Observation and photo identificationof Lahille's bottlenose dolphins in Lagoa dos Patos, Brazil, with our research boat Charlotte. These trips take place regularly and are very important for recording the population in Lagoa dos Patos. The photo ID method is based on the distinctive characteristics of the dolphins' dorsal fins, as these are different for each animal. This allows individual animals to be identified and the total population to be estimated. With the help of a database, the animals can be recognized and sightings recorded.