The Portuguese were some of the earliest fishermen to visit Placentia. Historians generally agree that the first of all peoples to exploit the Newfoundland fisheries were the Portuguese. In 1507, the fishing trade had assumed such importance in this country that King Emmanuel le Fortune imposed a tax on cod imports .
The Placentia area was explored by the Portuguese navigators, Gaspar and Miguel Corte Real. Gaspar Corte Real sailed to Newfoundland in 1500 and he was followed by other great Captains of discovery, who sailed into Placentia Bay or Bay St. Andrew as it was then called. In 1501, Gaspar made the first map of Newfoundland, and in 1503, a Portuguese expedition searching for the Cort Reals made a second map. The Portuguese at that time were among the greatest navigators of the world.
A legend that the Corte Reals had a colony at Placentia tells of the navigator planting a flag and a priest saying mass on the beach. This may have stemmed from the fact that the Cort Reals gave their name to the Placentia area for the "Reinal Map" of 1504, shows it has the "Insulae Cortrealis". It appears that the Corte Reals explored the eastern and southern coast of the island, landing at various places, where they raised flags to mark the places. It seems that it was from these landings that the legend of the Corte Reals' Colony at Placentia had its origin.
By 1547, the name had changed to a variation of its present name, for the "Kallard Map" of that year shows the area as the "Isle de Plaziencia". It is believed that the Portuguese built the first church on the Jerseyside of Placentia on the site of Fort Louis Park.
The Portuguese played a significant role in the early fishery but seemed to give way to other European nations such as France and England. Documents of 1504 bear witness to the Bretons in Newfoundland territory by the Portuguese, or Lusitanian-Portuguese maps which confirm this by the following reference: "c. do bretaos; tierra de los bretones..."