Gulf of Saint-Lawrence

The Gulf of Saint Lawrence joined Atlantic fisheries to the great river leading into northeastern North America. Cartier explored the gulf in 1534 and entered the river on his voyage of 1535–1536, using knowledge acquired from Indigenous people. European sailors were already developing seasonal fisheries: Basque cod voyages are documented from the 1520s and 1530s, before specialised whaling expeditions expanded in the late 1540s.

Shore stations turned catches into goods for distant markets. Around the Strait of Belle Isle, small chalupas pursued whales, while crews rendered their blubber into valuable oil. As whaling there declined around 1600, activity continued elsewhere in the gulf, including its north shore and islands. French colonial shipping also depended on these approaches. Louisbourg, on Cape Breton, protected fisheries, offshore commerce and the entrance towards Quebec. British forces captured it in 1745 and again in 1758; its subsequent demolition marked a decisive change in the military control of the gulf's Atlantic gateway.