Guiana dolphin

Species of mammal

Guiana dolphin

Guiana dolphin
Size compared to an average human

Conservation status

Near Threatened  (IUCN 3.1)[1]

CITES Appendix I (CITES)[2]

Scientific classification
Domain:  | Eukaryota
Kingdom:  | Animalia
Phylum:  | Chordata
Class:  | Mammalia
Order:  | Artiodactyla
Suborder:  | Whippomorpha
Infraorder:  | Cetacea
Family:  | Delphinidae
Genus:  | Sotalia
Species:  |

S. guianensis

Binomial name
Sotalia guianensis

(van Bénéden, 1864)

Range of Guiana dolphin
Sound of Sotalia guianensis

The Guiana dolphin (Sotalia guianensis), also known as the estuarine dolphin or costero, is a dolphin found in the coastal and estuary waters to the north and east of South America, and east of Central America. It is a member of the oceanic dolphin family (Delphinidae).

## English name

[edit]

During its 2008 Annual Meeting in Santiago, Chile, as proposed by Flores et al. (2008),[3] the Scientific Committee of the International Whaling Commission (IWC) endorsed "Guiana dolphin" as the common English name for (Sotalia guianensis) in its IWC List of Recognized Cetacean Species (LRCS). Following this endorsement, Flores and colleagues also made the case for the adoption of the English name in the Latin American Journal of Aquatic Mammals.[4]

## Description

[edit]

The Guiana dolphin is frequently described as similar to the bottlenose dolphin in appearance, but it is typically smaller, at only up to 2.1 m (6.9 ft) in length. Individuals are light to bluish grey in coloration on their back and sides. The ventral region is light grey. The dorsal fin is typically slightly hooked, with a triangular shape. The beak is well-defined and of moderate length.

The Guiana dolphin is very similar in appearance to the closely related Tucuxi (Sotalia fluviatilis) with most differences only apparent in skull shape and body size. The Guiana dolphin is the larger of two at a maximum mass of 121 kilograms versus 53 kilograms for the tucuxi.[5]

Researchers have recently shown that the Guiana dolphin has an electroreceptive sense, and speculate this may also be the case for other odontocetes.[6]

## Taxonomy

[edit]

Although described as species distinct from the tucuxi Sotalia fluviatilis by Pierre-Joseph van Bénéden in 1864, the Guiana dolphin Sotalia guianensis was subsequently synonymized with Sotalia fluviatilis with the two species being treated as subspecies, or marine and freshwater varieties.[7] The first to reassert differences between these two species was a three-dimensional morphometric study of Monteiro-Filho and colleagues.[8] Subsequently, a molecular analysis by Cunha and colleagues[9] unambiguously demonstrated that Sotalia guianensis was genetically differentiated from Sotalia fluviatilis. This finding was reiterated by Caballero and colleagues[10] with a larger number of genes. The existence of two species has been generally accepted by the scientific community.[11]

## Distribution

[edit]

The Guiana dolphin is found close to estuaries, inlets and other protected shallow-water areas around the eastern and northern South American coast. It has been reported as far south as southern Brazil and north as far as Nicaragua and possibly Honduras. This species has been observed to tolerate a wide range of temperatures and salinities[12][13][5]

## Behaviour

[edit]

This species generally forms small groups averaging about 2-6 individuals, but does occasionally form larger aggregations of up to several hundred animals. They are quite active and may jump clear of the water (a behaviour known as breaching), somersault, spy-hop or tail-splash. They are unlikely, however, to approach boats. Guiana dolphins feed mainly on a wide variety of bony fish and occasionally on shrimps, cephalopods, and crabs. Studies of growth layers suggest the species can live more than 40 years.[14][5]

More than 60 species of demersal and pelagic schooling fish have been reported as prey. Small fish of 8 in (20 cm) or less are preferred. Foraging may be carried out individually or in groups. Different dolphin communities may adopt their own foraging strategies based on local circumstances. One of the best studied groups herds fish onto beaches and half strands themselves for a few seconds while grabbing their prey.[15]

A study of a population off the coast of southern Brazil in the late 1990s found that females matured at 5-8 years of age and had a mean reproductive cycle of 2 years. The gestation period was found to be approximately 12 month gestation period. After age 25, the researchers found that the reproductive cycle had increased to 2.5 years a possible indication of reproductive senescence, or aging.[16]

In December 2006, researchers from the Southern University of Chile and the Rural Federal University of Rio de Janeiro witnessed attempted infanticide by a group of Guiana dolphins in Sepetiba Bay, Brazil.[17] A group of six adults separated a mother from her calf, four then keeping her at bay by ramming her and hitting her with their flukes. The other two adults rammed the calf, held it under water, then threw it into the air and held it under water again. The mother was seen again in a few days, but not her calf. Since females become sexually receptive within a few days of losing a calf, and the group of attacking males were sexually interested in the female, it is possible that the infanticide occurred for this reason.[18] Infanticide has been reported previously in bottlenose dolphins but is thought to be generally uncommon among cetaceans.[18]

## Conservation

[edit]

The Guiana dolphin is listed on Appendix II[19] of the Convention on the Conservation of Migratory Species of Wild Animals (CMS). It is listed on Appendix II[19] as it has an unfavourable conservation status or would benefit significantly from international co-operation organised by tailored agreements. As with all coastal cetaceans, the Guiana dolphin suffers from negative interactions with humans. Entanglement in gill nets, seine nets, and shrimp traps is responsible for the death of many animals each year. There is very limited gene flow between concentrations of this dolphin, and large stretches of coast contain no animals at all, so recovery from depletion of a local population may take time.[15]

A population decline was noted in Guanabara Bay near Rio de Janeiro with 34 individuals surviving in 2016, down from 70 in 1995 and 400 in 1985.[20] The bays around Rio de Janeiro are known to be polluted with industrial waste and sewage, a possible cause of this population's decline. By 2024 the number in Guanabara Bay was below 30, and while populations in Sepetiba Bay and Ilha Grande Bay to the west are larger, they are thought also to be at risk.[21]

## See also

[edit]

* Cetaceans portal
* Mammals portal
* Marine life portal

* List of cetaceans

## References

[edit]

1. ^ Secchi, E.; Santos, M.; Reeves, R. (2019) [errata version of 2018 assessment]. "Sotalia guianensis". IUCN Red List of Threatened Species. 2018: e.T181359A144232542. doi:10.2305/IUCN.UK.2018-2.RLTS.T181359A144232542.en.
2. ^ "Appendices | CITES". cites.org. Retrieved 14 January 2022.
3. ^ Flores, PAC; Bazzalo, M; Caballero, S; Santos, MCO; Trujillo, F; Azevedo, AF; Cremer, MJ; SIMÕES-LOPES, PC; MAY-COLLADO, LJ; Flach, L; others (2008). "Proposed English common name of Sotalia guianensis to the IWC List of Recognized Cetacean Species". Scientific Committee of the IWC/60/SM16: 3.
4. ^ Flores, PAC; Bazzalo, M; Santos, MC; Rossi-Santos, MR; Trujillo, F; Bolaños-Jimenez, J; Cremer, MJ; May-Colado, LJ; Silva, FJL; Montiel-Villalobos, MG; Azevedo, AF; Meirelles, ACO; Flach, L; Barrios-Garrido, H; Simões-Lopes, PC; Cunha, HA; van Waerebeek, K (2010). "Proposed English common name for the neotropical delphinid Sotalia guianensis (P.-J. Van Beneden, 1864)". Latin American Journal of Aquatic Mammals. 8 (1–2): 179–181\. doi:10.5597/lajam00167.1–2&rft.pages=179-181&rft.date=2010&rft_id=info:doi/10.5597/lajam00167&rft.au=Flores,+PAC&rft.au=Bazzalo,+M&rft.au=Santos,+MC&rft.au=Rossi-Santos,+MR&rft.au=Trujillo,+F&rft.au=Bolaños-Jimenez,+J&rft.au=Cremer,+MJ&rft.au=May-Colado,+LJ&rft.au=Silva,+FJL&rft.au=Montiel-Villalobos,+MG&rft.au=Azevedo,+AF&rft.au=Meirelles,+ACO&rft.au=Flach,+L&rft.au=Barrios-Garrido,+H&rft.au=Simões-Lopes,+PC&rft.au=Cunha,+HA&rft.au=van+Waerebeek,+K&rft_id=https://doi.org/10.5597%2Flajam00167&rfr_id=info:sid/en.wikipedia.org:Guiana+dolphin" class="Z3988">
5. ^ a b c Flores, Paulo A. C.; da Silva, Vera M. F.; Fettuccia, Daniela de C. (2018). "Tucuxi and Guiana Dolphins: Sotalia fluviatilis and S. Guianensis". In Bernd Würsig (ed.). Encyclopedia of Marine Mammals. Elsevier. pp. 916–918\. ISBN 978-0-12-804327-1.
6. ^ Nicole U. Czech-Damal; Alexander Liebschner; Lars Miersch; Gertrud Klauer; Frederike D. Hanke; Christopher Marshall; Guido Dehnhardt; Wolf Hanke (2011). "Electroreception in the Guiana dolphin (Sotalia guianensis)". Proc. R. Soc. B. 279 (1729): 663–8\. doi:10.1098/rspb.2011.1127. PMC 3248726. PMID 21795271.
7. ^ Borobia, M.; S. Siciliano; L. Lodi & W. Hoek (1991). "Distribution of the South American dolphin Sotalia fluviatilis". Canadian Journal of Zoology. 69 (4): 1024–1039\. Bibcode:1991CaJZ...69.1025B. doi:10.1139/z91-148.
8. ^ Monteiro-Filho, E.L.D.A.; L. Rabello-Monteiro & S.F.D. Reis (2008). "Skull shape and size divergence in dolphins of the genus Sotalia: A morphometric tridimensional analysis". Journal of Mammalogy. 83: 125–134\. doi:10.1644/1545-1542(2002)083<0125:SSASDI>2.0.CO;2.
9. ^ Cunha, H.A.; V.M.F. da Silva; J. Lailson-Brito Jr.; M.C.O. Santos; P.A.C. Flores; A.R. Martin; A.F. Azevedo; A.B.L. Fragoso; R.C. Zanelatto & A.M. Solé-Cava (2005). "Riverine and marine ecotypes of Sotalia dolphins are different species". Marine Biology. 148 (2): 449–457\. Bibcode:2005MarBi.148..449C. doi:10.1007/s00227-005-0078-2. S2CID 49359327.
10. ^ Caballero, S.; F. Trujillo; J. A. Vianna; H. Barrios-Garrido; M. G. Montiel; S. Beltrán-Pedreros; M. Marmontel; M. C. Santos; M. R. Rossi-Santos; F. R. Santos & C. S. Baker (2007). "Taxonomic status of the genus Sotalia: species level ranking for "tucuxi" (Sotalia fluviatilis) and "costero" (Sotalia guianensis) dolphins". Marine Mammal Science. 23 (2): 358–386\. Bibcode:2007MMamS..23..358C. doi:10.1111/j.1748-7692.2007.00110.x.
11. ^ Secchi, E.; Santos, M.C. de O.; Reeves, R. (2018). "Sotalia guianensis". IUCN Red List of Threatened Species. 2018: e.T181359A144232542. doi:10.2305/IUCN.UK.2018-2.RLTS.T181359A144232542.en. Retrieved 12 November 2021.
12. ^ Caballero, S.; Trujillo, F.; Vianna, J. A.; Barrios-Garrido, H.; Montiel, M. G.; Beltrán-Pedreros, S.; Marmontel, M.; Santos, M. C.; Rossi-Santos, M.; Santos, F. R.; Baker, C. S. (2007). "Taxonomic Status of the Genus Sotalia: Species Level Ranking for "Tucuxi" (sotalia Fluviatilis) and "Costero" (sotalia Guianensis) Dolphins". Marine Mammal Science. 23 (2): 358–386\. doi:10.1111/j.1748-7692.2007.00110.x. ISSN 1748-7692. Retrieved 28 December 2024.
13. ^ Flach, Leonardo; Flach, Patricia Amaral; Chiarello, Adriano G. (15 February 2023). "Density, abundance and distribution of the guiana dolphin, (Sotalia guianensis van Benéden, 1864) in Sepetiba Bay, Southeast Brazil". J. Cetacean Res. Manage. 10 (1): 31–36\. doi:10.47536/jcrm.v10i1.657. Retrieved 28 December 2024.
14. ^ Araújo, Janaina P.; Souto, Antonio; Geise, Lena; Araújo, Maria Elisabeth (2008). "The behavior of Sotalia guianensis (Van Bénéden) in Pernambuco coastal waters, Brazil, and a further analysis of its reaction to boat traffic". Revista Brasileira de Zoologia. 25: 1–9\. doi:10.1590/S0101-81752008000100001. ISSN 0101-8175.
15. ^ a b Berta, Annalisa, editor. Whales, Dolphins & Porpoises: A Natural History and Species Guide. University of Chicago Press, 2015.
16. ^ Weber Rosas, Fernando C.; Monteiro-Filho, Emygdio L. A. (2002). "Reproduction of the Estuarine Dolphin (Sotalia guianensis) on the Coast of Paraná, Southern Brazil". Journal of Mammalogy. 83 (2): 507–515\. doi:10.1644/1545-1542(2002)083<0507:ROTEDS>2.0.CO;2.
17. ^ "Dolphins seen trying to kill calf". BBC News. 18 May 2009. Retrieved 30 April 2010.
18. ^ a b Nery, M. F.; S. M. Simão (2009). "Sexual coercion and aggression towards a newborn calf of marine tucuxi dolphins (Sotalia guianensis)". Marine Mammal Science. 25 (2): 450–454\. Bibcode:2009MMamS..25..450N. doi:10.1111/j.1748-7692.2008.00275.x.
19. ^ a b "Appendix II Archived 21 February 2012 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. Convention on Migratory Species page on the Guiana dolphin Archived 20 May 2013 at the Wayback Machine
20. ^ "Rio 2016: Dolphins threatened by toxic waters where sailing event to be held". Australian Broadcasting Corporation. 27 June 2016. Retrieved 16 July 2016.
21. ^ Sarah Brown (30 April 2024). "Education & research bring Rio's dolphins back from the brink of extinction". Mongabay. Retrieved 14 May 2024.

## External links

[edit]

* Whale and Dolphin Conservation Society (WDCS)

* v
* t
* e

Extant Cetacea species

* Kingdom Animalia
* Phylum Chordata
* Class Mammalia
* Infraclass Eutheria
* Superorder Laurasiatheria
* Order Artiodactyla
* Suborder Whippomorpha

Parvorder Mysticeti (Baleen whales)

| Balaenidae|

| Balaena|

* Bowhead whale (B. mysticetus)

|

Eubalaena
(Right whales)|

* Southern right whale (E. australis)
* North Atlantic right whale (E. glacialis)
* North Pacific right whale (E. japonica)

Balaenopteridae
(Rorquals)|

| Balaenoptera|

* Common minke whale (B. acutorostrata)
* Antarctic minke whale (B. bonaerensis)
* Sei whale (B. borealis)
* Bryde's whale (B. brydei)
* Pygmy Bryde's whale (B. edeni)
* Blue whale (B. musculus)
* Omura's whale (B. omurai)
* Fin whale (B. physalus)
* Rice's whale (B. ricei)

|

Eschrichtius|

* Gray whale (E. robustus)

Megaptera|

* Humpback whale (M. novaeangliae)

Cetotheriidae|

| Caperea|

* Pygmy right whale (C. marginata)

|

Parvorder Odontoceti (Toothed whales)

| Delphinidae
(Oceanic dolphins)|

| Cephalorhynchus|

* Commerson's dolphin (C. commersonii)
* Chilean dolphin (C. eutropia)
* Heaviside's dolphin (C. heavisidii)
* Hector's dolphin (C. hectori)

|

Delphinus|

* Common dolphin (D. delphis)

Feresa|

* Pygmy killer whale (F. attenuata)

Globicephala
(Pilot whales)|

* Short-finned pilot whale (G. macrorhynchus)
* Long-finned pilot whale (G. melas)

Grampus|

* Risso's dolphin (G. griseus)

Lagenodelphis|

* Fraser's dolphin (L. hosei)

Lagenorhynchus|

* White-beaked dolphin (L. albirostris)
* Atlantic white-sided dolphin (L. acutus)
* Peale's dolphin (L. australis)
* Hourglass dolphin (L. cruciger)
* Pacific white-sided dolphin (L. obliquidens)
* Dusky dolphin (L. obscurus)

Lissodelphis
(Right whale dolphins)|

* Northern right whale dolphin (L. borealis)
* Southern right whale dolphin (L. peronii)

Orcaella|

* Irrawaddy dolphin (O. brevirostris)
* Australian snubfin dolphin (O. heinsohni)

Orcinus|

* Orca or killer whale (O. orca)

Peponocephala|

* Melon-headed whale (P. electra)

Pseudorca|

* False killer whale (P. crassidens)

Sotalia|

* Tucuxi (S. fluviatilis)
* Guiana dolphin (S. guianensis)

Sousa
(Humpback dolphins)|

* Indo-Pacific humpback dolphin (S. chinensis)
* Indian Ocean humpback dolphin (S. plumbea)
* Australian humpback dolphin (S. sahulensis)
* Atlantic humpback dolphin (S. teuszii)

Stenella|

* Pantropical spotted dolphin (S. attenuata)
* Clymene dolphin (S. clymene)
* Striped dolphin (S. coeruleoalba)
* Atlantic spotted dolphin (S. frontalis)
* Spinner dolphin (S. longirostris)

Steno|

* Rough-toothed dolphin (S. bredanensis)

Tursiops
(Bottlenose dolphins)|

* Indo-Pacific bottlenose dolphin (T. aduncus)
* Burrunan dolphin (T. australis)
* Tamanend's bottlenose dolphin (T. erebennus)
* Common bottlenose dolphin (T. truncatus)

Monodontidae|

| Delphinapterus|

* Beluga whale (D. leucas)

|

Monodon|

* Narwhal (M. monoceros)

Phocoenidae
(Porpoises)|

| Neophocoena
(Finless porpoises)|

* Indo-Pacific finless porpoise (N. phocaenoides)
* Yangtze finless porpoise (N. asiaeorientalis)
* East Asian finless porpoise (N. sunameri)

|

Phocoena|

* Spectacled porpoise (P. dioptrica)
* Harbour porpoise (P. phocoena)
* Vaquita (P. sinus)
* Burmeister's porpoise (P. spinipinnis)

Phocoenoides|

* Dall's porpoise (P. dalli)

Physeteridae|

| Physeter|

* Sperm whale (P. macrocephalus)

|

Kogiidae|

| Kogia|

* Pygmy sperm whale (K. breviceps)
* Dwarf sperm whale (K. simus)

|

Iniidae|

| Inia|

* Araguaian river dolphin (I. araguaiaensis)
* Bolivian river dolphin (I. boliviensis)
* Amazon river dolphin (I. geoffrensis)

|

Lipotidae|

| Lipotes|

* Baiji (L. vexillifer)

|

Platanistidae|

| Platanista|

* Ganges river dolphin (P. gangetica)
* Indus river dolphin (P. minor)

|

Pontoporiidae|

| Pontoporia|

* La Plata dolphin (P. blainvillei)

|

Ziphiidae
(Beaked whales)|

| Berardius|

* Arnoux's beaked whale (B. arnuxii)
* Baird's beaked whale (B. bairdii)
* Sato's beaked whale (B. minimus)

|

Hyperoodon
(Bottlenose whales)|

* Northern bottlenose whale (H. ampullatus)
* Southern bottlenose whale (H. planifrons)

Indopacetus|

* Tropical bottlenose whale (I. pacificus)

Mesoplodon
(Mesoplodont whales)|

* Sowerby's beaked whale (M. bidens)
* Andrews' beaked whale (M. bowdoini)
* Hubbs' beaked whale (M. carlhubbsi)
* Blainville's beaked whale (M. densirostris)
* Ramari's beaked whale (M. eueu)
* Gervais's beaked whale (M. europaeus)
* Ginkgo-toothed beaked whale (M. ginkgodens)
* Gray's beaked whale (M. grayi)
* Hector's beaked whale (M. hectori)
* Deraniyagala's beaked whale (M. hotaula)
* Strap-toothed whale (M. layardii)
* True's beaked whale (M. mirus)
* Perrin's beaked whale (M. perrini)
* Pygmy beaked whale (M. peruvianus)
* Stejneger's beaked whale (M. stejnegeri)
* Spade-toothed whale (M. traversii)

Tasmacetus|

* Shepherd's beaked whale (T. shepherdi)

Ziphius |

* Cuvier's beaked whale (Z. cavirostris)

Taxon identifiers

Sotalia guianensis|

* Wikidata: Q2649322
* Wikispecies: Sotalia guianensis
* BioLib: 1437046
* BOLD: 722432
* CoL: 6YVS3
* CMS: sotalia-guianensis
* EoL: 46559311
* GBIF: 2440542
* iNaturalist: 112853
* IRMNG: 11773690
* ITIS: 770938
* IUCN: 181359
* MDD: 1006431
* NCBI: 338729
* Observation.org: 595965
* OBIS: 344009
* Open Tree of Life: 250045
* Paleobiology Database: 69750
* SeaLifeBase: 152260
* Species+: 10624
* WoRMS: 344009

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