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6 The West African Manatee Akoi Kouadio The West African manatee (Trichechus senegalensis) is a slow-moving, herbivorous aquatic mammal found in shallow coastal waters, rivers, estuaries, and lagoons. Until fairly recently the West African manatee was among the “forgotten” marine mammals, the sirenian about which the least was known. Only a handful of individual scientists had attempted to carry out preliminary studies on the distribution and biology of the species. A broad-scale survey, based mostly on information gleaned from fishermen, was first conducted by Nishiwaki et al.1, who visited 13 African countries in July–August 1980 and January–March 1981. These authors presented a regional picture of the manatees and reported numerous animals occupying a variety of habitats. Reeves et al.2 studied the West African manatee in Sierra Leone and Nigeria, while Roth and Waitkuwait3 investigated manatee distribution and status in Côte d’Ivoire. More recently, Powell4 spent nine years in West Africa studying manatee biology and management in seven countries. His report contains perhaps the best current presentation of regional information. Research on the biology and the ecology of the West African manatee was conducted by Akoi5, who tagged and tracked 18 animals in the lagoon complex of Fresco in Côte d’Ivoire from April 2000 to September 2002. This lack of information is in part due to the fact that the species lives exclusively in less-developed countries, where research funding is inadequate and field conditions are harsh. The conservation and management of a species for which so little information exists remains a real challenge. This chapter aims to provide some baseline information on the species’ distribution, its value to people, threats to its survival, local beliefs, and conservation efforts undertaken to date. West African manatees are very similar to West Indian manatees in their exterior morphology. However, experts familiar with the appearance of both species have noted that the West African manatee is less robust, more fusiform in shape, and its eyes protrude slightly more from their sockets. An average adult West African manatee is about 3 m in length and weighs from 450 to 500 kg, although some exceptional individuals can reach 4 m long and weigh more than 1,000 kg. Eighteen manatees (eight males and ten females) trapped and tagged in the Fresco lagoon complex in Côte d’Ivoire had a body length from 2.04 m to 2.94 m, with a mean length of 2.57±0.25 m. West African manatees are mostly solitary animals that spend most of their time resting, traveling, feeding, and cavorting. In Gabon, Keith6 has documented manatees sighted in groups in 22% of total sightings (n=44); groups are also reported frequently in Angola and Senegal . Although little is known about the feeding behavior of the West African manatee, the species is believed to have a diverse diet. Recent studies suggest that their diet mostly consists of emergent grasses, plants, and even fruits that fall into the water7. Distribution The West African manatee is found along Africa’s Atlantic coast from the Senegal River in the north to the Longa River of Angola in the south8. Manatees have also been recorded far inland, some 2,000 km from the sea in the Niger River from Koulikoro to Gao, in Lakes Debo and Léré in Mali, and in Lake Tréné in Chad (map 6.1). West African manatees are believed to inhabit practically all aquatic habitats. Optimal habitats, however, based on reported sightings in various areas, are coastal lagoons and estuaries with abundant growth of mangrove or emergent herbaceous vegetation9. Population Trends and Threats to Survival A population estimate has never been produced for the West African manatee. Past and current population sizes are unknown, but it is believed that the population has drastically declined and that several local populations have been extirpated. Manatees here are subjected to a The West African Manatee 55 number of human impacts, and the species’ long-term decline in many areas is probably caused principally by subsistence and commercial hunting. The only known significant predator is man. The species continues to be taken for consumption throughout its range, and manatee meat is frequently sold openly in local markets and sometimes exported to other countries. In Côte d’Ivoire around six manatees are believed to be killed per village in the coastal area every year10. The animals are caught in traps constructed of multiple wooden sticks, secured together with vines and sunk...

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