Thursday, December 4, 2014

Polar Bears Endangered? Are Some Researchers Hiding Evidence?

PolarBeargate? Are Some Researchers Hiding Evidence? 

Suggesting impending climate doom, headlines have been trumpeting polar bears are “barely surviving” and “bears are disappearing” prompted by a press release hyping the paper Polar bear population dynamics in the southern Beaufort Sea during a period of sea ice decline (hereafter Bromaghin 2014), which based on an ongoing US Geological Survey (USGS) study. Dr. Susan Crockford rightfully criticized the media’s fear mongering and failure to mention increasing bear abundance since 2008. She also pointed out that modelers have consistently failed to account for the negative impacts of heavy springtime ice here.
I want to reinforce Crockford’s posts, plus argue the problem is much worse than she suggested. Bromaghin 2014’s purported 25 to 50% population decline is simply not realThe unprecedented decline is a statistical illusion generated by the unrealistic modeling of polar bear survival from 2003 to 2007.  The highly unlikely estimates of low survival were made possible only by ignoring the documented effect of cycles of heavy springtime sea ice which forces bears to hunt outside the researchers’ study area. Although several of Bromaghin’s co-authors had previously published about negative impacts of heavy springtime ice, they oddly chose to never incorporate that evidence into the USGS models. The following demonstrates how the statistical illusion of “disappearing polar bears” was generated and I urge you to forward your concerns about USGS fear-mongering via subjective modeling to your congressmen and push them to fully investigate these USGS’ polar bear studies.

Perhaps polar bear researchers are just victims of confirmation bias. Co-authors of Bromaghin 2014 have long tied their authority, fame and fortune to predictions of impending polar bear extinctions due to lost summer sea ice.  In a 2008 Dr. Andrew Derocher predicted, “It's clear from the research that's been done by myself and colleagues around the world that we're projecting that, by the middle of this century, two-thirds of the polar bears will be gone from their current populations”. Dr Steve Amstrup, chief scientist for Polar Bear International and the USGS researcher that initiated the Beaufort Sea studies, previously published “Declines in ice habitat were the overriding factors determining all model outcomes. Our modeling suggests that realization of the sea ice future which is currently projected, would mean loss of ≈ 2/3 of the world’s current polar bear population by mid-century.”1Furthermore the USGS’ political reputation is on the line because their studies led to the listing of polar bears as “threatened” due to decreasing summer ice they attributed to CO2 warming. But why do USGS model estimates differ from Inuit experts and the Nunavut government who have steadfastly claimed it is the time of the most polar bears. And why does the USGS’ models differ from numerous surveys (i.e here and here) that support the Inuit claims?

There are 2 major flaws in USGS models:

1)   USGS Polar bear researchers tirelessly point to hypothesized stress due to lost summer sea ice, yet they completely ignore much more critical cycles of heavy springtime ice. As previously documented by Bromaghin’s co-authors, the condition of springtime sea ice determines the abundance and/or accessibility of ringed seal pups. Eighty percent or more of the bears’ annual stored fat is accumulated during the ringed seal pupping season that stretches from late March to the first week of May. At that time female bears emerge from their maternity dens to feast on ringed seal pups, and accordingly USGS mark and recapture studies focus virtually all their efforts during the month of April. Yet not one model has incorporated known changes sea ice during that same period. Is that data purposefully omitted because heavy spring time ice does not support their CO2-driven extinction scenarios?
2)   Furthermore heavy springtime ice forces movement outside the study area because it prevents local access to seal pups. Any movement outside the study area prevents subsequent recapture and can erroneously cause models to assume emigrant bears are dead. That false assumption creates lower survival estimates which then dramatically lower population estimates. Misinterpreting a temporary or permanent exodus away from a stressful local environment was the same critical error that led to bogus extinction claims for the Emperor Penguins.  Coincidently one modeler, Hal Caswell, created both models falsely suggesting Emperor Penguins and Polar Bears are both on the verge of extinction.

Why Spring Ice Conditions Are More Critical than Summer Ice.

South Beaufort Sea bears increase their body weight primarily by binging on ringed seal pups, and the bears’ springtime weight gains are huge. Researchers reported capturing a 17-year-old female, with three cubs-of-the-year, in November 1983 when she weighed just 218 lbs. Her weight would have continued to drop, as it does for all bears, throughout the icy winter. Weights do not increase until seal pups become available in late March and April. But after gorging on seal pups, she was recaptured in July and weighed 903 lbs, a four-fold weight change in just 4 months. 2 (her picture is below). The ability to rapidly gain weight, hyperphagia, evolved as a crucial survival strategy to take advantage of abundant but temporary food sources. Springtime ice conditions govern their access to the fleeting availability of ringed seal pups.
Polar Bear Quadruples Weight on Bay Ringed Seals
Fat Polar Bear
In 2001, Bromaghin 2014 co-author Stirling described the negative impacts of heavy rafted springtime ice. 
“In the eastern Beaufort Sea, in years during and following heavy ice conditions in spring, we found a marked reduction in production of ringed seal pups and consequently in the natality of polar bears.” 
Stirling noted it took about 3 years for both seal and bear populations to rebound. Stirling also reported the South Beaufort Sea undergoes ~10-year cycles of such heavy ice, and those stressful cycle had been observed in the 70s, 80s and 90s. 5 The most recent cycle of heavy ice is well documented and occurred precisely when bears increasingly exited the study area from 2003 to 2007.
In 2008, Bromaghin 2014 co-authors Stirling, Richardson, Thiemann, and Derocher published Unusual Predation Attempts of Polar Bears on Ringed Seals in the Southern Beaufort Sea: Possible Significance of Changing Spring Ice Conditions10 Those researchers had observed that “unusually rough and rafted sea ice extended for several tens of kilometers offshore in the southeastern Beaufort Sea from about Atkinson Point to the Alaska border during the seals’ breeding season from 2003 through 2006”, precisely when their models calculated low survival and a rapid decline in the polar bear population.
Those researchers reported 

heavy ice reduces the availability of low consolidated ridges and refrozen leads with accompanying snowdrifts typically used by ringed seals for birth and haul-out lairs.” And they observed, “Hunting success of polar bears (Ursus maritimus) seeking seals was low despite extensive searching for prey. It is unknown whether seals were less abundant in comparison to other years or less accessible because they maintained breathing holes below rafted ice rather than snowdrifts, or whether some other factor was involved.“ 

(Forcing bears to claw through rafted ice gives the seals ample time to escape.) Polar bears never defend territories. Instead polar bears are highly mobile. Dependent upon seal pups for most of their annual energy supply, a supply that varies annually, bears simply migrate to regions with greater seal abundance.
After giving birth and completing their annual molt by late June, most ringed seals migrate out to sea to fatten and are no longer available to the bears. After late June the amount of sea ice is no longer important habitat for ringed seals.So any correlations with summer sea ice extent from August to November have a relatively insignificant impact on survival. In fact, more open water benefits seals. In a previous essay, Why Less Summer Ice Increases Polar Bear Populations, I explained why ringed seals avoid thick multi-year ice, and why more open water later in the season benefits the whole food web. Bromaghin 2014’s co-author Stirling previously co-authored a paper reporting ringed seals must feed intensively in the open waters of summer in order to store the fat needed to survive the winter, and that seals suffer when sea ice is slow to break up4
He pointed out that in 1992 when breakup of sea ice was delayed by 25 days,the body condition of all ringed seals declined resulting in declining body condition of bears. To supplement their diet, bears will feed on a wide array of alternative items from whale carcasses, walruses to geese eggs. Despite the 2ndlowest extent of Arctic summer ice in 2007, researchers on Wrangel Island reported fatter bears than they had previously documented.6 All the evidence suggests summer ice is far less critical than the condition of springtime ice. So is the erroneous focus on summer ice conditions merely driven by researchers predictions that rising CO2 will cause widespread polar bear extinctions in 30 years?

 Movement Lowers Survival Estimates which Lowers Population Estimates

Bromaghin 2014 authors acknowledged that the observed movement could bias model results, but simply dismissed the observed transiency of wandering bears writing, 
“The analyses of movement data suggested that Markovian dependency in the probability of being available for capture between consecutive years remains a potential source of bias. However, we view these results with some caution because of the small sample sizes and prior evidence that bears prefer ice in waters over the narrow continental shelf. Further, there is no reason to suspect behavior leading to non-random movement during the spring capture season changed during the investigation.” 
But their dismissal is nothing less than dishonest. Bromaghin 2014 authors had indeed observed that heavy springtime ice resulted inreduced hunting success and reduced body condition and would force bears to hunt elsewhere.
Bromaghin 2014 authors were denying their own evidence. A subset of bears had been radio-collared in order to track their movements. Between 2001-2003 when their study area experienced normal springtime ice conditions, researchers estimated high survival probability and high abundance, and only 24% of the radio-collared females had wandered outside their study area making them unavailable for recapture. In contrast during the years of heavy springtime ice between 2004 and 2006 researchers estimated unprecedented low survival, low abundance and observed an increased number of collared females outside the study area doubling to 47% in 2005 and 36% in 2006. 7,9 Yet Bromaghin 2014 argue  “there is no reason to suspect behavior leading to non-random movement during the spring capture season changed during the investigation.”
A previous study by Amstrup had mapped the range over which radio-collared bears travelled each year. From his 3 examples illustrated below it is clear that polar bears are not always found in the same place each year. Furthermore in accordance with the changing availability of seal pups due to cycles of heavy springtime ice, he reported polar bears exhibited their lowest fidelity to any given area during the spring pupping season. Finally Amstrup’s map shows bears naturally wander outside the boundaries of the study areas searching for food. Because researchers restricted their search efforts to the east of Barrow Alaska, bears moving in and out of the Chukchi sea area have a far less recapture probabilities. Likewise bears that wander between Alaska and Canada will have different recapture probabilities because different amounts of effort were expended in each country.
polar bear movement out of study area
Polar Bear movement out of study area
Due to movement of bears in and out of the Chukchi Sea region, Amstrup had determined those movements heavily biased previous survival and abundance estimates. 8, 12 Bromaghin 2014 also report that the Chukchi Sea region is more productive than the Beaufort Sea. So it is highly likely that bears migrate between the Beaufort Sea study area and the Chukchi Sea in response to varying periods of localized heavy springtime ice and seal pup availability. So why does Bromaghin 2014 dismiss observed movement bias by arguing  “there is no reason to suspect behavior leading to non-random movement during the spring capture season changed during the investigation” and contrary to their own evidence suggest bears would remain in the more productive Chukchi Sea region. 
In 2001 Amstrup had previously estimated survival rates of South Beaufort bears as 96.2% and natural survival rates were 99.6% and a population could be more than 2500 bears in 1998. 3  Amstrup reported “polar bears compensate for a low reproductive rate with the potential for long life” (i.e high survival). Because movements of bears into and out of his study area had greatly biased his results he warned, “models that predict rapid increases or decreases in population size would not mirror reality.” Curiouser and curiouser he no longer heeds his own advice. Amstrup and his colleaguessuddenly embraced the unprecedented low survival rates of 77%, and a rapid 25 to 50% decline in the population between 2004 and 2008 as seen in their graph of estimated abundance.

Polar bear population lower due to springtime ice
South Beaufort Sea Polar Bear population estimates

In order for their model to generate that unprecedented low survival rate of 77%, (despite no observed change in the trend of body condition for 95% of Beaufort Sea bears) 11 modelers had to dismiss the observed movements outside their study area. Once Bromaghin’s authors had dismissed the significance of springtime movement, their models would interpret a lack of recaptures as an indicator of dead bears which then produced the illusion of a rapidly declining polar bear population.
Below is a table illustrating the simplified effects of historical survival estimates on abundance calculations (assuming no additions from new births and immigration). The numbers listed in the gray columns on the left are the USGS study’s actual number of bears captured annually, and the number of that total capture that were previously marked bears. As the study progressed and newly captured bears are marked, the pool of marked bears increases.  If the study area was a closed system, we would expect each year’s total number of captures to consist of an increasingly higher percentage of marked bears once the pool of marked bears was large enough. But each year the number of previously marked bears made up only ~50% of the total captures, suggesting a larger population was more likely than what was currently estimated, and that the length of this study was not yet long enough.
In the simplest models, abundance is determined by dividing the total number of bears captured each year by the percentage of captured marked bears from the pool of previously marked bears. (Read How science Counts Bears for a further discussion of mark and recapture studies) However the size of the pool of marked bears depends upon the bears’ survival probability. To illustrate, for each year I generated 3 different pools according to different historical survival estimates. The resulting change in abundance calculated from those 3 different survival probabilities are highlighted in yellow.
polar bear uncertainty
How survival estimates alter polar bear population estimates
If researchers assumed 100% survival, which is close to Amstrup’s 99.6% in his original study, (but with no additions from birth or immigration) then Bromaghin’s data would estimate a 2010 growing population of 2,255 bears. An estimate that is remarkably similar to Amstrup’s 1998 estimate of ~2500 bears. 
If the researchers assumed Amstrup’s 96% survival, a lower survival estimate due to the impact of hunting, then the 2010 abundance would be calculated at 1865 bears. Again remarkably close to Amstrup’s suggested abundance of 1800 for a hunted population.
In the 2006 USGS analyses7 the authors interpreted fewer recaptures as an averaged lower survival rate of 92%.  A 92% survival rate would produce a stable 2010 population estimate of 1664 bears, which is also 70% higher than Bromaghin’s results.  
The only way to generate a tragically declining bear population was to employ much lower survival estimates. And as evidenced by their graph below, that is just what they did for the period of heavy springtime ice with low seal availability and much greater movement out of the study area. When the springtime ice returned to normal so did the bears, and their estimated survival rates likewise returned to the expected high ~95%. The huge error bars in Bromaghin’s survival probabilities (see graph below) during those heavy ice years, illustrates the great uncertainty regards the actual fate of marked bears that were never recaptured.
polar bear survival increases with less heavy ice
Lower survival Polar Bear survival during heavy springtime ice
So we must question why these polar bear researchers ignored their co-author’s earlier warning, “models that predict rapid increases or decreases in population size would not mirror reality.” 
Were polar bear researchers blinded by climate change beliefs, or acting dishonestly?

Literature Cited

1. Amstrup (2007) Forecasting the Range-wide Status of Polar Bears at Selected Times in the 21st Century  USGS Science Strategy to Support U.S. Fish and Wildlife Service Polar Bear  Listing Decision
2. Ramsay, M, and Stirling, I. (1988) Reproductive biology and ecology of female polar bears (Ursus maritimus). Journal of Zoology (London) Series A 214:601–634.

3. Amstrup, S. et al. (2001) Polar Bears in the Beaufort Sea: A 30-YearMark–Recapture Case History. Journal of Agricultural, Biological, and Environmental Statistics, Volume  6, Number 2, Pages 221–234

4. Chambellant, M. et al. (2012) Temporal variations in Hudson Bay ringed seal (Phoca hispida) life-history parameters in relation to environment.Journal of Mammalogy, vol. 93, p.267-281

5. Stirling, I. (2002)Polar Bears and Seals in the Eastern Beaufort Sea and Amundsen Gulf: A Synthesis of Population Trends and Ecological Relationships over Three Decades. Arctic, vol. 55, p. 59-76

6. Ovsyanikov N.G., and Menyushina I.E. (2008) Specifics of Polar Bears Surviving an Ice Free Season on Wrangel Island in 2007. Marine Mammals of the Holarctic. Odessa, pp. 407-412.

7. Regehr et al 2006, Polar bear population status in the southern Beaufort Sea: U.S.  Geological Survey Open-File Report 2006

8. Amstrup et al (2000) Movements and distribution of polar bears in the Beaufort Sea. Can. J. Zool. Vol. 78, 2000
 9.  Regehr, E., et al. (2010) Survival and breeding of polar bears in the southern Beaufort Sea in relation to sea ice. Journal of Animal Ecology 2010, 79, 117–127
10. Stirling, I. et al. (2008) Unusual Predation Attempts of Polar Bears on Ringed Seals in the Southern Beaufort Sea: Possible Significance of Changing Spring Ice Conditions.  Arctic, vol 61, p. 14-22.

 11. Rode, K. et al. (2007) Polar Bears in the Southern Beaufort Sea III: Stature, Mass, and Cub Recruitment in Relationship to Time and Sea Ice Extent Between 1982 and 2006. USGS Alaska Science Center, Anchorage, Administrative Report.
 12. Amstrup, S.  and Durner, G. (1995) Survival rates of radio-collared female polar bears and their dependent young. Canadian Journal of Zoology, vol. 73. P. 1312?1322.

Hijacking Successful Walrus Conservation!

Successful Walrus Conservation
The walrus is another example of improving environmental stewardship. Valued for its oil and ivory tusks, the Pacific walrus was subjected to intense commercial slaughter in the mid 1800s, and by the early 1900s, many worried they would soon go the way of the dinosaurs. Although population estimates have always been highly uncertain, as hunting was progressively limited, Pacific Walrus populations “increased from 50,000 to 100,000 animals in the late 1950s to more than 250,000 animals by 1985,” and they are believed to have now reached their maximum carrying capacity. As walrus numbers rebounded, they have crowded together at historic coastal haul-outs (Haul-outs are land locations where walruses congregate when not swimming). However some global warming advocates are using the walrus’ recovery as evidence of ecological disruption caused by rising CO2 and the loss of sea ice. But their fears would vanish if they had a more historical perspective.
In 1923 Captain Joseph Bernard published an account in the Journal of Mammalogy about the inspiring conservation efforts he had observed in the village of Ingshong on the Siberian coast. There the wisdom of walrus conservation, dressed in the trappings of shamanic beliefs, had fostered a dramatic comeback in local walrus abundance.
 Walrus historically on land
Natural Walrus land haul outs
When Capt. Bernard had first visited the village of Ingshong, he met an ordinary hunter named Tenastze. Eighteen years later, Tenastze had become Chief. His rise to the top began when he gathered together the men of Ingshong and neighboring villages to discuss a decade of failed walrus hunts and disappearing herds. Walruses had once come to rest on their beaches in countless numbers, but the beaches were now empty. Tenastze believed that there was no one in the village looking after the spirit of the walrus and summoned a small group of shamans to peer more deeply into the problem.
After days of extended drumming and an induced trance, the shamans reported that indeed someone had offended the spirit of the walrus and poisoned the land. To break the spell of evil, the people had to choose a strong chief who promised to guard the walrus’ spirit.
Their first step was to sacrifice the first walrus that presented itself to the village’s hunters. After ritualistic preparation, its skull was placed on a long stick. Holding the other end of that stick, the strongest man in the village would attempt to lift the skull in response to each question. Like a shaman’s version of the Ouija board, questions were directed to the walrus spirit. If the strongman was unable to lift the skull, it was a negative answer. If the spirits wanted to respond positively, the spirits imbued the man with enough strength to lift the skull. One by one, the names of all the men vying to be the new chief were offered to the walrus spirit. Only when the name Tenastze was spoken could the strongman lift the skull. (Although I love the story’s ending, the skeptic in me can’t help but wonder if Tenastze paid off the strongman.)
Now in charge, Tenastze quickly designated a round-the-clock guard to insure that the walruses were not disturbed. When the walruses first appeared in the coastal waters, fires were not allowed and alcoholic drink was forbidden. Shortly thereafter, a lone venturous walrus finally settled on their beach, and spent the night undisturbed. After each feeding foray, that walrus returned again and again and each time brought more and more walruses. By the time the autumn sun was retreating south, and the winter freeze beginning, several hundred walruses had come ashore. Only then were the people allowed to take their allotted kill; most walrus were permitted to go away unharmed. The walruses seemed unaffected by this limited hunt, and the next year many more came ashore. As the years passed, the herd grew to such proportions that villagers told Bernard, “last year the beach was so crowded when the walruses hauled there, many walruses were crushed to death just from overcrowding.”
Walrus driven historical land haul outs
Hunting forced walrus from historical land haul outs
In 1925 Bernard again wrote in the Journal of Mammalogy, advocating for walrus sanctuaries in Alaska to the south of Barrow. He contrasted the more conservation-minded village of Ingshong to the settlement of Point Hope on the Alaskan Coast. Thirty years before, the walruses had hauled out by the thousands and some would even wander into town. However the traders, whalers, and Inuit of the settlement were all too quick to shoot any weary walrus coming ashore. Subsequently, for the last twenty years live walruses had become a rare sight on that beach.
The European settlers of that time had embarked on a withering onslaught, motivated by a lucrative ivory market. In just a few decades the only surviving walruses were the ones that had learned to avoid coastal haul-outs, finding greater safety on the ice floes or more remote islands. Nomadic Inuit hunters showed no greater restraint than the Europeans. They followed the wary walrus herds out onto the ice floes. Although walrus meat was highly valued, ivory tusks brought much greater returns. Along the 200 miles of shoreline near Pt Barrow, Alaska, Bernard counted 1000 walrus corpses washed ashore. One third of the corpses still retained their tusks; although shot, they had managed to slip into the waters before the hunters could cleave their tusks. The nightmare was likely far greater than evidenced by mere shoreline counts. If Bernard counted 1000 rotting carcasses washed ashore by the westerly winds, how many more were carried by the currents out to the Arctic Ocean, or to other distant beaches?
From 1900-1930, the annual harvest of Pacific walrus averaged 5000 per year. Despite growing concerns voiced by Bernard and others, that figured doubled to 10,000 per year between 1930 and 1950. The Pacific walrus was seemingly headed for extinction. Fearing this may be the last chance to observe living walruses, Francis Fay began compiling one of the most complete accounts of the ecology and biology of the Pacific Walrus for the US Fish and Wildlife Service. After more than two decades of research, “The Ecology and Biology of the Pacific Walrus” was published in1982.
The 1950s were the 20th century’s nadir of walrus abundance. Over-hunting of whales and walruses had been so severe, the native Yupik of the St Lawrence Island found themselves on the verge of starvation. The Yupik had dodged an earlier threat of extirpation in 1879 when disease was introduced by visiting whalers. When John Muir and a Smithsonian naturalist visited the island they were horrified to find huts strewn with hundreds of dead bodies. There were few survivors. Although the Yupik population had only rebounded to just one-third of their pre-epidemic population, the slaughter of whales and walruses now denied the surviving Yupik adequate sustenance. According to Fay, “If remedial food supplies had not been provided by Federal and State governments, the islanders probably would have been afflicted again by starvation and death in 1954-55.”
When the walrus were plentiful in the 1800s, they had hauled out in great numbers on beaches. Fay reported that of “numerous coastal hauling grounds that were used on the Siberian coast in the early part of the century, only three remained in use by the mid-1950’s.” There were just too few Tenastze to guard the walruses. Thanks to hunting restrictions, the walrus rebounded. As populations returned to historical peak abundance, they began returning to former coastal haul-outs. Most recently walruses returned to an Alaskan beach about 140 miles southwest of Barrow. It was the general location that Captain Bernard wanted protected as a walrus preserve, and news of the walruses’ return would have certainly caused the good captain to celebrate. But not the global warming advocates. A stampede, most likely provoked by a hunting polar bear, left several trampled walruses. Although historically tramplings had been associated with great abundance, advocates spun it as proof of deadly CO2.
The Huffington Post published the following: “ANCHORAGE, Alaska — Trampling likely killed 131 mostly young walruses forced onto the northwest coast of Alaska by a loss of sea ice, according to a preliminary report released Thursday.” “Obviously it's a real tragedy, and it's one we're going to see repeated more and more as the climate warms and the sea ice melts," said Rebecca Noblin, staff attorney at the Center for Biological Diversity (CBD). The CBD had petitioned to list walrus as threatened or endangered because of increased CO2 levels. The article makes the bold claim, "Were it not for the dramatic decline in the sea ice, the young walruses at Icy Cape most likely would be alive on the ice and not dead on a beach," said WWF [World Wildlife Fund] biologist Geoff York.”
However, by all historical accounts, walrus land haul-outs were very common in a time of abundant sea ice. The lawyers and advocates were ignoring (or ignorant of) Bernard’s 1925 lament that “Thirty or forty years ago in various places along the Alaskan coast walruses were known to haul-out in countless numbers (emphasis added).”  It’s also doubtful they had ever read Fay’s mid-century accounts in which death by trampling was listed as one of the “top 3 natural causes of death to walrus calves exceeded only by deaths caused by killer whales and polar bears (emphasis added).” 
Fay’s research had compiled numerous reports depicting far greater mortality from trampling. Those deadly events happened when animals either hauled out in panic when pursued by killer whales, or when stampeded by attacking polar bears or humans. For example, in 1975, researchers reported a large number of dead animals during a stampede from a traditional hauling ground at Cape Blossom on Wrangell Island. The low-flying aircraft of the researchers had caused that stampede.
In the heavy ice year of 1979, Fay examined the remnants of the greatest trampling tragedy yet recorded. On Punuk and St Lawrence Island, “At least 537 animals died at one haul-out area,” and approximately 400 other carcasses washed ashore from other locations. Nearly all of the dead were extremely lean, having less than half as much subcutaneous fat as healthy animals examined in previous years.” St Lawrence Island and the Punuk islands lie directly in the migratory path of the walrus’ southward journey from their summer feeding grounds in the Chukchi Sea to their wintering areas in the Bering Sea. The tramplings were spread out over both traditional haul-out locations on the Punuk Islands and in “four other locations on St. Lawrence Island where locals claimed they had not been seen in recent memory.” A more thorough investigation unearthed abundant old carcasses and bones and laboratory dating techniques revealed those “new” haul-outs had been very active in the early 1900’s before hunting pressures decimated their populations.
The Demise of the Atlantic Walrus
Walrus pups vulnerable
Walrus pups vulnerable to trampling
All evidence indicates that walruses have always hauled onto land even during the severe ice conditions of the Little Ice Age. It was overhunting that drove walruses from the beaches, and this is clear from historical accounts of the first encounters between walrus and European hunters on the pristine Svalbard archipelago. In archaeologist Robert McGhee’s superb book on the Arctic, The Last Imaginary Place, he devotes an entire chapter to the “rape of Spitsbergen” (Svalbard’s largest island) and vividly documents the excesses of European harvests and glimpses of previously untouched Arctic wildlife.  
Svalbard is located about 180 kilometers to the east of Greenland across the Fram Strait. Each year the Arctic winds remove much of the Arctic’s sea ice through the Fram Strait, sending ice southward to melt in the northern Atlantic. The Arctic ice piles up on the frigid northern half of Svalbard, in contrast to its ice-free southern half. In March, sea ice has reached its maximum extent and thickness, but the warm nutrient-rich waters can keep Svalbard’s south side ice-free. Those nutrient-rich waters once sustained an awe-inspiring profusion of life that has yet to fully recover from overhunting.
Although ancient hunters had reached the Arctic 5000 years ago, they never reached the islands of the Svalbard archipelago. It remained pristine until the Europeans first discovered the islands in the 1500s. In 1596, the Dutch explorer Willem Barents is believed to be the first person to ever set eyes on Svalbard and the Barents Sea now bears his name. Barents wrote about feasting on the eggs laid by the Barnacle goose, which was the biggest scientific news of the times. Until Barents’ discovery, the Barnacle goose was the poster child for the theory of spontaneous generation. No European had ever seen a Barnacle goose egg. Yet every winter the Barnacle goose returned from its arctic breeding grounds to become one of the most abundant birds in Europe. It was a devious twist to the old question, “Which came first, the chicken or the egg?” There was no egg. So their knowledge gap was filled with the prevailing bias of the time: the Barnacle goose appeared by spontaneous generation.
Despite Barents’ important contribution to scientific thinking, the Arctic showed him no mercy. Sharing the fate of many early explorers, he was trapped by unpredictable winter ice and died while overwintering on an Arctic island. But the news of a stupendous Arctic bounty spread. Eight years after Barents’ discovery, the English Muscovy Company set sail to harvest Svalbard’s abundant meat and furs. Their ships’ logs provide vivid accounts of massive herds of “sea horses” resting on the beaches. From company records, biologists estimate that the Svalbard Archipelago alone supported close to 25,000 walruses before European hunting began. That’s thousands more than currently populates the entire Atlantic sector today. By trapping the walrus on the beaches, within just six hours they butchered six to seven hundred walruses, and filled their boat with tusks and hides. But even more valuable were the 11 tons of oil for cosmetics and oil lamps that were highly prized by Europeans battling the frequent bouts of extreme cold that punctuated the ongoing Little Ice Age. Walruses and even polar bear were boiled to render their oil.
Intruding warm Atlantic water
Warm Atlantic waters melt sea ice inside Arctic Circle
The walrus survived the first wave of hunters because Europeans quickly turned their harpoons on a far greater source of oil, Svalbard’s whales. The logs from those early walrus hunts spoke of an “endless pool of whales,” as did Henry Hudson’s during his ill-fated search for the Northwest Passage. After the whales were virtually eliminated by the 1800s, hunters again focused on the walrus; the most vivid description of their hunting techniques were preserved in Sir James Lamont’s 1852 Seasons with the Sea Horses: “On one venture, after discovering a herd of several thousand walrus reposing on the land, four boats carried 16 men armed with lances. They stalked the shoreline in order to place themselves between the walrus herd and the ocean. As the first wave of stampeding walrus tried to enter the water, they were killed or injured creating a row of dead bodies inhibiting the escape of the others. With lance or axe in hand, the crews marched forward and descended on the trapped herd, killing the rest. A total of 900 walrus were killed that day.”
The hunters also mastered the technique of luring in any walruses that had successfully fled to open waters. Manipulating the walrus’ family devotion, hunters captured and tortured a calf. The calf’s barking and agonizing grunts pulled on the heartstrings of the fleeing herd. As the entire herd returned to rescue the calf, they entered into harpoon range. Lamont described one harpooned mother that continued to tow their hunting boat while she valiantly carried her calf under her flipper and tusks, desperately trying to shuttle it to safety. Such gallantry prompted Lamont to praise “the wonderful maternal affection displayed by this poor walrus.”
Several northern European nations rushed to avail themselves of Spitsbergen’s cornucopia of marine life, sending warships to protect the hunters. The frenzied competition led to the destruction of Svalbard’s wildlife. Although most wildlife had already been eliminated, the 1920 treaty of Spitsbergen finally ended the tragedy of the commons and the “rape of Spitsbergen”. In 1986 when McGhee went to Svalbard to search for any evidence that early Inuit or more ancient Tuniit may have reached the island, he only found evidence of the European overkill. Massive whalebones abounded, and beaches were littered with tusk-less walrus skulls. The birds had returned to the ponds and cliffs, while the reindeer and fox were now more common. But the beaches that once sheltered thousands of walrus were still empty and silent. But there are new reports due to recent colonists Svalbard walruses are now rebounding.
Walrus Summer Migration
Females and pups follow retreating sea ice
Male walruses will migrate south to ice free waters
The notion that walruses only haul-out on land when deprived of ice is a story that would have been laughed at just 30 years ago. Previously it was thought that ice denied walruses access to their hunting grounds. Walrus require shallow seas where they suction the seafloor for shellfish. As late as 1982 scientists stated, “the maximum absence of ice in the Chukchi Sea beneficially influences the population of the Pacific walrus permitting the animals to use vast feeding grounds in the summer and autumn seasons (emphasis added).”  Walruses do not require sea ice to hunt. Like Gray whales, they are associated with Arctic sea ice because it covers their food supply, and the current patterns of walrus migration support that view.
Unlike most females, thousands of male walruses never follow the receding ice pack but instead migrate southward to ice-free waters of the southern Bering Sea. Around Bristol Bay, Alaska, walruses readily forage up to 130 kilometers from their nearest haul-out site. The walrus’ main constraint is the water’s depth; they avoid regions where depths exceed 60 meters. Throughout the summer, adult males rest at their land haul-out sites for several days at a time between their offshore foraging trips which last four to ten days.” Swimming at normal swim speeds of 10 km/hour, walrus can cover the entire span of most shallow sea shelves in a few days, so there is little need for ice floe transportation. The males that do migrate north generally abandon the sea ice in spring and congregate on land haul-outs along the coasts of Russia and Alaska.
Alarmists suggest the increasing use of land haul-outs is a sign of disaster, caused by the loss of sea ice. However all the evidence argues that as walrus populations increase, so does the use of land haul-outs. It is a sign of the walrus’ successful recovery. When the Pacific walrus was teetering on the edge of extinction, “no walruses were observed along the Alaska Peninsula”, and only about a thousand animals were recorded at Walrus Island in Bristol Bay Alaska. By 1960 both Russia and Alaska had instituted protective measures and within 20 years, walrus populations rebounded to pre-exploitation levels. As the numbers grew, they began to reoccupy traditional land haul-outs. By 1980, the numbers of walrus hauling out on Walrus Island in the Pribilofs had grown from 3,000 to 12,000.

The use of land haul-outs still varies annually and (although poorly studied) is likely due to fluctuations in food supply. Massive herds suctioning the sea floor will eventually deplete a local food supply. Furthermore, regime shifts such as the Pacific Decadal Oscillation alter the winds and currents that deliver nutrients. Most likely the productivity of ocean floors also oscillate in approximate 20 year cycles. For example, at Cape Pierce in southern Bristol Bay, more than 12,000 walruses were hauling out on the beaches each summer in the 1980s. Then suddenly most walruses disappeared for over two decades. Recently they have been returning to Cape Pierce and as of 2008, their numbers increased to over 5000.
More curious is the fact that these walruses are not content to just clamber out onto the nearest vacant piece of solid real estate and hunker down in an exhausted heap. The walruses of Cape Pierce appear to enjoy jaunty bouts of adventurous hiking.They also developed a fondness for climbing to the top of grassy plateaus. Unfortunately when they decide to reenter the water and feed, they sometimes charge off on an ill-advised shortcut. Some biologists have suggested that because they are limited by poor eyesight, they are just following their sense of smell and a direct line back to the ocean. Others suggest they are easily spooked by human disturbance or aircraft and stampede in a blind panic. Whatever the reason, between 1994 and 1996 over 150 bulls launched themselves into an undulating swan-dive. Lacking Greg Louganis’ grace, they plunged from the cliffs to their deaths 150 feet below. Only a few lucky ones were cushioned by their late brethren’s blubber, got a favorable bounce, and continued to the sea. Biologists have now erected a fence, hoping to deter other neer-do-well thrill seekers from taking the same fateful path to the top of the plateau.
The Pacific Walrus is now believed to have recovered fully to its historic population of about 200,000, but surveys have been limited and therefore carry great statistical uncertainty. However in the Atlantic there is no question this subspecies has never recovered from the human quest for blubber and ivory. Large herds had once hauled out on islands and the mainland beaches as far south as Sable Island off the coast of Nova Scotia, Canada. All those southern populations were completely exterminated. The early walrus population along the St. Lawrence River alone has been estimated at over 100,000. In contrast, today the entire Atlantic subspecies is confined to waters further north. No longer migratory, they typically reside in polynya, and their total population is a mere 20,000. With such low numbers, stories of trampling are rare from the Atlantic sector. 
A beach packed with walruses is evidence of better conservation, not global warming doom. 

Walrus underwater. credit Dr. James Kelley