The gulf flows into the Atlantic Ocean through the following outlets:
The Strait of Belle Isle between Labrador and Newfoundland: between 15 kilometres (9.3 miles) and 60 kilometres (37 miles) wide and 60 metres (200 feet) deep at its deepest.
The Cabot Strait between Newfoundland and Cape Breton Island: 104 km (65 mi) wide and 480 m (1,575 ft) deep at its deepest.
The Strait of Canso between Cape Breton Island and the Nova Scotia peninsula had been an outlet 1.0 km (0.6 mi) wide and 60 m (200 ft) deep at its deepest. Due to the construction of the Canso Causeway across the strait in 1955, it no longer permits exchange of water between the Gulf of Saint Lawrence and the Atlantic Ocean.
Limits
Since its appearance on maps, there has been no consensus on the demarcation of the St Lawrence River from the Gulf, nor whether it is hydrographically a gulf or an estuary.[11][12]
According to Fisheries and Oceans Canada 2023, the Estuary and Gulf of St. Lawrence planning area covers most of the Estuary and Gulf of St. Lawrence bioregion, an area with some of the warmest surface waters in Atlantic Canada during summer and the largest amount of sea ice during winter. The planning area is approximately 240,000 km².[3]
According to Encyclopedia Britannica, the name of gulf Saint Lawrence in a hydrologic context is not accurate, a gulf has to be considered more as a sea bordering the North American continent than as simply a river mouth.[13]
The Laurentian Channel is a feature of the floor of the Gulf that was formed during previous ice ages, when the Continental Shelf was eroded by the Saint Lawrence River during the periods when the sea level plunged. The Laurentian Channel is about 290 m (950 ft) deep and about 1,250 km (780 mi) long from the Continental Shelf to the mouth of the Saint Lawrence River. Deep waters with temperatures between 2 and 6.5 °C (36 and 44 °F) enter the Gulf at the continental slope and are slowly advected up the channel by estuariane circulation.[18] Over the 20th century, the bottom waters of the end of the channel (i.e. in the Saint Lawrence estuary) have become hypoxic.[19]
History
The gulf has provided a historically important marine fishery for various First Nations that have lived on its shores for millennia and used its waters for transportation.[citation needed]
The first documented voyage by a European in its waters was by the French explorer Jacques Cartier in the year 1534. Cartier named the shores of the Saint Lawrence River "The Country of Canadas", after an indigenous word meaning "village" or "settlement", thus naming the world's second largest country.[20]
Basque whalers from Saint-Jean-de-Luz sailed into the Gulf of Saint Lawrence in 1530 and began whaling at Red Bay.[21] They established their base on the Strait of Belle Isle and worked closely with the Iroquois in the Gulf of Saint Lawrence. In 1579 the English government closed all English ports to Spanish oil imports. As a result, a third of Basque whale oil could not be sold. Basque whaling collapsed in the Gulf of Saint Lawrence and never recovered.
^Claudine Loiselle; Jean Raveneau (December 1997). "The Environmental Atlas of the St. Lawrence"(PDF). Environnement Canada, Geography department. Université Laval. pp. 34 of 67. Retrieved 21 February 2024. A River, Estuaries, a Gulf: The Great Hydrographic Divisions of the St. Lawrence
^ ab"Estuary and Gulf of St. Lawrence". Gouvernement of Canada. Fisheries and Oceans Canada. 2023-01-27. Retrieved 19 February 2024. The area represents one of the largest and most productive estuarine/marine ecosystems in Canada and in the world.
^Jean-Claude Therriault (2012). "The Gulf od St. Lawrence: Small Ocean or Big Estuary"(PDF). Fischeries and Oceans Canada (in French and English). Canadian special Publication of Fischeries and Aquatic Science. p. 359. Retrieved 21 February 2024. the Gulf must be considered a complete and coherent systern: for example, what happens in the Gaspé current cannot be completely isolated from the phenomena that occur elsewhere. The degree of interdependence of the various areas remains to be explored.
^"St. Lawrence River and Seaway". Great Lakes Commission. Retrieved 22 February 2024. . . . can be divided into three broad sections: the freshwater river, which extends from Lake Ontario to just outside the city of Quebec; the St. Lawrence estuary, which extends from Quebec to Anticosti Island; and the Gulf of St. Lawrence, which leads into the Atlantic Ocean
^"St Lawrence River". The Canadian Encyclopedia. Retrieved 22 February 2024. According to the Royal Proclamation of 1763, a line from the mouth of Rivière St-Jean on the north shore past the western tip of Île d'Anticosti to Cap des Rosiers on Gaspé marks the end of the river and the beginning of the gulf.
^"The Pointe-des-Monts Lighthouse" (in French). Corporation de Promotion et de Développement du site du Phare historique de Pointe‑des‑Monts. 2024. Retrieved 25 February 2024. Built on a rocky outcrop that forms an islet at high tide, the lighthouse bears witness to a time when navigation in the Gulf of St. Lawrence was perilous.
^Edward F. Bush (1975). "The Canadian Lighthouse"(PDF). National Historic Parks and Sites, Branch, Indian and Northern Affairs. pp. 55 of 188. Retrieved 25 February 2024. The first lighthouse, completed in 1830, had walls six feet thick at the base, tapering to two feet at the lantern deck.20
^"Gulf of Saint Lawrence". Commission de toponymie Quebec (in French). Government of Quebec. 1968-12-05. Retrieved 23 February 2024. Sixteenth-century cartographers, historians and memorialists were most often inspired by the Spanish and Italian translations of the Brief récit, and not by the original French published in 1545 to impose the toponym Gulf of St. Lawrence
^"Pointe des Monts". Commission de toponymie Quebec (in French). Government of Quebec. 1968-12-05. Retrieved 24 February 2024. These points serve as a boundary between the Estuary of the St. Lawrence River upstream and the much wider Gulf of St. Lawrence downstream
^Lionel Groulx (1960). "History of French Canada since the Discovery"(PDF) (in French). Fides, Montreal and Paris. pp. 16 of 404. Retrieved 23 February 2024. In the absence of decisive, first-hand documents, historians and cartographers can only assert probabilities.
^Jean-Claude Therriault. "The Gulf of St. Lawrence: Small Ocean or Big Estuary"(PDF) (in English and French). Fisheries and Oceans Canada. p. 359. Retrieved 23 February 2024. The Gulf of St. Lawrence contains a wide range of hydrodynamic conditions including seasonal ice cover, polynyas, fronts, gyres, freshwater input and influences, and large seasonal variations in vertical stratification.
^"Gulf of Saint Lawrence". Encyclopedia Britannica. Britannica, The Editors of Encyclopaedia. 2024-02-20. Retrieved 23 February 2024. body of water covering about 60,000 square miles (155,000 square km) at the mouth of the St. Lawrence River. The reefs on these surfaces, coupled with the hazards of fog and ice, have caused a large number of shipwrecks.
^"Gulf of St. Lawrence"(PDF). Limits of Oceans and Seas. International Hydrographic organization. 1953. pp. 14 of 42. Retrieved 19 February 2024. Limits of Oceans and Seas
^Zydler, Tom (18 October 2018). "Cruising Canada's Gulf of St. Lawrence". Cruising World. Retrieved 12 March 2023. As I stepped ashore onto a blanket-size piece of sand, I realized I was probably trespassing; landing on the island requires an official permit from the Canadian coast guard.
^Galbraith, P.S., Pettipas, R.G., Chassé, J., Gilbert, D., Larouche, P., Pettigrew, B., Gosselin, A., Devine, L. and Lafleur, C. 2009. Physical Oceanographic Conditions in the Gulf of St. Lawrence in 2008. DFO Can. Sci. Advis. Sec. Res. Doc. 2009/014. iv + 69 p.
^Gilbert, D., B. Sundby, C. Gobeil, A. Mucci and G.-H. Tremblay. 2005. A seventy-two-year record of diminishing deep-water oxygen in the St. Lawrence estuary: The northwest Atlantic connection. Limnol. Oceanogr., 50(5): 1654–1666.