A Little Bit About Salmon:

Salmon (fish), common name applied to fish characterized by an elongate body covered with small cycloid (rounded, with smooth edges) scales and possessing an adipose (fleshy) fin between the dorsal fin and tail. These fish belong to the salmon family. Most members of this family are valuable food fish and excellent game fish. They are found in both fresh and salt water in the colder regions of the northern hemisphere. Many return from salt water to fresh water to breed, and the young migrate to salt water from fresh water after they reach maturity. The migratory instinct of members of the salmon family is remarkably specific, each generation returning to spawn in exactly the same breeding places as the generation before it. Even those species that do not migrate from fresh water to salt water spawn in the same freshwater streams as did their ancestors. The spawning ground of these fish is usually a rapidly flowing, clear stream with gravel and rocks on the bottom.

Salmon Breeding and Nests:

Although usually drab in color before the breeding season, which varies with the species, members of the salmon family develop bright hues at spawning time. The male, during this season, usually develops a hooked snout and a humped back. Before mating, one parent excavates a nest for the eggs; after the eggs are deposited and fertilized, the female stirs up the stream bottom so that earth and stones cover the eggs and protect them. The eggs hatch in two weeks to six months, depending on the species and the water temperature. During the migrations and nest-building activity preceding mating, neither the females nor the males consume food.

Members of the salmon family subsist on smaller fish, crustaceans, and insects. In addition to the true salmon, the salmon family also contains many species known as char (see Trout); zoologists also include the grayling and whitefish, which are similar in structure, in the salmon family.

Atlantic Salmon:

The true salmon, the largest members of the salmon family, are characterized by tasty flesh that is often orange-red. The common salmon of the North Atlantic Ocean that is sent to market averages about 7 kg (about 15 lb) in weight, but specimens weighing more than 45 kg (more than 100 lb) have been caught. The Atlantic salmon migrates to cold, fresh water in late spring or early summer, swimming upstream at an average rate of up to 6.4 km (4 mi) per day. Because salmon can jump as much as 3.7 m (12 ft) out of water, they clear most obstacles in their path. The female lays as many as 20,000 eggs in October or November, after which time the adult salmon float downstream and return to the sea.

Unlike the various species of Pacific salmon, the Atlantic salmon does not die after its first spawning but returns year after year to its breeding place. The newly hatched young, which are known as parrs or brandlings because of the dark transverse markings on their sides, remain in fresh water for about two years. At this time, the young, which are known as smolts and which have become silvery in color, descend to the sea. Upon the first return of the Atlantic salmon to its spawning ground, the fish is known as a grilse. After spawning, it is known as a kelt.

Several subspecies of the Atlantic salmon live in the lakes of the northern United States without ever descending to sea; such salmon are known as landlocked salmon. Landlocked salmon are much smaller than are migrating salmon, attaining a maximum weight of about 35 pounds. The two most important landlocked populations of the Atlantic salmon are the Sebago salmon, found from New Hampshire to New Brunswick, and the ouananiche, of Lac Saint-Jean, Canada.

Pacific Salmon:

Salmon found in the North Pacific Ocean spawn only once, dying after depositing and fertilizing their eggs. The best-known and most valuable species is the chinook salmon, which is also known as the king salmon, Columbia River salmon, quinnat, chowichee, and takou. Market specimens of this fish average about 9 kg (about 20 lb) in weight, but numerous specimens more than 1.5 m (more than 5 ft) in length and well over 45 kg (more than 100 lb) in weight have been recorded. The chinook salmon migrates farther than any other salmon, often traveling 1600 to 3200 km (1000 to 2000 mi) inland to its spawning ground. Its eggs usually hatch within two months, and the young descend to the sea when 5 to 7.5 cm (2 to 3 in) long. The sockeye, red, or blueblack salmon is another valuable species, as is the coho, or silver salmon, which has light pink flesh. Other salmon in the Pacific basin are commonly known as the pink, or humpbacked salmon, and the chum, or dog salmon.

Anglers fish for salmon with rod and reel, often using flies as bait. Commercial fishing for salmon is done on a much larger scale, employing traps and pound nets to catch the fish on the way to their spawning grounds. Salmon canning is one of the major industries of the American Pacific coast. To mitigate the decimation of wild salmon runs caused by construction of dams and overfishing, the U.S. Fish and Wildlife Service yearly deposits billions of salmon eggs and young, propagated in nurseries, into natural breeding grounds and constructs fish ladders for the upstream journey of mature salmon. However, hatchery-raised salmon have aggressive feeding habits-that is, they spend most of their time at the water's surface looking for food unlike the wild salmon that spend most of their time in deep water or under cover. As a result, hatchery-raised salmon consume most of the food wild salmon need to live. At the same time, this aggressive feeding makes hatchery salmon more vulnerable to predators because they stay near the surface. Hatchery salmon usually have less genetic diversity (see Genetics: Genes in Populations) than wild salmon, which can lead to lowered resistance to disease and other environmental hazards. The annual harvest of wild and farm-raised salmon in the United States averages about 478,000 metric tons, of which about 60 percent is canned.