Jump to content

Dusky dolphin

This is a good article. Click here for more information.
From Wikipedia, the free encyclopedia
(Redirected from Lagenorhynchus obscurus)

Dusky dolphin
Diagram showing a dolphin and scuba diver from the side: the dolphin is about the same size as the human
Size compared to an average human
CITES Appendix II (CITES)[2]
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Artiodactyla
Infraorder: Cetacea
Family: Delphinidae
Genus: Lagenorhynchus
Species:
L. obscurus
Binomial name
Lagenorhynchus obscurus
(J. E. Gray, 1828)
Subspecies
  • L. o. fitzroyi
  • L. o. obscurus
  • L. o. posidonia
  Dusky dolphin range

The dusky dolphin (Lagenorhynchus obscurus) 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.

Taxonomy

[edit]

It is commonly thought that the dusky dolphin was first described by John Edward Gray in 1828 from stuffed skin and a single skull shipped from the Cape of Good Hope to the British Museum. Gray first described the species as Delphinus obscurus and reported that the animal was captured around the Cape of Good Hope by a Captain Haviside (often misspelt "Heaviside") and sent to the British Museum though the Royal College of Surgeons in 1827.[3]

However, Gray later wrote that a similar dolphin was described as Delphinus supercilious by French surgeons and naturalists René Primevère Lesson and Prosper Garnot from a specimen collected off the coast of Tasmania two years before his own classification.[4] Gray classified D. supercilious as a junior synonym of his D. obscurus.[3] Meanwhile, Charles Darwin also described what turned out to be this species as Delphinus fitzroyi from a specimen harpooned off Argentina in 1838. The dusky dolphin was reclassified as Prodelphinus obscurus in 1885 by British naturalist William Henry Flower,[5][3] before gaining another name, Lagenorhynchus obscurus, from American biologist Frederick W. True in 1889.[6][3]

Phylogeny

[edit]

The dusky dolphin and the Pacific white-sided dolphin are considered phylogenetically related species. Some scientists have proposed that they are the same species, but morphological and life-history evidence shows otherwise.[7] The two sister species diverged at around 1.9–3.0 million years ago.[8] A 1999 mitochondrial cytochrome b gene indicates that the genus Lagenorhynchus, as traditionally conceived, is not a natural (monophyletic) group.[9]

A 2006 finds that the dusky and the Pacific white-sided dolphin form the sister group to the (expanded) genus Cephalorhynchus. If this placement is accurate, a new genus name will need to be coined to accommodate these two species.[10] It has therefore been proposed that the dusky dolphin, together with Pacific white-sided, hourglass, and Peale's dolphin are moved to the resurrected genus Sagmatias.[11] Hybrids of dusky dolphins have been suggested, including with a long-beaked common dolphin[12] and a southern right whale dolphin.[13]

The following cladogram is based on Banguera-Hinestroza and colleges (2014):[14]

Lissodelphininae

Subspecies

[edit]

Three dusky dolphin subspecies have been classified: the African dusky dolphin (Lagenorhynchus obscurus obscurus), Fitzroy's dolphin (L. o. fitzroyi), and the Peruvian/Chilean dusky dolphin (L. o. posidonia).[15][16] A fourth subspecies, L. o. superciliosus or the New Zealand dusky dolphin, has been proposed but is not currently accepted.[11][17] Most populations have low genetic diversity, with the Peruvian population being an exception.[7]

Description

[edit]
Closeup of dusky dolphin surfacing

The dusky dolphin is a small but somewhat stocky species. There is a clear split between the forehead and the short, pointed beak. Both the dorsal fin and flippers are curved, the former being more pointed. The teeth number between 108 and 144.[18] Their size can vary between populations. The size for dusky dolphins in New Zealand have been recorded to be a length range of 167–178 cm (5.48–5.84 ft) and a weight range of 69–78 kg (152–172 lb) for females and a length range of 165–175 cm (5.41–5.74 ft) and a weight range of 70–85 kg (154–187 lb) for males.[3] Peruvian dolphins appear to be the largest but this is based off small sample sizes.[18] A female from Peru was measured at 204.5 cm (6.71 ft) while a male measured 206 cm (6.76 ft).[19]

The dusky dolphin have a distinctive colouration that resembles the Pacific white-sided dolphin. Its pigmentation consists of a dark gray or black area around the dorsal fin and spine, light gray face and chest area, a blazed flank patch that is the same colour, and a white underside.[3][7][18] Gray-black colouration exists around the eyes and on the beak. The dorsal fin is darker in front and lightens towards the back while the flippers are light gray with darker edges.[18]

Distribution

[edit]
Dusky dolphins of New Zealand

The dusky dolphin has a discontinuous semi-circumpolar range.[18] The dolphins can be found off the coasts of western and southeastern South America, southwestern Africa, New Zealand, and some oceanic islands in the south Atlantic and Indian Ocean. They have also been sighted off southern Australia.[7]

Dusky dolphins are found throughout New Zealand waters. They are most common on the eastern coasts, between East Cape on the North Island and Timaru and Oamaru on the South Island. They are sighted year-round in the stable, cold waters off the coast off the northern Canterbury Region.[20] Off South America, they range from southern Peru to Cape Horn in the west and then up to around 36°S in the east, along with the Falkland Islands.[7] They are suggested to be "relatively uncommon" off the Falklands.[21]

Around Africa, the dusky dolphin ranges from Lobito Bay, Angola in the north to False Bay, South Africa in the south.[7] Within Australian waters, dusky dolphins have been recorded off Kangaroo Island, eastern Tasmania, and in the Bass Strait,[22] although they are uncommon and those that are sighted there are possibly transients from New Zealand.[23] Dusky dolphins are also found around the islands of Tristan da Cunha, Prince Edward, Crozet, Île Amsterdam and Île Saint-Paul.[3][18]

Ecology and behaviour

[edit]
Dusky dolphins leaping off Kaikōura

Dusky dolphins prefer cool, upwelling waters, as well as cold currents. They largely live in inshore waters and can be found up to the outer continental shelf and in similar zones in offshore islands.[18][20] They can travel up to 780 km (480 mi), but do not appear to go on seasonal migrations. However, dolphins off Argentina and New Zealand move to and from shore daily and seasonally.[7]

In Argentina, dusky dolphins can be seen in groups with southern right whales and South American sea lions. They have been found around bottlenose dolphins, but seem to ignore them, and may share feeding areas with Risso's dolphins. They also associate with various seabirds, such as kelp gulls, cormorants, terns, shearwaters, petrels, and albatrosses.[24] Off New Zealand, dusky dolphins feed with Australasian gannets, shearwaters, terns, gulls, spotted shags, New Zealand fur seals, spiny dogfish and common threshers.[25] Dusky dolphins have also been observed with southern right whale dolphins off Namibia.[26]

Dusky dolphins are preyed on by orcas and large sharks. Dolphins avoid orcas by swimming into shallower water.[24] Dusky dolphins are also susceptible to parasitism by certain nematode, cestode, and trematode species, mostly the genera Nasitrema and Anisakis, and Phyllobothrium delphini, Braunina cordiformis, and Pholeter gasterophilus.[27]

Vocalisations and echolocation

[edit]

In general, three different types of sounds are produced by dolphins (and many other toothed whales). These are echolocative click trains, burst pulses and tonal whistles.[28] Dusky dolphins produce all three sounds.[29]: 77  Their echolocation signals are quick and broadband, much like those other whistle-producing toothed whales.[29]: 95  These signals have two peaks; between 40 and 50 kHz at low frequency and between 80 and 110 kHz at high frequency. The white-beaked dolphin, which is over twice the size of the dusky dolphin, has signals that are about 9–12 dB higher.[30] Burst pulses are similar to echolocation signals but the pauses between clicks are much shorter, at 0.5–10 milliseconds.[29]: 81  They often consist of 2–14 clicks in succession and appear to be important for communication.[28] Whistling are more common when dusky dolphins mingle with other dolphin species such as common dolphins.[29]: 78  Whistles in general are not often produced in New Zealand dolphins[29]: 93  and in one study which recorded vocalisations off both New Zealand and Argentina, no whistles were detected.[28]

Foraging

[edit]
Dusky dolphins

Dusky dolphins mainly feed on fish and squid. Common fish species eaten include anchovies, lantern fish, pilchards, sculpins, hakes, horse mackerel, hoki and red cod, while squids preyed on include those of the genera Nototodarus, Todarodes and Loligo.[7] They are generally coordinated hunters. Their very flexible foraging strategies can change depending on the environment.[31]: 103  In Kaikōura Canyon, New Zealand, where deep oceanic waters meet the shore, dusky dolphins forage in deep scattering layers at night. They arrive at the hunting site individually, but form groups when in the layer.[32] The dolphins use their echolocation to detect and isolate an individual prey.[30] The number of dolphins in a foraging group inversely correlates with the depth of the scattering layer.[32]

In San Jorge Gulf, Argentina and Admiralty Bay, New Zealand, dusky dolphins will forage during the day.[33]: 117  The dolphins chase schools of fish and, depending on the size, herd them into stationary balls.[33]: 119 [24][34] Dolphins appear to use to water surface a barrier for the fish as they circle around and below them.[24] They may also scare them using sound or by flashing their white bellies.[33]: 121  The larger the group, the more effective they are in herding the school.[34] These hunts may also involve other species, including other dolphins, seabirds, sharks, and pinnipeds.[24][34] Common dolphin seems to participate in herding with dusky dolphins. By contrast, pinnipeds, sharks and other predatory fish steal food without helping in the hunt.[35]: 65  Attacks from above by diving birds like gannets can make herding more difficult for dolphins.[34]

Social behaviour and reproduction

[edit]
See also: Dolphin § Reproduction and sexuality

Dusky dolphins live in a fission-fusion society, with most group size increases occurring during foraging and decreases in group sizes occurring during resting and traveling. In the Golfo San José off the Valdes Peninsula, dolphins commonly switch between small traveling groups and large sociosexual groups, and encounter a variety of associates. Studies of dolphins off Kaikōura, New Zealand, showed the dolphins normally live in large groups that split into smaller subgroups.[36] These subgroups are composed of mating adults (mating groups), mothers with calves (nursery groups) and nonbreeding adults.[36] Dusky dolphins have a promiscuous mating system in which both males and females mate with multiple partners. Mating groups are generally made of around 10 males and a single female.[36] These mating groups can be found in both shallow and deep water but more often gather near shore.[37]: 162 

Dolhins mating

In the mating groups, the males pursue a female in high-speed chases. Females seem to prefer males with great speed and agility over size, strength, or aggression.[37]: 164 : 175  Females may extend the chase as long as possible so only the best male remains.[38] Females may try to evade males that are less energetic and lack social skill.[37]: 170  Males also may form alliances to catch females.[37]: 167–69  Unlike male bottlenose dolphins, male dusky dolphins do not defend multiple females.[37]: 166  Dusky dolphins may reach sexual maturity between four and eight years depending on the region. Female Dusky dolphins off the coast of Peru were found to have pregnancies lasting for 12.9 months and nurse their young for a further 12 months. There are 3.7 month intervals before the reproductive cycle begins again.[3] During intermisson, females usually take the top position.[37]: 170  As with other species where females mate with multiple partners, male dusky dolphins have large testes for sperm competition.[37]: 164  Dusky dolphins sometimes engage in sexual behaviour for reasons other than reproduction, perhaps for greeting, communication, or strengthening social bonds. Homosexual behaviour between males has been observed.[36] Dolphins having sex for social reasons tend to be more serene, with none of the high speed chasing.[37]: 175 

Females with calves tend to gather in nursery groups. Nursery groups likely provide mothers and calves more time to rest, which is important for both. Resting is the most common behaviour most of the year. Calves may learn to hunt from their mothers and nursery groups typically forage in shallow water as deeper water is too dangerous for young.[39]: 188–89  Calves are particularly vulnerable to predators like orcass and shallow water may provide a refuge for predation.[39]: 183  Nursery groups also facilitate socialisation among the young.[39]: 190–191  Nursery groups keep away from mating groups, as adult males will aggressively chase mothers. Calves often get lost in these frenzies and may be also be targeted by the males or predators.[37]: 174 [39]: 185 

Dusky dolphin performing a flip

Aerial behaviour

[edit]

Dusky dolphins perform a number of aerial displays, including leaps, backslaps, headslaps, tailslaps, spins, and noseouts.[24] They also perform head-over-tail leaps which have been called the most "acrobatic" of the displays.[24] A headfirst re-entry is performed when a dolphin leaps entirely out of the water and positions its back in a curve while it flips the tail to land back in the water head-first. "Humping" is similar, except the snout and tail remain in the water when the dolphin is the arch.[24] Leaps, head-over-tail leaps, backslaps, headslaps, tailslaps, and spins are often done over and over again.[24] The ability to make these leaps is apparently not inborn but is learned. Calves are recorded to learn more complex leaps as they develop, learning in the follow order: noisy leaps, head first re-entries, coordinated leaps, and acrobatic leaps. Young also learn when to preform these leaps though socialisation.[39]: 190–91 

Relationship with humans

[edit]

Status

[edit]

The dusky dolphin, protected in much of its range, is listed as Least Concern by the IUCN Red List because; "... Although information is sparse, several Dusky Dolphin populations are large, seemingly stable, and not subject to high levels of anthropogenic threats".[1] Dusky dolphins may fall victim to the small cetacean fisheries of Peru and Chile. The expansion of these fisheries could have started in Peru when the anchoveta fishery collapsed in 1972.[1] Off New Zealand, gill nets have also been a threat, though bycatches seem to have decreased since the 1970s and 1980s.[7] In Peru, dusky dolphins are killed in large numbers (10,000–15,000 per year) and used as shark bait or for human consumption, which has led to a status of Vulnerable for the Peru subspecies.[40] The dolphins are also thought to have been harpooned off South Africa, but the numbers are not considered large.[41]

The dusky dolphin is listed on Appendix II of the Convention on the Conservation of Migratory Species of Wild Animals (CMS) as it has an unfavourable conservation status or would benefit significantly from international co-operation organised by tailored agreements.[42][43]

A pair of dusky dolphins swimming alongside a boat

Mussel farming

[edit]

The effect of mussel farming on dusky dolphins has been studied in Admiralty Bay, New Zealand.[44] Dusky dolphins are commonly seen in this area, which is also where the greatest density of farming activity is proposed. Apparently, dolphins rarely enter existing farms, and when they do, they usually swim quickly up the lanes and between rows of lines and floats.[44]

Tourism

[edit]
Dusky dolphin tours off New Zealand's South Island

Dusky dolphins are popular attractions for whale-watching tours. Since 1997, dolphin-watching activities have increased in Patagonia, with dusky dolphins (along with Commerson's dolphins) as the target species.[45] Tourists interested in seeing dusky dolphins grew from 1,393 in 1997 to 1,840 in 2000. Encounters with dolphins increased from 25% during 1999 to 90% in 2001.[45] Dolphin watching in this areas started as an alternative to whale watching, which was mostly based on that of the southern right whale.[45] Dusky dolphin watching is also popular in New Zealand, whose dolphin-watching industry started in the late 1980s, as a side attraction to sperm whales. Whale and dolphin watching tours have risen to around 75 officialtour operators by 2010.[46]: 235–236  Attractions in the country include viewing and swimming with dusky dolphins, notably in Kaikōura and Marlborough Sounds.[46]: 236 

While dusky dolphin tourism is a larger industry in New Zealand than it is in Argentina, tourism has less of an effect on dolphins in the former than the latter. This is likely due to more regulations and guidelines, and a limited amount of permits. The larger and more nocturnal foraging groups of dusky dolphins in New Zealand also leads to less disturbance by vessels.[46]: 241  By contrast, dolphin watching is less regulated in Argentina, with no permits or guidelines.[45] This has led to vessels interfering more in their activates.[46]: 233–35 

See also

[edit]

References

[edit]
  1. ^ a b c Alafaro-Shiguieto, J.; Crespo, E.; Elwen, S.; Lundquist, D.; Mangel, J. (2020) [errata version of 2019 assessment]. "Lagenorhynchus obscurus". IUCN Red List of Threatened Species. 2019: e.T11146A175604493. doi:10.2305/IUCN.UK.2019-3.RLTS.T11146A175604493.en. Retrieved 17 June 2024.
  2. ^ "Appendices | CITES". cites.org. Archived from the original on 5 December 2017. Retrieved 14 January 2022.
  3. ^ a b c d e f g h Brownell, R. L.; Cipriano, F (1998). "Dusky Dolphin Lagenorhynchus obscurus {Gary, 1828)". In Ridgway, S. H.; Harrison, R (eds.). Handbook of Marine Mammals: The second book of dolphins and the porpoises, Volume 6. Elsevier. pp. 85–95. ISBN 0-12-588506-7.
  4. ^ Gray, J. E. (1846). "On the British Cetacea". Annals and Magazine of Natural History. 17 (110). London: 82–5. doi:10.1080/037454809495560. Archived from the original on 23 September 2020. Retrieved 25 June 2019.
  5. ^ Flower, W. H. (1885). List of the specimens of Cetacea in the Zoological Department of the British Museum. London: British Museum. pp. 28–29.
  6. ^ True, F.W. (1889). "Contribution to the natural history of the cetaceans: a review of the family Delphinidae". Bulletin of the United States National Museum (36): 1–191. doi:10.5479/si.03629236.36.1. hdl:2027/hvd.32044066292764. Archived from the original on 30 October 2019. Retrieved 22 September 2019.
  7. ^ a b c d e f g h i Waerebeek, K. V.; Wursi, B (2008). "Dusky Dolphin Lagenorhynchus obscurus". In Perrin, W. F.; Wursig, B; Thewissen, J. G. M. (eds.). Encyclopedia of Marine Mammals (2nd ed.). Academic Press. pp. 335–37. ISBN 978-0-12-373553-9.
  8. ^ Cassens, I; Van Waerebeek, K; Best, PB; Tzika, A; Van Helden, AL; Crespo, EA; Milinkovitch, MC (2005). "Evidence for male dispersal along the coasts but no migration in pelagic waters in dusky dolphins (Lagenorhynchus obscurus)". Molecular Ecology. 14 (1): 107–21. Bibcode:2005MolEc..14..107C. doi:10.1111/j.1365-294X.2004.02407.x. hdl:11336/105921. PMID 15643955. S2CID 21935077.
  9. ^ LeDuc, R.G.; Perrin, W.F.; Dizon, A.E. (1999). "Phylogenetic relationships among the delphinid cetaceans based on full cytochrome b sequences". Marine Mammal Science. 15 (3): 619–48. Bibcode:1999MMamS..15..619L. doi:10.1111/j.1748-7692.1999.tb00833.x.
  10. ^ May-Collado, L.; Agnarsson, I. (2006). "Cytochrome b and Bayesian inference of whale phylogeny". Molecular Phylogenetics and Evolution. 38 (2): 344–54. Bibcode:2006MolPE..38..344M. doi:10.1016/j.ympev.2005.09.019. PMID 16325433.
  11. ^ a b Vollmer, Nicole L.; Ashe, Erin; Brownell, Robert L.; Cipriano, Frank; Mead, James G.; Reeves, Randall R.; Soldevilla, Melissa S.; Williams, Rob (2019). "Taxonomic revision of the dolphin genus Lagenorhynchus". Marine Mammal Science. 35 (3): 957–1057. Bibcode:2019MMamS..35..957V. doi:10.1111/mms.12573. ISSN 1748-7692. S2CID 92421374. Archived from the original on 11 November 2021. Retrieved 13 July 2021.
  12. ^ Reyes, Julio C. (1996). "A Possible Case of Hybridism in Wild Dolphins". Marine Mammal Science. 12 (2): 301–07. Bibcode:1996MMamS..12..301R. doi:10.1111/j.1748-7692.1996.tb00581.x.
  13. ^ Yazdi, Parissa (2002). "A possible hybrid between the dusky dolphin (Lagenorhynchus obscurus) and the southern right whale dolphin (Lissodelphis peronii)" (PDF). Aquatic Mammals. 28: 211–17. Archived from the original (PDF) on 9 December 2022. Retrieved 3 February 2011.
  14. ^ Banguera-Hinestroza, E; Hayano, A; Crespo, E; Hoelzel, A. R. (2014). "Delphinid systematics and biogeography with a focus on the current genus Lagenorhynchus: Multiple pathways for antitropical and trans-oceanic radiation". Molecular Phylogenetics and Evolution. 80 (217–230): 217–230. Bibcode:2014MolPE..80..217B. doi:10.1016/j.ympev.2014.08.005. hdl:11336/7703. PMID 25130419.
  15. ^ Perrin, William (2009). Perrin WF (ed.). "Lagenorhynchus obscurus (Gray, 1828)". World Cetacea Database. World Register of Marine Species. Retrieved 12 March 2014.
  16. ^ "List of Marine Mammal Species and Subspecies|June 2021". Society for Marine Mammalogy. 13 November 2016. Archived from the original on 27 November 2020. Retrieved 14 July 2021.
  17. ^ "List of Proposed, Un-named Marine Mammal Species and Subspecies|June 2021". Society for Marine Mammalogy. Archived from the original on 14 December 2023. Retrieved 14 July 2021.
  18. ^ a b c d e f g Jefferson, Thomas A.; Webber, Marc A.; Pitman, Robert L. (2015). Marine Mammals of the World: A Comprehensive Guide to Their Identification (2nd ed.). Academic Press. pp. 293–296. ISBN 978-0-12-409542-7.
  19. ^ Manzanilla-Naim, S (1989). "The 1982–1983 El Niño event recorded in dentinal growth layers in teeth of Peruvian dusky dolphins (Lagenorhynchus obscurus)". Canadian Journal of Zoology. 67 (9): 2120–2125. Bibcode:1989CaJZ...67.2120M. doi:10.1139/z89-301.
  20. ^ a b Gaskin, D E. (1972). Whales dolphins and seals with special reference to the New Zealand region. Heinemann Educational. pp. 124–126. ISBN 9780435622855.
  21. ^ Weir, C. R.; Black, A (2018). "Records of the dusky dolphin (Lagenorhynchus obscurus) in the Falkland Islands, including associations with Peale's dolphin (L. australis)". Marine Biodiversity Records. 11 (18). Bibcode:2018MBdR...11...18W. doi:10.1186/s41200-018-0153-2.
  22. ^ Menkhorst, Peter (2001). A Field Guide to Mammals of Australia. South Melbourne, Victoria: Oxford University Press. pp. 226–27. ISBN 0-19-550870-X.
  23. ^ Gill, Peter C.; Ross, Graham J. B.; Dawbin, William H.; Wapstra, Hans (2000). "Confirmed Sightings of Dusky Dolphins (Lagenorhynchus Obscurus) in Southern Australian Waters". Marine Mammal Science. 16 (2): 452–59. Bibcode:2000MMamS..16..452G. doi:10.1111/j.1748-7692.2000.tb00937.x.
  24. ^ a b c d e f g h i Würsig, B.; Würsig, M. (1980). "Behavior and ecology of the dusky dolphin, Lagenorhynchus obscurus, in the South Atlantic" (PDF). Fishery Bulletin. 77: 871–90. Archived (PDF) from the original on 1 April 2011. Retrieved 3 February 2011.
  25. ^ Vaughn, R. L.; Shelton, D. E.; Timm, L. L.; Watson, L. A.; Würsig, B (2007). "Dusky dolphin (Lagenorhynchus obscurus) feeding tactics and multi‐species associations". New Zealand Journal of Marine and Freshwater Research. 41 (4): 391–400. doi:10.1080/00288330709509929.
  26. ^ Rose, B; Payne, A. I. L. (1991). "Occurence and behavior of the southern right whale dolphin Lissodelphis peronii off Namibia". Marine Mammal Science. 7 (1): 25–34. doi:10.1111/j.1748-7692.1991.tb00547.x.
  27. ^ Van Waerebeek, K; Reyes, JC; Alfaro, J (1993). "Helminth parasites and phoronts of dusky dolphins Lagenorhynchus obscurus (Gray, 1828) from Peru" (PDF). Aquat Mamm. 19 (3): 159–69. Archived from the original (PDF) on 4 September 2011. Retrieved 3 February 2011.
  28. ^ a b c Vaughn-Hirshorn, R. L.; Hodge, K. B.; Würsig, B; Sappenfield, R. H.; Lammers, M. O.; Dudzinski, K. M. (2012). "Characterizing dusky dolphin sounds from Argentina and New Zealand". The Journal of the Acoustical Society of America. 132 (1): 498–506. doi:10.1121/1.4728191.
  29. ^ a b c d e Au, W.W.L.; Lammer, M.O; Yin, S (2010). "Acoustics of Dusky Dolphins (Lagenorhynchus obscurus)". In Würsig, B; Würsig, M. (eds.). The Dusky Dolphin: Master Acrobat off Different Shores. Academic Press. pp. 75–98. ISBN 0-12-373723-0.
  30. ^ a b Au, WW; Würsig, B (2004). "Echolocation signals of dusky dolphins (Lagenorhynchus obscurus) in Kaikoura, New Zealand". The Journal of the Acoustical Society of America. 115 (5 Pt 1): 2307–13. Bibcode:2004ASAJ..115.2307A. doi:10.1121/1.1690082. PMID 15139642.
  31. ^ Dahood, A. D.; Beniot-Bird, K. J. (2010). "Dusky Dolphins Foraging at Night". In Würsig, B; Würsig, M. (eds.). The Dusky Dolphin: Master Acrobat off Different Shores. Academic Press. pp. 99–114. ISBN 0-12-373723-0.
  32. ^ a b Benoit-Bird, K.J.; Würsig, B.; McFadden, C.J. (2004). "Dusky dolphin (Lagenorhynchus obscurus) foraging in two different habitats: active acoustic detection of dolphins and their prey" (PDF). Marine Mammal Science. 20 (2): 215–31. Bibcode:2004MMamS..20..215B. doi:10.1111/j.1748-7692.2004.tb01152.x. Archived (PDF) from the original on 27 November 2010. Retrieved 3 February 2011.
  33. ^ a b c Dahood, A. D.; Beniot-Bird, K. J. (2010). "Dusky Dolphins Foraging in Daylight". In Würsig, B; Würsig, M. (eds.). The Dusky Dolphin: Master Acrobat off Different Shores. Academic Press. pp. 115–132. ISBN 0-12-373723-0.
  34. ^ a b c d Vaughn, R; Würsig, B; Packard, J (2009). "Dolphin prey herding: Prey ball mobility relative to dolphin group and prey ball sizes, multispecies associates, and feeding duration". Marine Mammal Science. 26 (1): 213–225. doi:10.1111/j.1748-7692.2009.00317.x.
  35. ^ Dans, S. L.; Crespo, E. A.; Koen-Alonso, M; Markowitz, T. M.; Vera, B. B.; Dahood, A. D. (2010). "Dusky Dolphins Trophic Ecology: Their Role in the Food Web". In Würsig, B; Würsig, M. (eds.). The Dusky Dolphin: Master Acrobat off Different Shores. Academic Press. pp. 49–74. ISBN 0-12-373723-0.
  36. ^ a b c d Markowitz, T.M. (2004). "Social organization of the New Zealand dusky dolphin". PhD . dissertation, Texas A&M University, College Station.
  37. ^ a b c d e f g h i Markowitz, T.M.; Markowitz, W.J.; and Morton, L.M. "Mating habits of New Zealand dusky dolphins". Pp. 151–76 in: Würsig, B., and Würsig, M., editors. The Dusky Dolphin: Master Acrobat off Different Shores. Academic Press. (2010) ISBN 0-12-373723-0.
  38. ^ Whitehead, H.; and Mann, J. (2000). "Female reproductive strategies of cetaceans". In Cetacean Societies. Mann, J., editor. University of Chicago Press, pp. 219–246. ISBN 0-226-50341-0
  39. ^ a b c d e Weir, J.; Deutsch, S.; and Pearson, H.C. "Dusky Dolphin Calf Rearing". Pp. 177–94 in: Würsig, B.; and Würsig, M., editors. The Dusky Dolphin: Master Acrobat off Different Shores. Academic Press. (2010) ISBN 0-12-373723-0.
  40. ^ Mangel, J.; Alfaro-Shigueto, J. (2019). "Lagenorhynchus obscurus ssp. posidonia". IUCN Red List of Threatened Species. 2019: e.T134820643A151580809. doi:10.2305/IUCN.UK.2019-3.RLTS.T134820643A151580809.en. Retrieved 17 June 2024.
  41. ^ Randall R. Reeves; Brent S. Stewart; Phillip J. Clapham; James A. Powell (2002). National Audubon Society Guide to Marine Mammals of the World. Alfred A. Knopf, Inc. ISBN 0-375-41141-0.
  42. ^ "Appendix II Archived 11 June 2011 at the Wayback Machine" of the Convention on the Conservation of Migratory Species of Wild Animals (CMS). As amended by the Conference of the Parties in 1985, 1988, 1991, 1994, 1997, 1999, 2002, 2005 and 2008. Effective: 5 March 2009.
  43. ^ "Convention on Migratory Species page on the Dusky dolphin". Archived from the original on 3 October 2011. Retrieved 31 August 2011.
  44. ^ a b Markowitz, Tim M.; Harlin, April D.; Würsig, Bernd; McFadden, Cynthia J. (2004). "Dusky dolphin foraging habitat: overlap with aquaculture in New Zealand". Aquatic Conservation: Marine and Freshwater Ecosystems. 14 (2): 133–49. Bibcode:2004ACMFE..14..133M. doi:10.1002/aqc.602.
  45. ^ a b c d Coscarella, M. A; Dans, S. L; Crespo, E. A; Pedraza, S. N. (2023). "Potential impact of unregulated dolphin watching activities in Patagonia". J Cetacean Res Manag. 5: 77–84. doi:10.47536/jcrm.v5i1.829.
  46. ^ a b c d Markowitz, T.M.; Dans, S.L.; Crespo, E.A.; Lundquist, D.L.; and Duprey, N.M.T. "Human interactions with dusky dolphins: harvest, fisheries, habitat alteration, and tourism". Pp. 211–44 in: Würsig, B., and Würsig, M., editors. The Dusky Dolphin: Master Acrobat off Different Shores. Academic Press. (2010) ISBN 0-12-373723-0.

General

[edit]
  • Encyclopedia of Marine Mammals. Perrin, W. F., Wursig, B and J. G.M. Thewissen., editors. (2008) Academic Press; 2nd edition, ISBN 0-12-373553-X
  • The Dusky Dolphin: Master Acrobat off Different Shores. Würsig, B., and Würsig, M., editors. (2010) Academic Press. ISBN 0-12-373723-0.
  • Whales, Dolphins and. Porpoises, K. S, Norris. editor, (1977) University of California Press. ISBN 0-520-03283-7
  • Sensory Abilities of Cetaceans. Thomas, J.; Kastelein, R., editors. (1990) Plenum Press. ISBN 0-306-43695-7.
  • Cetacean Societies. Mann, J., editor. (2000) University of Chicago Press, ISBN 0-226-50341-0.
[edit]
Wikimedia Commons has media related to Lagenorhynchus obscurus.
Retrieved from "https://en.wikipedia.org/w/index.php?title=Dusky_dolphin&oldid=1266222788"