Eubalaena japonicaNorth Pacific right whale

Geographic Range

North Pacific right whales, Eubalaena japonica, are found in temperate and sub-arctic waters in the Pacific Ocean between 20 and 60 degrees latitude. They range from Japan and Russia in the west to Alaska and the west coast of North America in the east. They migrate to higher latitudes in the summer and to lower latitudes and coastal areas in winter. In summer, north Pacific right whales are found in the Sea of Okhotsk, Bering Sea, around the Aleutian Island chain, and in the Gulf of Alaska. In winter they are found (or were once found) in the Sea of Japan, Taiwan straits, and Ogasawara Bunto in the western Pacific and south to coastal Baja California in the eastern Pacific. They have also been seen occasionally in the Hawaiian Islands. Populations in the eastern and western Pacific are considered discrete populations. North Pacific right whales were formerly abundant throughout this range, but they are now rare and primarily observed in the Okhotsk Sea, southeastern Bering Sea, and occasionally along coastal Japan. North Pacific right whales primarily occur in coastal or shelf waters, though they have also been sighted in deep waters. ("North Pacific right whale (Eubalaena japonica)", 2010; Gaines, et al., 2005; Reilly, et al., 2010)


Little is known about the specific habitats used by north Pacific right whales. They primarily occur in coastal or shelf waters, though they have also been observed moving through deep waters. They migrate to higher latitudes during the spring and summer, and much of their distribution is strongly correlated to the distribution of their prey. North Pacific right whiles occupy four habitats based on use: feeding, calving, nursery, and breeding areas. Feeding areas are visited seasonally and have dense populations of copepod and krill. Calving areas are used for calving and neonatal nursing. During the winter, many right whales feed and suckle their young in nursery areas, which are generally located in shallow, coastal waters at low latitudes. Other winter habitat is unknown. Finally, conception occurs in breeding areas. However, there is no evidence of breeding aggregations of north Pacific right whales in winter, as with their close relative southern right whales. During the summer, the majority of the population of north Pacific right whales can be found the Bering Sea, Gulf of Alaska, Sea of Okhotsk and northern North Pacific during summer. North Pacific right whales pass through the southeastern Bering Sea only for a few days at a time and mainly from July to October (but as early as May and as late as December). (NOAA Fisheries and OPR, 2010)

Physical Description

North Pacific right whales are massive creatures with heads that can be almost one-third of their total body length. Males are generally measure between 14 and 17 m in length, and females are longer than males. Adults weigh between 70 and 100 tons. Newborn right whales are generally 4 to 6 m long. The skin of north Pacific right whales is largely black, although individuals may have white patches on their undersides. They are marked by large callosities, large patches of raised tissue, on the rostrum, near the blowholes and eyes, and on the chin and lower lip. The largest callosity, on the top of the rostrum, is referred to as a "bonnet." These callosities harbor barnacles (Cirripedia) and whale lice (Cyamidae), which make the callosities appear white, yellow, or pink. Callosities emerge after birth, but a pattern of callosities is not established for 7 to 10 months. Callosities may grow upwards and even break off, but their placement on a whale's head generally does not change. ("North Pacific right whale (Eubalaena japonica)", 2010; Crane and Scott, 2002; Cummings, 1985; NOAA Fisheries and OPR, 2010; New England Aquarium, 2010; OBIS-SEAMAP, 2009; Reilly, et al., 2010; Slijper, 1979)

North Pacific right whales are stocky baleen whales with broad rounded flippers, no dorsal fin or ridge, and lacking a grooved throat. The tail of a right whale is all black, broad, and is deeply notched in the center with a smooth trailing edge. Their flippers are broad and fan-shaped. Right whales are slow swimmers, only achieving speeds up to 5 knots (just over 9 km/hr) and averaging 2 knots (3.7 km/hr). Their head and jaws are massive, making up almost 1/3 of the length of these whales. Baleen plates are brownish-gray in color, range from 200 to 270 in number on each side of the mouth, and can reach 3 m in length. Their blowholes are separated on their dorsal surface and exhalations result in a large, V-shaped blows up to 5 m high. Their 7 cervical vertebrae are fused into a single unit. These whales got their name for being the "right" whales to catch. Once killed, their large amounts of blubber cause them to float at the surface and result in huge yields of oil. Their blubber can be up to 71 cm thick and make up to 45% of their body mass. ("North Pacific right whale (Eubalaena japonica)", 2010; Crane and Scott, 2002; Cummings, 1985; NOAA Fisheries and OPR, 2010; New England Aquarium, 2010; OBIS-SEAMAP, 2009; Reilly, et al., 2010; Slijper, 1979)

North Pacific right whales may be confused with bowhead whales, but are distinguishable by the presence of callosities on their body and white patches on their undersides. They are also closely related to southern right whales, though north Pacific right whales have larger and wider flippers than their southern counterparts. North Pacific right whales were, until recently, considered the same species as north Atlantic right whales. The species were separated because of genetic evidence ("North Pacific right whale (Eubalaena japonica)", 2010; Crane and Scott, 2002; Cummings, 1985; NOAA Fisheries and OPR, 2010; New England Aquarium, 2010; OBIS-SEAMAP, 2009; Reilly, et al., 2010; Slijper, 1979)

  • Sexual Dimorphism
  • female larger
  • Range mass
    63,500 to 72,574 kg
    to lb
  • Average mass
    90,718 kg
  • Range length
    13.7 to 17 m
    44.95 to 55.77 ft
  • Average length
    15 m
    49.21 ft


Although mating systems have not been described for north Pacific right whales, it is likely that mating is similar in other right whale species such as southern right whales and north Atlantic right whales. Southern right whales and north Atlantic right whales form non-aggressive mating aggregations in which individuals engage in gentle physical contact and nuzzling. Females are likely to mate with multiple males and males do not compete aggressively for females. Behaviors associated with mating in right whales include fin and tail slapping at the surface, "headstanding," and breaching. In headstanding, right whales float at the water surface in a vertical position with the flukes extended into the air. They may also rock back and forth while in this position and hold it for several minutes. This is thought to be a mating display. Breaching and tail/fin slapping are also more common during mating aggregations and may be a kind of courtship display. (Crane and Scott, 2002; Cummings, 1985; NOAA Fisheries and OPR, 2010; Reilly, et al., 2010; Slijper, 1979; Smith, 2000)

The sex organs of male right whales are positioned on their abdomen. Right whales have no scrotum or baculum, however they have exceptionally large testes. One north Pacific right whale was reported to have a testis 201 cm in length, 78 cm in diameter, and 525 kg in mass. Males have a darkly pigmented, long, slender, retractile penis that can reach 215 to 270 cm in length. The ovaries of female right whales are also positioned on the abdomen. The largest measured ovary weighed 6.3 kg. Right whales have a bicornuate uterus, and it is thought a fetus can develop in either horn of the uterus, as with most baleen whales. (NOAA Fisheries and OPR, 2010)

Like other right whales, northern Pacific right whales have exceptionally low reproductive rates. They give birth in winter to a single young every 3 to 4 years after a gestation period of just over a year. Breeding generally occurs in winter with births occurring the next spring. The length of lactation is unknown but has been estimated to last 6 or 7 months. Although the duration is unknown for right whales, weaning is usually gradual and prolonged in ceteceans. A 1-year-old north Pacific right whale was found with a large amount of milk in its stomach, and another individual 11.3 m in length appeared fully weaned. Males reach sexual maturity when they reach 15.2 m in length and females at 15.8 m, which is about 10 years in age. (Crane and Scott, 2002; Cummings, 1985; Reeves and Brownell, 1982; Slijper, 1979; Smith, 2000)

  • Breeding interval
    Female north Pacific right whales give birth to a single young every 3 to 4 years.
  • Breeding season
    North Pacific right whales breed during the winter.
  • Average number of offspring
  • Range gestation period
    12 (low) months
  • Average age at sexual or reproductive maturity (female)
    10 years
  • Average age at sexual or reproductive maturity (male)
    10 years

North Pacific right whales measure up to 6 m in length when they are born, and they grow quickly for their first few years, reaching lengths up to 12 m by 18 months of age. The milk of mother north Pacific right whales is high in protein and is lipid-rich. Mothers nurse, protect, and care for their young, investing significant energy into each offspring. Little is known about the duration of lactation and care, but it is likely to be long, given the 3 to 4 year interval between breeding attempts in females. There may be a long period of association with the mother and an extended period of learning. Female right whales have strong inclinations to protect their young. Females position themselves between their claves and sources of danger including other whales, boats, aircrafts, or divers. (Crane and Scott, 2002; Cummings, 1985; Reeves and Brownell, 1982; Slijper, 1979)

  • Parental Investment
  • precocial
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • female
  • pre-independence
    • protecting
      • female


Little is known about the lifespan of north Pacific right whales, but it is likely quite long. An individual of a closely related species, Eubalaena glacialis (north Atlantic right whale) lived to be at least 67 years of age. Other close relatives, Balaena mysticetus (bowhead whales), have been confirmed living to 200 years of age. (Crane and Scott, 2002; NOAA NMFS SWFSC PRD, 2010)


North Pacific right whales migrate between summer and wintering grounds. Little is known about their behavior, in large part because of their extreme rarity. They have been observed singly and in small groups. Groups of other species of Eubalaena are generally small, less than 12 individuals, and can be fluid and mixed-sex. It is believed that right whales stay in the same area for days or even weeks at a time. Right whales are generally considered non-aggressive, even tender, towards other right whales, including potential mates, competing males, and young. (Crane and Scott, 2002; NOAA NMFS SWFSC PRD, 2010; Reeves and Brownell, 1982; Reilly, et al., 2010; Slijper, 1979; Smith, 2000)

Home Range

Home range sizes are not reported for right whales.

Communication and Perception

North Pacific right whales use vocalizations extensively, as do other whales. Their vocalizations include both complex and simple, low-frequency sounds. The low-frequency sounds have been described as "belch-like." Other sounds include moans, grunts, sighs, and bellows. In a study of north Pacific right whale vocalization in the Bering Sea, over 80% of vocalizations were "up-calls," calls that were frequency modulated and ended on a higher frequency. These calls were from 90 to 150 Hz and about 0.7 seconds in duration. The remainder of calls were either "down-up calls," with a downward frequency change before becoming an up call (5%) or constant frequency moans. North Pacific right whale calls are generally less than 250 Hz and occur at irregular intervals of over 10 seconds apart. (Munger, et al., 2008; NOAA NMFS SWFSC PRD, 2010; Slijper, 1979)

Food Habits

Northern Pacific right whales feed mainly at the surface on concentrations of zooplanktonic crustaceans, such as krill, calanoid copepods, and larval barnacles. Specifically, they are known to eat Neocalanus plumchrus, Calanus finmarchius, and Calanus cristatus, along with north Pacific krill and Oaratgenusti japonica. Food is gathered by skimming the surface of the water with rostrum exposed in the air, mouth open. They take in large amounts of sea water through triangular openings at the front of their mouth. After passing through the baleen, water is expressed from their mouth by the tongue, leaving their zooplankton prey behind. Northern Pacific right whales have baleen plates with exceptionally fine fringes to collect their very small prey. (Crane and Scott, 2002; Cummings, 1985; Reeves and Brownell, 1982; Reilly, et al., 2010; Slijper, 1979; Smith, 2000)

  • Primary Diet
  • carnivore
    • eats non-insect arthropods
  • Animal Foods
  • aquatic crustaceans
  • other marine invertebrates
  • zooplankton


Because of their very large size, adult right whales have no natural predators. Newborn calves may fall prey to killer whales or large sharks. In the last several hundred years, humans have been the primary predators of northern Pacific right whales. (Gaines, et al., 2005; NOAA Fisheries and OPR, 2010; Reilly, et al., 2010)

Ecosystem Roles

Right whales are important predators of krill and microcrustacean faunas. The relative rarity of north Pacific right whales may mean that their impact on these faunas is currently small. Right whales have communities of barnacles and whale lice on their bodies. Whale lice are abundant on the callosities along the lips and tend to accumulate around wounds, as do amphipods. Barnacles have also been found on the callosities of north Atlantic and southern right whales, but no evidence has shown the presence of these barnacles of north Pacific right whales. Right whales are thought to use breaching to try and dislodge parasites. Right whales also have a low infestation rate of endoparasites, including Priapocephauls grandis, Bolbosoma brevicolle, and Bolbosoma turbinella. (Cummings, 1985; Reeves and Brownell, 1982)

Commensal/Parasitic Species
  • barnacles Cirripedia
  • whale lice Cyamidae
  • Priapocephauls grandis
  • Bolbosoma brevicolle
  • Bolbosoma turbinella

Economic Importance for Humans: Positive

Right whales, including north Pacific right whales, have been hunted for their oil and baleen. Whale oil is used in the manufacturing of soaps, candles, and lard substitutes. Before petroleum, whale oil was a valuable illuminant. The baleen of right whales was used to stiffen clothing and can be used to make whips and canes. In Japan and Norway, baleen whales are also used as a food source. Hunting of right whales, however, has been outlawed by international conventions since 1935. (Gaines, et al., 2005; NOAA Fisheries and OPR, 2010; Reeves and Brownell, 1982; Reilly, et al., 2010)

  • Positive Impacts
  • food
  • body parts are source of valuable material

Economic Importance for Humans: Negative

There are no known adverse effects of north Pacific right whales on humans.

Conservation Status

North Pacific right whales are currently one of the rarest whale species, with some estimates placing the world population at around 1400 individuals and other estimates substantially smaller (~500 in the western Pacific and numbering less than 100 in the eastern Pacific). They were previously common in the north Pacific but were relentlessly pursued by whalers throughout the 19th century. Japanese whaling of this species began in the late 1500's and whaling by Americans and Europeans began in the 1800's. As many as 37,000 north Pacific right whales were killed in a 70 year period from 1839 to 1909, leaving populations at a fraction of their previous levels. Right whales became protected by international agreement in 1935 and by law in 1946 by the International Whaling Commission. Illegal hunting continued through the 1960's, during which time Soviet whaling ships took almost the entire remaining population of eastern Pacific right whales (372 individuals), leaving the population at an estimated 50 individuals. The eastern Pacific population is considered critically endangered and populations in the western Pacific are considered endangered by the IUCN. These whales have been protected from hunting since 1970, but entanglements and deaths continue to occur occasionally. Only 1,965 north Pacific right whales were observed in the 20th century. (NOAA Fisheries and OPR, 2010; OBIS-SEAMAP, 2009; Reilly, et al., 2010)

Appointed in 1987, The Northern Right Whale Recovery Team created a recovery plan for both north Pacific and north Atlantic right whales. The National Marine Fisheries Service approved the recovery plan in 1991, which strives to see both species fully recover but first focuses on recovery to bring their status from “endangered” to merely “threatened”. Some actions recommended in the recovery plan include eliminating injury caused by ship collision, fisheries, and fishing gear; monitoring population size and trends; maximizing efforts to free entangled or stranded right whales; obtaining scientific information from dead specimens; and protecting habitats that are essential for right whales to survive. (NOAA Fisheries and OPR, 2010)

Other Comments

Right whales were previously considered a single species, Eubalaena glacialis. Strong mitochondrial and nuclear genetic evidence, however, suggests three species: north Atlantic right whales (Eubalaena glacialis), southern right whales (Eubalaena australis), and north Pacific right whales (Eubalaena japonica). These same data also yield strong evidence for a close sister relationship between E. australis and E. japonica. (Gaines, et al., 2005)


Ariana Grasgreen (author), University of Oregon, Stephen Frost (editor), University of Oregon, Gail McCormick (editor), Animal Diversity Web Staff.


Pacific Ocean

body of water between the southern ocean (above 60 degrees south latitude), Australia, Asia, and the western hemisphere. This is the world's largest ocean, covering about 28% of the world's surface.

World Map


uses sound to communicate

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.


an animal that mainly eats meat


uses smells or other chemicals to communicate


the nearshore aquatic habitats near a coast, or shoreline.


animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.


a method of feeding where small food particles are filtered from the surrounding water by various mechanisms. Used mainly by aquatic invertebrates, especially plankton, but also by baleen whales.


A substance that provides both nutrients and energy to a living thing.


offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).


makes seasonal movements between breeding and wintering grounds


having the capacity to move from one place to another.


specialized for swimming

native range

the area in which the animal is naturally found, the region in which it is endemic.


An aquatic biome consisting of the open ocean, far from land, does not include sea bottom (benthic zone).


the regions of the earth that surround the north and south poles, from the north pole to 60 degrees north and from the south pole to 60 degrees south.


the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.

saltwater or marine

mainly lives in oceans, seas, or other bodies of salt water.

seasonal breeding

breeding is confined to a particular season


reproduction that includes combining the genetic contribution of two individuals, a male and a female


associates with others of its species; forms social groups.


lives alone


uses touch to communicate


that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).


uses sight to communicate


reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

young precocial

young are relatively well-developed when born


animal constituent of plankton; mainly small crustaceans and fish larvae. (Compare to phytoplankton.)


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