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File:Oncorhynchus keta.jpeg
Illustration of a male Coho Salmon

Salmon is the common name for several species of Fish of the family Salmonidae. 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 land locked lakes.

Typically, salmon are anadromous: they are born in fresh water, migrate to the ocean, then return to fresh water to reproduce. Folklore has it that the fish return to the exact spot where they were born to spawn.

In Alaska, the crossing-over to other streams allows salmon to populate new streams, such as those that emerge as a glacier retreats. The precise method salmon use to navigate has not been entirely established, though their keen sense of smell is involved. In all species of Pacific salmon, the mature individuals die within a few days or weeks of spawning, a trait known as semelparity. However, even in those species of salmon that may survive to spawn more than once (iteroparity), post-spawning mortality is quite high (perhaps as high as 40 to 50%.)

The salmon has long been at the heart of the culture and livelihood of coastal dwellers. Most peoples of the Northern Pacific shore had a ceremony to honor the first return of the year. For many centuries, people caught salmon as they swam upriver to spawn. A famous spearfishing site on the Columbia River at Celilo Falls was inundated after great dams were built on the river. The Ainu, of northern Japan, taught dogs how to catch salmon as they returned to their breeding grounds en masse. Now, salmon are caught in bays and near shore.

File:Becharof Wilderness Salmon.jpg
Spawning sockeye salmon in Becharof Creek, Becharof Wilderness, Alaska

Salmon population levels are of concern in the Atlantic and in some parts of the Pacific but in Alaska stocks are still abundant. Fish farming is outlawed[How to reference and link to summary or text] and the State of Alaska's fisheries management system is viewed as the global leader in the management of wild, sustainable fish stocks. The most important Alaska Salmon wild sustainable fisheries are located near the Kenai River, Copper River, and in Bristol Bay. In Canada, the Skeena River wild salmon returning which support commercial fisheries, aboriginal food fisheries, sports fisheries and the area's diverse wildlife on the coast and around communities hundreds of miles inland in the watershed. The Columbia River salmon population is now less than 3% of what it was when Lewis and Clark arrived at the river.[1]

Both Atlantic and Pacific Salmon are important to recreational fishing around the world.

Life cycleEdit

File:Salmoneggskils.jpg
Eggs in different stages of development. In some only a few cells grow on top of the yolk, in the lower right the blood vessels surround the yolk and in the upper left the black eyes are visible, even the little lens
File:Salmonlarvakils.jpg
Salmon fry hatching - the larva has grown around the remains of the yolk - visible are the arteries spinning around the yolk and little oildrops, also the gut, the spine, the main caudal blood vessel, the bladder and the arcs of the gills

In order to lay her roe, the female salmon uses her tail fin to excavate a shallow depression, called a redd. The redd may sometimes contain 5,000 eggs covering Template:Convert/sqftTemplate:Convert/test/A.[2] The eggs usually range from orange to red in color. One or more males will approach the female in her redd, depositing his sperm, or milt, over the roe.[3] The female then covers the eggs by disturbing the gravel at the upstream edge of the depression before moving on to make another redd. The female will make as many as 7 redds before her supply of eggs is exhausted. The salmon then die within a few days of spawning.[3]

The eggs will hatch into alevin or sac fry. The fry quickly develop into parr with camouflaging vertical stripes. The parr stay for one to three years in their natal stream before becoming smolts which are distinguished by their bright silvery colour with scales that are easily rubbed off. It is estimated that only 10% of all salmon eggs survive long enough to reach this stage.[4] The smolt body chemistry changes, allowing them to live in salt water. Smolts spend a portion of their out-migration time in brackish water, where their body chemistry becomes accustomed to osmoregulation in the ocean.

The salmon spend about one to five years (depending on the species) in the open ocean where they will become sexually mature. The adult salmon returns primarily to its natal stream to spawn. When fish return for the first time they are called whitling in the UK and grilse or peel in Ireland. Prior to spawning, depending on the species, the salmon undergoes changes. They may grow a hump, develop canine teeth, develop a kype (a pronounced curvature of the jaws in male salmon). All will change from the silvery blue of a fresh run fish from the sea to a darker color. Condition tends to deteriorate the longer the fish remain in freshwater, and they then deteriorate further after they spawn becoming known as kelts. Salmon can make amazing journeys, sometimes moving hundreds of miles upstream against strong currents and rapids to reproduce. Chinook and sockeye salmon from central Idaho, for example, travel over Template:Convert/miTemplate:Convert/test/A and climb nearly Template:Convert/ftTemplate:Convert/test/A from the Pacific ocean as they return to spawn.

Each year, the fish experiences a period of rapid growth, often in summer, and one of slower growth, normally in winter. This results in rings (annuli) analogous to the growth rings visible in a tree trunk. Freshwater growth shows as densely crowded rings, sea growth as widely spaced rings; spawning is marked by significant erosion as body mass is converted into eggs and milt.

Freshwater streams and estuaries provide important habitat for many salmon species. They feed on terrestrial and aquatic insects, amphipods, and other crustaceans while young, and primarily on other fish when older. Eggs are laid in deeper water with larger gravel, and need cool water and good water flow (to supply oxygen) to the developing embryos. Mortality of salmon in the early life stages is usually high due to natural predation and human induced changes in habitat, such as siltation, high water temperatures, low oxygen conditions, loss of stream cover, and reductions in river flow. Estuaries and their associated wetlands provide vital nursery areas for the salmon prior to their departure to the open ocean. Wetlands not only help buffer the estuary from silt and pollutants, but also provide important feeding and hiding areas. The salmon is eaten almost everywhere in the world.

SpeciesEdit

The various species of salmon have many names, and varying behaviors.

Atlantic Ocean speciesEdit

File:Atlantischer Lachs.jpg
Atlantic salmon

Atlantic ocean species belong to the genus Salmo. They include,

  • Atlantic salmon or Salmon (Salmo salar), is the species after which all the others are named.

Pacific Ocean speciesEdit

Pacific species belong to the genus Oncorhynchus, some examples include;

  • Cherry salmon (Oncorhynchus masu or O. masou) is found only in the western Pacific Ocean in Japan, Korea and Russia and also landlocked in central Taiwan's Chi Chia Wan Stream.[5]
  • Chinook salmon (Oncorhynchus tshawytscha) is also known in the USA as King or Blackmouth Salmon, and as Spring Salmon in British Columbia. Chinook are the largest of all Pacific salmon, frequently exceeding Template:Convert/LoffAonDbSoffTemplate:Convert/test/Aon.[6]The name Tyee means Chinook over 30 pounds in British Columbia.
  • Chum salmon (Oncorhynchus keta) is known as Dog or Calico salmon in some parts of the USA. This species has the widest geographic range of the Pacific species:[7] south to the Sacramento River in California in the eastern Pacific and the island of Kyūshū in the Sea of Japan in the western Pacific; north to the Mackenzie River in Canada in the east and to the Lena River in Siberia in the west.
  • Coho salmon (Oncorhynchus kisutch) is also known in the USA as Silver salmon. This species is found throughout the coastal waters of Alaska and British Columbia and up most clear-running streams and rivers.
  • Pink salmon (Oncorhynchus gorbuscha), known as humpies in south east Alaska, are found from northern California and Korea, throughout the northern Pacific, and from the Mackenzie River in Canada to the Lena River in Siberia, usually in shorter coastal streams. It is the smallest of the Pacific species, with an average weight of Template:Convert/LoffAonDbSoffTemplate:Convert/test/Aon to Template:Convert/LoffAonDbSoffTemplate:Convert/test/Aon. [8]
  • Sockeye salmon (Oncorhynchus nerka) is known in the USA as Red salmon.[9] This lake-rearing species is found south as far as the Klamath River in California in the eastern Pacific and northern Hokkaidō Island in Japan in the western Pacific and as far north as Bathurst Inlet in the Canadian Arctic in the east and the Anadyr River in Siberia in the west. Although most adult Pacific salmon feed on small fish, shrimp and squid; sockeye feed on plankton that they filter through gill rakers.[3]
  • Steelhead or Steelhead trout or Rainbow trout (Oncorhychus mykiss) are river spawners, usually found in the same rivers that produce chinook, especially the Columbia, Snake, Skeena, and other large rivers on the Pacific Coast. Steelhead have also been introduced into some rivers surrounding the Laurentian Great Lakes.

Other speciesEdit

  • Land-locked salmon (Salmo salar sebago) live in a number of lakes in eastern North America. This subspecies of Atlantic Salmon is non-migratory, even when access to the sea is not barred.
  • Kokanee salmon is a land-locked form of sockeye salmon.
  • Huchen or Danube salmon (Hucho hucho), the largest permanent fresh water salmonid


References Edit

File:Durham Ranger salmon fly.jpg
Durham Ranger, a classic design of salmon fly used in the sport of fly fishing.
  1. Endangered Salmon. U.S. Congressman Jim McDermott. URL accessed on 2006-11-17.
  2. McGrath, Susan Spawning Hope. Audubon Society. URL accessed on 2006-11-17.
  3. 3.0 3.1 3.2 Pacific Salmon, (Oncorhynchus spp.). U.S. Fish and Wildlife Services. URL accessed on 2006-11-17.
  4. A Salmon's Life: An Incredible Journey. U.S. Bureau of Land Management. URL accessed on 2006-11-17.
  5. Formosan salmon. Taiwan Journal. URL accessed on 2006-12-13.
  6. Chinook Salmon. Alaska Department of Fish and Game. URL accessed on 2006-11-17.
  7. Chum Salmon. Alaska Department of Fish and Game. URL accessed on 2006-11-17.
  8. Pink Salmon. Alaska Department of Fish and Game. URL accessed on 2006-11-17.
  9. Sockeye Salmon. Alaska Department of Fish and Game. URL accessed on 2006-11-17.

External linksEdit

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