Bowhead whales (Scientific name:Balaena mysticetus) are sometimes called "Greenland rights" and are somewhat similar to right whales. Found mostly in Arctic waters, they have an enormous head, which they occasionally uses to break through thick ice for a breath. Although only around 10,000 remain aboriginal groups in northern Alaska are allowed to hunt a few of them each year.
Bowheads and right whales first appeared about 22 million years ago. One reason they can grow so large is that have developed the longest and most elaborate baleens.
Bowhead whales are one of the few whale species that reside almost exclusively in Arctic and subarctic waters experiencing seasonal sea ice coverage, primarily between 60° and 75° north latitude. Of all large whales, the bowhead is the most adapted to life in icy water. Its adaptations to this environment include an insulating layer of blubber up to 1.6 feet thick. [Source: NOAA]
Commercial whaling for bowheads off Alaska began in the mid-1700s, and lasted until the early-1900s. The economic value of the bowheads’ oil and baleen, combined with their slow swimming speeds and tendency to float when killed, made them a prime target for whalers. By the time commercial whaling of bowheads effectively ended in 1921, the worldwide bowhead abundance had declined to less than 3,000 whales. Today, bowhead whales may be still threatened by loss of food sources, climate change, vessel strikes, entanglement in fishing gear, ocean noise, offshore oil and gas development, and pollution. [Source: NOAA]
Websites and Resources: Animal Diversity Web (ADW) animaldiversity.org; National Oceanic and Atmospheric Administration (NOAA) noaa.gov; Fishbase fishbase.se; Encyclopedia of Life eol.org; Smithsonian Oceans Portal ocean.si.edu/ocean-life-ecosystems ; Monterey Bay Aquarium montereybayaquarium.org ; MarineBio marinebio.org/oceans/creatures
Bowhead Whales Live to Be 212 Years Old
Bowhead whales has the longest lifespan of all marine mammals — and all mammals period. According to scientists, this colossal year-round Arctic dweller may live 200-plus years. Only the 500-year North Atlantic clam, the ocean quahog, and the 400-Year-Old Greenland shark are known to live longer. [Source: NOAA]
The average age of animals captured during whaling era were estimated at 60 to 70 years old, based on examination of changes in the nucleus of the eye over time. However, several individuals have been discovered with ancient ivory and stone harpoon heads in their flesh and examination of their eye nucleus has resulted in estimated lifespans up to 200 years and even more. [Source: James Justice, Animal Diversity Web (ADW) /=]
Historically, age determination in bowhead whales has been difficult, and life history parameters are better known in terms of body length than age. Based on the recovery of stone harpoon tips from harvested bowheads, it is evident that bowhead whales live well over 100 years. However, new techniques allow for more precise estimation of bowhead whale age, and studies suggest they may live to be over 200 years old. Genes that allow for repair of damaged DNA may be responsible for their longevity. [Source: NOAA]
One particular bowhead was estimated to be 211. In May 2007, according to Medical Daily, a group of Iñupiat (Eskimos) in Alaska caught a 50-ton bowhead whale and made an interesting discovery: impeded deep in the animal blubber was a harpoon point made in New Bedford, Massachusetts in the 1880s. It seems that the harpoon was fired sometime around then, making the age of the whale at least 130 years old. There were other clues suggesting the whale was about 211 years old at the time it died. [Source: Zoë Miller,Azmi Haroun, Business Insider, December 25, 2022]
Bowhead Whale Habitat and Where They Are Found
Bowhead whales are are found in the Arctic Ocean and the far northern Atlantic and Pacific Oceans. They inhabit the Bering, Chukchi, and Beaufort seas, Hudson Bay and Foxe Basin, Baffin Bay and Davis Strait, the Sea of Okhotsk, and in waters from eastern Greenland and Spitsbergen to eastern Siberia. They spend the winter near the southern limit of the pack ice and move north as the sea ice breaks up and recedes during spring. They are rarely found below 45 degrees north latitude [Source: NOAA]
Four stocks of bowhead whales have been recognized worldwide by the International Whaling Commission. 1) and 2) Small stocks of only a few hundred individuals occur in the Sea of Okhotsk and the offshore waters of Spitsbergen. 3) Genetic, aerial survey, and tagging data suggests that bowheads from western Greenland (Hudson Bay and Foxe Basin) and eastern Canada (Baffin Bay and Davis Strait) should be considered one stock that may number more than a thousand individuals. 4) The only stock found within U.S. waters is the Western Arctic stock, also known as the Bering-Chukchi-Beaufort stock, which includes an estimated 10,400 to 23,000 whales.
Bowhead whales once inhabited oceans throughout the northern hemisphere. Over the last hundred years the population of bowhead whales has been greatly reduced into stocks mentioned above. They live in polar, saltwater and marine environments and are typically found in coastal areas, diving to an average depth to 100 meters (328 feet). In the late 1990s, approximately 700 bowhead whales were found in the north Atlantic while 7,000 were located in the north Pacific. Bowhead whales usually follow the receding ice drifts. During summer they can be found in bays, straits, and estuaries. [Source: James Justice, Animal Diversity Web (ADW)]
Balaenidae: Bowhead Whales and Right Whales
Right whales and bowhead whales are closely related. They both have huge baleens and heads. They first appeared about 22 million years ago. One reason they can grow so large is that have developed the longest and most elaborate baleens, which allow them to draw more food from the water.
bowhead and right whales
Balaenidae refers to a baleen whale (mysticete) family of two genera and four species: 1) North Atlantic right whale; 2) North Pacific right whale; 3) southern right whale); and 4) bowhead whales. Bowhead and right whales can reach up to 18 meters in length and over 100 tons at maturity. Their heads are huge, nearly one tthird of their total length. The dorsal fin is often either lacking or greatly reduced. Flippers are short and rounded. The throats of balaenids are smooth, lacking the furrows or grooves of some other mysticetes. [Source: Phil Myers, Animal Diversity Web (ADW) /=]
Balaenidae are different from the other three baleen whale families: Balaenopteridae (rorquals), which include blue, fin, sei, humpback and minke whales and Eschrichtiidae ( gray whales). There is a separate baleen family for Cetotheriidae (the pygmy right whale).
According to Animal Diversity Web: The skull of balaenids has reduced nasals, and the frontals are barely exposed on the dorsal surface. The posterior border of the nasals and premaxillae lie anterior to the supraorbital processes of the frontals. The rostrum is high, narrow, and arched. Baleen plates are long and narrow, and they number more than 350 on each side of the upper jaw. The right and left baleen rows are separated in the front of the mouth. /=\
Bowhead whales feed largely on copepods, which they catch by swimming slowly, with their mouths open, through concentrations of these crustaceans. Water flows into the huge mouth and out between the baleen plates. Food is trapped on the fringes of the plates and scraped off with the tongue. They normally feed at or near the surface. These whales live singly or in small groups of up to three or 4 individuals. Their stocks were severely depleted by whaling, and they remain low. The name "right whale" is said to have originated because these were the "right" whales for whalers to kill. /=\
Bowhead Whale Physical Characteristics
Bowhead whales are one of the world’s heaviest animals and possess the largest mouth of any creature in the animal kingdom. They are second largest (heaviest) whales — and animal — in the world after blue whales. Bowheads range in length from 14 to 18 meters (46 to 59 feet) and range in weight from 75 to 100 tonnes (82 to 110 US tons, 75,000 to 100,000 kilograms 165,200 to 220,265 pounds). Females are larger than males. Females measure between 16 and 18 meters in length, males measure between 14 and 17 meters in length. Bowheads are endothermic (use their metabolism to generate heat and regulate body temperature independent of the temperatures around them) and homoiothermic (warm-blooded, having a constant body temperature, usually higher than the temperature of their surroundings). [Source: James Justice, Animal Diversity Web (ADW) /=]
Bowhead whales have a dark body with a distinctive white chin and, unlike most cetaceans, do not have a dorsal fin. Bowheads have stocky bodies. Their bow-shaped skull is curved and asymetric. And can be over five meters (16.5 feet) long — about a third of a bowhead’s body length. The bowhead whale also has a 43 to 48 centimeter (17- to 19-inch) thick blubber layer — thicker than that of any other whale. [Source: NOAA]
The bowhead’s large, thick skull allows them to break through 20-centimeter (8-inch) -thick sea ice. Some Alaska Native whalers have even reported whales surfacing through two 2 feet of ice. Bowhead whales often accumulate scars on their bodies from breaking ice, killer whale encounters, entanglement in fishing gear, and propellers. Scientists use these scars to identify individual whales.
The bowhead whale’s arched shape and bowed mouth are the sources of its name. The enormous head can comprise nearly 6 meters (25 feet) of a mature male’s 20-meter (65-foot) length. The overall length of the bowhead is long enough to stretch across a four-lane highway with plenty of room to spare. Their 1.6-foot-wide layer of insulating blubber definitely helps with the Arctic cold. The whale’s baleen is up to four meters (13 feet) long, the longest of any baleen whale. Bowheads also have two blowholes, as do all baleen whales. The lower jaw forms a U-shape around the upper jaw. This lower jaw is usually marked with white spots, contrasting with the rest of the whale's black body. There are 300 baleen plates measuring 300-450 centimeters in vertical length. Bowhead whales have small pectoral fins for their size, less than 200 centimeters in length. /=\
Bowhead Whale Behavior and Communication
Bowhead whales are motile (move around as opposed to being stationary), migratory (make seasonal movements between regions, such as between breeding and wintering grounds), and social (associates with others of its species; forms social groups). When migrating during the spring and fall, bowhead whales divide into three groups — subadults, intermediate mature whales, and large adults. Each of the four stocks has distinct migration patterns dependent on the supply of food and the extent of the Arctic ice. [Source: James Justice, Animal Diversity Web (ADW) /=]
Bowhead whales sense using touch and chemicals usually detected with smell. Sound is critical to the survival of bowhead whales. They rely on keen hearing abilities to detect, recognize, and localize biologically important sounds for navigation, predator avoidance, foraging, and communication in the marine environment. Bowhead whales are highly vocal and have a large variety of calls. The echoes of some of their calls are used to help the whales find food and navigate through the ice as they migrate. [Source: NOAA]
Although direct measurements of hearing ability in baleen whales are lacking, scientists predict, based on anatomy and vocalizations of other closely related whales, that bowheads hear best at low-frequencies. Low-frequency sounds are capable of propagating great distances through the ocean and can allow for potential communication over long ranges.
Bowhead Whale Feeding and Predators
Bowhead whales are baleen whales. They filter their food by straining huge volumes of ocean water through their baleen plates (like the teeth of a comb). Bowhead whales have the longest baleen plates of all whales, and feed almost exclusively on marine invertebrates, including small to moderately sized crustaceans like shrimp-like euphausiids (krill), mysids (opossum shrimps), gammarid amphipods (shrimp-like crustaceans) and copepods. They also ingest other invertebrates and small fish. Scientists estimate that a bowhead whale needs to eat about 100 metric tons (over 220,000 pounds) of crustaceans per year. [Source: NOAA]
Bowhead whales feed by gulping water and food and use their baleen plates to filter and catch the food while pushing the water out with their massive tongue. These whales sometimes feed opportunistically such as during the spring migration, but mostly feed during the winter in their feeding grounds. They eat some benthic (bottom-dwelling) creatures and wells as organisms suspended in the water column. Copepods and other crustacean zooplankton are not important food sources for young Bowhead whales, but they increase in importance with age Bowheads can filter at approximately 50,000 copepods per minute. Bowhead whales sometimes form groups of up to fourteen individuals, in which they make a V-shape formation. In this formation they travel at the same speed and filter feed together [Source: James Justice, Animal Diversity Web (ADW) /=]
Their main known predators of bowhead whales are orcas (killer whales) and humans. Some indigenous groups tat have traditionally hunted the whales have permission to hunt them now. Bowhead whales are protected from other predators such as orcas by their large size. They are also sometimes seek shelter under ice drifts and sheets, where orcas dare not to go. In order to survive under the ice, bowhead whales can break through the ice to breathe. A 1995 study revealed that one-third of bowhead whales in the Davis Strait had scars from orca attacks. Barnacles use bowhead whales as both a mode of transportation and a way to encounter fresh food supplies.
Bowhead Whale Mating, Reproduction and Offspring
Bowhead whales are viviparous, meaning they give birth to live young that developed in the body of the mother. They engage in seasonal breeding. Typical calving intervals are every three to four years. The breeding season is from in late winter to early spring., with the number of offspring being one. The gestation period ranges from 12 to 16 months, with average being 13-14 months. The weaning age ranges from nine to 15 months. On average females and males reach sexual maturity at age 20 to 25 years. [Source: James Justice, Animal Diversity Web (ADW) /=]
Bowhead whales reach sexual maturity when their total body length is about 11 to 14 meters (35 to 45 feet). Mating behavior has been observed year-round, though most conceptions are believed to occur during late winter or spring. Most calves are born between April and early June during spring migration. Calves are usually about 4.5 meters (13 feet) long, weigh about 900 kilograms (2,000 pounds), and can swim at birth. Mothers and calves form a very close attachment. [Source: NOAA]
Males attract female bowhead whales through songs. It is unknown how long these pair bonds last or how many matings male bowhead whales take part in during mating season. Spring migration takes place soon after the mating season. Females usually reach sexual maturity before males and are also one to two meters larger than males at this time. In some cases pseudohermaphroditism can occur, leaving a whale to appear female, but also having male sex organs.
Young are precocial. This means they are relatively well-developed when born. Pre-fertilization, pre-birth and pre-weaning provisioning and protecting is done by females. Pre-independence protection is provided by females. Calves grow approximately 1.5 centimeters a day. The calf is fed with its mother's milk until it is weaned. After weaning, the growth rate decreases. After births occur, whales segregate into groups in order to migrate. Calves and mothers are in the front group. Perhaps this is to allow them to be the first to feed on food aggregations that are encountered. For the most part it seems that females take care of the young, although there have been some cases of Bowhead whales travelling in groups of three: a mature male, a mature female, and a calf (Shelden and Rugh 1995). (Shelden and Rugh, 1995) /=\
Endangered Bowhead Whales, Humans and Conservation
By some measures bowhead whales are not endangered by other measures they are. They are considered a species of ‘Least Concern’ on the International Union for Conservation of Nature (IUCN) Red List . However, the East Greenland-Svalbard-Barents Sea subpopulation and the Okhotsk Sea subpopulation are classified as Endangered. The Convention on International Trade in Endangered Species (CITES) lists them in Appendix I, which lists species that are the most endangered among CITES-listed animals and plants. /=\
The United States has listed all bowhead whales as endangered under the Endangered Species Conservation Act in 1970 and the Endangered Species Act ((ESA, U.S. Fish and Wildlife) in 1973. Bowhead whales are protected and listed as depleted under the Marine Mammal Protection Act (MMPA). [Source: NOAA]
Bowhead whales were highly after by whalers, Their large size yielded a large bounty of meat, baleen, blubber and oil. By some reckonings they were the most economically valuable of all whales. Many native people including Eskimos depended on them for the survival. The whales supplied them with baleen for tools, blubber for fuel, and whale meat for food and trade. Commercial whaling severely reduced bowhead whale numbers from historical levels. The worldwide number of bowheads prior to commercial exploitation is estimated at a minimum of 50,000, including an estimated 10,400 to 23,000 whales in the Western Arctic stock, the stock found in U.S. waters. Commercial whaling drove global abundance down to less than 3,000 by the 1920s.
Western Arctic bowheads have shown considerable recovery since the end of commercial whaling in the early 1900s, and they now comprise the largest population of bowheads in the world. The most recent stock assessment report abundance data for the Western Arctic bowhead stock, collected during spring 2011, indicates there are over 16,000 Western Arctic bowheads. However, the smaller Okhotsk Sea population, more heavily exploited in the past, remains at a dangerously low population of only a few hundred individuals. Genetic research has shown that these two North Pacific populations are distinct, indicating that movement of individuals between the two populations is rare.
Threats to Bowhead Whales
Threats to bowhead whales populations include a variety of human-caused stressors and threats, including: pollution (such as, spilled oil, heavy metals, chemicals, debris), vessel strikes, entanglement in fishing gear, climate change, ocean noise, climate change and offshore oil and gas development. Climate-change-induced ocean acidification can affect bowhead whale prey, and noise pollution may affect their feeding, navigation, communication, and ability to detect and avoid predators. Conservation efforts for bowhead whales involve reducing or ending the hunting of them. Native people have been allowed to take only one whale every two years.
Entanglement: About 12 percent of the Western Arctic stock show scars from entanglement in fishing gear, mostly from commercial pot-fishing gear. Entangled whales either swim off with the gear attached or may become anchored in place. Once entangled, whales may drag gear or lines for long distances, ultimately resulting in fatigue, compromised feeding ability, or severe injury, which may lead to reduced reproductive success and/or death. An unknown number of whales die from entanglement, as some entanglements likely go undetected. In cases where a carcass is still entangled or bears entanglement scars, it is not always possible to determine if entanglement was the cause of death. [Source: NOAA]
Contaminants enter ocean waters from municipal wastewater discharges, runoff, accidental spills, atmospheric deposition of airborne contaminants, discharges from commercial operations such as fishing, shipping, and oil and gas development, and other sources. Many contaminants move up the food chain and accumulate in top predators. Bioaccumulating contaminants are present in bowhead prey and in their environment. Bowheads accumulate these contaminants because of their long lifespan, position at the top of the food chain, and large blubber stores. These pollutants may harm bowheads’ immune and reproductive systems.
Ocean Noise: Underwater noise may threaten bowhead whales by interrupting their normal behavior and driving them away from areas important to their survival. Noise from seismic exploration for petroleum reserves was found to drive bowheads from waters within about 12 miles of the sound source, although avoidance behavior is likely related to the activity that the bowhead is engaged in at the time of exposure. For instance, feeding whales may be more reluctant to abandon food concentrations due to noise. In addition, evidence suggests that bowheads’ prey, primarily small marine invertebrates, may be negatively affected by noise from seismic exploration.
Vessel Strikes can injure or kill bowhead whales. About two percent of bowheads show signs of scars from vessel strikes. However, as seasonal sea ice continues to retreat due to climate change, vessel traffic in Arctic waters is increasing and could increase the risk of future collisions.
Image Source: Wikimedia Commons, NOAA
Text Sources: Animal Diversity Web (ADW) animaldiversity.org; National Oceanic and Atmospheric Administration (NOAA) noaa.gov; Wikipedia, National Geographic, Live Science, BBC, Smithsonian, New York Times, Washington Post, Los Angeles Times, The New Yorker, Reuters, Associated Press, Lonely Planet Guides and various books and other publications.
Last Updated May 2023