Fraser River

• Category: Inland Aquatic Biomes.
• Geographic Location: Canada.
• Summary: The Fraser River, the largest river in British Columbia, is a profoundly rich habitat for salmon, migratory birds, and a host of other animals and plants. However, it is vulnerable to human overuse.

The Fraser River biome in western Canada is the largest river system in British Columbia; the river flows some 850 miles (1,375 kilometers) from its sources in the Rocky Mountains to its mouth at the Strait of Georgia, a channel between the mainland and Vancouver Island in the Pacific Ocean. The catchment basin is approximately 90,000 square miles (230,000 square kilometers). Beginning near Mt. Robson Provincial Park, the Fraser streams through the Rockies and cuts through the Cariboo Mountains and the Coastal Range on its way to the sea. Major tributaries include the Nechako-Stuart River system, the Quesnel, the Chilcotin, the Thompson-Clearwater system, and the Lillooet.

On its way, the Fraser winds through alpine habitat, rugged boreal forests, several major plains, tundra, arid sagebrush scrublands, grasslands, long-tamed farmlands, canyons and white water, marshland, and coastal rainforest zones.

Flora

The central valley area of the Fraser River is a fertile floodplain that features such plants as Indian hemp (Apocynum cannabinum), western white clematis (Clematis ligusticifolia), blanketflower (Gaillardia aristata), and sand dropseed (Sporobolus cryptandrus), as well as the occasional ponderosa pine (Pinus ponderosa), and Rocky Mountain juniper (Juniperus scopulorum) that sprout from cones that get washed down the river. Further downstream, the waters slow, and finer materials accumulate to form sandy bars and shores where more stable plants are located, including red alder (Alnus rubra), paper birch (Betula papyrifera), tatarian dogwood (Cornus stolonifera), black cottonwood (Populus balsamifera).

The receded shorelines have rounded stones stabilized with such perennials as Columbia River wormwood (Artemisia lindleyana), Canada wildreye (Elymus canadensis), brown-eyed Susan (Gaillardia aristata), Douglas aster (Symphyotrichum subspicatum), and reed canarygrass (Phalaris arundinacea). In lower runs, where the waters are calm and salt-influenced species thrive, are found seacoast bulrush (Bolboschoenus maritimus), sedge (Carex lyngbyei), and common threesquare (Schoenoplectus pungens).

Fauna

The estuary of the Fraser River is home to more than 400 species of vertebrates and 20 species of birds of prey, including the bald eagle. Waterfowl and shorebirds from Siberia, Alaska, Yukon, and other arctic and prairie areas all stop along the Fraser to refuel. A vast proportion of the continental population of western sandpipers stops here to rest along their migration route. The Fraser River delta is located midway along the Pacific coast, providing an international crossroad for bird migration. During the year, it supports over 1.7 million birds.

One of the largest salmon rivers, the Fraser provides spawning habitat for Pacific salmon, including chinook, chum, coho, pink, and sockeye. While the largest, Chinook salmon is the least abundant of the Pacific varieties. Pink salmon is the smallest species in the river. Most salmon are anadromous—they mature and live in the ocean's saltwater but return to the freshwater of their native river to spawn.

Millions of hatched young salmon spend their early life cycle in the Fraser River before entering the ocean to grow to full adult size. Estuarine marshes, mudflats, floodplains, and river channels of the Fraser are critical transition habitats for the young salmon. Some species spend several years in the Fraser before heading out to sea. The white sturgeon, the largest freshwater fish in North America and another anadromous type, also spawns in the Fraser.

Mammals making their home in the Fraser River biome include beavers, coyotes, mink, deer, cougar, black bear, grizzly bear, moose, and caribou. Seals are frequent marine mammal visitors to the delta area. Among the waterbirds breeding within the Fraser River basin are western grebes, mergansers, great blue herons, and mallards. Hawks, owls, wrens, and blackbirds are active at the shore and inland.

Environmental Issues

The ecosystem of Fraser and its surrounding lands has been compromised by municipal development, farming, mining, logging, hydroelectric power production, paper manufacturing, fishing, and tourism. Overfishing, damming for hydroelectric power, pollution, and runoff from deforestation also have impacted the Fraser River biome. As a result of water diversion for hydroelectric production and crop irrigation, the river flow and depth have changed in various river segments. Global warming has increased the overall temperature of the river, threatening some salmon spawning grounds and stressing numerous types of habitat in the biome. Climate change has changed the hydrological cycle of the river, which scientists predict will result in earlier and more frequent spring floods, followed by drought in the summer months. Climate change has already increased water levels, contributing to increased likelihood and severity of flooding.

About two-thirds of British Columbia's population lives and works in the Fraser River biome, and approximately two-thirds of the province's income is generated here. Half of the province's timber yield and 60 percent of its metal mine production come from this area. Ecological conservation and preservation measures are constantly tense with these human land-use facts.

The Fraser Delta is a Western Hemisphere Shorebird Reserve Network (WSHRN) site. This is an international initiative designed to identify and protect habitats in stopover points used by shorebirds during migrations across North and South America. One of the critical sites here for bird migration is the Boundary Bay-Roberts Bank-Sturgeon Bank wetlands; it has been recognized and is protected by provincial, federal, and international bodies. The Alaskan National Wildlife Area on the Fraser River delta has been identified as one of two Ramsar wetlands sites in British Columbia. The Fraser Delta wetlands are regulated by several different agencies within the Canadian government; salmon fishing is monitored by Fisheries and Oceans Canada.

Bibliography

Benke, Arthur C., and Colbert E. Cushing, eds. Rivers of North America. Maryland Heights, MO: Academic Press, 2005.

Bocking, Richard, C. Mighty River: A Portrait of the Fraser. Seattle: University of Washington Press, 1997.

Brice, Becky L. et al., “Paleohydrological Context for Recent Floods and Droughts in the Fraser River Basin, British Columbia, Canada.” Environmental Research Letters, vol. 1, no. 12, Dec. 2021, iopscience.iop.org/article/10.1088/1748-9326/ac3daf. Accessed 21 Oct. 2024.

Klinkenberg, Brian, ed. “E-Flora BC: Electronic Atlas of the Plants of British Columbia.” Lab for Advanced Spatial Analysis, Department of Geography, University of British Columbia, 2012.

Schmunk, Rhianna. "B.C.'s Fraser Valley Is No Stranger to Floods. Experts Warn Extreme Weather Is Likely to Become More Common." CBC, 17 Nov. 2021, www.cbc.ca/news/canada/british-columbia/fraser-valley-flooding-climate-change-1.6251267. Accessed 21 Oct. 2024.