Salmo (the Atlantic salmon and trout), Oncorhynchus (the Pacific salmon and trout), and Salvelinus (chars) are the largest of the several genera in the subfamily Salmoninae. Unfortunately, the common names of the species do not correspond to the natural divisions. The speckled, or brook, trout of the E United States, for example, is a Salvelinus and should more properly be called a char, as similar fishes in Europe are. The brown trout and many other species called trouts are members of the genus Salmo.
The only native North American species of Salmo is the Atlantic salmon. The Atlantic salmon was a plentiful source of food for the Native Americans and the colonists, but its populations have declined. A large fish (15 lb/6.8 kg average), it is found along the Atlantic coast of NE America, in Greenland, and in Europe. When in the sea it feeds on crustaceans, but as it approaches the the large rivers to spawn, it changes its diet to small fish. A landlocked form of the Atlantic salmon, the Sebago salmon, is found in Maine. The brown trout, a Salmo species introduced from Europe in 1883, requires warmer waters than the native species of trout and is important in fish-management programs. The term brown trout is used for freshwater forms of the fish; those that are largely marine are known as sea trout.
The genus Oncorhynchus is comprised of a dozen species of Pacific salmon and trout, found from S California to Alaska. Pacific salmon are the most important commercial species. Canning centers are located on the Columbia River and on Puget Sound and in British Columbia, Siberia, and N Japan. The largest and commercially most important of the Pacific salmon is the chinook (or quinnat or king) salmon, which averages 20 lb (9 kg) and may reach 100 lb (45 kg). It is found from the Bering Sea to Japan and S California and is marketed fresh, smoked, and canned. The white-fleshed fish of this normally red-fleshed species have become highly prized in the restaurant trade. The blueback salmon (called sockeye in Oregon and redfish in Alaska) has firm reddish flesh and forms the bulk of the canned salmon. Also of economic importance are the humpback, or pink, salmon, the smallest of the group; and the silver, or coho, salmon, important in the fall catch because of its late spawning season. The meat of the dog salmon is palatable when fresh or smoked. Among the trouts in this genus are the rainbow trout and cutthroat trout. The steelhead trout, also known as the salmon trout and ocean trout, is the silvery saltwater phase of the colorful rainbow trout. Of the many races of cutthroat trout, some are now extinct.
The genus Salvelinus includes the various European chars; the common brook, or speckled, trout, a popular game fish of E North America, introduced in the West; and the Dolly Varden, or bull, trout, a similar western form. The largest of the chars, the common lake trout of North America, is a deepwater fish of lakes, more sluggish, less migratory, and bulkier than the other Salmoninae. Individuals have been recorded at 100 lb (45 kg). A fish called the splake has been produced by crossing the speckled trout and the lake trout.
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