Bowhead whales

NOAA biologist Amy Willoughby took this photo of a feeding group of bowhead whales in fall 2020 during an airplane survey of the whales. 

Editor’s note: This is one of a series of columns exploring bowhead whales and the bowhead whale exhibit now on display at the University of Alaska Museum of the North.

Bowhead blubber is thicker than that of any other whale. Scientists long regarded thick blubber as primarily a physiological adaptation to prevent heat loss to cold water, yet other marine mammals of the high Arctic, such as ringed seals and belugas, develop much thinner blubber.

Some Arctic marine waters may become seasonally rich with food, but overall, the Arctic is less productive than lower latitudes. The Beaufort and Chukchi seas, where BCB bowheads do most of their feeding, are not as reliably productive as seas where other baleen whales feed. Photosynthesis by primary producers in the Arctic has been shown to be highly variable. Thick blubber is now regarded mainly as an ample energy storage organ that can sustain bowheads during a year or more of food scarcity.

The bowhead whales’ huge baleen rack is one of the most distinctive and important features of the species. Their head makes up about one-third of their body length, which accommodates and suspends their extensive baleen rack. As in other baleen whales, bowheads’ baleen filters prey from the water, but compared to rorquals and gray whales, bowheads can efficiently retain prey like tiny copepods as small as 1 mm in length.

Like many other whale species, bowheads continue to grow after attaining sexual maturity. Males reach sexual maturity at a smaller size than females. As a possible consequence of their life pace and a lower metabolic rate, bowheads have extremely low cancer rates and may live more than 200 years, making them the longest-lived mammals on Earth. Other Arctic vertebrates like the narwhal and the Greenland shark live in environments where food is limited and are also relatively long-lived.

Bowhead whales have had varied relationships with humans. Sustainable subsistence whale hunting may have begun 2,000 years ago. Coastal Indigenous Beringians by about 1,000 years ago practiced bowhead whaling from a number of permanent communities. They developed sophisticated hunting tools including toggle-head harpoons, line, and floats, all deployed from lightweight skin-covered wooden-frame boats, such as the umiaq and the kayak.

Commercial exploitation of Atlantic right whales, then Atlantic bowhead whales, developed slowly and fitfully from Basques’ traditional ship-based whaling, starting some 1,200 years ago. Yankee commercial whalers discovered and first exploited the BCB stock of bowheads in 1848 for blubber and baleen. When Yankee commercial whaling ceased 60 years later, observers feared that the population was nearly extinct. Ironically, conservation concerns first expressed by Yankee commercial whalers were aroused by Pacific walrus. Whalers took walrus in years of adverse conditions for hunting bowheads. Commercial whalers saw that Yupik and Iñupiaq subsistence hunters who had been unfailingly hospitable to them, faced starvation when deprived of walrus as alternative food sources.

By the beginning of World War I in 1914, commercial whaling had severely reduced the four stocks of bowhead whales. A League of Nations Convention in 1931 formally prohibited all but Indigenous subsistence harvesting of bowhead whales.

J.C. “Craig” George, Ph.D., recently retired as a research biologist with the North Slope Borough’s Department of Wildlife Management in Utqiagvik. J.G.M. “Hans” Thewissen, Ph.D., is on the faculty of the Northeast Ohio Medical University in Rootstown, Ohio.