There is something difficult to grasp about the number of lakes in Canada. A few thousand would already seem excessive. Tens of thousands would be hard to picture. Canada has more than two million by federal estimates, scattered across a landscape shaped by ice.

The number is so large that it almost stops meaning anything. You could visit a different Canadian lake every day for an entire lifetime and still see only a small fraction of them. On a map they appear as blue flecks, crowded together across the north, but each one is a real body of water with its own shoreline, islands, depths and surrounding ecosystem.

What does “60 per cent of the world’s lakes” mean?

The often repeated claim that Canada holds around 60 per cent of the world’s lakes needs some qualification. There is no universally agreed count of every lake on Earth, because the result depends on what size of body is included and how lakes are distinguished from ponds, reservoirs and seasonal water.

One of the most widely used global databases, HydroLAKES, maps about 1.4 million lakes and reservoirs with a surface area of at least ten hectares. According to research describing the database, roughly 62 per cent of those water bodies are in Canada.

That does not mean Canada contains 62 per cent of the world’s freshwater. It means that nearly two-thirds of the lakes included in that particular global dataset lie inside Canada. The country nevertheless holds an enormous amount of water, and fresh water covers about eight per cent of its surface area.

What the ice left behind

The explanation lies largely in the Ice Ages. During repeated periods of glaciation, much of Canada was covered by continental ice sheets several kilometres thick. These were not static blocks of ice. They moved slowly across the land, grinding against the bedrock beneath them.

As the glaciers advanced and retreated, they scraped away soil and rock, deepened existing valleys and gouged countless depressions into the surface. When the climate warmed and the ice melted, water collected in those hollows.

The glaciers also carried enormous quantities of stone, sand and clay. As they withdrew, they left behind ridges and irregular piles of debris that blocked rivers and trapped meltwater. Some lakes formed in basins carved directly into rock. Others developed behind natural dams of glacial sediment.

This process happened across an immense area. The Canadian Shield, which stretches around Hudson Bay and across much of central and eastern Canada, is particularly full of exposed rock, shallow soil and water-filled depressions. From the air, much of the region looks less like solid land dotted with lakes than a broken mixture of rock, forest and water.

A landscape made of water

Some Canadian lakes are among the largest in the world. The Great Bear Lake and Great Slave Lake dominate the Northwest Territories, while parts of four of the five Great Lakes lie within Canada. But the extraordinary total comes mainly from the vast number of smaller lakes scattered across the country.

Many are remote enough to have no roads, settlements or permanent names. Some can be reached only by aircraft, canoe or long journeys through forest and tundra. Others sit within sight of towns and cities, forming part of ordinary Canadian life through fishing, swimming, transport, tourism and hydroelectric power.

The abundance of lakes also creates problems. Water may appear limitless, but it is unevenly distributed, often far from the country’s largest population centres. Pollution, warming temperatures, invasive species and changing rainfall patterns can still damage individual lakes, no matter how much water exists elsewhere.

Closing thoughts

Standing beside one cold lake in the Canadian bush, there would be no way to sense that it was one of more than two million. That is the odd thing about scale. From the shore, the lake is simply a place: water against rock, trees reflected on the surface, perhaps an island in the distance. Only from the level of a map or a database does it become part of something almost impossible to imagine. 

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The strangest thing about a blue whale’s heart is not its bulk. It is how close that heart comes to stopping. On a deep foraging dive, the largest heart on the planet can slow to as few as two beats a minute, a pace so far below what physiology predicts for an animal that size that it looks, at first, like an error in the data.

It was not an error. In 2019, a team led by Stanford’s Jeremy Goldbogen, with Paul Ponganis of the Scripps Institution of Oceanography as senior author, made the first recording of a blue whale’s heart rate in the wild. What they found raised a question the whale’s size alone never could: how does a heart that big run that slow, then race back so fast, dive after dive, without faltering?

How do you record the heartbeat of the largest animal that ever lived?

Carefully, and with a long pole. Working in Monterey Bay, co-author David Cade attached a suction-cup electrocardiogram tag near the left flipper of a male blue whale estimated to be about 15 years old. The tag, roughly the size of a lunchbox, was held by four suction cups, two carrying the electrodes that picked up the electrical signal of the heart.

It stayed on for about 8.5 hours of diving before detaching and floating up to be retrieved. The team almost did not believe what came back. “We had no idea that this would work and we were skeptical even when we saw the initial data,” Goldbogen said. Reading the trace was its own task. “With a very keen eye, Paul Ponganis … found the first heart beats in the data,” he recalled. Goldbogen later told Smithsonian the whole attempt felt unlikely: “I honestly thought it was a long shot because we had to get so many things right.”

The results were published on 25 November 2019 in Proceedings of the National Academy of Sciences, under a title that named the puzzle directly: extreme bradycardia and tachycardia in the world’s largest animal. This is a single animal measured once in the field, not a survey of the species, so the pattern is best read as a first window rather than a settled rule.

What did the data actually show?

A heart swinging between two extremes on every dive. During dives that reached as deep as 184 metres and lasted up to 16.5 minutes, the heart rate typically settled to four to eight beats a minute and bottomed out at just two beats per minute. For a body this large, the predicted resting rate is closer to 15 beats per minute, so the diving heart was running far below what its size alone would suggest.

Then came the reversal. The moment the whale returned to the surface to breathe and re-oxygenate, the heart climbed to its highest recorded rate of 30 to 37 beats per minute. There was one wrinkle even at depth. During a lunge to feed, the rate briefly jumped to about 2.5 times the dive minimum, before sinking again.

Why would a heart run itself so close to stopping?

The slow pace is oxygen management. Holding a single breath through a long dive, the whale conserves its limited oxygen by dropping its heart rate and routing blood to the organs that need it most, the same dive response seen across diving mammals, scaled up to the largest body on Earth. The surface surge is the repayment, the heart racing to reload oxygen before the next plunge.

What struck the team was how little headroom remained. The surface rate sat near the whale’s estimated physiological maximum, which led them to suspect the heart may already be working at its functional ceiling. That ceiling, set by body size and the demands of lunge feeding, “can help us understand biological limits to size,” Goldbogen said. The idea that a maxed-out heart is one reason blue whales never grew larger is the team’s hypothesis, not a proven fact, and they have been clear that much more work is needed to test it.

So is the heart really the size of a small car?

Probably not. The comparison is repeated everywhere, but it does not survive a close look at an actual specimen. A preserved blue whale heart weighed roughly 400 pounds, while National Geographic noted that a Volkswagen Beetle weighs around 3,000 pounds, which makes the car framing closer to legend than measurement. A researcher’s suggestion of a small golf cart is nearer the mark, though even that overshoots, since golf carts run heavier than the heart itself. The simpler version holds: it is the largest heart of any animal, and its size is not the most interesting thing about it.

What makes the 2019 recording matter is the method as much as the numbers. One tag, one whale, 8.5 hours. The questions the data invites next are the ones that take a fleet of recordings to answer: whether the same cardiac swing holds across larger and smaller individuals, whether it shifts with feeding, depth, or age, and how close other giants of the ocean run to their own limits. The first beat was the hard part. What it measures next is still open.

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The discovery happened in the routine course of an Iñupiat subsistence hunt off the coast near Utqiaġvik, the northernmost settlement in Alaska. The whale, a 49-foot male, had been killed in May 2007 by hunters working under the quota system administered by the Alaska Eskimo Whaling Commission and the International Whaling Commission. The Iñupiat have hunted bowhead whales for at least two thousand years, and subsistence whaling continues under tightly regulated annual quotas. The whale was being processed for meat and blubber, in the traditional method, on the sea ice near the village.

Craig George, a wildlife biologist with the North Slope Borough Department of Wildlife Management, was on site as part of his long-standing research collaboration with the Iñupiat whaling community. As the hunters carved the carcass with chainsaws, George noticed an unusual fragment of metal lodged in the bone between the whale’s neck and shoulder blade. The fragment was approximately 3.5 inches long, arrow-shaped, and recognisable to George as something other than modern equipment. He sent it to John Bockstoce, an adjunct curator at the New Bedford Whaling Museum and a leading authority on the history of 19th-century Arctic whaling.

Bockstoce identified the fragment as the explosive tip of a bomb lance, a patented Victorian-era whaling weapon manufactured in New Bedford, Massachusetts. The particular design and notch pattern allowed him to date its manufacture to between 1885 and 1895, give or take a few years. The bomb lance had been embedded in the whale’s body for approximately 120 years.

The whale had been alive when Queen Victoria was still on the British throne.

How the whale survived

The bomb lance was designed to detonate after embedding itself in a whale’s body, with the explosion intended to deliver a fatal internal wound. In the case of the 2007 whale, the device had either failed to detonate fully or the explosion had missed the vital organs the design was meant to reach. The fragment had lodged in bone in the shoulder region, which is well outside the heart, lungs, and major blood vessels. The whale’s blubber, which on bowhead whales reaches up to 50 centimetres thick, would have absorbed much of the residual impact. Bowhead whales also have exceptionally efficient wound-healing capabilities, which the genetic literature on the species has since linked to specific molecular adaptations.

The whale survived. It continued to feed, migrate, and presumably reproduce for another 12 decades, carrying the metal fragment as a permanent passenger embedded in its shoulder bone, until it was killed by a modern projectile from the next generation of the same indigenous community that had likely been the original target of the 19th-century hunters.

How the whale’s age was confirmed

The bomb lance fragment was not the only evidence of the whale’s extreme age. Since 1999, a team led by the same Craig George, working with the chemist Jeffrey Bada at the Scripps Institution of Oceanography, has been using a different method to estimate bowhead whale ages, published in the Canadian Journal of Zoology. The method depends on a chemical process called aspartic acid racemization. In humans and other mammals, the aspartic acid in the protein-rich nucleus of the eye lens is laid down in one specific molecular orientation, called the L-isomer, when the lens forms in the developing fetus. From that point onward, the molecules slowly convert to the alternative orientation, called the D-isomer, at a temperature-dependent rate that does not change throughout the animal’s lifetime. By measuring the ratio of D to L in the eye lens of a deceased whale, researchers can estimate how many years have elapsed since the lens first formed.

The George and Bada study applied this method to 48 bowhead whale eye globes collected from subsistence hunts between 1978 and 1997. Of the 48 samples, 42 produced usable age estimates. Most of the whales were in the expected range for marine mammals, between 20 and 60 years. A small number, however, returned ages well above 100 years. One sample produced an estimated age of 211 years, with a standard error of approximately 35 years either way. The figure was extraordinary enough that the researchers checked the calibration repeatedly before publishing.

The 2007 whale’s age, on aspartic acid racemization, was independently estimated at approximately 130 years. The Victorian harpoon embedded in its shoulder, with its independently traceable manufacturing date, confirmed the estimate within the method’s standard error. The convergence of the two independent dating methods is now considered, in the peer-reviewed literature, one of the strongest confirmations of bowhead longevity ever obtained.

What the genome reveals

In 2015, a team led by Michael Keane at the University of Liverpool, working with João Pedro de Magalhães, Craig George, and a consortium of researchers across multiple universities, published the first complete sequencing of the bowhead whale genome in the journal Cell Reports. The team compared the bowhead genome to the genomes of other cetaceans and other mammals to identify the molecular mechanisms that allow the bowhead to live for two centuries while other large whales rarely exceed 100 years.

The findings identified specific genetic adaptations that distinguish the bowhead. The first was in the ERCC1 gene, which encodes a protein involved in DNA repair, particularly the repair of DNA strands damaged by oxidative stress and ultraviolet radiation. The bowhead has a unique variant of ERCC1 not found in any other cetacean, with mutations consistent with enhanced repair capacity. The second adaptation was a duplication of the PCNA gene, which encodes a protein essential for DNA replication and damage repair. The duplication is rare in mammals and is associated, in other species, with reduced rates of cancer. The third adaptation was a set of changes in genes involved in cell-cycle regulation, several of which appear to slow the rate at which cells become cancerous.

The Keane team noted that bowhead whales have approximately a thousand times more cells than humans, which by basic statistical reasoning should make them roughly a thousand times more likely to develop cancer over a given lifespan. They do not. Bowhead whales show very low rates of cancer until extremely advanced age, despite their enormous cell number and their two-century lifespan. The genome data suggests that the bowhead has evolved a suite of molecular cancer-resistance mechanisms that compensate for what should otherwise be a substantial cellular risk.

The findings have implications well beyond bowhead biology. The molecular mechanisms that allow the bowhead to live for 200 years without developing cancer are precisely the mechanisms that human ageing research has been searching for. Several research groups are currently working to characterise the bowhead-specific gene variants in laboratory mouse models, with the aim of identifying whether the same mechanisms could be transferred to other mammalian systems.

What the Iñupiat already knew

One of the more interesting threads in the scientific literature on bowhead longevity is that the peer-reviewed findings have largely confirmed something the Iñupiat had been saying for generations. Iñupiat oral tradition describes bowhead whales as living for “two human lifetimes”, a description that maps directly to the modern peer-reviewed estimate of 150 to 200 years. Iñupiat whalers have for centuries recognised specific individual whales by their scars, behaviour, and markings, and have passed observations of particular whales through multiple generations of the same hunting families. Several of the whales that have produced the oldest scientific age estimates were identifiable to Iñupiat hunters as animals their grandparents had also seen.

The recognition that indigenous ecological knowledge had pre-empted the scientific finding has been increasingly explicit in the peer-reviewed literature. Craig George, who has worked with the Iñupiat whaling community for more than three decades, has been a co-author on most of the bowhead longevity papers and has consistently credited the original observations to Iñupiat hunters. The 2007 harpoon discovery itself was made possible by the close working relationship between George and the hunters who killed the whale.

The honest limitations of the evidence

Several methodological caveats apply to the bowhead longevity literature.

The aspartic acid racemization method has substantial standard errors, particularly for the oldest whales. The 211-year estimate, with its ±35-year standard error, could in principle range from approximately 175 to 245 years. The method is sensitive to the temperature at which the eye lens formed and to the calibration of the underlying chemistry. The original George and Bada 1999 paper acknowledged these uncertainties explicitly. Subsequent refinements, including a 2013 update by Cheryl Rosa and colleagues in Marine Mammal Science, have improved the precision but have not eliminated the underlying limitation.

The peer-reviewed lifespan estimate of “over 200 years” is therefore a strong central tendency rather than an exact figure for any particular whale. What is established beyond reasonable doubt is that bowhead whales routinely live past 100 years and that the oldest individuals in the population probably live to at least 150 years. The exact upper bound is less precisely known.

The 2007 harpoon-and-whale finding is, by contrast, one of the most precisely datable longevity records in the literature on any wild mammal, because the harpoon’s manufacturing date is independently verifiable from historical records.

What it means

Several things follow from the bowhead longevity evidence that are worth saying clearly.

The first is that the longest-lived mammal on Earth is not a primate, a rodent, or a domesticated species. It is a baleen whale that lives almost its entire life under the ice of the Arctic Ocean, in conditions where systematic study is extraordinarily difficult. The discovery of bowhead longevity required the convergence of indigenous ecological knowledge, modern molecular biology, and the chance survival of a 19th-century weapon inside a 21st-century whale.

The second is that the bowhead’s longevity is not, on the current scientific evidence, an accidental feature of cold-water marine life. It is the result of specific molecular adaptations, including enhanced DNA repair and cancer suppression, that have been identified at the genome level. These mechanisms are now being studied as potential models for extending healthy lifespan in humans.

The third is that some of the bowhead whales currently feeding in the Arctic Ocean were already adult animals when the United States entered the First World War. The whales swimming under the ice near Utqiaġvik today include individuals that have lived through the entire span of modern industrial history, the development of motorised whaling, the near-extinction of their own species, the moratorium that protected them, and the slow recovery of their population in the late twentieth century.

They will, on the available evidence, continue to swim under the ice well after every human alive today is dead.

The 19th-century whaler from New Bedford who fired that bomb lance in 1890 had no way of knowing that his target would still be alive in 2007. The whale that carried his weapon had no way of knowing that the same indigenous community that had likely sent the original hunters would, more than a century later, kill the same whale with a more modern weapon.

The Iñupiat, on the available oral evidence, were not surprised.

The post A 49-foot bowhead whale killed by Iñupiat hunters in May 2007 was found to have been carrying a Victorian-era harpoon in its shoulder for approximately 120 years, evidence that the whale was at least 115 years old at the time of its death, because bowhead whales are the longest-lived mammals on Earth, with peer-reviewed lifespan estimates exceeding 200 years appeared first on Space Daily.