Gulf of Saint Lawrence

The Gulf of Saint Lawrence

The Gulf of Saint Lawrence (French: golfe du Saint-Laurent), the world's largest estuary, is the outlet of North America's Great Lakes via the Saint Lawrence River into the Atlantic Ocean. It is a semi–enclosed sea, covering an area of about 236,000 km² (91,000 sq mi) and containing 35,000 km³ (7.7×10¹⁵ imp gal) of water.

Geography

The gulf is bounded on the north by the Labrador Peninsula, to the east by Newfoundland, to the south by the Nova Scotia peninsula and Cape Breton Island, and to the west by the Gaspé and New Brunswick. It contains Anticosti Island, Prince Edward Island, and the Magdalen Islands. Half of Canada's ten provinces—the Maritime provinces of New Brunswick, Nova Scotia, and Prince Edward Island, as well as Quebec and Newfoundland and Labrador -- adjoin the Gulf.

Besides the Saint Lawrence River itself, semi-major tributaries of the Gulf of Saint Lawrence include the Miramichi River, the Natashquan River, the Restigouche River, the Margaree River, and the Humber River. Arms of the Gulf include the Chaleur Bay, Miramichi Bay, St. George's Bay, Bay of Islands, and Northumberland Strait.

Outlets

The gulf flows into the Atlantic Ocean through the following outlets:

• The Strait of Belle Isle between Labrador and Newfoundland (17 km wide and 60 m at its deepest).

• The Cabot Strait between Newfoundland and Cape Breton Island (104 km wide and 480 m at its deepest).

• The Strait of Canso between Cape Breton Island and peninsular Nova Scotia (1 km wide and 60 m at its deepest). Since construction of the Canso Causeway in 1955, the Strait of Canso does not permit free-flowing exchange of waters between the gulf and the Atlantic.

Extent

The International Hydrographic Organization defines the limits of the Gulf of Saint Lawrence as follows:

On the Northeast. A line running from Cape Bauld (North point of Kirpon Island, 51°40′N 55°25′W) to the East extreme of Belle Isle and on to the Northeast Ledge (52°02′N 55°15′W). Thence a line joining this ledge with the East extreme of Cape St. Charles (52°13'N) in Labrador.

On the Southeast. A line from Cape Canso (45°20′N 61°0′W) to Red Point (45°35′N 60°45′W) in Cape Breton Island, through this Island to Cape Breton [45°57′N 59°47′W] and on to Pointe Blanche (46°45′N 56°11′W) in the Island of St. Pierre, and thence to the Southwest point of Morgan Island (46°51′N 55°49′W).

On the West. The meridian of 64°30'W, but the whole of Anticosti Island is included in the Gulf.

Protected areas

St. Paul Island, Nova Scotia, off the northeast tip of Cape Breton Island, is referred to as the "Graveyard of the Gulf" for its many shipwrecks; access to the island is controlled by the Canadian Coast Guard.

Bonaventure Island on the eastern tip of the Gaspé Peninsula, Île Brion and Rochers-aux-Oiseaux (Bird Rock) northeast of the Magdalen Islands are important migratory bird sanctuaries administered by the Canadian Wildlife Service.

The Government of Canada maintains national parks in the Gulf of St. Lawrence estuary at Forillon on the eastern tip of the Gaspé, Prince Edward Island on the north shore of the island, Kouchibouguac on the northeast coast of New Brunswick, Cape Breton Highlands on the northern tip of Cape Breton Island, Gros Morne on Newfoundland's west coast, and a national park reserve in the Mingan Archipelago on Quebec's Côte-Nord.

The five provinces bordering the gulf also maintain various provincial parks, some of which preserve coastal features.

Bathymetry of the gulf, with the Laurentian Channel visible

Undersea features

The Laurentian Channel is a feature of the gulf floor that was formed during previous glaciations, where the continental shelf was eroded by the St. Lawrence River during periods of global sea level minimums. The Laurentian Channel is 290 m (950 ft) in depth and approximately 1,250 km (780 mi) in length from the continental shelf to the Estuary. Deep waters with temperatures between 2 and 6.5 degrees Celsius (35 and 44 °F) enter the Gulf at the continental slope and are slowly advected up the channel by estuariane circulation. Over the last century, the bottom waters of the end of the channel (i.e. in the St. Lawrence estuary) have become hypoxic.

Cultural importance

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.

The first documented voyage by a European in its waters was by French explorer Jacques Cartier in 1534; the Cartier expedition is reported to have been the first known encounter between Europeans and First Nations inhabiting the Gulf of St. Lawrence basin, which occurred in present-day New Brunswick on July 7, 1534.

References

• St. Lawrence Global Observatory
• The Gulf of St. Lawrence - A Unique Ecosystem, Department of Fisheries and Oceans
• Timing and position of late Wisconsinan ice-margins on the upper slope seaward of Laurentian Channel