Observation and photo identification of Lahille's bottlenose dolphins in the Lagoa dos Patos in Brazil with our research boat Charlotte. These trips take place regularly and are very important for the registration of the population in the Lagoa dos Patos. The photo ID method is based on the distinguishing feature of the dolphins' dorsal fin, as it is different for each animal. In this way, individual animals can be identified and the total population can be estimated. With the help of a database, the animals can be recognized and sightings registered.