Editing Gulf of St. Lawrence (section)

== Geography ==
===Extent===

The Gulf of St. Lawrence is bounded on the north by the [[Labrador Peninsula]] and [[Quebec]], on the east by [[Saint-Pierre, Saint Pierre and Miquelon|Saint-Pierre]] and [[Island of Newfoundland|Newfoundland]], on the south by the [[Nova Scotia peninsula]] and [[Cape Breton Island]], and on the west by the [[Gaspé Peninsula]], [[New Brunswick]], and Quebec. The Gulf of St. Lawrence contains numerous islands, including [[Anticosti Island|Anticosti]], [[Prince Edward Island|Prince Edward]], [[Saint Pierre Island|Saint Pierre]], [[Cape Breton Island|Cape Breton]], [[Miquelon-Langlade]], and the [[Magdalen Islands|Îles-de-la-Madeleine archipelago]].

Half of Canada's ten provinces adjoin the Gulf: [[New Brunswick]], [[Nova Scotia]], [[Prince Edward Island]], [[Newfoundland and Labrador]], and [[Quebec]].

There is no consensus on the demarcation of the [[St. Lawrence River|St Lawrence River]] from the Gulf, nor whether it is hydrographically a [[gulf]] or an [[estuary]].<ref name="Histoire du Canada Français depuis la découverte">{{cite web |author1=Lionel Groulx |title=History of French Canada since the Discovery |url=https://fondationlionelgroulx.org/sites/default/files/documents/lionel-groulx-histoire-du-canada-francais-depuis-la-decouverte-tome-1.pdf |publisher=Fides, Montreal and Paris |access-date=23 February 2024 |pages=16 of 404 |language=fr |date=1960 |quote=In the absence of decisive, first-hand documents, historians and cartographers can only assert probabilities.}}</ref><ref name="Small Ocean or Big Estuary">{{cite web |author1=Jean-Claude Therriault |title=The Gulf of St. Lawrence: Small Ocean or Big Estuary |url=https://waves-vagues.dfo-mpo.gc.ca/library-bibliotheque/20971_1.pdf |publisher=Fisheries and Oceans Canada |access-date=23 February 2024 |pages=359 |language=en, fr |quote=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.}}</ref><ref name="Encyclopedia Britannica">{{cite web |title=Gulf of St. Lawrence |url=https://www.britannica.com/place/Gulf-of-Saint-Lawrence |website=Encyclopedia Britannica |publisher=Britannica, The Editors of Encyclopaedia |access-date=23 February 2024 |date=2024-02-20}}</ref>

According to Commission of Toponymy Quebec, the St. Lawrence River becomes the gulf at Pointe des Monts on the [[Côte-Nord]] and [[Matane]] [[Bas-Saint-Laurent]] or [[Sainte-Anne-des-Monts]] [[La Haute-Gaspésie Regional County Municipality|La Haute-Gaspésie]], the [[Estuary of St. Lawrence|Estuary]] is upstream, the Gulf of St. Lawrence, much wider, downstream.<ref name="Toponymie Quebec">{{cite web |title=Gulf of St. Lawrence |url=https://toponymie.gouv.qc.ca/ct/ToposWeb/Fiche.aspx?no_seq=57035 |website=Commission de toponymie Quebec |publisher=Government of Quebec |access-date=23 February 2024 |language=fr |date=1968-12-05 |quote=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}}</ref><ref name="Pointe des Monts">{{cite web |title=Pointe des Monts |url=https://toponymie.gouv.qc.ca/ct/ToposWeb/Fiche.aspx?no_seq=42200 |website=Commission de toponymie Quebec |publisher=Government of Quebec |access-date=24 February 2024 |language=fr |date=1968-12-05 |quote=These points serve as a boundary between the Estuary of the St. Lawrence River upstream and the much wider Gulf of St. Lawrence downstream}}</ref>

The [[International Hydrographic Organization]] defines the gulf's extent as follows:<ref name="Gulf of St. Lawrence 1953">{{cite web |title=Gulf of St. Lawrence |url=https://iho.int/uploads/user/pubs/standards/s-23/S-23_Ed3_1953_EN.pdf |website=Limits of Oceans and Seas |publisher=International Hydrographic organization |access-date=19 February 2024 |pages=14 of 42 |date=1953 |quote=Limits of Oceans and Seas}}</ref>
:''On the Northeast:'' A line running from [[Cape Bauld]] (North point of [[Quirpon Island|Kirpon Island]], {{Coord|51|40|N|55|25|W|display=inline}}) to the East extreme of [[Belle Isle (Newfoundland and Labrador)|Belle Isle]]<ref name="Strait of Belle Isle, toponymy">{{cite web |title=Strait of Belle Isle |url=https://toponymie.gouv.qc.ca/ct/ToposWeb/Fiche.aspx?no_seq=228162 |website=Gouvernement of Quebec |publisher=Commission de Toponymy Quebec |access-date=14 August 2024 |language=fr |date=13 December 1988 |quote=In addition to Grande Bay, this arm of the sea had notably borne the names of Friar Lewis, on maps from 1505, then Gulf of Chasteaulx, Charles Streights and Passage du Nord which a cartographer describes as "subject to Glaces” later in the 16th and during the 17th century.}}</ref> and on to the Northeast Ledge ({{Coord|52|02|N|55|15|W|display=inline}}). 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]] ({{Coord|45|20|N|61|0|W|display=inline}}) to [[Red Point (Nova Scotia)|Red Point]] ({{Coord|45|35|N|60|45|W|display=inline}}) in Cape Breton Island, through this Island to Cape Breton [{{coord|45|57|N|59|47|W|display=inline}}] and on to Pointe Blanche ({{Coord|46|45|N|56|11|W|display=inline}}) in the Island of [[Saint-Pierre, Saint Pierre and Miquelon|St. Pierre]], and thence to the southwest point of Morgan Island ({{Coord|46|51|N|55|49|W|display=inline}}).

:''On the West:'' The meridian of 64°30'W from Pointe-Jaune ({{coord|49.06|N|64.5|W|format=dms|display=inline}}) to Magpie ({{coord|50.31|N|64.5|W|format=dms|display=inline}}), but the whole of Anticosti Island is included in the Gulf.

[[Image:011_015_Pointe_des_Monts.jpg|thumb|Pointe-des-Monts Lighthouse, [[Baie-Trinité, Quebec]]]]
At Baie-Trinité, the [[Baie-Trinité, Quebec#Pointe-des-Monts Lighthouse|Pointe-des-Monts Lighthouse]], a [[National Historic Sites of Canada|National historic site of Canada]], was built in 1829–1830 on a point that geographers throughout history, since as early as [[Samuel de Champlain]] (1567–1655), have classified as the demarcation point between the [[St. Lawrence River]] and the Gulf of St. Lawrence.<ref name="The Pointe-des-Monts Lighthouse">{{cite web |title=The Pointe-des-Monts Lighthouse |url=https://www.pharedepointedesmonts.com/ |publisher=Corporation de Promotion et de Développement du site du Phare historique de Pointe‑des‑Monts |access-date=25 February 2024 |language=fr |date=2024 |quote=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.}}</ref><ref name="The Canadian Lighthouse">{{cite web |author1=Edward F. Bush |title=The Canadian Lighthouse |url=http://parkscanadahistory.com/series/chs/9/chs9-eng.pdf |publisher=National Historic Parks and Sites, Branch, Indian and Northern Affairs |access-date=25 February 2024 |pages=55 of 188 |date=1975 |quote=The first lighthouse, completed in 1830, had walls six feet thick at the base, tapering to two feet at the lantern deck.20}}</ref>

[[Fisheries and Oceans Canada]]'s "Estuary and Gulf of St. Lawrence planning area" covers most of the [[Estuary of St. Lawrence|Estuary and Gulf of St. Lawrence]] bioregion, an area with some of the warmest surface waters in [[Atlantic Ocean|Atlantic]] Canada during summer and the largest amount of sea ice during winter. The planning area is approximately 240,000&nbsp;km².<ref name="Estuary and Gulf of St. Lawrence - Fisheries and Oceans Canada">{{cite web |title=Estuary and Gulf of St. Lawrence |url=https://www.dfo-mpo.gc.ca/oceans/planning-planification/areas-aires/estuary-gulf-st-lawrence-estuaire-golfe-saint-laurent-eng.html |website=Government of Canada |publisher=Fisheries and Oceans Canada |access-date=19 February 2024 |date=2023-01-27 |quote=The area represents one of the largest and most productive estuarine/marine ecosystems in Canada and in the world.}}</ref>

===Tributaries and nested bays===
Besides the St. Lawrence itself, significant rivers emptying into the Gulf of St. Lawrence include the [[Miramichi River|Miramichi]], [[Natashquan River|Natashquan]], [[Romaine River|Romaine]], [[Restigouche River|Restigouche]], [[Margaree River|Margaree]], [[Humber River (Newfoundland and Labrador)|Humber]] and [[Mingan River|Mingan]].

Branches of the Gulf include [[Chaleur Bay]], [[Fortune Bay]], [[Miramichi Bay]], [[St. George's Bay (Nova Scotia)|St. George's Bay]], [[St. George's Bay (Newfoundland and Labrador)|Bay St. George]], [[Bay of Islands, Newfoundland and Labrador|Bay of Islands]], and the [[Northumberland Strait]].

=== Outlets ===
[[Image:Detroit_Belle_Isle_960718_11_3557_2360.jpg|thumb|[[Strait of Belle Isle]], as seen from [[Blanc Sablon]], Quebec]]
Around Anticosti Island and to flow into the Atlantic Ocean, the waters of the Gulf take the following [[strait]]s:

* [[Jacques Cartier Strait]], between the shore of [[Côte-Nord]] region and the North of [[Anticosti Island]].<ref name="Canadian sailing directions. ATL 110, St. Lawrence River, Cap Whittle/Cap Gaspé to Les Escoumins and Anticosti Island.">{{cite web |title=Canadian sailing directions. ATL 110, St. Lawrence River, Cap Whittle/Cap Gaspé to Les Escoumins and Anticosti Island. |url=https://publications.gc.ca/collections/collection_2023/mpo-dfo/Fs74-52-2023-11-eng.pdf |website=Fischeries and Oceans Canada |publisher=Canadian Hydrographic Service |access-date=6 September 2024 |pages=9 of 89 |date=November 2023 |quote=... covers the north shore of the Gulf of St. Lawrence and the St. Lawrence River, from Cap Whittle (50°11'N, 60°07'W) to Pointe des Monts (49°19'N, 67°23'W), as well as the north shore of Anticosti Island.}}</ref>
*[[Honguedo Strait]], a wide passage between the [[Gaspé Peninsula]] and [[Anticosti Island]].<ref name="Honguedo Strait, toponymy">{{cite web |title=Honguedo Strait, toponymy |url=https://toponymie.gouv.qc.ca/ct/ToposWeb/Fiche.aspx?no_seq=28928 |website=Gouvernement of Quebec |publisher=Commission de Toponymy Quebec |access-date=22 September 2024 |language=fr |date=5 December 1968 |quote=The Commission de géographie du Québec, now the Commission de toponymie, adopted this toponym in 1934 to commemorate the 400th anniversary of the arrival of Jacques Cartier in New France.}}</ref>
*[[Strait of Belle Isle]]<ref name="Strait of Belle Isle, toponymy" /> between [[Labrador]] and [[Newfoundland (island)|Newfoundland]]: between {{convert|15|km|mi|abbr=off}} and {{convert|60|km|mi|abbr=off}} wide and {{convert|60|m|ft|abbr=off}} deep at its deepest.
*[[Cabot Strait]], about 56 miles wide, is the entrance to the Gulf of St. Lawrence between [[Cape Ray]], Newfoundland, and [[Cape North Lighthouse|Cape North]], the NE point of [[Cape Breton Island]].<ref name="ATL 104: Cape North to Cape Canso (including Bras d’Or Lake)">{{cite web |author1=Canadian Hydrographic Service |title=ATL 104: Cape North to Cape Canso (including Bras d'Or Lake) |url=https://waves-vagues.dfo-mpo.gc.ca/library-bibliotheque/chs-shc-ATL104-eng-202404-41238060.pdf |website=Fisheries and Oceans Canada |publisher=Canadian Sailing Directions |access-date=16 August 2024 |pages=9 of 95 |date=16 April 2024 |quote=St. Paul Island presents the only danger in the Cabot strait. Mariners are advised to navigate with caution during periods of reduced visibility.}}</ref>
*[[Strait of Canso]]<ref name="Strait of Canso - Water Resources - Map">{{cite web |title=Strait of Canso - Map |url=https://www.novascotia.ca/nse/groundwater/images/GroundwaterResourcesMap_StraitofCanso.pdf |website=Water Resources, Nova Scotia |publisher=Strait of Canso Environment Committee |access-date=17 August 2024 |date=1975 |quote=From George Bay to Chedabucto Bay}}</ref> is located between [[Cape Breton Island]] and mainland [[Nova Scotia]], it originally served as an outlet 1.0&nbsp;km (0.6&nbsp;mi) wide and 60&nbsp;m (200&nbsp;ft) deep at its deepest.<ref name="Strait of Canso Environment Committee - Water resources">{{cite web |author1=Strait of Canso Environment Committee |title=Water Resources |url=https://novascotia.ca/nse/groundwater/docs/GroundwaterResourcesReport_StraitofCanso.pdf |pages=33 |date=1975 |quote=The Strait is relatively narrow, varying in width from 800 m to 2,000 m (2,600 to 6,600 ft.), although it is most commonly 1,600 m (1 mile) wide throughout the 27 km (17 mi.) length.}}</ref><ref name="Flow through the Canso Causeway">{{cite web |author1=Gary L. Bugden |author2=Brent A. Law |author3=Edward P.W. Horne |author4=Shawn E. Roach |title=Flow through the Canso Causeway |url=https://waves-vagues.dfo-mpo.gc.ca/library-bibliotheque/40884533.pdf |website=Fischeries and Oceans Canada |publisher=Canadian Technical Report of Fisheries and Aquatic Sciences |access-date=16 August 2024 |pages=21 of 55 |language=en, fr |date=2020 |quote=Although blocked in the 1950’s by the Canso Causeway, Canso Strait could potentially be a transport pathway for the spread of Malpeque Disease}}</ref> Due to the construction of the [[Canso Causeway]] across the strait in 1955, the roadway no longer allows exchange of water between the Gulf of St. Lawrence and the [[Atlantic Ocean]].<ref name="Canso Causeway - Road to the Isles">{{cite web |title=Canso Causeway - Road to the Isles |url=https://epe.lac-bac.gc.ca/100/205/301/ic/cdc/cansocauseway/index.htm |publisher=Canada's Digital collections |access-date=16 August 2024 |quote=The mile long eighty foot wide man-made causeway is known as the deepest in the world}}</ref>

=== Undersea Features ===
[[Image:StLawrence Gulf bathymetry.jpg|thumb|[[Bathymetry]] of the gulf, with the Laurentian Channel visible]]

The [[Laurentian Channel]] is a feature of the floor of the Gulf that was formed during [[Quaternary glaciation|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 {{convert|290|m|ft|abbr=on}} deep and about {{convert|1250|km|mi|abbr=on}} long from the Continental Shelf to the mouth of the [[St. Lawrence River]]. Deep waters with temperatures between {{convert|2|and|6.5|°C|0}} enter the Gulf at the continental slope and are slowly [[advection|advected]] up the channel by estuariane circulation.<ref>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.</ref> Over the 20th century, the bottom waters of the end of the channel (i.e. in the St. Lawrence estuary) have become [[Hypoxia (environmental)|hypoxic]].<ref>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 [[Estuary of St. Lawrence|St. Lawrence estuary]]: The northwest Atlantic connection. Limnol. Oceanogr., 50(5): 1654–1666.</ref>