Wintering narwhals thrive amid the pack ice

          I’m really beginning to feel the chill here in Rhode Island as we approach the winter solstice and the coldest time of the year. But I’ve got it easy compared to those living in the Arctic.  And yet narwhals seem to thrive at this time of year in the frozen conditions of the waters between Greenland and Baffin Island, Canada. They spend their days repeatedly diving 1,800 meters beneath the surface on a 30-minute round trip to the seafloor in search of food. And if that’s not remarkable enough, they then have to surface for air in tiny openings in the sea ice that are often few and far between.

To get a sense for the habitat narwhals live in during the winter and how many are out there, biologist Kristin Laidre and others flew an aerial survey of the pack ice in late winter 2008 to see for themselves what it looked like.  Flying in a small plane from Kangerlussuaq, Greenland, they flew eight zigzag transects back and forth over the wintering grounds – as many as they could do with the fuel available in such a small plane – before returning to the mainland.

 “During their migration, the ice begins to chase them south and they arrive in their wintering grounds and the ice just forms right around them,” explained Laidre.  “The narwhals become enveloped by the ice.  It’s very dense ice, but it’s moving very fast; there’s a strong current that moves the ice to the south, and the ice floes are constantly changing, the leads are constantly opening and closing.”

Photos by Flip Nicklin

Laidre’s objective in conducting the aerial survey was, in part, to quantify the amount of open water where the narwhals are found.  By combining the data collected on the aerial survey with satellite images of the sea ice, she determined that just two percent of the area surveyed was open water, and there were between 17,000 and 19,000 narwhals there, or 73 narwhals per square kilometer of open water.

“That means you have this large density of animals that need open water to breathe packed into a very small amount of habitat,” she said.  “The overall habitat area is large, but what’s actually usable to them is quite small.”

Listening to Laidre describe what anyone would agree was an immensely challenging environment in which to live, it got me wondering why the narwhals stay there, when just 10 or 20 or 30 miles further south there is far less ice and the living conditions would be much easier with far fewer concerns about a sudden freeze making it impossible to reach the surface for air.  Greenland halibut must surely be found in open water as well as beneath the pack ice, right?  It must be easier living in ice-free water than in the dense ice pack, so why do they remain where the risk of meeting their death in an ice entrapment is so high?

The answer, Laidre said, is partly because that’s simply how they have evolved.  “They really have a niche, they’re totally adapted to this pack ice, more than any other northern hemisphere cetacean, and they don’t have many competitors.  Why go further south when you’re adapted to live in the pack ice and don’t need to go further?  It’s evolution.  They’ve become adapted to being in a certain climate and exploiting it and being successful, and I think that’s just what they’ve done.”

          But there’s more to it than that, she added.  It probably also has a great deal to do with competition and the partitioning of resources.  Narwhals, belugas and bowheads are the only whales that spend their entire lives in the Arctic, but there is a large pool of more southerly whales and marine mammals – minke and fin and humpback and blue and killer whales among them, as well as several varieties of smaller whales, porpoises and seals -- that come to the Arctic in summer to feed in its highly productive ecosystem.  Those subarctic species avoid the Arctic when it’s dark and ice-covered and miserably cold in the winter but move in during the spring and stay throughout the summer and early fall.  The narwhal has developed a strategy to exploit the ecosystem at a time when there are few competitors in an area where they know they have a reliable food supply available.  Belugas and bowheads do the same thing – they feed intensively in the winter and early spring when the other subarctic species aren’t there to compete with them.  And when the ice recedes, the Arctic whales move north just as the slew of subarctic species arrive in the area they just left.
          It is a strategy that has served them well, despite how cold it makes me feel.

Coming soon

           Narwhals have been in the news a great deal lately, but not in the way I would have hoped.  President Barack Obama named his system of tracking election volunteers after the ice whale, and the Natty Narwhal is the codename for a Linux software program that is being replaced this month by an upgraded version named Quetzel.  As those references to narwhals soon fade, I will be making a personal push to deliver some much-needed attention to the real narwhal, an animal whose physical qualities and behavioral abilities far exceed what software marketers and political operatives can even imagine.
            My book, Narwhals: Arctic Whales in a Melting World, is due in stores in the U.S. and Canada by March 1, and it is already available for presale through Amazon.  You can get a flavor for the book by watching the video trailer produced by my friend Rodd Perry, whose company The Ant Farm makes trailers and advertisements for many of the top Hollywood movies.  I’m really pleased with how the trailer turned out, and even more pleased with the book.
            Published by University of Washington Press, it examines in detail the remarkable Arctic whale and the many issues it faces, from a warming climate to hunting pressures, from pollutants in its environment to ice entrapments, from increased oil and mineral exploration to competition for food with a growing fishing industry.  And yet the narwhal seems to thrive in the harsh Arctic conditions, despite these challenges.
            The book takes readers along on my adventures far above the Arctic Circle to see and study narwhals. I joined teams of narwhal researchers who are trying to answer the many questions that remain about the animal’s life cycle; visited the laboratories of a group of dental researchers delving into the mysteries of its tusk; met with the Inuit to learn about narwhal legends and to observe them on their narwhal hunts; examined centuries-old logbooks from whalers and explorers for early observations and insights; and interviewed climate scientists to better understand how changing ice conditions may affect the whales. Along the way I observed and learned about the many other unique animals living in the narwhal’s frozen world, from walruses and polar bears to bowhead and beluga whales, ivory gulls and two kinds of seals.
            I was pleased that one of my favorite authors of marine science books, Carl Safina, offered to read my manuscript before its publication. In his usual eloquent prose, Carl wrote that “Todd McLeish takes us far in several dimensions—across space, through time, and into the interiors of the human mental landscape—to paint a vivid and eloquent portrait of an animal seldom seen, wrongly imagined, and too often mistreated. This is one of those rare books that lifts you up and takes you in.”
            I have had a remarkable four years of research and writing the book, and I hope you’ll soon join me in learning about this iconic animal.

Arctic whales in a melting world

          Readers of this blog may not realize that I’m not just a life-long fan of whales, and narwhals in particular, but I have been writing a book about the amazing sea unicorn and its unusual left tooth. That’s why I traveled to northern Greenland to learn about hunting practices and the importance of narwhals in Inuit culture. It’s why I spent two weeks in a research camp far above the Arctic Circle on Baffin Island, Canada, as scientists attempted to trap live narwhals and attach satellite tags to their dorsal ridge to track their movements during migration. And it’s why I have interviewed numerous others around the globe about narwhal biology, ecology, and physiology, as well as experts on Arctic climate, the science of sea ice and icebergs, the movement of pollutants into the polar regions, and many other topics.
                I am happy to finally report, that after four years of research and writing, the book is in the late stages of production. Entitled Narwhals: Arctic Whales in a Melting World and to be published by University of Washington Press, it is due to be officially released in March 2013, but it will be available to be ordered sometime next month. And I am pleased to make public the final design for the cover, which I am quite happy with (thanks to designer Tom Eykemans). Very soon I’ll have a video trailer to share with you as well, produced by my good friend Rodd Perry at The Ant Farm, one of the most prestigious movie trailer producers in Hollywood.
                When Narwhals is on bookstore shelves and available through Amazon and other outlets, I’ll be making presentations at aquariums, natural history museums, marine conservation organizations, libraries, universities and elsewhere. If you are interested in having me speak in your area, I’d love to hear from you. Perhaps together we can find an appropriate venue to host it.
                In the meantime, visit my website to get up-to-date information about the publication of the book, and follow me on Twitter for the latest details. I’ll continue to share what I learn about narwhals and other marine conservation issues here in this blog, and I hope you will continue to follow along with me. It has been an exciting journey so far, and it’s long from over.

Another season of narwhal tracking

                I was pleased to see that the narwhal tagging research project that I joined on Baffin Island, Canada, in 2010 is underway again this month, and unlike my experience – when we didn’t catch any narwhals for the two weeks I was there – they caught a narwhal on the first day of trapping. The objective of the trapping is to attach radio tracking devices to the whales so they can be monitored to gain insight into their migratory pathways and other behavior.

Photo by Flip Nicklin

            As I wrote a year ago, the value of this kind of work is immeasurable. “You can count whales from the air, you can count them from land, you can see what the herd is doing, but you don’t really get an idea of what an individual does on a daily basis [without tagging them],” said Jack Orr, the chief scientist in charge of the project and a biologist with the Canada Department of Fisheries and Oceans. “These tags provide us information on where they are geographically on the Earth, but we also get an idea of how they use the water column. Tags will tell us how long a whale is at a certain depth, and then we can set up dive profiles…Coupling this with information on water depths and what animals use these depths – we know, for instance, that turbot (Greenland halibut) and crustaceans live on the bottom, we know that squid are pelagic so they’re in the water column – and working with other data on ice and other environmental parameters, we can determine what these animals are doing over the course of a year. It gives us insights into not only its movements but also its behavior.”

            The knowledge gained from this kind of research is particularly useful to understanding population dynamics, which plays an important role in appropriately managing the annual narwhal hunts conducted by the local Inuit communities.  By tracking the movement of individual narwhals, scientists can learn how many hunting villages they travel by during their migration, which gives the researchers an idea of how susceptible the whales are to being killed.  And this can affect the quotas the Canadian government sets for how many narwhals can be hunted by each community.

            Narwhal management and hunting quotas continues to be a sticking point between Inuit hunting communities in the eastern Canadian Arctic and wildlife managers.  The latest government plan is to drill holes at the base of every narwhal tusk harvested and attach a permanent metal tag to it so the tusk can be tracked to ensure the tusk isn’t sold illegally. The Inuit communities disagree with this strategy, but it is an issue that doesn’t appear to be going away.  Just this week, a U.S. appeals court upheld the conviction of an antiques dealer in Massachusetts who illegally sold narwhal tusks and sperm whale teeth.

            Hopefully, as researchers continue this summer to tag and track narwhals, the scientists will gain enough information to be able to manage the narwhal population to ensure their long-term survival.

Tusk export ban lifted, issues remain

The Canadian government announced last week that it has lifted the ban on the export of narwhal tusks that it enacted in 2010 to protect the population of narwhals living in the eastern Canadian Arctic.  Seventeen narwhal hunting communities had been affected by the ban, and all but one – Grise Fjord, which has no known narwhals living in its vicinity – can resume exporting the tusks.

Photo by Paul Nicklen

            With a population of about 80,000 narwhals in the region and annual hunting quotas of just 700 animals, hunting by the Inuit communities should not be causing a decline in the narwhal populations in the area.  But government biologists were concerned enough about hunting pressures to enact the ban, so there are probably other issues at play.  One issue that should be in play but doesn’t appear to have been included in the negotiations to lift the ban is the issue of those narwhals that are “struck and lost.”  Because narwhals are known to sink when they die, Canadian narwhal hunters using rifles to hunt the whales are known to kill far more narwhals than they recover. And those that are struck and lost are not counted toward the quota.

An article in National Geographic magazine in 2007 by photographer Paul Nicklen, who grew up among the Inuit on Baffin Island, graphically illustrates the problem and suggests that hunting practices may need to be reviewed and recordkeeping expanded.  He wrote that during one 12 hour span, he counted 109 rifle shots but just nine narwhals were recovered.  One hunter reported that he killed seven narwhals, all of which sank.  “This was not the first time I had heard reports of many narwhals being shot but few landed.  Just weeks earlier, a man I know to be a skillful hunter confided that he had killed 14 narwhals the previous year but managed to land only one… So much ivory rests on the seafloor, said one hunter, that a salvager could make a fortune,” wrote Nicklen. 

At the very least, Nicklen’s observation suggests that wildlife managers should be paying much closer attention to narwhal hunting and, rather than banning the export of tusks should perhaps lower the quotas until a better system can be developed for accurately tracking the number of narwhals killed by hunters. 

There are plenty of arguments that have been made to eliminate any harvest of narwhals in Canada – including a lack of confidence in the government’s narwhal population estimates, the unfair advantage that hunters with rifles have over the defenseless animals, Canada’s unwillingness to follow the recommendations of the International Whaling Commission, and the belief, outlined in the recently drafted Declaration of Rights for Cetaceans, that whales have complex minds and societies and should be treated more like people than animals. Having spent time among the Inuit and knowing the importance narwhals play in their culture and health and subsistence, I am not ready to argue that hunting should be banned entirely. But I am convinced that the way it is taking place in Canada today is unsustainable and should be thoroughly reassessed.

Narwhals in temperate latitudes is ancient history

            Speculation that a dead narwhal had washed ashore last month in Ireland, a thousand miles from its normal range, got me thinking about the whale’s evolution and ancient range.  Although it turns out that the Ireland whale was misidentified and was actually a long-finned pilot whale, Ireland had been part of the narwhal’s range many thousands of years ago.

The line of evolutionary development that led to narwhals and the rest of today’s whales – and to humans as well – can be traced back to the Cretaceous and the carnivorous land mammals from which they descended. The branch that became whales follows that of the artiodactyls, hoofed mammals like antelopes and camels, as well as the hippopotamus, the whales’ nearest living relative on land.  The discovery in 1978 of a 52-million year old skull of what became known as Pakicetus was found to have features that showed a transition between terrestrial mammals and aquatic animals, including modifications that allowed for directional hearing under water, one of the first hints that mammals were returning to the sea.  But there were numerous additional steps before the first true whales emerged.

Narwhal fluke, by Paul Nicklen

            An amphibious animal called Ambulocetus, with hind feet clearly adapted for swimming, followed Pakicetus, and later still came Rhodocetus, which had additional adaptations for a marine lifestyle, including legs disengaged from its pelvis.  By the Eocene, about 40 million years ago, Basilosaurus emerged as a fully adapted marine mammal, with a streamlined body, paddle-like flippers, a strong whale-like tail, and the remnants of hind limbs that soon would disappear.  Other physiological changes took place along the way as well, including the relocation of the nostrils from the snout to the top of the head, the addition of an insulating layer of blubber, and changes in the circulatory system for the management of oxygen and for withstanding the pressures encountered at great depths.

            The two groups of modern cetaceans, the toothed whales and baleen whales, descended from a third group, the Archaeocetes, which disappeared about 30 million years ago.  It was just 500,000 years ago that narwhals evolved as a species, sometime in the late Pleistocene, about the same time that polar bears diverged from brown bears and the period when many large mammals and birds evolved and went extinct.  It was also a time when great changes in climate occurred.  While always believed to be an Arctic species, the range of the narwhal expanded and contracted over the millennia as variations in climate dictated.  During the last glaciations about 50,000 years ago, when ice extended as far south as England, narwhals were forced southward.  Fossils of the whales have been found there, along the coast of Norfolk.  When the glaciers began their retreat, narwhals followed them north again, with some traveling to the east of Greenland and others to the west.  That was the last time that narwhals from West Greenland and Canada came into contact with narwhals from East Greenland.  The 10,000 year separation of the two populations has led to genetic differences between them, a signal that evolutionary changes are still taking place, changes that one day far in the future could result in two distinct species of narwhals.  If they last that long.

Ancient and Exaggerated: Narwhals through History

          A while back I spent several days at the New Bedford Whaling Museum research library, where I uncovered some of the earliest known writings about narwhals. And last week I finally received some scanned images from the librarian of what early explorers believed narwhals looked like. The oldest volumes, like those by Swedish writer Olaus Magnus in 1555 and naturalist Konrad Gesner in 1558, written entirely in Latin, included woodcut prints illustrating what they identified as Monocerote or Monocerotis, an early variation on today’s taxonomical identifier, Monodon monoceros.  Next to an illustration of a sawfish – which several authors apparently believed were closely related to narwhals – Magnus showed a fish-like creature with a short, thick horn emerging from its forehead. He described it as “a sea-monster that has in its brow a very large horn wherewith it can pierce and wreck vessels and destroy many men.” Gesner’s narwhal, depicted with just its head emerging from the water, looked more like an alligator, with a long snout and abundant teeth, large dog-like eyes and, like Magnus, a horn sticking straight up from the top of its head. 

Surgeon Ambrose Paré, in 1582, writing in French about unicorns, described a sea unicorn “with a horn on his forehead like a saw, three feet long and a half, and four inches wide, with its two peaks very acute.”  The accompanying lithographic illustration featured a monstrous creature labeled Vletif with a long, scaly body, a mermaid tail, two pairs of pectoral fins that looked to me like dragon wings, a wolf-like face and teeth, and a horn like the rostrum of a sawfish rising from the top of its head. It exhibited an angry look as hunters poked at it from land while whaling ships sailed by in the distance. Theologian Isaac de La Peyrère in Relation du Groenland (1663) includes three excellent views of a narwhal skull alongside an illustration of a narwhal looking more like a fish than a whale but with a bear-like snout and its tusk growing from its nose. It is clear that he had access to narwhal skulls and tusks from which to create accurate illustrations, but he had not been able to study complete narwhal specimens and were instead left to interpret brief sightings of the animals in the water.

In 1700, ship’s surgeon Pierre Martin de la Martiniére published observations from an Arctic expedition in A New Voyage to the North, which includes an extraordinarily unique depiction of a narwhal hunt that the Whaling Museum’s librarian said “has no precedent.”  Yet it is the image of the narwhal that was most disturbing to me: a scaly body, a hawk-like beak and eyes, and a spiral tusk emerging from its forehead, with its head the size of a rowboat

Not long afterward, descriptions and illustrations of narwhals finally became more and more true to life. Explorer Henry Ellis’s A Voyage to Hudson’s-Bay (1748) was the first I found to correctly illustrate the tail of a narwhal as a horizontal fluke as opposed to the vertical caudal fin of a fish tail that most earlier illustrations feature. Bernard O’Reilly’s written description of narwhals in Greenland, the Adjacent Seas, and the Northwest Passage to the Pacific Ocean (1818) is much more accurate in its physical descriptions and behaviors than most earlier works, though critics claim most of his book is fiction. He must have had a specimen available to him, as he included such details as its tongue length and placement in the mouth (“very short, immoveable, and placed very far behind”), the size of the throat passage to its stomach (“very small, not three inches over”), and its mouth size (“very small; its greatest expansion being not more than six inches”).

         While descriptions of what narwhals look like were getting more accurate, descriptions of narwhal behavior remained just exaggerated guesses. For instance, William Henry Dewhurst, a surgeon on an English whaling ship, wrote in The Natural History of the Order of Cetacea and the Oceanic Inhabitants of the Arctic Region (1834) that the narwhal “is an animal possessing almost colossal strength, inasmuch as it precipitates itself upon every thing giving it the least offense, and furiously rushes against the most trifling obstacle.  Its habitual sojourn is among the ice and icebergs of the Arctic Seas.  Here, in the vast empire of eternal frost, where darkness reigns for so great a portion of the year, this giant of the frozen ocean dares every power, braves every danger; and bent upon carnage, he attacks without provocation, combats without rivalry, destroying without necessity; and the only enemy to whom he is occasionally compelled to yield to, is man.”

Legendary author Jules Verne continued these exaggerations in his 1870 classic Twenty Thousand Leagues Under the Sea.  His main character, Captain Nemo, a marine biologist, said:  “The ordinary narwhal, or unicorn fish, is a kind of whale which grows to a length of sixty feet… [It] is armed with a kind of ivory sword, or halberd, as some naturalists put it.  It is a tusk as hard as steel. Occasionally these tusks are found embedded in the bodies of other kinds of whales, against which the narwhal always wins.  Others have been removed, not without difficulty, from the hulls of ships which they had pierced clean through as easily as a drill pierces a barrel.”

The truth about the narwhal’s abilities, from its flexible tusk to its extraordinary diving abilities, is far more extraordinary than Verne’s fiction.

More concerns about Arctic ship traffic

“A rapid increase in shipping in the formerly ice-choked waterways of the Arctic poses a significant increase in risk to the region’s marine mammals and the local communities that rely on them for food security and cultural identity.”  That’s the conclusion drawn by a group of Alaska native groups and the Wildlife Conservation Society following a workshop last week.

            Before the climate started warming, sea ice had been a major obstacle to large ships traveling in the high Arctic, but that is less and less of an issue for the ships, and more and more of an issue for marine life.

“The disappearance of summer sea ice from the region’s coastal areas is leading to major changes in this part of the world,” said Martin Robards, director of the Wildlife Conservation Society’s Beringia Program. “The presence of large ocean-going vessels is expected to increase as the region becomes more attractive to both international shipping and extractive industries seeking minerals, oil, and gas. The northern sea route is 30 percent shorter than the comparable route linking northern Europe to Asia via the Suez Canal, which only supports the conclusion that the Bering Strait is likely to get busier.”

While this workshop and its conclusions focus on the marine mammals in the Bering Sea and the waters around Alaska – a region that is far from the range of the narwhal – it is just as true for the eastern Canadian Arctic and the waters around Greenland where narwhals will be similarly affected.

One strategy suggested by the workshops participants for combatting the effects of increased shipping was to enforce a reduced speed for shipping through the Arctic region. The strategy has been successful in reducing ship collisions with the imperiled North Atlantic right whale along the U.S. East Coast, and it is worth trying in the North as well.  

But ship strikes are primarily an issue for larger whales like bowheads.  Narwhals are more likely to be affected by the low-frequency noises that the ships emit. The sea unicorn is skittish and the noise from increased shipping is certain to be a significant disturbance to their feeding, migration and communication.

“There is mounting evidence that human-generated sounds in the marine environment have negative effects on marine life,” said Howard Rosenbaum, director of The Wildlife Conservation Society’s Ocean Giants Program. “An increase in background noise from increased shipping, coupled with increases in underwater noise from industrial activities and other potential stressors, is of great concern for the Arctic’s marine species and their important habitats.”

An even greater threat comes from increased oil exploration and the likelihood of an oil spill in a region with little or no capacity to contain it.  As I wrote here last year, the U.S. Geological Survey believes that there may be as many as 50 billion barrels of oil off the coast of Greenland, a quantity similar to that of Libya, which could provide an economic boost that would transform the island and sever its financial dependence on Denmark.  The expense of drilling in the region, along with the short drilling season and the risks that oil rigs would get rammed by icebergs, had made oil drilling in the region unattractive.  But increasing oil prices, satellite tracking of icebergs, and warming temperatures have created a huge opportunity and growing interest among oil companies around the world.

“The lack of international response capability to a spill in these waters is a serious concern in light of the increased interest in oil and gas exploration, or the rise in transportation of petroleum products by tankers through the Arctic,” added Robards. “A comprehensive approach is clearly needed to prepare for a potential environmental disaster in a region where marine mammals transit both national and international waters.”

Hopefully the concerns raised at the Alaska workshop will be heard by U.S. policymakers and the Coast Guard and shared with their counterparts in Canada and Greenland.  Arctic marine life will have plenty to deal with from the warming climate without having to also defend themselves from a flotilla of noisy ships.

Retreating ice means orcas are increasing threat to narwhals

            The effect of the declining extent of sea ice in the Arctic continues to raise new questions among scientists and generate attention in the media.  The latest stories reveal concerns about killer whales and what impact they will have on prey species like narwhals as disappearing ice provides the orcas with greater access to the region.

            On my first visit to Arctic Canada in 2008, I watched as a pod of about 12 killer whales chased a group of perhaps 200 narwhals through Eclipse Sound in northern Baffin Island.  That’s when I first began to wonder how much of a threat the orcas are to the ice whale.  My guide that week, who has lived his whole life in the region, had never seen a killer whale, so I suspected that they must not be common in the area.  But like most questions about wildlife in the Arctic, answers aren’t easy to come by.

While killer whales are considered resident in the Canadian Archipelago when the water is ice free, their numbers are small and they are seldom observed because they are spread out over a wide area. Despite their small numbers, however, killer whales may be the top predator on narwhals – next to humans – according to many Arctic marine mammalogists, including one who referred to narwhals as “orca candy.”   

“My general feeling,” said University of Washington biologist Kristin Laidre, “is that the densities of killer whales in the Arctic are low.  Sightings of killer whales are, in general, pretty rare. We do know that they feed on narwhals and belugas, and some killer whale pods, it seems, have evolved to know precisely where narwhals are located in summer, especially in the southern part of their range like in Foxe Basin or Hudson Bay.  There they show up pretty regularly, as narwhals are a predictable prey resource that occur in high densities in ice-free shallow waters.” Killer whales are sighted only rarely along the coast of West Greenland, she added.

Laidre is one of very few biologists to have observed orcas feasting on narwhals.  In August 2005, while satellite tagging narwhals in Admiralty Inlet in northwestern Baffin Island, she and two colleagues watched as a pod of 12 to 15 killer whales attacked and killed at least four narwhals among a group of several hundred over a six-hour period.  From their observation point at Kakiak Point, they saw what they described as “vigorous surface and diving activity” by the orcas which resulted in a large oiled area on the water, presumably from whale oils released from the dead narwhals, and congregations of seabirds. It appeared that the orcas consumed the narwhals below the surface.  The biologists had tagged several narwhals a few days before the attack, so they were able to monitor the movements of the animals in response to the killer whale aggression.  According to Laidre, the narwhals in the area suddenly moved into shallow water as the killer whales approached, some forming tight groups and others lying still at the surface or moving slowly and quietly.  One narwhal even stranded itself on a beach and thrashed its tail violently for 30 seconds as if to warn its pod mates.  During the attack, most of the narwhals in the area moved as much as 50 miles south and spread out much more than usual.  The animals resumed their normal behaviors within an hour after the killer whales departed the area.
            In a surprising coincidence, given how seldom killer whale attacks on narwhals are observed, another biologist watched killer whales prey on narwhals on the exact same day in Repulse Bay, about 400 miles south of where Laidre made her observation.  Laidre surmised that if the predation level from these two attacks were representative of the daily activity of killer whales in the region, then 200 to 300 narwhals are likely killed on their summering grounds by orcas during the two months of open water in the area.  Coupled with the annual harvest by Inuit hunters and predicted reductions in sea ice, enabling killer whales to hunt narwhals over a longer period each year, this mortality rate raises questions about how these elements will affect the sustainability of narwhal populations.