roaz [tursiops truncatus],
a unique case in Portugal and rare in the world
The resident population of roazes on the Sado and the adjacent marine coast of Tróia and Arrábida, is a singular case in Portugal and a rare one in the world. It is not yet clear for how long the roazes have been living in Sado. It tis likely that they have been living here for a long time. The oldest record of the sight of two dolphins in the Sado, dates from 1863 by the naturalist José Vicente Barboza du Bocage.
the 80’s _ the first studies
The first studies of the Sado roazes population date back to the early 1980s. At that time there were about 40 dolphins but in the last decades there has been a decline. In the 1990s the number of roazes kept an average of 30 individuals. In 2005 we only counted a population of 22 animals. Between 1998 and 2005, we recorded the birth of 14 offspring but only 3 survived. Between 2005 and 2011, 11 offspring were born and 9 survived. Since 2011 the population has remained on an average of 27 dolphins. However, in the last 3 years, we have failed to register the same breeding success: 7 offspring were born and only 3 survived. Currently, the Sado dolphin population remains a threatened and very vulnerable population.