Canadian Atlantic Islands




Mary Burridge and Nicholas Mandrak


St. Pierre and Miquelon

Major Habitat Type

Temperate coastal rivers

Drainages flowing into

All rivers flow into the Atlantic Ocean or the Gulf of St. Lawrence.

Main rivers to other water bodies

The main rivers draining the island of Newfoundland include the Exploits, Gander, Humber, and Main rivers. There are many long fingerlike lakes that have formed in glacial valleys, such as the Grand and Red Indian lakes. Grand Lake, on the west side of Newfoundland, is the largest lake on the island, with depths reaching 300 m. The Humber River (153 km) is the main river in western Newfoundland. Rising in the Long Range Mountains, it flows south through Grand Lake and Deer Lake before reaching the Gulf of St. Lawrence. The Exploits River (246 km) is the longest river on the island of Newfoundland. It begins at Red Indian Lake in the center of the island, and flows northeast toward the Atlantic Ocean. Gander River (175 km) is the primary river in northeastern Newfoundland, and drains into the Atlantic Ocean via Gander Bay.

Prince Edward Island has very few freshwater rivers, as most of their lengths are tidal with interchanges of saltwater from the Gulf of St. Lawrence or Northumberland Strait. Hillsborough River is the largest and flows through the center of the island.

Anticosti Island has several small rivers including Salmon River, Riviere de la Chaloupe, and Jupiter River. Two small lakes of note are Lac du Renard and Lake Wickenden.

The Magdalen Islands have little freshwater.



This ecoregion includes islands in the Gulf of St. Lawrence: Newfoundland, Prince Edward Island, Anticosti Island, and the Magdalen Islands.  It also includes St. Pierre and Miquelon, located 25 km off the coast of Newfoundland.


Newfoundland forms the northern limit of the Appalachian Range of eastern North America. On the west is a narrow coastal plain, which is part of the Saint Lawrence Lowlands. These lowlands abut the Long Range Mountains that run 500 km along the island’s west coast. This range is deeply cut by faults and glaciation, with deep fjords and bays. The range slopes gently away to the east to become the Central Lowlands, which is formed of soft sedimentary rocks. To the east lies the Atlantic Uplands, which are underlain by ancient erosion-resistant rocks. 

Prince Edward Island has deep red soil, the result of a high concentration of iron oxide. The shoreline has headlands of steep sandstone bluffs and extensive sandy beaches.

Larger than Prince Edward Island, Anticosti Island has a coastline of steep limestone cliffs and a large saltwater marsh covering the eastern end.

The Magdalen Islands are a group of sixteen islands between Prince Edward Island and Newfoundland. They are often attached by slender sandspits, with the larger ones having red and grey sandstone cliffs.

Freshwater habitats

The Main and Bay du Nord rivers of Newfoundland and the Hillsborough and Three Rivers (Cardigan, Brudenell, and Montague/Valleyfield rivers) of Prince Edward Island are Canadian Heritage Rivers. These freshwater habitats range from slow-flowing meandering rivers in Newfoundland and Prince Edward Island, to swift rapids and falls in the headwaters of the Long Range Mountains. The finger lakes of Newfoundland are deeply scoured from glaciers. The Hillsborough River has extensive fresh and saltwater marshes, and is a rich breeding area for wildlife.

Terrestrial habitats

This ecoregion spans five terrestrial ecoregions, including the Eastern Canadian Forests, Newfoundland Highland Forests, South Avalon-Burin Oceanic Barrens, and the Gulf of St. Lawrence Lowland Forests. Balsam fir (Abies balsamea) is a dominant species in the east as a result of the maritime influence of the Atlantic. Black spruce (Picea mariana), paper birch (Betula papyrifera), and aspen (Populus tremuloides) are typical of disturbed sites. White spruce (P. glauca) is a dominant species in coastal areas with sea salt spray. The Newfoundland Highlands have dwarf patches of black spruce, balsam fir, dwarf kalmia (Kalmia polifolia), and mosses.

The original mixedwood forest of Prince Edward Island was characterized by red oak (Quercus rubra), sugar maple (Acer saccharum), yellow birch (Betula allegheniensis), and beech (Fagus grandifolia). The warm summers and poor drainage of the Magdalen Islands result in a forest dominated by black spruce and balsam fir.

Description of endemic fishes

There are no known endemic species within the ecoregion.

Ecological phenomena

Many species in this ecoregion exhibit diadromy, including shads (Alosa spp.), Atlantic rainbow smelt (Osmerus mordax), American eel (Anguilla rostrata), Atlantic salmon (Salmo salar), and temperate basses (Morone spp.). Many seasonal birds pass through this ecoregion as part of the Atlantic migratory flyway.

Justification for delineation

The ecoregions of Canada were identified based on the faunal similarity of 166 major watersheds based on a cluster analysis of freshwater fish occurrences in these watersheds. The Canadian Atlantic Islands ecoregion includes islands in the Gulf of St. Lawrence, including Newfoundland, isolated by saltwater. The freshwater fish fauna of this ecoregion is very depauparate, and is dominated by saltwater-tolerant freshwater fishes.

Level of taxonomic exploration



  • Abell, R.,Olson, D.,Dinerstein, E.,Hurley, P. T.,Diggs, J. T.,Eichbaum, W.,Walters, S.,Wettengel, W.,Allnutt, T.,Loucks, C. J.;Hedao, P. (2000). "Freshwater ecoregions of North America" Washington, D.C.: Island Press.
  • Eswg (1995) \A national ecological framework for Canada\ Ottawa/Hull, Ontario, Canada. Agriculture and Agri-food Canada, Research Branch, Centre for Land and Biological Resources Research; and Environment Canada, State of the Environment Directorate, Ecozone Analysis Branch..
  • Ricketts, T. H.,E. Dinerstein,D.M Olson;C.J. Loucks (1999). "Terrestrial ecoregions of North America: A conservation assessment" Washington, D.C.: World Wildlife Fund.
  • Scott, W. B. and Crossman, E. J. (1998). "Freshwater fishes of Canada" Fisheries Research Board of Canada Bulletin 184 pp. 966 + xvii..