Critter Catalog

What do they look like?

Northern right whale dolphins have a mostly black body, although they also have a white stripe that runs from their throat, widens at their chest and continues as a thin band that ends at their tail. Both males and females have a white mark behind the tip of their lower jaw. The top of their tail is mostly light grey and mostly white on the back side. Their coloring can vary slightly in certain areas including the white strip on the edges of their body, the white color of the whole lower jaw, the white smudge on the side of the melon and beak and the amount of white on their flippers. They can be told apart from other dolphins by a few features, first, northern right whale dolphins are the only dolphin species in the North Pacific Ocean without a dorsal fin. They also have a straight mouth line and a short beak. Their flippers are slightly curved with pointed tips. Both their flippers and flukes (tail region) look small compared to their body. Overall, they are a very streamlined shape. (Baird and Stacey, 1991; Baird and Stacey, 1993; Jefferson and Newcomer, 1993; Jefferson, et al., 1994a; Jefferson, et al., 1994b; Leatherwood and Walker, 1979; Okada and Hanaoka, 1940)

Northern right whale dolphins can weigh up to 115 kg. Adult males tend to be longer than adult females. Males 12 years old and older are usually about 237.9 cm long, while the largest known male was 307 cm long. Females 12 years old or older tend to be about 211.2 cm long. Their teeth are cone shaped, small, thin and sharp. The amount of teeth an individual has can vary. Each side of their upper jaw holds 37 to 52 teeth, with 42 to 54 teeth on each side of their lower jaw. They can have 158 to 212 teeth total. Calves get their adult coloration when they are about one year old. Before this, they are a paler version of the adults, and are mostly brown, grey or cream. (Baird and Stacey, 1991; Baird and Stacey, 1993; Ferrero and Walker, 1993; Jefferson and Newcomer, 1993; Jefferson, et al., 1994a; Jefferson, et al., 1994b; Leatherwood and Walker, 1979; Okada and Hanaoka, 1940)

• Other Physical Features
• endothermic
• homoiothermic
• bilateral symmetry

• Sexual Dimorphism
• male larger
• sexes colored or patterned differently

• Range mass

  115 (high) kg

  253.30 (high) lb

• Range length

  307 (high) cm

  120.87 (high) in

Where do they live?

Northern right whale dolphins (Lissodelphis borealis) are found in the North Pacific Ocean. On the eastern coast of Asia, they are found from Paramushir Island, Russia to Cape Nojima, Japan. On the western coast of North America, they can be found from Vancouver Island, Canada to Baja California, Mexico. They have also been sighted outside their normal range in the Gulf of Alaska and near the Aleutian Islands. (Bjorge, et al., 1992; Jefferson and Newcomer, 1993; Kajimura and Loughlin, 1988; Leatherwood and Walker, 1979; Nishiwaki, 1967)

• Biogeographic Regions
• nearctic
  • native
• oriental
  • native
• pacific ocean
  • native

What kind of habitat do they need?

Northern right whale dolphins mostly live in deep offshore waters. However, they are sometimes seen near the coast, especially in areas where the water close to the shore is deep. They prefer cool waters, and are most often seen in waters ranging in temperature from to 7.8° to 18.9° C. These animals migrate south and inshore during the winter, and north and offshore during the summer. In their eastern range, specifically California, they are sighted inshore in the fall and increase in numbers until mid-winter, and then decrease towards the late spring and early summer. In their western range, off the coast of northern Honshu, Japan, northern right whale dolphins are only seen during non-summer months. The reasons for these movements are unknown, but may have to do with the water temperature. In the fall, northern right whale dolphins move toward the cool waters of the California coast and leave as they warm. Likewise, it could be based on how many prey are available. In California, most northern right whale dolphins are seen when the greatest amount of California market squid are present. (Bjorge, et al., 1992; Forney and Barlow, 1998; Jefferson and Newcomer, 1993; Jefferson, et al., 1994a; Kasuya, 1971; Leatherwood and Walker, 1979)

• These animals are found in the following types of habitat
• temperate
• saltwater or marine

• Aquatic Biomes
• pelagic
• coastal

How do they reproduce?

Currently, nothing is known about the mating system of northern right whale dolphins.

Little is known about the reproduction of northern right whale dolphins. The shortest amount of time between calves is probably 2 years, particularly because their gestation period lasts about 12 months. Most calves are born in July and August and are usually about 99.7 to 103.8 cm long at birth. It is not known how long females allow their calves to nurse. Females can begin mating when they are 9.7 to 10.4 years old, when their body is about 199.8 to 201.1 cm long. Males can begin mating when they are 9.9 to 10.1 years old. (Ferrero and Walker, 1993)

• Key Reproductive Features
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual
• viviparous

• How often does reproduction occur?

  There is likely at least 2 years between each calving event.

• Breeding season

  Since northern right whale dolphins have about a 12 month gestation period and many calves are born in July and August, their breeding season is likely around the same time seasonally.

• Average gestation period

  12.1 to 12.3 months

• Average age at sexual or reproductive maturity (female)

  9.7 or 10.4 years

• Average age at sexual or reproductive maturity (male)

  9.9 or 10.1 years

Currently, nothing is known about the parental investment of northern right whale dolphins.

How long do they live?

There is very little information available regarding the lifespan of northern right whale dolphins. Two captive individuals have been housed by the live-capture fishery. One died due to stress three days after it was introduced. The other lived 15 months in a 540,000 gallon display tank, its cause of death is unknown. (Walker, 1975)

How do they behave?

Northern right whale dolphins are very social. Off the eastern Pacific coast, they travel in pod sizes of about 110 individuals, while off the western Pacific coast, they travel in pods of about 200 individuals. They are also sometimes seen alone. When they swim slowly, very little of their body can be seen above the surface, usually only their blowhole, to breath. They swim closer to the surface when they swim fast, coming up quickly to breathe or surfacing with low angle leaps. Northern right whale dolphins have also been seen performing belly flops, fluke slaps and side slaps. They have different responses when they see a boat. They may avoid them or they may approach and interact with them. They breathe about every 10 to 75 seconds, and entire pods can dive for up to 6.15 minutes. They can swim at speeds up to 34 km per hour. They swim in one of four pod formations. The first is densely packed groups, lacking subgroups. The second includes subgroups of a varying number of individuals. Third, is a v-shaped formation and fourth is a line formation. When northern right whale dolphins are in the company of other cetacean species, they typically stay in small, tightly packed groups. Northern right whale dolphins are often seen interacting with other marine mammals. They will sometimes form mixed pods with Pacific white-sided dolphins, they have also been seen with common bottlenose dolphins, short-beaked common dolphins, striped dolphins, Risso's dolphins, Dall's porpoises, short-finned pilot whales, fin whales, sei whales, humpback whales, grey whales and California sea lions. These dolphins are rarely stranded, usually only a few are stranded each year. (Au and Weihs, 1980; Baird and Stacey, 1991; Baird and Stacey, 1993; Ferrero, et al., 2002; Jefferson and Newcomer, 1993; Jefferson, et al., 1994a; Leatherwood and Walker, 1979; Wilke, et al., 1953)

• Key Behaviors
• motile
• social

Home Range

There is currently no information available regarding the home range size of northern right whale dolphins.

How do they communicate with each other?

Northern right whale dolphins mostly communicate by making clicks and pulsed vocalizations. Unlike other dolphin species, they do not make whistles. They often make a burst-pulse series vocalization, which includes 6 to 18 individual burst-pulse sounds. Eight unique burst-pulse series have been heard, and most are repeated. Compared to echolocation clicks, burst-pulse vocalizations are shorter and lower in frequency. These burst-pulse sounds may play the same role as the whistles made by other dolphin species. (Rankin, et al., 2007)

• Communication Channels
• acoustic

• Perception Channels
• tactile
• acoustic
• echolocation
• chemical

What do they eat?

Northern right whale dolphins mostly eat fish and squid. They dive to depths of at least 200 m in search of food. About 89% of their fish prey include lanternfishes such as brokenline laternfishes and Warming's lanternfishes. They eat fewer squid, making up about 11% of their diet. The most common squid species were Boreopacific armhook squid and Abraliopsis felis. Non-food items found inside their stomach have included parts of marine plants, a honey bee, white bird feathers, a plastic bag, pieces of blue vinyl plastic and a rusted metal bottle cap. (Chou, et al., 1995; Fitch and Brownell, 1968; Jefferson and Newcomer, 1993; Walker and Coe, 1989)

• Primary Diet
• carnivore
  • piscivore
  • molluscivore

• Animal Foods
• fish
• mollusks

What eats them and how do they avoid being eaten?

Natural predators of northern right whale dolphins are unknown, but likely include orcas and large sharks. (Jefferson and Newcomer, 1993; Jefferson, et al., 1994a)

What roles do they have in the ecosystem?

Northern right whale dolphins can have several species of internal parasites; Nasitrema species in their brain and air sinuses, Crassicauda species in their inner ear and air sinuses, Anisakis simplex in their stomach, Monorygma grimaldii in their body cavity, Phyllobothrium delphini in their blubber, and Sarcosporidia in their skeletal muscles. External parasites include barnacles, such as Xenobalanus species, and copepods including Penella and Nasitrema species, which may cause major damage to their brain and air sinuses and may be play a role in their strandings and death. (Cowan, et al., 1986; Dailey and Walker, 1978; Jefferson and Newcomer, 1993; Jefferson, et al., 1994a)

Do they cause problems?

Northern right whale dolphins feed on commercially important squid species. They are known to occur in areas frequently used by commercial fisherman, and could possibly be seen as competition. (Leatherwood and Walker, 1979)

How do they interact with us?

Northern right whale dolphins are sometimes captured by Japanese whalers for food, oil, leather and fertilizers. Their flesh, heart, liver and kidneys are consumed, their blubber provides oil, their hide is tanned into low grade leather and their skeleton is used as a fertilizer. (Robards and Reeves, 2011; Wilke, et al., 1953)

• Ways that people benefit from these animals:
• food
• body parts are source of valuable material

Are they endangered?

The population size of northern right whale dolphins has been estimated at about 247,000 individuals. Their main threat used to be the large scale driftnet fisheries near Japan, Korea and Taiwan. Dolphins would become tangled in the driftnets set for squid, and drown. Tangled dolphins were sometimes freed, but they usually became injured while they were tangled, which made their survival less likely. Their injuries included eating hooks, open wounds and body damage, among others. Because these animals travel in groups, these nets could kill entire pods at once. Between 1985 to 1990, this fishery killed about 15,000 to 20,000 individuals each year. In 1993, the United Nations ended the use of large-scale drift nets, protecting this species and many others. Northern right whale dolphins are one of the most commonly tangled marine mammal species in the California drift gillnet fishery, which targets broadbill swordfishes and common thresher sharks. From 1996 to 2002, 31 northern right whale dolphins were killed; however, the estimated mortality was 151 individuals. The reported value did not include any deaths or injuries not directly observed by researchers, so it is probably just a minimum estimate of mortality. Although fishermen are required to report any interactions with marine mammals, it is likely that most interactions were not recorded. Northern right whale dolphins are not usually directly hunted; however, Japanese whalers sometimes take them. (Bjorge, et al., 1992; Carretta, et al., 2003; Ferrero and Walker, 1993; Jefferson and Newcomer, 1993; Jefferson, et al., 1994b; Mangel, 1993; Wilke, et al., 1953)

• IUCN Red List

  Least Concern
  More information

• IUCN Red List

  Least Concern
  More information

• US Federal List

  No special status

• CITES

  Appendix II

• State of Michigan List

  No special status

Contributors

Michelle Pasnak (author), University of Manitoba, Jane Waterman (editor), University of Manitoba, Leila Siciliano Martina (editor), Animal Diversity Web Staff.

References

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