Salmon is the common name for several species of fish of the Salmonidae family ““ although several other fishes in the family are called trout. Salmon live in both the Atlantic and Pacific Oceans.
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 and modern research shows that usually at least 90% of the fish spawning in a stream were born there. In Alaska, the crossing over to other streams allows salmon to populate new streams, such as those that emerge as a glacier retreats. How they navigate is still a mystery, though their keen sense of smell may be involved. In all species of Pacific salmon, the mature individuals die within a few weeks of spawning.
Coastal dwellers have long respected the salmon. Most peoples of the Northern Pacific shores had a ceremony to honor the first return of the year. For many centuries, people caught the salmon as they swam upriver. A famous spearfishing site on the Columbia River at Celilo Falls was inundated after great dams were built on the river. Now, salmon are caught in bays and near shore. Long drift net fisheries have been banned on the high seas except off the coast of Ireland.
Both Atlantic and Pacific Salmon are important to recreational fishing around the world.
The female salmon lays fertilized eggs in stream bottom gravel nests called redds. These eggs are usually orange to red in color. The eggs 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 native stream before becoming smolts. The smolt body chemistry changes allowing them to live in salt water. As soon as they become covered with silvery scales they are called grilse. They migrate to the ocean where they will develop in about two to three years into mature salmon. The adult salmon will return to their native stream to repeat the spawning cycle. Once the adult spawns, it is called a kelt and often dies. If it survives, it will repeat the migration and spawning cycle.
Salmon as Food
Salmon is a popular food item and reasonably healthy due to its high protein and Omega-3 fatty acids and its overall low fat levels. According to reports by Science, however, farmed salmon may contain high levels of dioxins. PCB (Polychlorinated biphenyl) levels may also be up to 8 times higher in farmed salmon compared to wild salmon, and Omega-3 content may also be lower than wild caught species. But according to the British FSA (Food Standards Agency) the benefits of eating even farmed salmon still outweigh the risks. Conversely, salmon is generally one of the least tainted by methyl mercury of all fish.
A simple rule of thumb is that the vast majority of Atlantic salmon available on the world market is farmed (greater than 99%), whereas the majority of Pacific salmon is wild-caught (greater than 80%).
Salmon is a white-flesh fish. It’s natural color results from carotenoids — astaxanthin and to a lesser degree, canthaxanthin — in the fish flesh. Wild salmon get these carotenoids from eating krill and other tiny shellfish. Farm salmon get them in their feed, along with other essential nutrients. It is important to note that astaxanthin is a potent antioxidant that also stimulates fish nervous systems and improves fertility and growth.
Canned salmon in the U.S. is always wild Pacific catch. Smoked salmon is another popular preparation method, and can either be hot or cold smoked. Lox can refer either to cold smoked salmon, or to salmon cured in a brine solution (also called gravlax).
Raw salmon meat may contain anisakidae, a marine parasite to cause anasakiasis. Before the availability of refrigeration, Japanese did not consume raw salmon. Salmon and salmon roes were not used to make sashimi (raw fish) and sushi until recently.
Salmon is the third largest seafood product raised on fish farms, with shrimp being the second and carps being by far the largest product. Raising salmon on farms decreases the demand for wild salmon but paradoxically increases the demand for other wild fish. Salmon are carnivorous and are currently fed a meal produced from catching other wild fish, so as the number of farmed salmon increase, the demand for other fish to feed the salmon increases. Work continues on substituting vegetable proteins for animal proteins in the salmon diet.
The various species of salmon have many names.
Atlantic Ocean species
- Atlantic salmon or Salmon (Salmo salar), is the species after which all the others are named.
- Another Atlantic species, Salmo trutta, is usually classified as a trout, despite being a closer relative of Atlantic Salmon than any of the Pacific species of salmon. See Brown Trout.
Pacific Ocean species
- Sockeye salmon (Oncorhynchus nerka) is known locally as “Red Salmon” or “Blueback Salmon.” This species is found south as far as the Klamath River in California in the eastern Pacific and northern Hokkaido 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.
- Chinook salmon (Oncorhynchus tshawytscha) is also known locally as King, Tyee, Spring Salmon, Quinnat, Tule, or Blackmouth salmon.
- Pink salmon or Humpback salmon (Oncorhynchus gorbuscha) is found from northern California and Korea, throughout the northern Pacific, and from the Mackenzie River in Canada to the Lena River in Siberia.
- Chum salmon (Oncorhynchus keta) is known locally as Dog or Calico aalmon. This species has a wide geographic range: south to the Sacramento River in California in the eastern Pacific and the island of Kyushu 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 or Silver salmon (Oncorhynchus kisutch) is found throughout the coastal waters of Alaska and up most clear-running streams and rivers.
- Cherry salmon (Oncorhynchus masu or O. masou) is found only in the western Pacific Ocean in Japan, Korea and Russia.