The North Pacific right whale (Eubalaena japonica) is a very large, thickset baleen whale species that is extremely rare and endangered.
The Northeast Pacific population, which summers in the southeastern Bering Sea and Gulf of Alaska, may have no more than 40 animals. A western population that summers near the Commander Islands, along the Kamchatka coast, along the Kuril Islands, and in the Sea of Okhotsk is thought to number in the low hundreds. Before commercial whaling in the North Pacific (i.e., pre-1835), there were probably over 20,000 right whales in the region. The taking of right whales in commercial whaling has been prohibited by one or more international treaties since 1935. Nevertheless, between 1962 and 1968, illegal Soviet whaling killed at least 529 right whales in the Bering Sea and the Gulf of Alaska as well as at least 132 right whales in the Sea of Okhotsk, plus an additional 104 North Pacific right whales from unspecified areas.
The International Union for Conservation of Nature categorizes the species as endangered; it categorizes the Northeast Pacific population as critically endangered. The Center for Biological Diversity argues that the North Pacific right whale is the most endangered whale on Earth.North Pacific right whale , Center for Biological Diversity.
Taxonomy
Since 2000, scientists have considered the right whales in the North Pacific and nearby seas to be a separate species, Eubalaena japonica, the North Pacific right whale. Genetic differences between E. japonica and E. australis are much smaller than those of other baleen whales among different ocean basins.
Before 2000, right whales in the North Pacific were considered conspecific with right whales in the North Atlantic and Southern Hemisphere, and all were described as Eubalaena glacialis in the scientific literature. All these animals closely resemble each other in outward appearance. The differences that separate them into separate species are genetic and discussed in the article on Balaenidae. The recognition of the different populations of Eubalaena whales as distinct species is supported by the Society for Marine Mammalogy, the U.S. National Marine Fisheries Service, and the International Whaling Commission.
The North Pacific, North Atlantic, and Southern right whales are all members of the family Balaenidae. The bowhead whale found in the Arctic is also a balaenid whale, but sufficiently different to warrant its own genus Balaena.
The cladogram is a tool for visualizing and comparing the evolutionary relationships between taxa. The point where a node branches off is analogous to an evolutionary branching – the diagram can be read left-to-right, much like a timeline. The following cladogram of the family Balaenidae serves to illustrate the current scientific consensus as to the relationships between the North Pacific right whale and the other members of its family.
Description
E. japonica is a very large, thickset baleen whale. It very closely resembles the North Atlantic right whale (E. glacialis) and the southern right whale (E. australis), so much so that they were long thought to be just one species. Indeed, without knowing which ocean an individual came from, the physical similarities are so extensive that individuals can only be identified to species by genetic analysis. Compared with other right whale species, E. japonica may be slightly larger. Like other baleen whales, female North Pacific right whales are larger than males. Also, North Pacific brindle-colored individuals are less common than they are among southern right whales.
E. japonica is easily distinguished from other North Pacific whale species by several fieldmarks: lack of dorsal fin or bump, very broad, black back, cyamid-covered callosities on the head and lips, a very arched jaw line, a very narrow rostrum, and often a V-shaped spout. North Pacific right whales can reach in length as adults, larger than the North Atlantic right whale. Typical body mass is from , or to which weighs twice as of typical humpback whales. There is one record of a whale captured during illegal Soviet operations, while reliability of larger measurements of with and 2 cases of one each from eastern and western pacific sides are uncertain. The largest officially recorded specimen was long and weighed . They are much larger than gray or humpback whales and also being very stout, particularly when compared to the other large baleen whales such as blue and fin whales. For 10 North Pacific right whales taken in the 1960s, their girth in front of the flippers was 0.73 of the total length of the whale. There have been claims that pectoral fins of pacific right whale are larger in portion than the other right whales and more pointed, and there may exist shape differences of tail by individuals or sex. Additionally, differences in coloration and shape (minor) of baleen plates between the Pacific and Atlantic have been noted. On each side of the upper jaw are 200–270 baleen plates. These are narrow and approximately long, and are covered in very thin hairs. The pectoral fin is long.
Right whales are also unique in that they all have callosities—roughened patches of epidermis covered with thousands of small light-colored cyamids. The callosities appear in patches on its head immediately behind the blowholes, along the rostrum to the tip, which often has a large callosity, referred to by whalers as the "bonnet". The functional purpose of the callosities has not been determined.
The North Pacific right whale has the largest testes of any mammal.
The closely related bowhead whale differs from the right whale by lacking any callosities, having a more arched jaw, and longer baleen. The seasonal ranges of the two species do not overlap. The bowhead whale is found at the edge of the pack ice in more Arctic waters in the Chukchi Sea and Beaufort Sea, and occurs in the Bering Sea only during winter. The bowhead whale is not found in the North Pacific.
Although whalers in the North Pacific killed more than 15,000 right whales, there are remarkably few detailed descriptions of these whales. Most of our information about the anatomy and morphology of E. japonica comes from 13 whales killed by Japanese whalers in the 1960s and 10 whales killed by Russian whalers in the 1950s. Basic information about right whale lengths and sex is also available from coastal whaling operations in the early part of the 20th century.
Females give birth to their first calf when they are between 9 and 10 years old. There is little data on its lifespan, but based on its close relatives, it is estimated to live at least 70 years.
Ecology and behavior
Feeding Like right whales in other oceans, North Pacific right whales feed primarily on copepods, mainly the species Calanus marshallae. They also have been reported off Japan and in the Gulf of Alaska, feeding on copepods of the genus Neocalanus with a small quantity of euphausiid larvae, Euphausia pacifica.
Like other right whale species, the North Pacific right whale feeds by skimming water continuously while swimming; this is in contrast to balaenopterid whales, such as the blue and humpback whales, which engulf prey in rapid lunges, surging upward rapidly from the depths. Right whales do not have pleated throats. Instead, they have very large heads and mouths that allow them to swim with their mouths open (similar to the basking and whale sharks); the water with the copepods flows in, then flows sideways through the right whale's very long, very fine baleen trapping the copepods, and then out over their large lower lips. The mouth is then closed tightly to expel excess water, effectively trapping the prey behind the baleen.
It takes millions of tiny copepods to provide the energy a right whale needs. Thus, right whales must find copepods at very high concentrations, greater than 3,000 per cubic meter, to feed efficiently. National Marine Fisheries Service researchers mapped the southeast Bering Sea and the Gulf of Alaska for areas with sufficient productivity to support such concentrations. They analyzed the roles of bathymetry and various gyres in concentrating copepods to such densities.
Behavior
There have been very few, short visual observations of right whale behavior in the North Pacific. The mid-19th-century whaling onslaught occurred before there was much scientific interest in whale behavior and included no scientific observation. By the time scientific interest in this species developed, very few whales remained, and nowhere in the eastern North Pacific or Bering Sea could observers reliably find them. Based on limited observations in the 19th century, it was noted that the more extensively whaling was conducted, the more aggressive whales became and the harder they were to approach. These traits correspond to observations made in 2014 documenting that these whales seem to be sensitive to the presence of surface vessels, swimming away or submerging for longer periods of time, enough for onlookers and observers to lose sight of them. Pre-World War I whaling logs from Japan also describe right whales as being among the most sensitive of targeted baleen or toothed species to the impacts of whaling, as they immediately fled from locations where whaling took place, possibly abandoning their habitat for good.Kondo I., 2001, 日本沿岸捕鯨の興亡, Sanyo-sha, original from University of Michigan
As of 2006, scientists had minimal success with satellite tagging North Pacific right whales. Observations total probably less than 50 hours over the last 50 years. What little is known about North Pacific right whale behavior suggests that it is similar to the behavior of right whales in other oceans, except in its choice of wintering grounds. The individual observed during a whale-watching tour off the Kii Peninsula, Japan, breached six times in a row in 2006.南紀マリンレジャーサービス. Nanki-marin.net. Retrieved September 15, 2011. The same whale watching operator had two sightings in 2006 and again had a very close encounter with a right whale in 2011. This animal was very curious and active; it swam around the vessel for more than 2 hours, breaching, spyhopping, tail-slapping, and pec-slapping close to the boat. The ship had to cruise away from the whale because it kept following them. Another curious and playful individual was encountered during a whale-watching trip off Bonin Islands in March 2014.橋本弦. 2014. 絶滅危惧種のセミクジラ、小笠原諸島で18年ぶり確認. The Asahi Shimbun. Retrieved December 23, 2015
Like the other Eubalaena species, North Pacific right whales are known to interact with other cetacean species. Several observations of North Pacific right whales interacting with groups or solitary humpback whales have been recorded in both the Eastern and Western North Pacific. In 1998, a pair of gray whales was seen showing signs of aggression towards a right whale, chasing it off the coast of California,Records of North Pacific Right Whales along the coasts of California, Baja, Oregon and Washington . Jim Scarff's Eclectic Home Page. Retrieved January 14, 2013. while in 2012, in the Piltun Bay region of Sakhalin Island's northeast coast, a young adult right whale was seen displaying typical social behavior within a group of critically endangered Western gray whales.Spotlight Russia: Western Grey Whale expedition sees a right whale . IFAW-International Fund for Animal Welfare homepage. Retrieved January 14, 2013.Shipulin 2012 А давайте я вам китов покажу, а? . LiveJournal. Retrieved June 9, 2014
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