Morphometrics

Morphometrics

Summary:

Collection of biological measurements taken from harvested bowhead whales (Balaena mysticetus) provides information on the basic biology of the bowhead whale population, including anatomy, physiology, development and evolution. See this harvest form for an idea of what measurements are taken. You can visit the Bowhead Whale Health Studies page for more information on samples collected and about the current findings.

NSB-DWM biologists, Josh Bacon and Cheryl Rosa, measuring the width of a flipper (or pectoral fin) on a bowhead whale. Flippers on males are larger than on females. The largest measured flipper was over 9 feet in length. (Photo courtesy of NSB-DWM)

As a result of these studies (George, 2009), and others, here is some information that we now know about bowhead whales.

Characteristics:

• They are very large “pagophilic” or “ice-loving” whales
• Black skin with white patches on chin and sometimes on the belly and genitals (and peduncle on adults)
• Up to 19 meters in length
• Baleen black, sometimes with whitish streaks
  • Up to 16 ft in length (this length noted in Yankee whalers’ records, but today’s lengths up to about 13 1/2 ft)
  • Longest of any whale (Order Cetacea)
• Mass up to 100+ tons
• Females slightly larger than males
  • Gestation: 14 months
  • Birth mass: 1,000 kg
• Males have large testicles, likely due to the reproductive strategy of sperm competition
• Head about 1/3 body length, flukes 1/3 body length

Uniquely adapted to life in the Arctic Ocean:

• Inhabit ice-covered waters in circumpolar Arctic
• Low metabolic rates
• Long-lived
  • Up to 150-200 years of age
  • Perhaps most long-lived mammal
• Huge body mass to surface area ratio
• Thick blubber up to 35 cm
  • Used as a ‘fuel tank’ or energy reserve
  • Thickest in Cetacea (whales)
• Huge mouth and longest baleen
  • Allows feeding on small, low-density prey
• Ability to break ice with top of skull
• Low body temperatures
  • Deep body temperature averages 33.8 degrees Celsius
• Do not migrate to temperate or tropical seas

Health assessment of bowhead whales:

• Low levels of contaminants
• Radionuclides and organochlorines at low levels
• Heavy metals at low levels, except for cadmium in the liver and kidney
• Disease incidence low
• Tissues seem to be cancer-free; no cancers noted to date
• Go to the Health Assessment Page for more on this topic

Anatomy of the Bowhead Whale Skull and Mandible:

In the mid-1990s, the Department received permission from the Barrow Whaling Captains to build anatomy displays of bowhead whales. Skulls and other parts were donated by whaling captains George Adams, Lawrence Ahmaogak, Carl Brower, Eugene Brower, Harry Brower, Jr., Tony Edwardsen, Van Edwardsen, Charles Hopson, William Leavitt, Don Nungasuk and Joash Tukle. Expertise on anatomy and bone preparation was provided by Daniel Hillman and William Henk, from the School of Veterinary Medicine, Louisiana State University, Qian Zhu from Weihai Campus, Shandong University, Shandong Province, China, and Paul Nader. NSB-DWM employees assisting in the preparation were Dave Ramey, Perry Anashugak, Joe Burgener, and Shawn Johnson.

Prepared bowhead whale skulls can be seen around Barrow in front of many buildings, including the three schools, the NSB Borough Administration Building, the Inupiat Heritage Center/Tuzzy Library, and Building 360 at NARL. The brochure below, Anatomy of the Bowhead Whale Skull & Mandible, was produced and distributed by the North Slope Borough Department of Wildlife Management. This project was funded by the North Slope Borough.

Bowhead whale flipper bones, displayed in the NSB Administration Building in Barrow

Bowhead whale humerus (longitudinal section) from 1990 harvest

Publications:

• Hillmann, D.J., Henk, W.G, and Nader, P. 1997. Initial observations on the skull and mandibles from Eskimo harvested bowhead whales (Balaena mysticetus). Report to the NSB Department of Wildlife Management, Barrow, AK.
• George, J.C., et al. 2007. Preliminary estimates of bowhead whale body mass and length from Yankee commercial oil yield records. Presented to the 59th International Whaling Commission. SC/59/BRG5.
• George, J.C. et al. 2016. Severe bone loss as part of the life history strategy of Bowhead Whales. PLoS ONE 11(6): e0156753. doi:10.1371/journal.pone.0156753.