The births take the pod to 30 members, and is one up on 2016, when just two calves were born in the Sado estuary.
The first baby dolphin was born in June, followed by the second in August, and the third and last calf in September.
In a statement, nature protection institute, the ICNF, said it had refrained from announcing the news “to protect the young dolphins”, giving them the best chances of survival.
Their names were recently chosen by pupils at a local primary school.
“Interest and enthusiasm demonstrated by the youngsters of Setúbal was great and reflects the growing interest in the group of Sado bottlenose dolphins that the team at the Sado Estuary Nature Reserve has been accompanying and promoting for some 30 years”, the ICNF said in its note.
Unique to the Sado estuary, the Sado Roaz pod is Portugal’s only resident dolphin community.
After the 1980’s and 1990’s the number of dolphins in the estuary dropped dramatically to around 22 individuals in 2005. Between 1998 and 2005, 14 births were registered but only three remained with the population. Between 2005 and 2011, 11 calves were born of which 9 survived.