Immortals of the Arctic
No one has ever found a bowhead whale that died of old age. Now armed with startling new data, scientists ask, just how old can this animal get?BY JAMES HRYNYSHYN
When the whale surfaces a second time, a hunter perched in the bow hurls the ivory-tipped harpoon into the whale's back. Slowly the enormous beast rolls on its side, its white eye-ring facing its attackers. Then it slaps its huge tail on the surface and slips beneath the water with a twist, snapping the harpoon and shearing off the rope and float attached to the shaft. It is April, 1791, and there will be no muktuk feast tonight.
Fast-forward to the spring of 1981 and another gathering of Inupiat hunters on Alaska's north coast. In the intervening centuries, commercial whalers almost eliminated the bowhead from the face of the earth. Fortunately enough remain in the Beaufort and Chuckchi seas to sustain a limited, but important, traditional hunt. Elation reigns as a spout is sighted and a powerboat pushes off. The whale is dispatched with an explosive-tipped harpoon and, with help of most of the hunters village, hauled ashore and butchered. As the treasured muktuk and meat is sliced, sampled and then divided up, one elderly Inuit's knife strikes something hard. He carves out the obstruction and holds up a small triangular ivory harpoon point.
Two-hundred-plus-year old whales? A lifespan this long would make them rivals of the giant tortoise as the earth's oldest animal. The fact that bowhead populations are taking a long time to recover from hundreds of years of whaling pressure is proof enough that old age must take its toll, but just when and how they die often remains a mystery. Aside from a single case of twisted intestines, the only cause of mortality that can be verified remains the efforts of hunters. No one is claiming the bowhead is immortal, but lifespan is fundamental to the study of any living species, and the estimates for the massive, hulking beasts that hug the pack ice on either side of the Arctic Archipelago keep growing, like fishermen's tales of the one that got away.
But George, a self-effacing and patient researcher who chooses to operate in the field where he can meet his subjects in their own environment, knew that the stone points offered only circumstantial evidence of longevity in bowhead whales. So, for the past 25 years, he has woven together field data collected by himself and other biologists working closely with aboriginal whalers, state-of-the art laboratory work by three Californian biochemists, and the careful analysis of a Seattle statistician. This collaborative study of bowhead eye lenses, ancient harpoon heads, and other observations of whale behaviour-a synthesis of hard data that most certainly did not get away and that was recently published in the Canadian Journal of Zoology-offers convincing evidence that bowheads are the longest-lived animals on Earth.
The idea that bowheads could live beyond two centuries has astounded some veteran biologists. John Ford, a marine mammal specialist at the Vancouver Aquarium Marine Science Centre, and no stranger to bowhead research, calls the new lifespan estimates "a real eye-opener" and a dose of humility. "It certainly surprised me, because I had gone along with the conventional wisdom of what whale ages are and seldom had I ever seen an estimate of over 100 years for any whale. I know many people at first didn't believe it, and thought it had to be prank," he says. "It's great example of just how much we don't understand about the biology of whales. It's right there with the discovery of new species."
However, for George and the Inupiat hunters who still harvest the whales each year, that bowheads should be among the oldest only makes perfect sense. Weighing upwards of 80 tonnes, the bowhead whale is a creature of extremes. It is the only baleen whale to make the Arctic its home, although it shares the icy waters with two species of toothed whales -- the narwhal and beluga. A bowhead can grow to 20 metres long, with a girth greater than that of even the oldest of old-growth cedars, and its blubber is the thickest (up to 50 centimetres) and its baleen the longest (as long as 4.5 metres) of any whale. Only the heaviest of the blue whales, the largest creatures in history, beat the bowhead on the weigh scales. Yet, bowheads take longer to mature and have the greatest calving intervals known.
It was the oil industry that first drew the attention of the marine biology community to the bowhead. Although familiar to aboriginal and then European and American hunters for centuries, little was know about the animal's life history until the early 1970s. Shell, Esso and other transnational corporations began to pay for studies of the ecosystems of the Beaufort Sea north of Alaska, Yukon and the western N.W.T., Hudson Bay, and the Baffin Bay region of the Eastern Arctic. By then, global bowhead stocks had dwindled to a fraction of the pre-exploitation estimates of about 65,000 whales. Prized for their baleen, which was turned into corsets and buggy whips, and the lamp oil and lubricant that could be produced from their blubber, the bowhead was so valuable a prey that some whalers called it simply "the whale," preferring it over bowhead's fatefully named cousin, the right whale. Though the two species superficially resemble one another - the bowhead is sometimes known as the Greenland right whale - the exaggerated curve of the jaw that gives the bowhead its name is more pronounced, and to those who have studied it closely, the bowhead is a singular species that is forever confounding expectations. Its social structure, its behavior, even its vocalizations are distinct and complex.
With only a few thousand bowheads left in the Beaufort Sea, where the oil companies were busy cataloging enormous fossil-fuel deposits, and only a few hundred left in the Eastern Arctic, the need to know about the population size, reproductive habits and life history of the bowhead became more than a scientific curiosity. At the time, Greenpeace was carving out a name for itself, and "Save the Whale" bumper-stickers were popping up across North America. By the mid 1990s, the bowhead was one of the better-studied of the large whales, despite the difficulties posed by an unforgiving natural environment and waning support from government research agencies.
Still, gauging a bowhead's age proved more difficult than expected; none of the techniques used successfully with other whales would work and accurate estimates of its age eluded scientists. Several populations of orcas, or killer whales, for example, have been followed so closely over the past 30 years that every member has been photographed and cataloged, using distinctive color patterns and fin markings. As a result, the year of each new addition can be recorded with high degree of precision.
In other species, such as the blue whale, the growth layers of ear plugs can be counted, again producing relatively useful estimate of age. More complicated techniques involve the oscillations in ratios of carbon isotopes laid down in baleen as whales migrate each year from one region of the ocean to another, feeding on prey composed of isotopes specific to each region. But with bowheads none of those techniques worked. Individuals are hard to identify, and no comprehensive catalog has been compiled. Their inner ears do not show signs of layering that can be counted, and the isotope oscillations in baleen peter out after a dozen years or so, making the technique useless for mature whales.
Fortunately, biochemistry offered an alternative, one that requires scientists to look deep into the bowhead's eyes. The lens of a marine mammal's eye is almost spherical, an adaptation that improves focusing ability underwater. Like an onion, it is composed of dozens of layers of protein, the first laid down while still in the womb. Once formed, each layer is no longer biologically active and begins a form of decay that can be used to estimate how long its been since it was first deposited.
Isomers of aspartic acid used to gauge the age of bowhead eye lenses.
Using the carcasses of 48 bowheads harvested between 1978 and 1996, George extracted the eyes and sent each lens to biochemist Jeff Bada at the Scripps Institution of Oceanography in San Diego. A leading expert in racemization analysis, Bada and his colleagues subjected the lens nuclei to high-performance liquid chromatography, a kind of filter that separates the two aspartic acid isomers according to their chemical properties, and allows him to measure the relative proportions of each. (Just as some drugs are chemically active as one isomer, but not as the mirror image, D-aspartic acid reacts with the chromatography filter differently than does L-aspartic acid.)
Bada turned over the results of the chromatography tests to University of Washington statistician Judy Zeh in Seattle, who came up with age estimates that left even veteran bowhead biologists stunned. Four of their whales were more than 100 years old, and one may have topped 211. And those estimates are relatively conservative. Although George, a self-effacing and patient researcher, concedes the technique still leaves open the possibility the ages could be overestimates, he says underestimates are more likely. But even with a margin of error of 25 years for the oldest individuals, that would make them the oldest mammals around, period. Elephants don't live much past 60, while female killer whales may make it to 90. But 200? And the whales George's team were measuring were only dead because hunters had killed them. How long could they live if allowed to die of natural causes? "Again, I think we're going to see bowheads out there on the edge," says George.
Kerry Finley, an independent biologist who spent 14 summers watching bowheads as they gathered to feed in Isabella Bay on the eastern coast of Baffin Island (see sidebar) was impressed when he read of George's findings. But he says he was less surprised than some, thanks to hours spend watching bowheads from a kayak, often only a few metres from their massive hulk. "When you see the scarring, how much these rugged animals are scratched up," he says, "you see the same marks year after year. You know they got those scars long ago." Besides, he adds, "every assumption we've had in the past about lifespans has been extended, and extended again, each time we look at these animals."
One of those earlier looks at bowhead lifespans was conducted by Bill Koski of LGL Ltd. Environmental Research Associates in Toronto in the early 1990s. "It kind of floored people at the time because I suggested that the whales were much older and matured much slower that the past thinking. And that was based on aerial photography over just eight or nine years," he recalls. "Now we have photographs of whales as much as 14 years apart and even the young, small whales are growing very slowly. We have one small whale that has grown about two metres in 13 years. And if it take 13 years to grow from 10 metres to 12 metres, think how long it must take them to grow from eight to 16 metres."
Until Koski's work, the best estimates of bowhead lifespans were drawn from work on similar species, such as the right whale, which lives to 50 or 80 years. Koski suggested perhaps 100 for the bowhead. Now George has better than doubled that figure, with no real maximum in sight. For George, however, the new estimates make a lot of sense. For one thing, his studies of whale carcasses has shown them to be almost completely free of illness. "We don't seem much evidence of progressive disease. It's normal to see no pathologies at all in these whales. It's even unusual to see parasites in the digestive tract in these whales," he says. Other studies have found few signs of single-celled parasites or relatively common roundworms. And even when roundworms have been found in the stomach of bowheads, they don't seem to be causing any real harm. Predation isn't much of a threat either. While the smallest and youngest bowheads may be vulnerable to the orca attacks, once fully grown, only large ships can do them any harm.
Of course, finding a bowhead that has died from disease, attacks, or run-of-the-mill old age isn't easy. Few dead bowheads wash up on the beach along the Arctic coast, most of which is far from settlements in any event. But the more biologists like George learn about what makes the bowhead tick, the more it matches the observations of those like Finley who study behaviour. The words most often associated with bowhead behaviour are usually synonymous with "slow," "ponderous" or "deliberate." They swim at only two to four kilometres an hour when feeding, ramping up to all of six km/hr while migrating, and spend a good deal of time resting or sleeping at the surface. Even slowpokes like the grey whale, says Finley, "move at lightning speed compared with bowheads." Still, he adds, they can be remarkable agile, and are careful to avoid kayaks despite the lack of threat posed by such as a small craft to such a large animal: "I have been nudged deliberately only once. I was lifted and very gently set down. They are rated as the shyest of all the whales."
With the traditional harpoon heads and statistical evidence bolstering the biochemical case for extreme longevity, the questions of how and why are now getting more attention. George speculates that the whales long life may be attributable to not one, but several factors. First, there is the need for a large body mass to insulate vital organs from the cold, and to push through ice up to 60 centimetres thick when air holes are unavailable have led to a long lifespan. Simply put, it takes time to grow so large. But blue whales are even larger, though often not as fat, and while they may live as long as 100 years, bowhead are still the old-age champions.
It is possible, says George, that evolutionary pressures of a hostile environment on a variety of fronts led to a species that invests an unusual amount of effort into a slow growth pattern, rather than rapid reproduction. To biologists, creatures that produced few offspring over a long period of time are known as "K-strategists," as opposed to the "r-strategists" that live short, fast lives and produce large numbers of offspring. In effect, says George, "bowheads are the extreme K-strategists." Finley agrees. The combination of an enormous size, a low reproductive capacity of just one calf every four years or more, and massive energy storage adds up to a metabolism that simply ages much slower than most mammals. It may not be anything more mysterious than that.
On the other hand, adds George, bowheads are proving to be full of surprises. For example, the amount of insulation they build up in the form of blubber is far in excess of what is needed for their environment, as cold as it is. "One model shows they wouldn't have any trouble conserving body heat , thermoneutral in other words, swimming in liquid oxygen," he says.
The extreme K-strategy has its drawbacks, however. As George points out, there are always tradeoffs in nature, and the bowhead's glacial life cycle has its share. "The price you pay for longevity in any species is a low reproductive rate and the possibility of extinction," he says. "It seems to have worked in the Arctic in this particular environment, but it looks like they've painted themselves into a corner." For the bowheads of the Western Arctic, recovery from the whaling era is measurable, at three per cent a year, though a long time coming. For their Eastern Arctic cousins, however, evidence of an increase in numbers is frustratingly scarce. Reliable estimates are hard to come by, but the total population is almost certainly much less than a 1,000 and may be closer to 450, divided among two stocks. If the eastern population is growing, it's growing slowly. But if there's one thing we know about bowheads, it's that they're not an animal in a hurry.
As more is learned about how the longevity of the bowhead influences its own long term survival, it becomes more and more apparent that the appearance of this ancient creature stirs excitement in more than just human observers. Ford recalls a memorable encounter in Hudson Bay that speaks of an animal that may have special significance among other inhabitants of the Arctic Ocean. Working as a scientific advisor on the 1974 NFB film Search for the Bowhead Whale, he was walking through an area he calls "a superhighway" for marine mammals and birds, when a bowhead mother and her calf materialized less than three metres away:
"The mom went off under the ice and left the calf-looking like a small Goodyear blimp-with narwhals and belugas circling around it," Ford says. "Then mom came back and the little guy took off with her. It was like a parade of whales following them, the narwhals and belugas, all moving off in an echelon formation after the bowheads." Persecuted and slaughtered by humans, the ageless bowheads seem to inspire an attitude among their animal kin that we might all do well to adopt: Respect your elders.
SIDEBAR: A political animal
Although bowhead whales have been the subject of scientific scrutiny for 30 years now, they have been political subjects for almost as long. It was Canada's refusal to recognize the authority of the International Whaling Commission to regulate aboriginal bowhead hunts that led to its withdrawal from the IWC in 1982. And the federal government's approval of several Inuit bowhead hunts since 1991, including two on the severely depleted Eastern Arctic stocks, has resulted in a minor diplomatic squabble with the U.S. Department of Commerce. In fact, U.S. trade law requires sanctions on countries which engage in whaling outside the auspices of the IWC. President Bill Clinton has neglected to enforce the provisions of the law, but in 1997 he instructed his diplomats to oppose Canadian efforts to ease U.S. sanctions on the import of Canadian seal products as a retaliatory measure.
The bowhead is even tied to the recent revival of a traditional grey whale hunt by the Makah tribe of Washington State. In 1997, following the Makah's request for whaling permits, the IWC agreed to set collective quotas for whales hunted by American and Russian aboriginal whalers. Although the official schedules separate the hunting quotas for the two species, a private deal was worked out between the two countries and that deal is reflected in the official IWC quotas. In effect, permission to land five bowhead whales was transferred from Alaska, where Inupiat whalers regularly fail to fill their quota, to Russia's Chuktokan aboriginal communities. In return, the Chukotkan whalers agreed to transfer five of their grey whales to the Makah.
SIDEBAR: Sanctuary in a Storm
Before Europeans took an interest in bowhead oil and baleen, more than 11,000 of the whales migrated each year across Baffin Bay, wintering in southwestern Greenland and summering in the waters north of Baffin Island. Estimates of the current population top out at about 350, and for many of the survivors, a small bay halfway up the island's eastern coast is a vital sanctuary. Thanks to currents flowing through a pair of underwater canyons that trap the bowhead's favored prey, planktonic crustaceans known as copepods, Isabella Bay is what biologist Kerry Finley calls "the largest known congregation of whales in the north Atlantic."
Fourteen summers watching the bowheads there convinced Finley that the bay must be protected. Many members of the nearby Inuit community of Clyde River agreed, and together they pushed to have the bay declared a whale sanctuary. More than 15 years later, however, negotiations are bogged down in disagreements between Nunavut Tunngavik Inc., which is charged with overseeing the economic welfare of the Nunavut land claim, and the Canadian Wildlife Service. NTI is withholding approval of an Inuit impact benefit agreement, arguing the draft agreement doesn't include enough economic spinoffs for the people of the region. "The draft that was prepared left out a lot that needed to be in there, so NTI called time on the process. We're going to have to go back to the drawing board," say implementation director John Lamb. At the CWS, Vicky Johnston has asked the government for more funds based on the last round of talks, but she notes that since the application was made, NTI "raised the bar" again and demanded further economic concessions.
If and when it is approved, the Iqaliqtuuq National Wildlife Area would cover most of Isabella Bay. "If there's a sanctuary, the bowheads may become more abundant," says Patrick Palluq of the Clyde River Hunters and Trappers Association. All parties say protection of the bowhead whale, which is listed as endangered in Canada, is the primary objective, and are optimistic that the differences can be worked out soon.
For further reading:
The Bowhead Whale, Editors John J Burns, J. Jerome Montague and Cleveland J. Cowles. The Society for Marine Mammalogy, Lawrence KS, 1993
Age and growth estimates of bowhead whales (Balaena mysticetus) via aspartic acid racemization. John C. George, Jeffrey Bada, Judith Zeh, Laura Scott, Stephen E. Brown, Todd O'Hara and Robert Suydam. Canadian Journal of Zoology. Vol. 77; 571-580.
-30-
Return to the Class M Home Page