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5 The Amazonian Manatee Miriam Marmontel, Fernando C. Weber Rosas, and Sarita Kendall Among the sirenians, the Amazonian manatee (Triche­ chus inunguis) is the only endemic species in the Amazon Basin and the only sirenian restricted to freshwater systems. Indigenous groups living in areas where the Amazonian manatee occurs have their own names for the species (yacu-huagra in Kichwa, entsania-yawa in Shuar, siáya-wêkî in Siona, airuwe in Ticuna, and yuwara in Cocama and Yagua). Non-Indigenous terms liken the manatee to land cattle (vaca de água, vaca del Amazonas , manatí, or vaca marina in Spanish, and peixe-boi in Portuguese), names that reflect the large, round nostrils both animals have in common, in addition to their shared herbivorous diet. The Amazonian manatee is probably a branch of the trichechids that invaded the Caribbean region in the early Miocene epoch and then became isolated in the Amazon Basin after the origin of the Andes in the early Pliocene, some 5 million years ago1. The species inhabits lakes, rivers and channels of white, black, and clear water in the Amazon region2 (map 5.1). However, highly productive white water is the preferred habitat of the species. Manatees have played a significant role in Amazon basin culture, having been hunted for subsistence by Indigenous people for hundreds of years3. Exploitation by non-Indigenous peoples apparently started in 1542 when Francisco de Orellana and crew went down the Amazon and were offered manatee meat by the Indians. Despite protective legislation currently in place, manatees are hunted to this day throughout the Amazon. While fishers with harpoons are currently the main threat, other more efficient techniques have reached the backwaters of the Amazon and may be on the increase. In particular, the use of nets is on the rise everywhere and presents a threat of both accidental and deliberate capture. The huge dimensions and complexity of the Amazon region make estimating the size of the population a real challenge. The manatee has been under pressure from human activities for centuries (including hunting, pollution , and habitat destruction), and there is good reaTrombeta s P u r u s M a r añón Negro Coari Napo Tigre COLOMBIA VENEZUELA PERU ECUADOR BOLIVIA BRAZIL GUYANA SURINAME FRENCH GUIANA Caribbean Sea Pacific Ocean Atlantic Ocean . Manaus Quito Lima Caracas . . . . .Georgetown .Paramaribo .Cayenne .Belém . Amazonian Manatee River Range Equator Putumayo T o c a n ti n s Caquet Japurá J u t a i J u r u á T e f é Solimões T a p a j ó s Marab Bogotá 500 miles 800 kilometers N X in g u M adeira U c a i a l i B r a n c o Amazonas 60 0 Map 5.1. Amazonian manatee distribution. (Map by Ellen McElhinny.) 48 Section I: Regional Issues in Sirenian Conservation son to believe the population level is below the carrying capacity of its environment4. In this chapter we present the general biology, habitat use, current status, and main threats and include recommendations for the manatee’s conservation. Distribution and Habitat Needs Amazonian manatees have a wide distribution, ranging from the headwaters in Ecuador, Peru, and Colombia to the estuary in Brazil. They are typically found throughout lowland forested areas at altitudes below 300 m. Manatees are rare in some areas and have been extirpated in others5. The largest populations probably occur in the Brazilian Amazon, most notably in the Solimões, Negro, Japurá, Juruá, Tocantins, and Tapajós river systems . Most records in Ecuador are from the extreme northeast6. In Peru, Amazonian manatees occur in the Samiria, Pacaya, and Yanayacu-Pucate rivers7 and in the Javari and Amazonas rivers near the Colombian border . In Colombia they also occur in the Amazon, Putumayo , and lower Caquetá rivers. All through their range manatees occupy a great range of black and mixed-water lakes, including large expanses of várzea (floodplains and seasonally flooded forest) and igapó (permanently waterlogged swamp forest)8. Amazonian manatees prefer shallow, 1–4 m deep, calm waters away from human activities with easy access to patches of aquatic vegetation. Annual variation in river levels through the Amazon Basin may reach 10–15 m. The seasonal variation of water levels profoundly influences manatee life in terms of both feeding and protection from human predation. Amazonian manatees undertake long seasonal movements, using lakes and várzea areas during high waters when the production of aquatic plants increases. As observed in the midSolim ões area in Brazil...

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