Jews from Portugal?

[Duncan Bennie]

Hi everyone, I was hoping someone can help me with this. One of my ancestors was a Portuguese sailor for the British East Indian Company. His ship wrecked at the Cape of Good Hope and he remained there, and joined the service of the Dutch East Indian Company.

Extensive research has been done on him in the Archives of Lisbon. His mother was the daughter of one Sebastiao da Costa. Which many sources state implies that he is descendent from the Portuguese Jewish community. I know that da Costa was a name used by Jewish converts to Roman Catholicism. What I would like to know is the prevalence of the surname amongst the rest of the population that is not of Jewish ancestry. Sebastiao da Costa lived in Alcantara in the 1600's, their minor daughter married in 1679.

Kind Regards

Duncan