Inia araguaiensis, a newly discovered species of river dolphin, is already endangered. A large population lives in Cantão.

Institute Araguaia is using drone photography to monitor the dolphin population in Cantão

How a drone can count dolphins

The Araguaia River Dolphin (Inia araguaiaensis) is one of the rarest and most endangered dolphins in the world. Cantão is home for this species and is a key protected area for its conservation. Instituto Araguaia has tested several methods to study these dolphins since the species was first described in January 2014, by INPA and University of Dundee.  We've surveyed lakes throughout the park and its surroundings and found that in the dry season all of Cantão, dolphins concentrate in a few large lakes whose period of isolation is shorter than most. One aspect of the behavior of Araguaia River Dolphin, distinct from other dolphins in the Amazon basin, is its ability to navigate in extremely shallow waters, pushing their bodies over shallow sandbanks. We developed and tested a method to count the dolphins from the air using drones and balloon cameras, and through field trials established that this was far more accurate than the standard method of counting dolphins from a boat.

Our work focused on comparing the traditional count method using a boat with counts utilising aerial images from drones and balloons. The result of this thesis validated our methodology and we have continued this aerial survey ever since. This method has also allowed us to monitor population trends within the park and to document dolphin behavior. This methodology was  published in the scientific journal ECOSPHERE. Two master’s theses describing the new methodology and dolphin behavior were conducted by graduate students in Instituto Araguaia, thus contributing to the recognition of the new species.

Instituto Araguaia has already adopted Inia araguaiensis as a flagship species, using it in presentations, the Internet, and media interviews to generate public interest for the protection of the species and its habitat. The additional knowledge and images generated by this project will greatly strengthen our ability to do so.

How can dolphins protect a river

In addition to Cantão, Instituto Araguaia performed sample counts of river dolphins throughout the Araguaia basin.  We found groups of Inia araguaiaensis that would become isolated by a dam in the Garças River – a tributary of the Araguaia -  and supported legal action that resulted with the project being suspended until it presents sound solutions to its negative impacts. 

Another tributary, the Formoso River, was being sucked dry by irrigation pumps. Our team rescued stranded dolphins, and obtained coordinates for current and planned projects in the region.  Our technical discussions and our bringing of the issue to the media helped convince authorities to install water level gauges and sealed digital flow meters at irrigation projects, and to order pumps to be stopped whenever river levels became too low.  

Since 2015 Instituto Araguaia has remained committed to monitor and publicize the plight of the Araguaia river dolphin in Cantão and its surroundings, and to work with partners, authorities and the media to ensure that Inia araguaiaensis survives this intensive and widespread change to its ancestral habitat.