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Overview
Brief Summary
Description
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Mammal Species of the World
- Original description: Gill, 1865. Proceedings of the Academy of Natural Sciences of Philadelphia, 17:177.
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Distribution
Range Description
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Geographic Range
Pacific white-sided dolphins have a primarily temperate distribution, remaining north of the tropics and south of the colder waters caused by arctic currents. Their range is from the Aleutian Islands through the Gulf of Alaska to the tip of Baja California in the eastern Pacific; and from Japan to the Kuril Islnads in the western Pacific.
Biogeographic Regions: pacific ocean (Native )
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Distribution
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National Distribution
Canada
Origin: Native
Regularity: Regularly occurring
Currently: Present
Confidence: Confident
Type of Residency: Transient
United States
Origin: Native
Regularity: Regularly occurring
Currently: Present
Confidence: Confident
Type of Residency: Year-round
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Global Range: Kamchatka Peninsula, Amchitka Island, and Kodiak Island south into Sea of Japan and along entire Pacific coast of Japan, and south to tip of Baja California in the eastern Pacific.
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Physical Description
Morphology
Physical Description
Pacific white-sided dolphins have torpedo-shaped bodies which help them move quickly through water. Body length of Pacific white-sided dolphins ranges from 150 to 310 cm. Their coloration is one of their most distinguishing features, they are black or dark gray on the dorsal surface with a white underside, and have bicolored fins and flippers. This coloration is believed to act as a form of camouflage in their aquatic environment.
Range mass: 82 to 124 kg.
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Size
Size in North America
Length:
Range: "1.7-2.5 m "
Weight:
Range: 75-200 kg
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Type Information
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Mammals
Sex/Stage: Unknown;
Preparation: Skull
Collector(s): Collector Unknown
Locality: Locality Unknown, Locality Unknown, North Pacific Ocean
- Type: Cope, E. D. 1866. Proc. Acad. Nat. Sci. Philadelphia. 18: 295.
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Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Mammals
Sex/Stage: Unknown;
Preparation: Skull
Collector(s): W. Froubridge
Locality: Locality Unknown, California, United States, North America, North Pacific Ocean
- Syntype: Gill. 1865. Proc. Acad. Nat. Sci. Philadelphia. 1865: 177.
© Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Mammals
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Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Mammals
Sex/Stage: Unknown;
Preparation: Skull
Collector(s): W. Trowbridge
Locality: Locality Unknown, California, United States, North America, North Pacific Ocean
- Syntype: Gill. 1865. Proc. Acad. Nat. Sci. Philadelphia. 1865: 177.
© Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Mammals
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Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Mammals
Sex/Stage: Unknown;
Preparation: Skull
Collector(s): Collector Unknown
Locality: Locality Unknown, California, United States, North America, North Pacific Ocean
- Syntype: Gill. 1865. Proc. Acad. Nat. Sci. Philadelphia. 1865: 177.
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Ecology
Habitat
Habitat and Ecology
Pacific white-sided dolphins feed on a wide variety of small pelagic schooling fish (e.g., lanternfish, anchovies, saury, horse mackerel, and hake), as well as cephalopods. They are commonly associated with other marine mammal species, particularly northern right whale dolphins, Risso's dolphins, and California sea lions (Brownell et al. 1999).
Systems
- Marine
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Habitat
They are usually seen in deep waters up to 160 km (100 miles ) offshore. There seem to be local migrations inshore in the winter months.
Aquatic Biomes: coastal
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Habitat
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UNESCO-IOC Register of Marine Organisms
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Water temperature and chemistry ranges based on 785 samples.
Environmental ranges
Depth range (m): 0 - 500.83
Temperature range (°C): 4.730 - 21.311
Nitrate (umol/L): 0.082 - 40.485
Salinity (PPS): 30.381 - 34.257
Oxygen (ml/l): 0.435 - 7.358
Phosphate (umol/l): 0.330 - 3.118
Silicate (umol/l): 1.436 - 78.143
Graphical representation
Depth range (m): 0 - 500.83
Temperature range (°C): 4.730 - 21.311
Nitrate (umol/L): 0.082 - 40.485
Salinity (PPS): 30.381 - 34.257
Oxygen (ml/l): 0.435 - 7.358
Phosphate (umol/l): 0.330 - 3.118
Silicate (umol/l): 1.436 - 78.143
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.
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Habitat Type: Marine
Comments: Mostly between seaward edge of continental slope and 100-fathom contour; sometimes closer to shore if there is deep water nearby (Leatherwood and Reeves 1983). In Canada, depth of water at sighting locations ranged from 10 to 2000 fathoms, with mean, median, and modal depths of 617, 400, and 100 fathoms, respectively (Stacey and Baird 1991).
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Migration
Non-Migrant: No. All populations of this species make significant seasonal migrations.
Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).
Locally Migrant: No. No populations of this species make annual migrations of over 200 km.
Seasonal movements not well understood in most areas. Off southern and central California and northwestern Baja California, apparently resident pods are augmented during fall through spring by influxes of animals possibly from north and offshore (Leatherwood and Reeves 1983).
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Trophic Strategy
Food Habits
Pacific white-sided dolphins eat fish that live in large schools, such as anchovies, herring, smelt, capelin, and mackerel. They feed in groups of 10-20 dolphins, each adult eating about 9 kilograms (20 lbs ) of food each day.
Animal Foods: fish
Primary Diet: carnivore (Piscivore )
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Comments: Eats various fishes (anchovies, hake, sauries) and squid. Apparently feeds primarily at night. Has been seen at dawn and dusk feeding with gulls on small surfacing balls of unidentified bait fishes. (Leatherwood and Reeves 1983).
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Population Biology
Global Abundance
10,000 to >1,000,000 individuals
Comments: Two 1970s estimates: 30,000-50,000 in Japanese waters; about 24,000 in 1.5 million sq km off California and Baja California (see IUCN 1991).
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General Ecology
Gregarious. Forms herds of a thousand or more, though usually groups are of several hundred or less; herds generally are of all age classes and both sexes.
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Life History and Behavior
Cyclicity
Life Expectancy
Lifespan/Longevity
Average lifespan
Status: captivity: 20.0 years.
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Lifespan, longevity, and ageing
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Reproduction
Reproduction
Pods are made up of one dominant male and a number of other males and females. The dominant male mates with reproductively available females.
Mating System: polygynous
Female Pacific white-sided dolphins reach sexual maturity around 5-6 years of age, males are sexually mature at 8-10 years. Generally breeding occurs in the summer or fall, and gestation lasts approximately 11-12 months. Females give brith to a single calf, which is almost 3 feet long and can weigh up to 14 pounds.
Breeding season: Generally breeding occurs in the summer or fall.
Average number of offspring: 1.
Range gestation period: 11 to 12 months.
Range age at sexual or reproductive maturity (female): 5 to 6 years.
Range age at sexual or reproductive maturity (male): 8 to 10 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); viviparous
Average birth mass: 14000 g.
Average number of offspring: 1.
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Calving season has been reported to be summer, but in recent studies calves have been found primarily in early fall (Leatherwood and Reeves 1983).
High seas drift net samples in Central North Pacific (Ferrero and Walker 1996): a calving period preceded sampling during late winter and spring; estimated gestation period 11-12 months; males sexually mature in 10-11 years, females in 8-11 years.
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Molecular Biology and Genetics
Molecular Biology
Barcode data: Lagenorhynchus obliquidens
There are 3 barcode sequences available from BOLD and GenBank. Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species. See the BOLD taxonomy browser for more complete information about this specimen and other sequences.
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Download FASTA File
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Statistics of barcoding coverage: Lagenorhynchus obliquidens
Public Records: 3
Species: 3
Species With Barcodes: 1
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Conservation
Conservation Status
IUCN Red List Assessment
Red List Category
Red List Criteria
Version
Year Assessed
Assessor/s
Reviewer/s
Contributor/s
Justification
History
- 1996Lower Risk/least concern
- 1994Insufficiently Known(Groombridge 1994)
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Conservation Status
Pacific white-sided dolphins are not considered to be endangered. A recent estimate of the population of these mammals in the central North Pacific ranged between a minimum of about 500,000, to a maximum of 930,000. Therefore there is not any immediate danger for the extiction of these animals. They are hunted by Japanese coastal fishermen in the East China and Japan seas and taken accidentally in the North Pacific purse-seine fishery.
US Federal List: no special status
CITES: no special status
IUCN Red List of Threatened Species: least concern
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National NatureServe Conservation Status
Canada
Rounded National Status Rank: NNA - Not Applicable
United States
Rounded National Status Rank: NU - Unrankable
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NatureServe Conservation Status
Rounded Global Status Rank: G5 - Secure
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Trends
Population
Separate subpopulations have been identified in the southern portions of the species range, off the west coast of North America (Lux et al. 1997) and in Japan (Hayano et al. 2004).
Population Trend
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Threats
Threats
Smaller catches (e.g. at least 194 in 1987) are reported from the Japanese land-based salmon drift net fishery, and small numbers are taken yearly in seines, set nets, and trap nets around Japan (Brownell et al. 1999). Pacific white-sided dolphins have never been primary targets of Japanese drive fisheries, but they were harpooned in Japanese waters during the 1940s, and cull programs killed at least 466 Pacific white-sided dolphins in Japanese waters between 1976 and 1980. The Japanese government is currently (2007) considering a renewed direct harvest of this species (Kasuya pers. comm.). The potential for renewed directed takes in Japanese waters, coupled with evidence for population substructure, particularly at the southern ends of this species' range, may require the re-examination of the threat to this species.
In the eastern Pacific, a total of 424 Pacific white-sided dolphins were estimated killed in the U.S. West Coast shark and swordfish driftnet fishery between 1988 and 2002 (Perkins et al. 1994; Julian and Beeson 1998, Carretta et al. 2005). Additional low levels of mortality have been documented for bottom-set gillnets in California coastal waters, for drift gill nets in British Columbia and Alaska, and for trawl fisheries in Alaska; however, no overall mortality estimates are available for these fisheries. Pacific white-sided dolphins are rarely taken in the tuna purse seine fishery in the eastern tropical Pacific, because most of the fishing takes place south of the range of these dolphins (Brownell et al. 1999). None of these sources of eastern North Pacific mortality appears of a sufficient magnitude to have caused a population decline in this region.
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Comments: Taken directly and incidently in small numbers in various fisheries through the range, but apparently not seriously threatened (Stacey and Baird 1991).
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Management
Conservation Actions
The most significant international conservation measure for this species was the United Nations (U.N.) moratorium on high-seas driftnet fishing implemented in 1993. In the eastern North Pacific, the U.S drift gillnet fishery has been required since 1996 to use acoustic warning devices (pingers) to reduce cetacean bycatch; however, low levels of bycatch of Lagenorhynchus obliquidens have continued (Carretta et al. 2005).
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Relevance to Humans and Ecosystems
Benefits
Economic Uses
Comments: Taken in small numbers for human consumption in Japan (IUCN 1991). Sometimes displayed in marine aquaria.
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Risks
IUCN Red List Category
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IUCN (2008) Cetacean update of the 2008 IUCN Red List of Threatened Species.
http://www.marinespecies.org/aphia.php?p=sourcedetails&id=125373
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Wikipedia
Pacific white-sided dolphin
The Pacific White-sided Dolphin (Lagenorhynchus obliquidens) is a very active dolphin found in the cool to temperate waters of the North Pacific Ocean.
Contents |
Taxonomy
The Pacific White-sided Dolphin was named by Smithsonian mammalogist Theodore Nicholas Gill in 1865. The Pacific White-sided Dolphin is morphologically similar to the Dusky Dolphin, which is found in the southern Pacific. Genetic analysis by Frank Cipriano suggests the two species diverged about two million years ago.
Though both are traditionally placed in the genus Lagenorhynchus, molecular analyses indicate that they are closer to dolphins of the genus Cephalorhynchus. The new genus Sagmatias has been proposed for these species.[3]
Physical description
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. There are light gray patches on the sides and a further light gray stripe running 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 kilograms (330 lb) and males 200 kilograms (440 lb) with males reaching 2.5 meters (8.2 ft) and females 2.3 meters (7.5 ft) in length. Pacific White-sided Dolphins tend to be larger than Dusky Dolphins. Females reach maturity at 7 years. The gestation period is one year. Individuals live 40 years or more.
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 is mainly hake, anchovies, squid, herring, salmon and cod.
They have an average of 60 teeth.[4]
Range and habitat
The range of the Pacific White-sided Dolphin arcs across the cool to temperate waters of the north Pacific. 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.
The total population may be as many as 1 million. However, the tendency of Pacific White-sided Dolphins to approach boats complicates precise estimates via sampling.
Relation to humans
Protection
Until the United Nations banned certain types of fishing nets in 1993, many Pacific White-sided Dolphins were killed in drift nets. One researcher estimated somewhere 50,000–89,000 individuals were killed in the twelve years to 1990. Some animals are still killed each year by Japanese hunting drives.
In popular culture
- Although overshadowed in popularity by Bottlenose Dolphins, Pacific White-sided Dolphins are also a part of some marine theme park shows.
- Venus Among the Fishes is a book by Elizabeth Hall, that has a female Pacific White-sided dolphin as its protagonist.
Captivity
Pacific White-sided Dolphins adapt well to captivity. Almost 50 reside in dolphinariums in North America and Japan.
Natural History
These dolphins keep close company. White-sided dolphins swim in groups of ten to one hundred, and can often be seen bow-riding and doing somersaults. Members form a close-knit group and will often care for a sick or injured dolphin.
Animals that live in such big social groups develop ways to keep in touch--each dolphin identifies itself by a unique name-whistle. Staying close helps, too. Young dolphins communicate with a touch of a flipper as they swim beside adults.
References
- ^ Mead, James G.; Brownell, Robert L., Jr. (16 November 2005). "Order Cetacea (pp. 723-743)". In Wilson, Don E., and Reeder, DeeAnn M., eds. Mammal Species of the World: A Taxonomic and Geographic Reference (3rd ed.). Baltimore: Johns Hopkins University Press, 2 vols. (2142 pp.). ISBN 978-0-8018-8221-0. OCLC 62265494. http://www.bucknell.edu/msw3/browse.asp?id=14300064.
- ^ Hammond, P.S., Bearzi, G., Bjørge, A., Forney, K., Karczmarski, L., Kasuya, T., Perrin, W.F., Scott, M.D., Wang, J.Y., Wells, R.S. & Wilson, B. (2008). Lagenorhynchus obliquidens. In: IUCN 2008. IUCN Red List of Threatened Species. Downloaded on 7 October 2008.
- ^ Shirihai, H. and Jarrett, B. (2006). Whales, Dolphins and Other Marine Mammals of the World. Princeton Field Guides. pp. 202–205. ISBN 0-61-12757-2.
- ^ Black, Nancy A. (2009). Perrin, William F.; Würsig, Bernd; Thewissen, J. G. M.. eds. Encyclopedia of Marine Mammals (2 ed.). 30 Corporate Drive, Burlington Ma. 01803: Academic Press. ISBN [[Special:BookSources/97801237335539|97801237335539]]. http://www.elsevier.com/wps/find/bookdescription.cws_home/716899/description#description.
- Pacific White-sided Dolphin and Dusky Dolphin by Koen van Waerebeek and Bernd Würsig Encyclopedia of Marine Mammals pp 859–60 ISBN 0-12-551340-2
- National Audubon Society: Guide to Marine Mammals of the World ISBN 0-375-41141-0
- Encyclopedia of Marine Mammals ISBN 0-12-551340-2
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Wikipedia
Unreviewed
Names and Taxonomy
Taxonomy
Comments: Lagenorhynchus obliquidens may be a Northern Hemisphere form of L. obscurus (Mead and Brownell, in Wilson and Reeder 1993, 2005). "Morphological differences exist between animals in the northeastern Pacific north of southern California and those 'resident' off Baja California" (IUCN 1991).
LeDuc et al. (1999) used cytochrome b gene sequences to examine phylogenetic relationships among delphinids and found that Lagenorhynchus albirostris (type species for the genus) and L. acutus are not closely related to each other or to nominal congeners; acutus was therefore assigned to the genus Leucopleurus. The remaining four Lagenorhynchus species are closely related to Lissodelphis and Cephalorhynchus and were placed in the genus Sagmatias. However, this revision has not been widely accepted and, pending further evidence, the mammal checklists by Baker et al. (2003) and Mead and Brownell (in Wilson and Reeder 2005) maintained acutus and obliquidens in the genus Lagenorhynchus.
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