The body that manages the Sado Estuary, the RNES (Sado Estuary Natural Reserve), which belongs to the national Institute for Nature and Forest Conservation (ICNF), announced the new arrival this week.
Born in June, the five-month-old calf is the offspring off a female named Bisnau.
The mammal’s birth has remained under wraps until now, as, a statement from the ICNF explained, “the RNES opted to not immediately divulge the birth to protect the new arrival and guarantee the tranquillity necessary for its first few months of life.”
The calf’s name will be chosen by local schoolchildren.
Its arrival takes the overall number of dolphins comprising the Sado pod to 28, which also includes a new adult mammal which joined the pod from the nearby coastline in March and is still in the estuary.
The Sado Estuary is famous for its resident pod of dolphins, which is unique to Portugal and rare throughout the world.
Its population dropped sharply in the 80s and 90s, having reached an all-time low of 25 animals in 2011.
However, a previously high infant death rate now seems to be on the mend and all calves born in recent years with the exception of one have survived and remain in the pod.
One of its oldest known members, Asa, died in August this year, and in 2013 the pod made headlines after a baby dolphin born in the Sado estuary in August that year was attacked and killed by three other young dolphins of its group, in a behavioural incident that was deemed as “unprecedented” in Portugal.
A number of tour companies operate dolphin-watching cruises on the Sado, which is one of the region’s most popular activities in the Setúbal-Troia area.