Bowhead Whale: The Arctic's Longest-Living Mammal

Unlike other large whales, the bowhead never migrates to the tropics: it stays in Arctic and subarctic waters year-round. According to NOAA Fisheries, its populations are found in the Bering, Chukchi and Beaufort seas, in the Sea of Okhotsk, and off eastern Greenland and Svalbard. Its movements follow the seasonal retreat and advance of sea ice, not a change in climate. The species belongs to the genus Balaena, which it shares with the whale, the largest animal on Earth, and the two have in common an enormous size and a diet of plankton filtered through baleen bristles.

Its size places it among the largest animals on the planet. NOAA Fisheries reports a maximum weight of about 90,000 kg and a length of up to 19 meters; NAMMCO puts the maximum at 100 tons and 20 meters, with a typical weight between 70 and 100 tons, and notes that females are larger than males. The head alone, according to NAMMCO, makes up more than a third of the total body length, and the arched skull that gives the species its English name, bowhead, can exceed 5 meters.

Practical example: imagine having to break through 20 centimeters of sea ice just to breathe. The bowhead whale does this routinely, pushing upward with the top of its skull: according to NOAA Fisheries, it’s the sheer strength of that bony structure that makes it possible, while most other cetaceans would have to settle for finding an opening that’s already there.

The body carries two other signs of Arctic adaptation. The first is the missing dorsal fin: unlike most cetaceans, according to NOAA Fisheries this species has none, and that absence spares it the drag a fin would cause while gliding along the underside of pack ice. The second is its layer of blubber, which according to NOAA Fisheries can reach nearly half a meter in thickness (between 43 and 48 cm), the thickest recorded among all whales: it insulates against Arctic water that often sits close to freezing.

What sets the bowhead whale apart more than anything else, though, is how long it lives. According to NAMMCO it’s the longest-living mammal known, with an age that can pass 200 years; the oldest individual ever estimated, an animal caught in Alaska, was about 211 years old according to a 2022 study (Vasquez et al.). Reaching a figure that large takes more than a simple calculation: the method, described by George et al. in a 1999 study in the Canadian Journal of Zoology, analyzes the core of the eye lens, a tissue the North Slope Borough calls “functionally dead,” because it stops renewing itself once it forms. Amino acids are extracted from that tissue, and researchers measure the ratio between two forms of aspartic acid, a chemical process called racemization: comparing that ratio against a known curve produces an age estimate. One of the samples analyzed in that 1999 study turned out to belong to a whale over 200 years old.

No other mammal known today comes close to that figure.

Even before this chemical method existed, whalers themselves had left indirect proof of the species’ longevity. Starting in the 1980s and 1990s, finding stone and metal harpoon points embedded in hunted whales led researchers, according to the North Slope Borough, to suspect ages far higher than the 50-60 years scientists had previously estimated. One case reported by NAMMCO involves a whale caught in Alaska that carried a harpoon point in its shoulder blade, used by whalers more than a century earlier: a sign that the animal had lived at least 115 years. A 2008 study (George and Bockstoce, in Polar Biology) used two fragments of historical weapons found in other whales to estimate the species’ longevity and movements. Among the reasons behind such a long life, NOAA Fisheries points to the hypothesis that genes dedicated to repairing damaged DNA may play a role, though the source doesn’t present this as a settled explanation.

Practical example: a 2013 NAMMCO study (Rosa et al.) finds that males and females reach sexual maturity around age 25, by which point they’re already about 13 meters long. For a human, 25 years is nearly a full adult lifetime; for a whale that can live to 200, it’s just the start: from that point on, females give birth to a calf every 3-4 years.

Its longevity and size haven’t shielded the species from commercial whaling. According to NOAA Fisheries, before hunting began, the worldwide population was estimated at least 50,000 animals, including between 10,400 and 23,000 in the Western Arctic stock; by 1921, when commercial whaling of the species had effectively ended, the worldwide total had fallen below 3,000 whales. The recovery has been slow but measurable: averaging an ice-based survey from spring 2019 and an aerial survey from summer 2019, NOAA Fisheries estimates the Western Arctic stock at about 15,229 animals, while NAMMCO reports that in 2016 the North Atlantic population, mainly the stock between eastern Canada and western Greenland, numbered nearly 8,000 animals. According to NAMMCO, the IUCN now classifies the species as “low risk” globally (2018 assessment) and as “vulnerable” at the European level (2023 assessment), with populations growing in both cases.

Understanding how a mammal can stay alive for two centuries naturally raises the question of how different other large animals are in this respect: comparing it with whale biology in general, or with an aquatic adaptation as specialized as that of otters, helps show just how wide a range of solutions evolution has found for living in water. A longevity this far outside the norm is also a good test case for the mechanisms of natural selection that Darwin described: a body that accumulates two centuries of wear has to keep structures like the immune system and its own DNA repair working far longer than most mammals need to, and this is exactly where the DNA repair genes NOAA Fisheries mentions could play a part.