Survey of the manatee´s (Trichechus manatus, Linnaeus, 1758) distribution, occurrence and status of conservation in the northeast coast of Brazil

Abstract

In the early 80's the first survey was conducted on the distribution of marine manatees in Brazil, which pointed out the north and northeast coasts as areas of occurrence, and recorded its disappearance in the Espirito Santo and Bahia States. Considering the absence of recent data, this study aimed to update existing information on the distribution and areas of occurrence of the Trichechus manatus in the Northeastern coast of Brazil, as well as evaluating the conservation status of species and to support the work of preserving this sirenian. The survey was conducted during the years 1990 and 1991 from the coast of Sergipe to Piaui. A questionnaire with eight questions was used being applied to fishermen. When we confirm the importance of location for the occurrence of the manatee, nautical raids were carried out in order to spot the animals, environments and recognition of the major threats to the species. The displacements along the study area were performed by a 4x4 Toyota Bandeirante, called "Igarakue." After 16 months of activities, the mobile unit "Igarakue" had travelled almost all the villages and coastal regions of seven northeastern states (Sergipe, Alagoas, Pernambuco, Paraiba, Rio Grande do Norte, Ceara and Piaui), with 552 interviews conducted in 199 locations . Worryingly it was observed the disappearance of the species in the Sergipe State, the isolation of populations present in the Alagoas State and the presence of discontinuous areas along the distribution in other states. The estimated abundance for the study area, with the minimum number of 117 specimens and a maximum of 242 specimens, where data showed a decrease in the total number of manatees sighted in recent decades. The marine environment has been indicated as the site of highest number of sightings and it was observed in the northeastern coastal region the presence of habitats favorable to the occurrence of the species. However, the siltation of rivers and bars, the rectification of river beds for agricultural purposes, deforestation of mangroves, pollution of water resources are some of the factors noted that compromise threatens habitats of manatees and sea irreversibly therefore the species. The harpoon was the main form of capture recorded in the history of hunting, but has not been widely used. The mortality of the animals is linked to events surrounding the stranding of puppies, accidental capture in fishing nets and stalls, hauls made by motorized boats and the use of explosives in fishing activities. From the results obtained, it is recommended the continuation of awareness campaigns along the northeast coast, the monitoring in the main areas of occurrence, the creation of protected areas, environmental education and the inclusion of sites with the highest occurrence of manatees and marine priority areas in the National Plan of Coastal Management.