The study of dolphins has never been an easy task, after all these charismatic animals spend most of their lives underwater. For many decades, studies have extracted as much information as possible from the little that can be recorded when these animals come to the surface to breathe. It’s amazing how many discoveries can be made in such a short time in the life of dolphins, the time of a few sprays. Fortunately, with the improvement of technology, opportunities arise to observe and follow more deeply (and at the bottom of the seas, ponds, and estuaries) the fascinating life of dolphins. Among the new tools nowadays, scientists have come to rely on acoustic monitoring. Dolphins and whales are animals that use sound for many of their life activities. The sounds dolphins make aren’t just used for communication. It is by the sounds that dolphins “see farther” and look for food. They are also able to recognize each other using sounds that represent their names. That’s right, dolphins recognize each other by specific sounds as we recognize each other by our names. Thus, with the possibility of recording the sounds underwater, scientists have opened a huge window to study the lives of these animals. It is this window that we are starting to open in Laguna, to understand the ecology of dolphins and the unique behavior of cooperative fishing.
The first initiative to implement the acoustic monitoring of dolphins in Laguna began in 2018, with a doctoral proposal. In 2020 and 2021, the acoustic monitoring of the population of dolphins in Laguna was effectively carried out: five to six recorders were placed in Santo Antônio pond to record the dolphins for 2-3 consecutive days.These records were made two times in each season in 2020, and a few more times in 2021.The objective of this monitoring is to understand how the dolphins use the pond, especially at night, when it is not possible to make visual records.Do you remember the sound dolphins use to “see”? That sound is called echolocation. It is a good indicator of the presence of the dolphins and allows you to know, through acoustic monitoring, where the dolphins are. Sometimes you can even tell if the porpoise is eating! No, he doesn’t chew with his mouth open, but there is a sound he makes when he catches the fish. What about the history of the dolphins’ “names”? Well, through acoustic monitoring you can even know who was in the area! Preliminary results show that it is also possible to know where the porpoise went, using the records of these sounds (i.e., the whistles), which allow identifying each porpoise individually.
Acoustic monitoring is a complementary method to the studies developed by PELD because it allows monitoring the dolphins day and night, regardless of weather conditions, for several hours in a row. Thus, monitoring of dolphins can take place at night, recording their presence in the ponds system and also how they use the area 24 hours a day. Besides, knowing if dolphins remain in the same areas at night, when fishermen are not present, can help us to understand the interaction between dolphins and fishermen. It is also possible to explore the use of the ponds by boats, as the sound of boats is also recorded. Thus, despite being a fresh initiative, acoustic monitoring is a tool with the potential to answer many questions and help monitor Laguna dolphins. Who knows… perhaps in the future we may be able to identify each porpoise in the population not only by photographs of the dorsal fin but also by the whistles they emit. We’re on the way!