Can The Estuarine Dolphin (Sotalia Guianensis)
Be Classified As Vulnerable Species
In Maranhão Coast, Northeastern Brazil?

By Carolina Tosi, Fagner Magalhães and Rosana Garri,
Maranhão State Cetacean Project

(One example of CSI's 79 grants provided in 2006
to support science, education and conservation projects)

The estuarine dolphin Sotalia guianensis is listed as "insufficiently known" by the IUCN - The World Conservation Union - although it presents a continuous distribution from southern Brazil to the border of Nicaragua and Honduras, in Central America. Recently, during the 1st Workshop on Research and Conservation of the Genus Sotalia, the species was subdivided in two: the tucuxi (Sotalia fluviatilis), which inhabits the Amazon River basin, and the estuarine dolphin (Sotalia guianensis) called by most Brazilians as the "boto-cinza". The incidental capture in gill nets represents the most serious threat to this species in Brazil, due to their preference for coastal and estuarine brackish waters.

The by-catch of dolphins from artisanal fishing in Maranhão State is possibly causing a serious threat to these dolphins' populations. As a result of PROCEMA/ICEP expeditions, interviews with fishermen revealed a common practice of meat consumption in the west coast of Maranhão. Field work is limited by the distance of this area from the São Luís, Maranhão state capital (approximately 200 km). The precarious conditions of some communities and social problems such as hunger are motivating the use of cetaceans as an animal protein source. It has also been observed the trading of teeth, dried eyes and genitals as love charms. This practice is a way of enhancing a better condition of life.

The by-catch of marine mammals in fishing gear could be affecting even more sharply the status of the most vulnerable species along the Brazilian coast. This assessment would be necessary in order to identify and measure the impact of human interactions and to apply policies tending to reduce by catch. The preliminary observations suggest that S. guianensis distribution would be seriously affected due to human activities along the Maranhão State coast.

Figure 1. Meat consumption by fishermen of estuarine dolphin,
Sotalia guianensis, in the west coast of Maranhão.
Photo by Carolina Tosi

In order to minimize the human impacts, the PROCEMA/ICEP is working extensively with coastal communities, trying to bring new alternatives of living to fishermen. A project will be developed by using diverse techniques of recycling, cultivation of fish, honey and workmanship.

During the present environmental education, the researchers have observed that some fishermen were interested in collaboration with the studies. Information about nets were collected and it was concluded that gillnets (60%) are the main type of nets that causes cetacean by catch in Maranhão State. The researchers have used some techniques to reach better results on the education programs, such as etnoecology which works as a tool for environmental education, by collecting specific information that will be used to subsidize the communities' work programs.

The information presented above has shown that S. guianensis may be classified as "vulnerable" for the Maranhão coast and possibly, in accordance with the work presented by Fernando Rosas in 2006, include the species as "vulnerable" in the IUCN Red Data Book.

Figure 2. Breaching estuarine dolphin S. guianensis in
São Marcos Bay, Maranhão State, Brazil.
Photo by Pedro Habibe