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 the Great Lakes of North America via the Saint Lawrence River into the Atlantic Ocean. The gulf is a semienclosed sea, covering an area of about 236,000 square kilometres (91,000 sq mi) and containing about 35,000 cubic kilometres (8,400 cu mi) of water.

Geography

The Gulf of St. Lawrence is bounded on the north by the Labrador Peninsula and Quebec, to the east by Newfoundland Island, to the south by the Nova Scotia peninsula and Cape Breton Island, and to the west by the Gaspe Peninsula, New Brunswick, and Quebec. As for significant islands the Gulf of St. Lawrence contains Anticosti Island, Prince Edward Island, and Cape Breton Island.

Half of the ten provinces of Canada adjoin the Gulf: Atlantic Canada, the provinces of New Brunswick, Nova Scotia, Prince Edward Island, Newfoundland and Labrador, in addition to Quebec.

Besides the Saint Lawrence River itself, significant streams empting into Gulf of Saint Lawrence include the Miramichi River, the Natashquan River, the Restigouche River, the Margaree River, and the Humber River.

Branches 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 kilometres (11 mi) wide and 60 metres (200 ft) deep at its deepest.

• The Cabot Strait between Newfoundland and Cape Breton Island — 104 km (65 mi) wide and 480 m (1,570 ft) deep at its deepest.

• The Strait of Canso between Cape Breton Island and the Nova Scotia peninsula — 1.0 km (0.62 mi) wide and 60 m (200 ft) deep at its deepest. Since the construction of the Canso Causeway across this in 1955, the Strait of Canso does not permit exchange of water between the Gulf of St. Lawrence and the Atlantic Ocean.

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 northeastern tip of Cape Breton Island, is referred to as the "Graveyard of the Gulf" because of its many shipwrecks. Access to this island is controlled by the Canadian Coast Guard.

Bonaventure Island on the eastern tip of the Gaspe 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 Federal Government of Canada has national parks along the Gulf of St. Lawrence at Forillon National Park on the eastern tip of the Gaspe Peninsula, Prince Edward Island National Park on the northern shore of the island, Kouchibouguac National Park on the northeastern coast of New Brunswick, Cape Breton Highlands National Park on the northern tip of Cape Breton Island, Gros Morne National Park on the west coast of Newfoundland Island, and a National Park Reserve in the Mingan Archipelago on the Côte-Nord of Quebec.

The five provinces bordering the Gulf of St. Lawrence also have several different provincial parks apiece, 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 floor of the Gulf that was formed during previous ice ages, when the Continental Shelf was eroded by the St. 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 St. Lawrence River. Deep waters with temperatures between two and six-and-one-half degrees Celsius (35 and 44 Fahrenheit) 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 the French explorer Jacques Cartier in the year 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