Sousa teuszii – Atlantic Hump-backed Dolphin

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Sousa teuszii – Atlantic Hump-backed Dolphin (Kükenthal, 1892)

A Synopsis by Felix Olusola Abayomi

Sousa teuszii

Ecosystem Role

Imagine going a fishing and you have a partner in the waters that helps you concentrate the fishes near the shore, supporting you like a hunting dog supports a hunter in the forest? That is what the Atlantic Hump-back Dolphin does for man. They help fishermen to meet Economic demands for their own livelihoods; other livelihoods in that value chain and supply of fish resources for food security.
They impact the Coastal fish populations of Western Africa positively. They have to hide from Killer Whales during all stages of their life by taking refuge near the shore and the coral reef, they shouldn’t be worried about humans who they help by schooling fishes into shore. How do we pay them back? We hunt them.

So when next you see a fishermen complain of no fish-catch or low fish-catch or high cost of fishes in Market, know that we have removed the one species that helps hurl fishes in ashore from the ocean by their eating habits as Piscivores (Animals that feed on Fish) by our own eating habits by hunting and eating them to extinction

Conservation Status

The Atlantic humpbacked dolphin is listed in International Union of Conservation of Nature and Natural Resources (IUCN) and on the Appendices of the Convention on International Trade in Endangered Species in Wild Fauna and Flora (CITES) and that of the Convention on Migratory Species (CMS). This indicates that this is a species that would benefit from International co-operation, with regards to its Conservation, and the Conventions encourages the relevant countries to implement suitable conservation measures. Considering its specific habitat preferences, estimated low abundance and the threats it faces, the Atlantic humpbacked dolphin is likely to be in great need of further research and conservation measures.

IUCN lists them as Vulnerable, that is the species face a high risk of Extinction in the wild and population trend decreasing.

CITES has also Listed this species as an Appendix I Endangered species thereby regulated its International Trade, which is not permitted for commercial purposes.

Description

Atlantic humpbacked dolphins have a long, distinct beak, single blow-hole, broad flippers with rounded tips, and a moderately deepened tail stock, with a prominent Median notch. The dorsal fin is variable in shape, but generally emerges from a wide hump or ridge on the animal’s back. Colouration is also variable. Animals are slate grey on the sides and back, and light grey below.

Adults are up to about 2.8 m in length, and weigh up to 284 kg. Length at birth is thought to be about 1 m.

Sousa teuszii - Compressed Image.JPG

Behaviour

The Atlantic humpbacked dolphin is a slow swimming species, which typically moves at about five kilometres per hour, surfacing briefly every minute or so. Typically occurring in groups of Four (4) to seven (7) individuals, the Atlantic humpbacked dolphin, unlike many other dolphins, will avoid boats and is rarely seen bow riding. This dolphin may also emit whistles and screams, vocalisations which may be important in communication with other dolphins. (Ross, G.J.B. 2002)

Diet

Groups often feed very near shore. Hump-backed dolphins feed near shore on schooling fishes such as Mullet (Mugil Spp), a cosmopolitan species throughout coastal tropical to warm temperate waters. Ethmalosa fimbriata.Which occur along the coasts and in the brackish water of coastal lagoons, rivers and lakes of West Africa, have been found in their guts and, contrary to some descriptions, probably do not eat vegetable matter. Off the coast of Mauritania, fishermen using beach seine’s cooperate with Atlantic hump-backed and bottlenose dolphins to capture mullet. (Van Waerebeek et al.2004).

Geographical Distribution

Distribution in Nigeria is said to be uncertain by CITES but we in Nigeria have evidence that these species are distributed in Nigeria.

Atlantic hump-backed dolphins occur off tropical to subtropical West Africa, from Mauritania south to at least Cameroon, possibly to northern Angola. They are found primarily in estuarine, river delta, Mangroves and coastal waters. Some hump-backed dolphins inhabit rivers, such as the Niger, but it is not known if there are separate freshwater populations. They have both Freshwater and Marine systems.

Threats and Exploitation

Direct threats to Hump-backed dolphins is Habitat loss, Mangrove destruction and excessive fishing of their fish food source, especially by offshore foreign fishing. They are also caught as by-catch in commercial fishing nets, beach seine’s and shark nets. There is apparently also direct hunting and capture for human consumption.

Conservation Actions

Conservation Action for this threatened and Endangered Atlantic Humpback Dolphins is in creating a safer coastal habitat for them and eliminating captures.This will assure the long-term viability, stabilized and growing populations and their health.

This measure will also have an umbrella effect on other endangered species like the African Manatee and the Marine Turtle species.

Some of the activities that can be carried out include but not limited to:

  1. Increasing community awareness of the species’ importance, ecosystem roles, rarity and benefits that could accrue from its conservation in targeted local coastal communities with a clearly defined Conservation Goal;
  2. Education, Management and Monitoring of local fishermen, local fishing and offshore fishing companies on proper Seine/net size and type and importance of returning those caught as by-catch back into the waters.
  3. Establishment of inshore fisheries exclusion zones.
  4. Patrols in the coastal waters in order to eradicate illegal fishing by trawlers.
  5. National Enlightenment programmes to cultivate in the citizenry a sense of Natural Resource Ownership.

References

  1. Jefferson, T.A., S. Leatherwood, and M.A. Webber. FAO species identification guide. Marine mammals of the world. Rome, FAO. 1993.320. p. 587 figs.
  2. Ross, G.J.B. (2002) Humpback dolphins. In: Perrin, W.F., Würsig, B. and Thewissen, J.G.M. (Eds) Encyclopedia of Marine Mammals. Academic Press, London.
  3. Reeves, R.R., Smith, B.D., Crespo, E.A. and Notarbartolo di Sciara, G. (2003) Dolphins, Whales and Porpoises: 2002–2010 Conservation Action Plan for the World’s Cetaceans. IUCN/SSC Cetacean Specialist Group, IUCN, Gland, Switzerland and Cambridge, UK.
  4. Van Waerebeek et al.2004. Distribution, Status, and Biology of the Atlantic humpback dolphin. Sousa teusziii Aquactic mammal, 30(1) 56 – 83
  5. 1922. “Guide to the Whales, Porpoises, and Dolphins (Order cetacea)” (On-line). HathiTrust. Accessed March 18, 2011 at http://catalog.hathitrust.org/Record/001502709.
  6. 2001. Conservation and management of humpback dolphins: the South African perspective. Oryx, 34/3: 207-216. Accessed April 21, 2011 at http://onlinelibrary.wiley.com.proxy1.cl.msu.edu/doi/10.1046/j.1365-3008.2000.00120.x/abstract.
  7. 1998-2998. “Atlantic Hump-backed Dolphin, Sousa teuszii” (On-line). Marine Bio. Accessed March 14, 2011 at http://marinebio.org/species.asp?id=344.
  8. 2008. “Atlantic Hump-backed Dolphin” (On-line). Accessed March 14, 2011 at
    http://www.sci.tamucc.edu/~wcrc/cetaceans/world/atlantichumpbackeddolphin.html.
  9. http://animaldiversity.org/accounts/Sousa_teuszii/#conservation_status
  10. www.iucnredlist.org
  11. www.cites.org
  12. www.speciesplus.net
  13. www.cms.int
  14. www.awf.org
  15. www.em.wikipedia.org

First Posted on

Picture Source: Unknown but the Identification is from the Identification Guide in 1 above in the References.

©Felix Olusola Abayomi

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