Pacific white-sided dolphin

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Pacific white-sided dolphin [1]
Pacific white-sided dolphins (Lagenorhynchus obliquidens) NOAA.jpg
Pacific white-sided dolphin size.svg
Size compared to an average human
CITES Appendix II (CITES) [3]
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Artiodactyla
Infraorder: Cetacea
Family: Delphinidae
Genus: Lagenorhynchus
Species:
L. obliquidens
Binomial name
Lagenorhynchus obliquidens
(Gill, 1865)
Cetacea range map Pacific White-sided Dolphin.PNG
  Pacific white-sided dolphin range

The Pacific white-sided dolphin (Lagenorhynchus obliquidens), also known as the hookfin porpoise, is an active dolphin found in the cool or temperate waters of the North Pacific Ocean. [4] [5]

Contents

Taxonomy

The Pacific white-sided dolphin was named by Smithsonian mammalogist Theodore Nicholas Gill in 1865. It is morphologically similar to the dusky dolphin, which is found in the South Pacific. [6] Genetic analysis by Frank Cipriano suggests the two species diverged around two million years ago.

Though traditionally placed in the genus Lagenorhynchus , molecular analyses indicate they are closer to dolphins of the genus Cephalorhynchus , in the Lissodelphininae subfamily, than to both the Atlantic white-sided dolphin and the White-beaked dolphin. It has therefore been proposed to move the Pacific white-sided dolphin to the resurrected genus Sagmatias together with other southern hemisphere Lagenorhyncus species (hourglass dolphin, Dusky dolphin and Peale's dolphin). [7] However, the detailed phylogenetic relationships within this group of dolphins is still not fully elucidated.

Description

Pacific white-sided dolphin's brain at Okinawa Churaumi Aquarium Brain of Pacific white-sided dolphin (Lagenorhynchus obliquidens) at Okinawa Churaumi Aquarium.jpg
Pacific white-sided dolphin's brain at Okinawa Churaumi Aquarium

The Pacific white-sided dolphin has three colors. The chin, throat and belly are creamy white. The beak, flippers, back, and dorsal fin are a dark gray. Light gray patches are seen on the sides and a further light gray stripe runs from above the eye to below the dorsal fin, where it thickens along the tail stock. A dark gray ring surrounds the eyes.

The species is an average-sized oceanic dolphin. Females weigh up to 150 kg (330 lb) and males 200 kg (440 lb) with males reaching 2.5 m (8.2 ft) and females 2.3 m (7.5 ft) in length. Pacific white-sided dolphins usually tend to be larger than dusky dolphins. Females reach maturity at seven years. From 1990 to 1991, a study conducted by Richard C. Ferrero and William A. Walker revealed the vast majority of Pacific white-sided dolphins that fell victim to the drift nets were between the ages of 8.3 to 11 when they sexually matured. [8] The gestation period usually last for one year. Individuals are believed to live up 40 years or more. [6]

The Pacific white-sided dolphin is extremely active and mixes with many of the other North Pacific cetacean species. It readily approaches boats and bow-rides. Large groups are common, averaging 90 individuals, with supergroups of more than 300. Prey includes mainly hake, anchovies, squid, herring, salmon, and cod. [9]

They have an average of 60 teeth. [10]

Range and habitat

The range of the Pacific white-sided dolphin arcs across the cool to temperate waters of the North Pacific. [6] [11] [12] Sightings go no further south than the South China Sea on the western side and the Baja California Peninsula on the eastern. Populations may also be found in the Sea of Japan and the Sea of Okhotsk. In the northern part of the range, some individuals may be found in the Bering Sea. The dolphins appear to follow some sort of migratory pattern – on the eastern side they are most abundant in the Southern California Bight in winter, but further north (Oregon, Washington) in summer. Their preference for off-shore deep waters appears to be year-round. [13] [14] The only known predator of the Pacific white-sided dolphin is the killer whale, [15] but at least one case of predation by the great white shark has been recorded. [16]

The total population may be as many as 1 million. [6] However, the tendency of Pacific white-sided dolphins to approach boats complicates precise estimates via sampling.

Behavior

These dolphins keep close company. [17] White-sided dolphins swim in groups of 10 to 100, and can often be seen bow-riding and doing somersaults. [6] [18] Members form a close-knit group and will often care for a sick or injured dolphin. Animals that live in such large social groups develop ways to keep in touch, with each dolphin identifying itself by a unique name-whistle. Young dolphins communicate with a touch of a flipper as they swim beside adults.

Studies conducted on Pacific white-sided dolphins, as well as Risso's dolphin have revealed a multitude of things about how they communicate as a species, which was revealed to be vastly different from bottlenose dolphins and common dolphins. [19] The studies have revealed that their notches and spectral peaks happen to be more low pitched when juxtaposed with the bottlenose dolphins and common dolphins as mentioned earlier. [20] Other studies have revealed similar behaviors. Two studies conducted back in 2010 and 2011 revealed that the vocalizations of Pacific white-sided dolphins can range differently only from their behavioral states, indicating strong similarities between the acoustic and surface behavior for various foraging behaviors, including the possibility of an undescribed subspecies. The oceanographical data in the area can also effect the behavioral patterns of the dolphins. The studies also revealed that the different types of echolocations do vary based on the geographical locations; the first population of Pacific white-sided dolphins that were observed, inhabiting the waters near the Pacific United States seemed to more activity during the night while the second population of Pacific white-sided dolphins, that were also observed, inhabiting areas near Baja California, were observed to be more active during the day, possibly due the seasons and the dolphins' search for prey. [21] [22]

The first sighting of the species on Commander Islands involved a single dolphin to travel along with a pod of killer whales in 2013. [23]

Pacific white-sided dolphins are known to sleep on average seven hours a night. [24]

Relation to humans

Vancouver aquarium dolphin.jpg
Pacific white-sided dolphin va 2.jpg
Left: High-jump during Pacific white-sided dolphin show at the Vancouver Aquarium
Right: Pacific white-sided dolphin named Spinnaker at Vancouver Aquarium

Protection

Until the United Nations banned certain types of large fishing nets in 1933, many Pacific white-sided dolphins were killed in drift nets. Some animals are still killed each year by Japanese hunting drives.

Captivity

Although overshadowed in popularity by bottlenose dolphins, Pacific white-sided dolphins are also a part of some marine theme park shows. Roughly 100 reside in dolphinaria in North America and Japan. In captivity, they tend to consume less amounts of food when compared to their wild counterparts, this could be the case due to the fact of temperatures changing in the water based on the seasons. However, the condition in which the dolphins lives, most likely in an aquarium tank, will impact how much energy is required for a captive dolphin to thrive in captivity. Studies have also shown that the highest amount of food intake that a captive Pacific white-sided dolphin displays in autumn when the dolphin increase their food intake as well as their body mass. [25] [26]

See also

Related Research Articles

<span class="mw-page-title-main">Dolphin</span> Marine mammals, closely related to whales and porpoises

A dolphin is an aquatic mammal within the infraorder Cetacea. Dolphin species belong to the families Delphinidae, Platanistidae, Iniidae, Pontoporiidae, and possibly extinct Lipotidae. There are 40 extant species named as dolphins.

<span class="mw-page-title-main">Bottlenose dolphin</span> Genus of dolphin

Bottlenose dolphins are aquatic mammals in the genus Tursiops. They are common, cosmopolitan members of the family Delphinidae, the family of oceanic dolphins. Molecular studies show the genus contains three species: the common bottlenose dolphin, the Indo-Pacific bottlenose dolphin, and Tamanend's bottlenose dolphin. Others, like the Burrunan dolphin, may be alternately considered their own species or be subspecies of T. aduncus. Bottlenose dolphins inhabit warm and temperate seas worldwide, being found everywhere except for the Arctic and Antarctic Circle regions. Their name derives from the Latin tursio (dolphin) and truncatus for the truncated teeth.

<span class="mw-page-title-main">Oceanic dolphin</span> Family of marine mammals

Oceanic dolphins or Delphinidae are a widely distributed family of dolphins that live in the sea. Close to forty extant species are recognised. They include several big species whose common names contain "whale" rather than "dolphin", such as the Globicephalinae. Delphinidae is a family within the superfamily Delphinoidea, which also includes the porpoises (Phocoenidae) and the Monodontidae. River dolphins are relatives of the Delphinoidea.

<span class="mw-page-title-main">Dusky dolphin</span> Species of mammal

The dusky dolphin is a dolphin found in coastal waters in the Southern Hemisphere. Its specific epithet is Latin for "dark" or "dim". It is very closely genetically related to the Pacific white-sided dolphin, but current scientific consensus holds they are distinct species. The dolphin's range is patchy, with major populations around South America, southwestern Africa, New Zealand, and various oceanic islands, with some sightings around southern Australia and Tasmania. The dusky dolphin prefers cool currents and inshore waters, but can also be found offshore. It feeds on a variety of fish and squid species and has flexible hunting tactics. The dusky dolphin is known for its remarkable acrobatics, having a number of aerial behaviours. The status of the dolphin is unknown, but it has been commonly caught in gill nets.

<span class="mw-page-title-main">Pygmy beaked whale</span> Species of mammal

The pygmy beaked whale, also known as the bandolero beaked whale, Peruvian beaked whale and lesser beaked whale, is the smallest of the mesoplodonts and one of the newest discoveries. There were at least two dozen sightings of an unknown beaked whale named Mesoplodon sp. A before the initial classification, and those are now believed to be synonymous with the species. The species was formally described in 1991, based on ten specimens obtained from Peru between 1976 and 1989, including a 3.72 m (12.2 ft) adult male as the type specimen. A specimen that stranded at Paracas, Peru in 1955 has since been identified as a pygmy beaked whale. Since 1987, there have been an additional 40 sightings of the species, for a total of 65.

<span class="mw-page-title-main">Heaviside's dolphin</span> Species of mammal

Heaviside's dolphin is one of four dolphins in the genus Cephalorhynchus. The small cetacean is endemic to the Benguela ecosystem along the southwest coast of Africa.

<span class="mw-page-title-main">False killer whale</span> Species of oceanic dolphin in the genus Pseudorca

The false killer whale is a species of oceanic dolphin that is the only extant representative of the genus Pseudorca. It is found in oceans worldwide but mainly in tropical regions. It was first described in 1846 as a species of porpoise based on a skull, which was revised when the first carcasses were observed in 1861. The name "false killer whale" comes from having a skull similar to the orca, or killer whale.

<span class="mw-page-title-main">Indo-Pacific bottlenose dolphin</span> Species of mammal

The Indo-Pacific bottlenose dolphin is a species of bottlenose dolphin. This dolphin grows to 2.6 m (8.5 ft) long, and weighs up to 230 kg (510 lb). It lives in the waters around India, northern Australia, South China, the Red Sea, and the eastern coast of Africa. Its back is dark grey and its belly is lighter grey or nearly white with grey spots.

<i>Lagenorhynchus</i> Genus of mammals

Lagenorhynchus is a genus of oceanic dolphins in the infraorder Cetacea, presently containing six extant species. However, there is consistent molecular evidence that the genus is polyphyletic and several of the species are likely to be moved to other genera. In addition, the extinct species Lagenorhynchus harmatuki is also classified in this genus.

<span class="mw-page-title-main">Southern right whale dolphin</span> Species of mammal

The southern right whale dolphin is a small and slender species of cetacean, found in cool waters of the Southern Hemisphere. It is one of two species of right whale dolphin. This genus is characterized by the lack of a dorsal fin. The other species, the northern right whale dolphin, is found in deep oceans of the Northern Hemisphere and has a different pigmentation pattern than the southern right whale dolphin.

<span class="mw-page-title-main">Hourglass dolphin</span> Species of mammal

The hourglass dolphin is a small dolphin in the family Delphinidae that inhabits offshore Antarctic and sub-Antarctic waters. It is commonly seen from ships crossing the Drake Passage, but has a circumpolar distribution.

<span class="mw-page-title-main">Peale's dolphin</span> Species of mammal

Peale's dolphin is a small dolphin found in the waters around Tierra del Fuego at the foot of South America. It is also commonly known as the black-chinned dolphin or even Peale's black-chinned dolphin. However, since Rice's work Peale's dolphin has been adopted as the standard common name.

<span class="mw-page-title-main">Common bottlenose dolphin</span> Species of dolphin

The common bottlenose dolphin or Atlantic bottlenose dolphin is one of three species of bottlenose dolphin in the genus Tursiops. The common bottlenose dolphin is a very familiar dolphin due to the wide exposure it receives in captivity in marine parks and dolphinariums, and in movies and television programs. Spending their entire life in water, common bottlenose dolphins inhabit temperate and tropical oceans throughout the world, absent only from polar waters. While formerly known simply as the bottlenose dolphin, this term is now applied to the genus Tursiops as a whole. As considerable genetic variation has been described within this species, even between neighboring populations, many experts think additional species may be recognized.

<span class="mw-page-title-main">Spinner dolphin</span> Species of mammal

The spinner dolphin is a small dolphin found in off-shore tropical waters around the world. It is famous for its acrobatic displays in which it rotates around its longitudinal axis as it leaps through the air. It is a member of the family Delphinidae of toothed whales.

<span class="mw-page-title-main">Atlantic white-sided dolphin</span> Species of mammal

The Atlantic white-sided dolphin is a distinctively coloured dolphin found in the cool to temperate waters of the North Atlantic Ocean.

<span class="mw-page-title-main">Australian snubfin dolphin</span> Species of mammal

The Australian snubfin dolphin is a dolphin found off the northern coasts of Australia. It closely resembles the Irrawaddy dolphin and was not described as a separate species until 2005. The closest relative to the genus Orcaella is the killer whale, Orcinus orca. The Australian snubfin has three colors on its skin, while the Irrawaddy dolphin only has two. The skull and the fins also show minor differences between the two species.

Simocetus is an extinct genus of toothed whale that lived during the Oligocene period, approximately 32 million years ago, making it the oldest named toothed whale, although older unnamed toothed whales exist.

Sagmatias was a genus of dolphins, defined in 1866 by Edward Drinker Cope with Peale's dolphin as type species, described as Sagmatias amblodon. It has been proposed to resurrect the genus to include four species of oceanic dolphins currently classified in the genus Lagenorhynchus. Mitochondrial DNA studies have indicated that Pacific white-sided dolphin, Peale's dolphin, dusky dolphin and hourglass dolphin are more closely related to dolphins in the Lissodelphininae subfamily, than to the two other members of the genus: Atlantic white-sided dolphin and white-beaked dolphin. This phylogenetic relationship is further supported by cladistic analysis of morphological characters. However, resurrection of the genus Sagmatias has not been accepted by the Society for Marine Mammalogy's taxonomic Committee, because the finer details of the phylogenetic relationships between the four species in the proposed Sagmatias genus and the four species of dolphins in the genus Cephalorhynchus remains to be resolved. Genetic and bioacoustical evidence suggest that Peale's dolphin and hourglass dolphin are closer related to the Cephalorhynchus species than to the Pacific white-sided dolphin and dusky dolphin, which, if true, would make the genus Sagmatias paraphyletic.

<span class="mw-page-title-main">Bernd Würsig</span> Marine mammal behavioral ecologist

Bernd Gerhard Würsig is an educator and researcher who works mainly on aspects of behavior and behavioral ecology of whales and dolphins. Much of his early work was done in close collaboration with his wife Melany Ann Würsig, and they have published numerous manuscripts and books together. He is now Professor Emeritus at Texas A&M University, teaching only occasionally but still involved with graduate student and other research. He is especially active with problems and potential solutions concerning Indo-Pacific humpback dolphins, Sousa chinensis, in and surrounding waters of Hong Kong.

References

  1. ↑ Mead, J. G.; Brownell, R. L. Jr. (2005). "Order Cetacea". In Wilson, D. E.; Reeder, D. M. (eds.). Mammal Species of the World: A Taxonomic and Geographic Reference (3rd ed.). Johns Hopkins University Press. pp. 723–743. ISBN   978-0-8018-8221-0. OCLC   62265494.
  2. ↑ Ashe, E.; Braulik, G. (2018). "Lagenorhynchus obliquidens". IUCN Red List of Threatened Species . 2018: e.T11145A50361866. doi: 10.2305/IUCN.UK.2018-2.RLTS.T11145A50361866.en . Retrieved 19 November 2021.
  3. ↑ "Appendices | CITES". cites.org. Archived from the original on 2021-01-19. Retrieved 2022-01-14.
  4. ↑ "Pacific White-Sided Dolphin". NOAA Fisheries. National Oceanic and Atmospheric Administration. 19 October 2021. Archived from the original on 15 November 2021. Retrieved 14 November 2021.
  5. ↑ "Kenai Fjords National Park". National Park Service. Archived from the original on 15 November 2021. Retrieved 17 November 2021.
  6. 1 2 3 4 5 Wursig, Bernd; Perrin, William F.; Thewissen, J. 'Hans' (2009-02-26). Encyclopedia of Marine Mammals. Academic Press. pp. 817–818. ISBN   978-0-08-091993-5. Archived from the original on 2021-12-27. Retrieved 2021-12-27.
  7. ↑ Vollmer, Nicole L.; et al. (January 31, 2019). "Taxonomic revision of the dolphin genus Lagenorhynchus". Marine Mammal Science. 35 (3): 957–1057. doi:10.1111/mms.12573. S2CID   92421374. Archived from the original on 2021-11-11. Retrieved 2021-09-17.
  8. ↑ Ferrero, R.C.; Walker, W.A. (1996). "Age, growth, and reproductive patterns of the Pacific white-sided dolphin (Lagenorhynchus obliquidens) taken in high seas drift nets in the central North Pacific Ocean". Canadian Journal of Zoology. 74 (9): 1673–1687. doi:10.1139/z96-185.
  9. ↑ Morton, A. (January 2000). "Occurrence, Photo‐identification and Prey of Pacific White‐sided Dolphins (Lagenorhyncus obliquidens) in the Broughton Archipelago, Canada 1984–1998". Marine Mammal Science. 16 (1): 80–93. doi:10.1111/j.1748-7692.2000.tb00905.x.
  10. ↑ Black, Nancy A. (2009). Perrin, William F.; Würsig, Bernd; Thewissen, J. G. M. (eds.). Encyclopedia of Marine Mammals (2nd ed.). Burlington Ma.: Academic Press. ISBN   978-0-12-373553-9. Archived from the original on 2009-11-09.
  11. ↑ Salvadeo, CJ; Lluch-Belda, D; Gómez-Gallardo, A; Urbán-Ramírez, J; MacLeod, CD (2010-03-10). "Climate change and a poleward shift in the distribution of the Pacific white-sided dolphin in the northeastern Pacific". Endangered Species Research. 11: 13–19. doi: 10.3354/esr00252 . ISSN   1863-5407.
  12. ↑ "PACIFIC WHITE-SIDED DOLPHIN (Lagenorhynchus obliquidens): North Pacific Stock" (PDF). NOAA Fisheries: 127–130. 2012. Archived (PDF) from the original on 2022-03-03. Retrieved 2022-12-31– via ResearchGate.
  13. ↑ Black, N.A. (1994). Behavior and ecology of Pacific white-sided dolphins (Lagenorhynchus obliquidens) in Monterey Bay, California. San Francisco State University.
  14. ↑ Walker, W.A.; Leatherwood, S.; Goodrich, K.R.; Perrin, W.F.; Stroud, R.K. (1986). "Geographical variation and biology of the Pacific white-sided dolphin, Lagenorhynchus obliquidens, in the north-eastern Pacific". Research on Dolphins. 441: 465.
  15. ↑ Dahlheim, M.E.; Towell, R.G. (1994). "Occurrence and Distribution of Pacific White-Sided Dolphins (Lagenorhynchus obliquidens) in Southeastern Alaska, With Notes On an Attack by Killer Whales (Orcinus orca)". Marine Mammal Science. 10 (4): 458–464. doi:10.1111/j.1748-7692.1994.tb00501.x. Archived from the original on 2020-09-25. Retrieved 2019-06-26.
  16. ↑ Peter Klimley, A.; Ainley, David G. (3 April 1998). Great White Sharks: The Biology of Carcharodon carcharias. Academic Press. ISBN   9780080532608. Archived from the original on 14 March 2023. Retrieved 25 March 2022.
  17. ↑ "Cooperation among Adult Dolphins | Journal of Mammalogy | Oxford Academic". academic.oup.com. Archived from the original on 2022-12-31. Retrieved 2022-12-31.
  18. ↑ "Unusual Leap by a Pacific White-Sided Dolphin (Lagenorhynchus obliquidens) | Journal of Mammalogy | Oxford Academic". academic.oup.com. Archived from the original on 2022-12-31. Retrieved 2022-12-31.
  19. ↑ Henderson, E. Elizabeth; Hildebrand, John A.; Smith, Michael H. (July 2011). "Classification of behavior using vocalizations of Pacific white-sided dolphins (Lagenorhynchus obliquidens)". The Journal of the Acoustical Society of America. 130 (1): 557–567. Bibcode:2011ASAJ..130..557H. doi:10.1121/1.3592213. ISSN   0001-4966. PMID   21786921. Archived from the original on 2023-03-14. Retrieved 2022-12-31.
  20. ↑ Soldevilla, M.S.; Henderson, E.E.; Campbell, G.S.; Wiggins, S.M.; Hildebrand, J.A.; Roch, M.A. (2008). "Classification of Risso's and pacific white-sided dolphins using spectral properties of echolocation clicks". The Journal of the Acoustical Society of America. 124 (1): 609–24. Bibcode:2008ASAJ..124..609S. doi:10.1121/1.2932059. PMID   18647003. S2CID   14685920. Archived from the original on 2020-07-27. Retrieved 2019-06-26.
  21. ↑ Henderson, E.E.; Hildebrand, J.A.; Smith, M.H. (2011). "Classification of behavior using vocalizations of pacific white-sided dolphins (Lagenorhynchus obliquidens)". The Journal of the Acoustical Society of America. 130 (1): 557–67. Bibcode:2011ASAJ..130..557H. doi:10.1121/1.3592213. PMID   21786921.
  22. ↑ Soldevilla, M.S.; Wiggins, S.M.; Hildebrand, J.A. (2010). "Spatio-temporal comparison of pacific white-sided dolphin echolocation click types". Aquatic Biology. 9: 49–62. doi: 10.3354/ab00224 .
  23. ↑ Commander Islands Nature and Biosphere Reserve. Тихоокеанский белобокий дельфин Sagmatias obliquidens Gill, 1865 Archived 2017-08-23 at the Wayback Machine . Retrieved on August 24, 2017
  24. ↑ Goley, Patricia Dawn (October 1999). "Behavioral Aspects of Sleep in Pacific White-Sided Dolphins (Lagenorhynchus Obliquidens, Gill 1865)1". Marine Mammal Science. 15 (4): 1054–1064. doi:10.1111/j.1748-7692.1999.tb00877.x. ISSN   0824-0469.
  25. ↑ Piercey, R. (2013). "Seasonal changes in the food intake of captive Pacific white-sided dolphins (Lagenorhynchus obliquidens)". Aquatic Mammals. 39 (3): 211–220. doi:10.1578/am.39.3.2013.211.
  26. ↑ "Seasonal Resting Metabolic Rate and Food Intake of Captive Pacific White-Sided Dolphins (Lagenorhynchus obliquidens)". Archived from the original on 2017-08-08. Retrieved 2017-07-12.
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