Atlantic humpback dolphin

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Atlantic humpback dolphin
Sousa teuszii1.jpg
Humpback dolphins size.svg
CITES Appendix I (CITES) [2]
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Artiodactyla
Infraorder: Cetacea
Family: Delphinidae
Genus: Sousa
Species:
S. teuszii
Binomial name
Sousa teuszii
(Kükenthal, 1892)
Cetacea range map Atlantic Humpback Dolphin.PNG
Range of Atlantic humpback dolphin
Synonyms [1]

Sotalia teusziiKükenthal, 1892

The Atlantic humpback dolphin (Sousa teuszii) is a species of humpback dolphin that is found in coastal areas of West Africa.

Contents

It is regarded as critically endangered by the IUCN. [1]

Description

Apart from its geographical range, it can be distinguishable from the Indo-Pacific humpback because of their distinct skin coloration and other morphological characteristics. Atlantic humpbacks have a gray or white color, unlike the Indo-Pacific humpbacks which have pink mottling. [3] Males, in particular, can have distinct humps under their dorsal fins. [3] They can also be distinguished by a robust body with a well-defined rostrum. They are typically slate gray on the back and sides, fading to light gray ventrally. The dorsal fin is small, slightly falcate, and triangular, and sits on a distinctive and well developed dorsal hump.

Atlantic humpbacks can also be distinguishable from the other species (S. plumbea, S. chinensis, S. sahulensis sp. nov., etc.) because of a significantly lower amount of teeth. On average, they have about 30 teeth per row versus other species having around 33–37. To compliment this, they typically have a shorter and wider skull than the other species. [4]

At birth, this species is 14 kg (31 lb) in weight and 100 cm (39 in) long. [3] A fully grown male can weigh up to 280 kg (620 lb) and is around 2.8 m (9 ft 2 in) long [3]

Range and habitat

This species is native to the tropical to subtropical west coast of Africa in the southeastern Atlantic Ocean, from western Sahara to Angola. The species is not commonly observed and is found sporadically across these waters. [1] It is mainly found in shallow coastal and estuarine waters in the marine Neritic zone, usually less than 20 m (66 ft) deep. [1] [5]

Behavior and diet

This species is known to be shy; it does not bow-ride and aerial displays are rarely seen. They occasionally leap, spy-hop, and tail-slap the water. Atlantic humpback dolphins prefer to keep a distance from boat engines, and when they are seen in the water, they are most likely traveling and foraging. They forage both independently and cooperatively. [6] The groups usually range from 1-8 animals, but gatherings of up to 20-40 animals have been observed. An average swim speed during travel has been measured at about 4 km/h (2.5 mph). [7] In Angola and Guinea, some individuals appear to exhibit high site fidelity and strong association patterns. [5] Atlantic humpback dolphins communicate similarly to other dolphin species via echolocation. [6]

Groups generally forage close to shore in shallow waters and often within the surf zone. They appear to feed mainly on inshore schooling fish such as mullet, though a variety of coastal fish and crustacean species are also known as their prey items. Their specific prey species depends on what geographic location they occupy and what is available. [6] These dolphins tend to feed in small bays, sheltered waters behind reef-breaks and in areas off dry river mouths, while traveling occurs mainly along exposed coastlines. [5]

Interaction with humans

The Atlantic humpback dolphin is known to engage in cooperative fishing with Mauritanian Imraguen fishermen, by driving fish towards the shore and into their nets. [8] Incidental capture in gill nets is considered their greatest threat followed by directed takes, habitat loss and degradation, overfishing, marine pollution, anthropogenic sound, and climate change. [5]

Threats

Marine oil pollution map Marine oil pollution map.png
Marine oil pollution map

Habitat loss and degradation are the measured causes of declines in the Atlantic humpback dolphin population. [9] Humans are continuously expanding coastal communities and polluting the oceans, which cause a threat to marine life. Overfishing reduces the number of prey available to the dolphins, which leads to an inadequate amount of diet available to them. They are vulnerable to marine pollution (oil spills, untreated sewage, run-off from agricultural areas, etc.) and subsequent marine bacterial bloom, which causes harm to coastal cetaceans. Toxins from the bacteria in the water can easily wipe out a critically endangered species, like the Atlantic Humpback dolphin. Anthropogenic sound includes the hearing loss and ear tissue damage of the dolphins from noisy coastal development and shipping. The geographic location of Atlantic humpbacks depend on the water temperature and prey distribution. Climate change causes the fluctuation of water temperatures, which forces the dolphins to adapt to environmental changes. [9]

Conservation

Surface air temperature change over the past 50 years. Change in Average Temperature With Fahrenheit.svg
Surface air temperature change over the past 50 years.

The current conservation status of the Atlantic Humpback is critically endangered, according to the IUCN. [1] This is because of the dolphin's restricted range, specific habitat, low population size, and continued human threats. [11] Coastal development with the associated disturbance in Africa is inevitable and will continue to harm the shy species, whether it is directly or indirectly. The dolphins have already been challenged by climate change and have evolved adequate adaptations because of the impact of human activities. It does not live in the cold, deep waters in the ocean because of the rise in world temperature. The only place left for these dolphins to live is the shallow, warm waters in the ocean. If the world temperature continues to rise, there will be no habitat for the dolphins to successfully thrive and reproduce. [11]

Properly enforced state laws about bycatch and marine protected areas are one solution in conserving the dolphins. [9] Enforcing such a law that states fishing nets cannot be cast a certain distance from the shore will ensure dolphin survival because there would be less incidental dolphin captures. Educating the community to be aware of the threats they are making to the dolphins via public awareness campaigns or training will improve their knowledge on marine life conservation.

Scientific researchers are finding more information about Atlantic Humpbacks and are currently investigating how human activities can decrease the impact on the species. [11]

See also

Related Research Articles

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

The Indo-Pacific humpback dolphin is a species of humpback dolphin inhabiting coastal waters of the eastern Indian and western Pacific Oceans. This species is often referred to as the Chinese white dolphin in mainland China, Macau, Hong Kong, Singapore and Taiwan as a common name. Some biologists regard the Indo-Pacific dolphin as a subspecies of the Indian Ocean humpback dolphin which ranges from East Africa to India. However, DNA testing studies have shown that the two are distinct species. A new species, the Australian humpback dolphin, was split off from S. chinensis and recognized as a distinct species in 2014. Nevertheless, there are still several unresolved issues in differentiation of the Indian Ocean-type and Indo-Pacific-type humpback dolphins.

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

Risso's dolphin is a dolphin, the only species of the genus Grampus. Some of the closest related species to these dolphins include: pilot whales, pygmy killer whales, melon-headed whales, and false killer whales.

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

The white-beaked dolphin is a marine mammal belonging to the family Delphinidae in the suborder Odontoceti.

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

The Irrawaddy dolphin is a euryhaline species of oceanic dolphin found in scattered subpopulations near sea coasts and in estuaries and rivers in parts of the Bay of Bengal and Southeast Asia. It closely resembles the Australian snubfin dolphin, which was not described as a separate species until 2005. It has a slate blue to a slate gray color. Although found in much of the riverine and marine zones of South and Southeast Asia, the only concentrated lagoon populations are found in Chilika Lake in Odisha, India and Songkhla Lake in southern Thailand.

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

The common dolphin is the most abundant cetacean in the world, with a global population of about six million. Despite this fact and its vernacular name, the common dolphin is not thought of as the archetypal dolphin, with that distinction belonging to the bottlenose dolphin due to its popular appearances in aquaria and the media. However, the common dolphin is often depicted in Ancient Greek and Roman art and culture, most notably in a mural painted by the Greek Minoan civilization.

<span class="mw-page-title-main">Short-finned pilot whale</span> Species of mammal

The short-finned pilot whale is one of the two species of cetaceans in the genus Globicephala, which it shares with the long-finned pilot whale. It is part of the oceanic dolphin family (Delphinidae).

<i>Orcaella</i> Genus of mammals

The snubfin dolphins (Orcaella) are a genus of cetaceans containing two members: the Irrawaddy dolphin and the Australian snubfin dolphin. The genus was long believed to be monotypic with the only species being the Irrawaddy dolphin; however, in 2005, supposed Irrawaddy dolphin populations inhabiting the Australian/New Guinean regions were found to be significantly different and were declared a separate new species named the Australian snubfin dolphin.

<span class="mw-page-title-main">Harbour porpoise</span> Species of mammal

The harbour porpoise is one of eight extant species of porpoise. It is one of the smallest species of cetacean. As its name implies, it stays close to coastal areas or river estuaries, and as such, is the most familiar porpoise to whale watchers. This porpoise often ventures up rivers, and has been seen hundreds of kilometres from the sea. The harbour porpoise may be polytypic, with geographically distinct populations representing distinct races: P. p. phocoena in the North Atlantic and West Africa, P. p. relicta in the Black Sea and Sea of Azov, an unnamed population in the northwestern Pacific and P. p. vomerina in the northeastern Pacific.

<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">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.

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

Humpback dolphins are members of the genus Sousa. These dolphins are characterized by the conspicuous humps and elongated dorsal fins found on the backs of adults of the species. Humpback dolphins inhabit shallow nearshore waters along coastlines across Australia, Africa, and Asia. Their preference for these habitats exposes them to various human activities such as fisheries entanglement, boat traffic, pollution, and habitat loss. Despite these risks, their nearshore presence facilitates easy observation from land. There are four recognized species: the Indo-Pacific humpback dolphin, Indian Ocean humpback dolphin (S. plumbea), Atlantic humpback dolphin (S. teuszii), and Australian humpback dolphin (S. sahulensis). Although generally shy and less active compared to bottlenose dolphins, they are occasionally featured in dolphin watching tours, particularly in locations like Hong Kong and the Musandam Peninsula of Oman.

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

The Indian Ocean humpback dolphin is a member of the Delphinidae family occupying coastal areas ranging from Southern Africa to Western Indochina. The Indo-Pacific humpback dolphin was formerly included within the same species, but a 2014 study revealed them to be a separate species.

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

The melon-headed whale, also known less commonly as the electra dolphin, little killer whale, or many-toothed blackfish, is a toothed whale of the oceanic dolphin family (Delphinidae). The common name is derived from the head shape. Melon-headed whales are widely distributed throughout deep tropical and subtropical waters worldwide, but they are rarely encountered at sea. They are found near shore mostly around oceanic islands, such as Hawaii, French Polynesia, and the Philippines.

<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">Pantropical spotted dolphin</span> Species of mammal

The pantropical spotted dolphin is a species of dolphin found in all the world's temperate and tropical oceans. The species was beginning to come under threat due to the killing of millions of individuals in tuna purse seines. In the 1980s, the rise of "dolphin-friendly" tuna capture methods saved millions of the species in the eastern Pacific Ocean and it is now one of the most abundant dolphin species in the world.

<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">Dwarf sperm whale</span> Species of whale

The dwarf sperm whale is a sperm whale that inhabits temperate and tropical oceans worldwide, in particular continental shelves and slopes. It was first described by biologist Richard Owen in 1866, based on illustrations by naturalist Sir Walter Elliot. The species was considered to be synonymous with the pygmy sperm whale from 1878 until 1998. The dwarf sperm whale is a small whale, 2 to 2.7 m and 136 to 272 kg, that has a grey coloration, square head, small jaw, and robust body. Its appearance is very similar to the pygmy sperm whale, distinguished mainly by the position of the dorsal fin on the body–nearer the middle in the dwarf sperm whale and nearer the tail in the other.

<span class="mw-page-title-main">Cetacean bycatch</span> Accidental capture of porpoises, whales and dolphins

Cetacean bycatch is the accidental capture of non-target cetacean species such as dolphins, porpoises, and whales by fisheries. Bycatch can be caused by entanglement in fishing nets and lines, or direct capture by hooks or in trawl nets.

<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.

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

The Australian humpback dolphin is a species of humpback dolphin and the fourth recognized humpback dolphin species chronologically. The specific name sahulensis is derived from the Sahul Shelf, located between northern Australia and southern New Guinea, where the Australian humpback dolphins occur.

References

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  2. "Appendices | CITES". cites.org. Retrieved 2022-01-14.
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  4. Jefferson, Thomas A.; Rosenbaum, Howard C. (October 2014). "Taxonomic revision of the humpback dolphins ( Sousa spp.), and description of a new species from Australia". Marine Mammal Science. 30 (4): 1494–1541. Bibcode:2014MMamS..30.1494J. doi:10.1111/mms.12152.
  5. 1 2 3 4 Berta, Annalisa, ed. (2015). Whales, Dolphins & Porpoises: A Natural History and Species Guide. University of Chicago Press. ISBN   978-0226183190.
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  7. Weir, C R (2009-12-01). "Distribution, behaviour and photo-identification of Atlantic humpback dolphins Sousa teuszii off Flamingos, Angola". African Journal of Marine Science. 31 (3): 319–331. Bibcode:2009AfJMS..31..319W. doi:10.2989/AJMS.2009.31.3.5.993. ISSN   1814-232X. S2CID   85354627.
  8. "Atlantic humpback dolphin". Whale & Dolphin Conservation USA. Retrieved 2022-09-11.
  9. 1 2 3 Weir, Caroline R.; Waerebeek, Koen Van; Jefferson, Thomas A.; Collins, Tim (2011-04-01). "West Africa's Atlantic Humpback Dolphin (Sousa teuszii): Endemic, Enigmatic and Soon Endangered?". African Zoology. 46 (1): 1–17. doi:10.3377/004.046.0101. ISSN   1562-7020. S2CID   86168629.
  10. "GISS Surface Temperature Analysis (v4)". NASA. Retrieved 12 January 2024.
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