Salmon is the common name for several species of fish of the family Salmonidae. The fish is pink and silver. Several other fish in the family are called trout. Salmon live in both the Atlantic and Pacific Oceans, as well as the Great Lakes and other lakes.
Typically, salmon are anadromous: they are born in fresh water, migrate to the ocean, then return to fresh water to reproduce. However, there are rare species that can only survive in fresh water habitats. This is most likely due to the domestication of these certain species of Salmon. Folklore has it that the fish return to the exact spot where they were born to spawn.
Many wild Salmon stocks have seen a marked decline in recent decades, especially north Atlantic populations which spawn in western European and eastern Canadian waters, and wild salmon of the Snake and Columbia River systems in the Northwest USA. The causes of these declines likely include a number of factors, among them:
- Disease transfer from open net cage salmon farming, especially sea lice. The European Commission (2002) concluded “The reduction of wild salmonid abundance is also linked to other factors but there is more and more scientific evidence establishing a direct link between the number of lice-infested wild fish and the presence of cages in the same estuary.” It is reported that wild salmon on the west coast of Canada are being driven to extinction by sea lice from nearby salmon farms.
- Overfishing in general but especially commercial netting in the Faroes and Greenland.
- Ocean and river warming which can delay spawning and accelerate transition to smolting.
- Loss of suitable freshwater habitat, especially degradation of stream pools and reduction of suitable material for the excavation of redds. Historically stream pools were, to a large extent, created by beavers. With the extirpation of the beaver, the nurturing function of these ponds was lost.
- The construction of dams, weirs, barriers and other "flood prevention" measures, which bring severe adverse impacts to river habitat and on the accessibility of those habitats to salmon. This is particularly true in the northwest USA, where large numbers of dams have been built in many river systems, including over 400 in the Columbia River Basin.
The Fraser River
The Fraser River is the longest river in British Columbia, Canada, rising near Mount Robson in the Rocky Mountains and flowing for 1,375 km (870 mi), into the Pacific Ocean at the city of Vancouver. The estuary at the river's mouth is a site of hemispheric importance in the Western Hemisphere Shorebird Reserve Network.
The Fraser is heavily exploited by human activities, especially in its lower reaches. Its banks are rich farmland, its water is used by pulp mills, and a few dams on some tributaries provide hydroelectric power. The main flow of the Fraser has never been dammed as its high level of sediment flows would result in a short dam lifespan. Today, Fraser Herald at the Canadian Heraldic Authority is named after the river. In 1858, the Fraser River and surrounding areas were occupied when the gold rush came to the Fraser Canyon and the Fraser River.
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