Eubalaena japonica
North Pacific right whale

Northern Pacific right whales are found throughout most of the North Pacific between 20 and 60 degrees latitude. They migrate to higher latitudes in the summer and to lower latitudes and coastal areas in winter. In summer, northern 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. Northern Pacific right whales were formerly abundant in this range but they are now rare and primarily observed in the Okhotsk Sea, southeastern Bering Sea, and occasionally along coastal Japan. (Butterworth et al., 2008; Gaines et al., 2005)

There is little known about habitat use by northern Pacific right whales. Historical whaling catch data suggest that the majority of the population was found in the Bering Sea, Gulf of Alaska, Sea of Okhotsk and northern North Pacific during summer. There is no evidence of coastal breeding aggregations in winter, as in their close relative Eubalaena australis. They may breed in offshore areas. Winter habitat use is unknown. In the southeastern Bering Sea, northern Pacific right whales seem to pass through the area for only a few days at a time and mainly from July to October (but as early as May and as late as December). (Butterworth et al., 2008; Munger et al., 2008)

Northern Pacific right whales were only recently recognized as a distinct species based on genetic evidence so much of the data on their natural history refers to the previously recognized single species, Eubalaena glacialis. These are large, baleen whales, up to 17 m long and 90,000 kg (~100 tons). Their skin is largely black, although individuals may have white patches on their undersides. They are marked by large callosities 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) and may appear white, yellow, or pink. These are robust baleen whales, with broad, rounded flippers, no dorsal fin, and lacking a grooved throat. Baleen plates can reach 3 m in length and number up to 270 on each side of the mouth. The head and jaws are massive, making up almost 1/3 of the length of these whales. Females are larger than males. These whales got their name for being the "right" whales to catch. Once killed their large amounts of blubber caused them to float at the surface and resulted in huge yields of oil. Their blubber can be up to 71 cm thick and make up to 45% of their body mass. 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. Right whales are slow swimmers, only acheiving speeds up to 5 knots (just over 9 km/hr) and averaging 2 knots (3.7 km/hr). (Butterworth et al., 2008; Crane and Scott, 2002; Cummings, 1985; NOAA Fisheries and OPR, 2008; OBIS-SEAMAP, 2009; Slijper, 1979)

Data on maximum lifespan of northern Pacific right whales is lacking. Lifespan is likely to be long. An individual Eubalaena glacialis was confirmed living to at least 67 years old and their close relatives, bowhead whales (Balaena mysticetus) have been confirmed living to nearly 200 years old. (Crane and Scott, 2002)

Northern 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 or in small groups. Most recent sightings are of individual animals, but population estimates suggest that local populations are extremely small. A 1999-2003 survey documented only 3.3 right whales per 1610 kilometers of survey in the western Pacific. Eastern Pacific populations may number in the 10's of individuals. In other Eubalaena species, groups are generally small, less than 12, and can be fluid and mixed-sex. Right whales are generally described as non-aggressive, even tender, towards other right whales, including potential mates, competing males, and young. (Butterworth et al., 2008; Crane and Scott, 2002; Slijper, 1979; Smith, 2000)

Home Range

Home range sizes are not reported for right whales.

Northern 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 Eubalaena australis the energy range used is 50 to 500 Hz, with durations from 0.5 to 6 seconds. In a study of northern 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. Northern Pacific right whale calls are generally less than 250 Hz and occur at irregular intervals of over 10 seconds apart. (Munger et al., 2008; Slijper, 1979)

Northern Pacific right whales feed mainly at the surface on concentrations of zooplanktonic crustaceans, such as krill, calanoid copepods, and larval barnacles. They take in large amounts of sea water and then express the water from their mouths with the tongue, leaving their zooplankton prey behind. Northern Pacific right whales have baleen plates with exceptionally fine fringes to collect their very small prey. (Butterworth et al., 2008; Crane and Scott, 2002; Cummings, 1985; Slijper, 1979; Smith, 2000)

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. (Butterworth et al., 2008; Gaines et al., 2005; NOAA Fisheries and OPR, 2008)

Right whales are important predators of krill and microcrustacean faunas. The relative rarity of northern 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. The extent of the negative effect of these communities on whales is uncertain, but they are thought to use breaching to try and dislodge parasites. (Cummings, 1985)

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

Northern Pacific right whales were previously hunted for their oil and other parts. Hunting of right whales has been outlawed by international conventions since 1935. (Butterworth et al., 2008; Gaines et al., 2005; NOAA Fisheries and OPR, 2008)

Northern Pacific right whales are currently one of the rarest whales 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 northern 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 northern Pacific right whales were observed in the 20th century. (Butterworth et al., 2008; NOAA Fisheries and OPR, 2008; OBIS-SEAMAP, 2009)

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)