Camila Carvalho de Carvalho
Other projects
29 Jun 2016
Exploring the Use of Side-Scan Sonar to Provide Population Estimates of Amazonian Manatees in the Amanã Sustainable Development Reserve, Amazonia, Brazil
Aerial and boat-based visual surveys are relatively ineffective to detect the discreet Amazonian manatees (Trichechus inunguis) in complex riverine habitats. The species is classified as Vulnerable on the IUCN Red List of Threatened Species and on the list of endangered species in Brazil, since there is a suspected population decline in the next generations. This population trend is a reflex of the intensive commercial hunting in the past and the persisting hunting activities nowadays. Therefore, it is important to develop an efficient and replicable method to estimate the abundance and density of manatees over the distribution area. Initially, previous work using the side scan sonars in the Brazilian Amazon were not successful to detect the manatees in large lakes and rivers.
Camila and Antonio Looking at the side-scan sonar screen searching for manatees.
Taking this experience into account, the new idea is to validate the images in a semi-captivity and to carry out surveys in narrow and shallow water bodies, with distinct water characteristics from previous surveyed areas. The transect locations will be defined based on the traditional ecological knowledge through the elaboration of mental maps collectively.
The final and desired goal is to have a robust number of manatee detection to provide an abundance estimative. This data will be important to assess the conservation status of the species and design regional strategies in partnership with the stakeholders, achieving the established goals of the National Action Plan of Sirenia. The improvement of the sonar use is a promising technique to have an unprecedented abundance estimate for this species in Brazil.
Header: Realizing transects by boat using side-scan sonar at Amanã Lake.