreck, which we encountered farther down the coast. St. Matthews Island was once known as a site for huge numbers of polar bears, and, although when we visited there was a rumor that a polar bear was stranded on the island, in recent years the light ice has not allowed major colonization of the island by these ice-dependent mammals. On May 31, 1881, members of the Corwin expedition were unable to land because of heavy ice. Today, it is rare to find polar bears on St. Matthew Island, and the sea ice has retreated by late April or early May.

This region is often stormy, and while spectacular, the seas are often not very comfortable. Our visit to the Bering Sea took place under exceptional conditions, and the experience was further enhanced by the knowledge that finally as a society we are recognizing the profound effects that have altered the Bering Sea ecosystem, and that governmental and non-governmental organizations as well as Native communities are taking steps to introduce improved conservation and management measures. The Bering Sea is the focus of a great deal of attention, and while we cannot change the course of natural processes, we can develop an understanding and sensitivity with respect to our role.


Selected Bibliography

[1] Boltnev, A. I. 1996. Status of the Northern Fur Seal (Callorhinus ursinus) Population of the Commander Islands. In Ecology of the Bering Sea: A Review of Russian Literature. O. A. Mathisen NS K. O. COYLE, EDS. University of Alaska Sea Grant Collage Program Report 96-01

[2] Jackson et al. 2001. Historical Overfishing and the Recent Collapse of Coastal Ecosystems. Science 293:629-638.

[3] Amphipod means many legs.

[4] National Research Council, Committee on the Bering Sea Ecosystem. 1996. The Bering Sea Ecosystem. National Academy Press. Washington, D.C.307 pp.


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