A Radio-Tracking Study of the Amazonian Manatee Trichechus inuguis (Mammalia: Sirenia)

Abstract

A juvenile male Amazonian manatee was captured in the wild, freeze-branded, and held in captivity for 20 months. It was then radio-tagged, translocated into a flood-plain lake system near Manaus, Brazil, and radio-tracked for 20 days. The study was terminated only because of logistical limitations. The 150 mHz transmitter was attached by a collar of machine belting around the caudal peduncle. Tracking was carried out by triangulation from small boats. The manatee spent almost all its time in areas where the food supply was greatest, in newly emerging aquatic vegetation near the edges of expanding lakes, and in floating meadows which were expanding as the water rose. The animal moved about 2.6 km/ day on average and was about equally active during day and night. THE AMAZONIAN MANATEE is endemic to freshwater environments of the Amazon Basin and may be found in the three primary water types of the region: white, black, and clear (Sioli 1956). Manatees occur in lakes, flood plains, and along river channels, wherever there is sufficient vegetation to sustain them (Pereira 1944). This species has a long history of exploitation, both as a food animal and, particularly during the period 1935-1954, for its extremely durable skin which was used in industry for belting material (Ferreira 1903, Carvalho 1967, Pereira 1944, Mendes 1938). During the period of intense commercial exploitation, an estimated 140,000 manatee skins were exported from Amazonia, resulting in severe depletion of manatee