Nile Crocodile “Crocodylus niloticus”

The Nile crocodile has various common names across the continent: Mamba (Swahili), Garwe (Shona), Ngwenya (Ndebele), Voay (Malagasy), Kwena (Tswana), Crocodilo (Portuguese), Crocodil du Nil (French), Temsah (Arabic), Denkyem (Twi) (see Figure 1). It belongs to the species Crocodylus niloticus, the most widely distributed crocodile in Africa. There are 23 crocodilian species commonly grouped as alligators, caimans, crocodiles, gharials and false gharials that comprise the order Crocodylia recorded in over 90 tropical countries and islands worldwide. The latter is arranged in three families Alligatoridae, Crocodylidae and Gavialidae.

There are 3 species of crocodilians found in Africa of the Crocodylide family. The most widespread species is the Nile crocodile (Crocodylus niloticus), that is found from South Africa to the South of Egypt and from the Eastern part of Madagascar to the Western parts of Senegal (Figure 2). The Nile crocodile found in the northern parts of West Africa is smaller compared to it compatriots found in the less arid and warmer areas of Africa. The other two species, the slender- snouted (Crocodylus cataplhiactus) and dwarfs crocodiles (Osteolaemuts tetraspis) are found in West and Central Africa from Senegal to Zambia respectively. Furthermore, the Nile crocodile can reach a maximum size of 6 meters weighing up to 730kg with average sizes being 5 meters and 225kg. The African crocodilians are found in Nile Basin, rivers, freshwater marshes and mangroves swamps.

Conservation and Management

The African crocodile were hunted almost to extinction between 1940s and 1960s. Severe pollution and habitat loss have additionally contributed to their decline. The Nile crocodile is now listed in the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) under Appendix I and II, Populations from Botswana, Ethiopia, Kenya, Madagascar, Malawi, Mozambique, Namibia, South Africa, Uganda, the United Republic of Tanzania are subject to an annual export quota of no more than 1,600 wild specimens including hunting trophies, in addition to the ranched specimens in Zambia and Zimbabwe.

The Nile crocodile has a reputation of being a vicious man-eater. It mainly feeds on fish and smaller vertebrates while it predates upon almost all other animals that pass its way such as humans, zebras, small hippopotamus, wildebeest etc. (Figure 3). It consumes half of its body weight at each feeding.

It is assumed that the Nile Crocodile have probably killed more people than all other crocodilian species combined. The challenge is the nonreporting and patchy or even incomplete reporting of the incidences in the African countries (Figure 4). Florida Museum of Natural History museum’s estimated that Nile crocodiles have attacked 480 people with 123 fatalities in Africa between 2010 and 2014. IUCN Crocodile Specialists Group mentioned that Nile crocodile attacks recorded ranged between 275 and 745 per year of which 63% of the attacks are fatal as compared to the saltwater crocodile with estimated 30 attacks per year with 50% fatalities.

Crocodile Farming

In Africa, the crocodile farms breed Nile crocodile which is the second largest breed after saltwater crocodile. The farming of Nile crocodile has become a lucrative business within the aquaculture sector in Africa. Crocodile farming is most prominent in South Africa, Zambia and Zimbabwe and the three countries remain the largest producers of crocodile skins (Figure 5). The East African countries particularly Kenya have well established commercial crocodile farms. Crocodile farming is an expensive venture requiring high capital and technological know-how. For example in Kenya, the start-up costs for crocodile farming are estimated at $500 000 which includes purchasing of land, consultancies work, purchasing crocodile breeding stock. The returns are good though. It takes 5 years to set up a profitable business and develop special diets for the crocodiles such as innards, cooked maize mixed with blood, meat and fish.

Being cold blooded animals, Nile Crocodiles are sensitive to temperature changes. A slight change in their core body temperature, a variance of 3°C, can reduce the rate of metabolism by half and enhance their inability to absorb food and grow as required the same author mentioned that Nile crocodile can mature as early as 3 years old. Despite their reputation as vicious predator, crocodiles have a soft spot for their unborn babies. The female crocodiles can lie between 7 and 77 eggs in one season and are usually incubated at 28-29˚C12. The eggs require 76-90 days to hatch and at that time both parents guard the nests until the eggs hatch and gently roll the eggs until the hatching babies emerge. The hatching takes place within 30 or 40 minutes. The male crocodile usually hatch at 28˚C whereas the female at 29˚C. The male are bigger than female when hatching. The crocodile egg is edible within 4 days otherwise it can be poisonous. Mother usually scoops the hatched babies and held them in a pouch in the bottom of her mouth until the babies are released in safe water and looked after for a period of 6-8 weeks.

Economic Benefits

The Nile crocodile is considered a high valued species for its boneless underbelly and soft leather. In contrast to traditional animal domestication, crocodile is farmed for its high valued skins and meat is the by-product. The crocodiles are slaughtered when four to five years mainly because the meat is tender and skin in good condition. Once deskinned the skin is preserved in four degrees centigrade. In addition, majority of the business sells the hatchlings depending on the age, length and health of the skin. The broodstock is also kept within the farm and some farms acquired licenses to collect crocodile eggs in the wild.

The international trade includes over one million crocodile skins per annum with exports from about 30 countries globally. Furthermore, Africa exports more than 250 000 crocodile skins. The skin is sold according to the belly width and a centimetre of first grade skin (top quality) of the reptile in the international market. The first grade skin is flawless and stains free. The total export for South Africa are valued at $73 m per annum whereas Zambia is $65m, Kenya and Zimbabwe are $62m and $30m respectively10. The main market for the skins is Europe for production of luxury designer handbags, shoes, belts and other leather accessories. Asia countries mainly China, Hong Kong and Taiwan imports African crocodile skins for production of non-branded leather products. Furthermore, the potential markets for Africa crocodile market is Middle East region. South Africa alone has 50 registered crocodile farms housing 500 000 crocodiles and exporting 80 000 crocodile skins worth 12-16 million USD. Kenya has registered 21 crocodile farmers with further 60 applications for license underway by Kenya Wildlife Service.

Apart from selling skins, the other by-products of crocodile farming is meat and classified as white meat (Figure 6). The meat is usually consumed in high-end restaurants especially by tourists seeking exotic food. China and Hong Kong remain the main importers of crocodile meat.

The following byproducts are also used:

• blood (for the pharmaceutical industry as antibiotics)
• bones, fat (for traditional medicines)
• teeth, heads, skulls (tourist curios)

The Chinese tap into the medicinal powers of crocodile meat to cure respiratory diseases. Dr Bodenstein and Professor du Toit of the University of KwaZulu-Natal found that the crocodile oil contain significant amount of in vitro antibacterial activity against the Staphylococcus aureus responsible for skin infections and Klebsiella pneumoniae responsible for lung infections. In addition, the same authors found out that crocodile oil triggered the highest level of antimicrobial activity against the fungus (Candida albicans), the most common fungus in humans.

Diseases Management

The farm management needs to impose strict biosecurity and hygiene measures in order to avoid diseases and produce high quality skins. Unhygienic facilities affect the crocodile’s susceptibility to diseases. One of the deadliest diseases a farmer must avoid is the crocodile pox as no vaccines have been successful and can kill all the crocodiles. It is crucial that each farm implements best management practices.

Interesting facts about Nile Crocodile borrowed from Robert Twigger book about the “Red Nile: A biography of the Worlds Greatest River”:

• Considered as the “land-going equivalent of Great White Shark
• Nile crocodile has 66 teeth
• Possess most sophisticated brain none than any reptile on the world
• Largest animal killers in Africa
• Lives in harmony with its worshipers:
  
  • Ancient Egyptians worshipped Sobek crocodile-god linked with fertility, protection, and the power of the pharaoh. A large crocodile cemetery is located in Tebtunis in the Fayoum oasis
  • Ghanaians particularly small village of Paga can even dry their clothes on their back as they sun bask
• Nile crocodile has the highest bite pressure per square inch with over 6000 pounds
  
  • Hippopotamus has 1820 pounds
  • Snapping turtle has 1000 pounds
  • Lion and great white shark has 600 pounds
  • German Shepard dog has 300 pounds
  • Human bite has 100 pounds
• Weigh up to a ton, that is, weight of Honda civic and Ford fiesta cars
• Standing on its back legs and tail can rise up to 9 feet
• Nile crocodile can lunge from submerged position to up to 30 feet to a beach
• Possess weak jaw opening muscles hence cant chew but prefer sideto-side motion and settle for tearing off chunks  violently from the prey
• Becomes inactive or passive and a signal to rest when mud is applied on their eyes
• Has 3^rd transparent eyelid called nictitating membrane crucial for eyesight underwater

References

1. Tony Mackrill's picture on National Geographic's Your Shot photo community.
2. Fergusson, R.A. (2010). Nile Crocodile Crocodylus niloticus. Pp. 84-89 in Crocodiles. Status Survey and Conservation Action Plan. Third Edition, ed. by S.C. Manolis and C. Stevenson. Crocodile Specialist Group: Darwin.
3. KING, F.W. and BURKE, R.L. (eds.) 1997. Crocodilian, Tuatara and Turtle species of the world. A taxonomic and geographic reference. Association of Systematics Collections, Washington. D.C.
4. Kofron, C. (1992). Status and Habitats of the Three African Crocodiles in Liberia. Journal of Tropical Ecology, 8(3), 265-273. Retrieved from Journal of Tropical Ecology
5. CITES - Nile crocodile
6. CrocBITE (2016). The Worldwide Crocodilian Attack Database, Big Gecko, Darwin, Accessed: 4/16/2016.
7. ”Crocodilian Attacks”. IUCN Crocodile Specialist Group. Retrieved 15 February 2017
8. Croc of gold: Kenya's booming crocodile farm industry
9. Robert Twigger. 2013. Red Nile- A biography of the World Greatest River
10. Crocodile Blood May Yield Powerful New Antibiotics by Michael Perry published on Reuters on the August 17, 2005
11. Crocodile Oil has Healing Properties- University of KwaZulu-Natal (UKZN) Research Finding by Dr Johannes Bodenstein and Professor Karen du Toit
12. Izintaba, Farm Crocodile (Pty) Ltd in South African producer of crocodile skins, meat and leather best quality.
13. Sobek, God of Crocodiles, Power, Protection and Fertility by Caroline Seawright

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