Saturday, November 2, 2013

Trout Fish

Trout Fish have strongly colored, active fishes of cold or temperate lake and rapid stream, the approximately 15 species of trout are grouped with the salmon in the family Salmonidae. All but two of the genus Salmo are regarded as trout. Once limited to the Northern Hemisphere, they are valued s game and food fish and have been introduced into the Southern Hemisphere. Although trout are predominantly freshwater fishes, some species migrate to the ocean after spawning upriver.

The trout has a moderately long, unspecialized body, that is laterally compressed, smooth, and muscular. Axial and paired fins are without spines. The softer fleshy adipose fin, between the dorsal and caudal fins, is an indicator that the trout is salmonid. All scales are small except for the elongated axial scale at the base of each pelvic fin.

The trout’s diet changes with age. Fry, or newly hatched fish, feed on aquatic insect larvae for the most part. Adults eat mainly small fish, shrimp, and winged insects.

Many male and female trout return after maturing (3 to 4 years) to the same place they were hatched in order to spawn. Most trout breed in early spring in running water. The female lays her eggs in a depression she makes by vigorously vibrating her tail in the gravelly shallows. The nearby male discharges his sperm to fertilize approximately 200 eggs, which hatch in about 40 days. As many as 10,000 eggs may be laid per season by a single female. More than 90 percent of fry are killed during the first 3 to 4 months of life by predators.

One of the best known trout is the brown trout, or sea trout, S. trutta, of Europe. This fish keep to the deeper pools and overchanging shelter of mountain streams. The seven lake trout, ischchan, and the cutthroat trout, S. clarkia, have been able to invade new and changing mountain drainages and occupy ephemeral lakes. Both species, however, have been subjected to severe recent modifications of habitat and reduction of population by dams and other human constructions.

One of the most popular game fish is the rainbow trout, S. gairdneri, the several forms of which are native to American Pacific Coast stream, The rainbow trout gets its name from the broad band of red along its sided.

For most trout populations, measures for control and conservation have been established trough government agencies and associations. Artificially propagated fish are planted in order to provide extra catches for more anglers.

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