[Family Salmonidae, Genus Oncorhynchus (Pacific) and Salmo (Atlantic) species]
Salmon are large seagoing Trout. Actually all Trout are Salmonidae but we've broken out those not called Salmon to a Trout heading for clarity, Salmon live most of their lives in the deep oceans but return to the river of their birth to spawn - and then die. Why they die I do not know, other fish of the same genus, even seagoing ones, survive spawning (so are classed as Trout). Atlantic salmon have a high mortality at spawning but some survive.
Leaner and with a more complex flavor than farmed salmon, wild is in short supply and will cost at least three times as much per pound as farmed salmon. Keeping the price and flavor in mind you should not use complex recipes that will mask the flavor and texture of the fish or you might as well use farmed.
Wild salmon may be caught in rivers and estuaries in nets or at sea on troll lines. Troll fishermen say their fish are handled more carefully than netted so are more consistent in quality.
Wild salmon vary considerable size differences even within a species because they reach sexual maturity at a variety of ages. There is also a quality difference within each species depending on which river they are associated with, but information on that is currently very unreliable.
Salmon are both fast growing and in great demand by consumers which makes them prime subjects for fish farming. Farming does have ecological impacts on the wild fishery, particularly from escaped fish (greatly reduced in recent years) and an economic impact from reducing the price wild salmon can fetch.
Many food writers campaign against farmed salmon and urge you to buy only wild salmon - but lets look at reality. The wild catch, worldwide, is less than 1 million tons. Worldwide farm production is well over 2 million tons. Without farmed salmon wild salmon would be so expensive it would all be shipped to Japan where an absurdly high price is considered a major enhancement to dining pleasure.
Farmed salmon are predominantly Atlantic salmon, even in Pacific coast farms, because they are less aggressive than Pacific salmon and produce a higher yield. A fair amount of Pacific salmon is still farmed and is considered preferable because ecological damage from fish escaping into the Pacific is very small.
Salmon flesh is normally a light gray color, but consumers demand the red color of returning ocean fish. To achieve this the farms add carotenoid dyes to the feed of maturing fish. These are the same dyes wild fish acquire from eating crustaceans.
For grilling, many people prefer farmed salmon over wild because it is fattier and easier to grill. Farmed salmon is generally free of tapeworms, nematodes and other parasites.Genetically Modified Salmon
The company AquaBounty Technologies of Maynard, Massachusetts has developed a "transgenic" farmed salmon that grows twice as fast normal salmon by modifying its genetic code. They have been growing these fish at an inland farm in Panama that can produce only about 100 tons a year.
The FDA has not yet (2013) approved these fish for sale in the United States, but approval is expected soon, despite strong public protest. The FDA has rated these fish safe for consumption - but there is simply no data on the long term effects of GM foods.
A major concern is ecological. Should these fish escape into the oceans, they could very severely effect, even destroy, wild stocks. For this reason, only inland farms are likely to be approved in the United States - but AquaBounty intends to sell eggs to China, where regulation is a joke. They'll be in the oceans within months.
Prep & Cooking Salmon
Because of its oiliness, salmon is often broiled or grilled, but it is also poached for many recipes.