Salmon is an important food and game fish. It is found in northern regions. The salmon is characterized by a long body, small cycloid scales, a small fatty fin on the dorsal surface opposite the anal fin, and the absence of spines. It is related to the trout, salmon typically swim up from the oceans or lakes into rivers or streams to spawn. They usually return to the same waters in which they were hatched; some scientists believe that the salmon find their way by smell. Some species of salmon are landlocked in lakes.
The Atlantic salmon, Salmo salar, is found on both sides of the Atlantic and once was common in waters north of the Hudson River. Now it is limited to a few rivers in eastern Maine and Canada. Pollution, impassable dams near the mouths of rivers, over fishing, destruction of spawning grounds through deforestation, and loss of young in power plant turbines have all contributed to the destruction of this fish. The adult first migrates from the ocean into rivers in its fifth year, when it weighs 8 to 16 pounds.
It spawns over gravel beds, where the eggs remain buried for five or six months before the fish hatch. When the fish is about one month old, it comes out of the gravel and feeds on crush-taceans. At the end of the third winter, when it has lost its markings and become silvery, it is called smolt. It is then 5 or 6 inches. The smolt moves downstream to the sea, where it feeds on fishes and grows rapidly for about two years. Then, as an adult, the salmon moves upstream but returns to the ocean after it has spawned.
Sources:
NA. “ARKive – Atlantic Salmon Videos, Photos and Facts – Salmo Salar.” ARKive – Discover the World’s Most Endangered Species. Web. 24 Jan. 2012. .
Myers, P., R. Espinosa, C. S. Parr, T. Jones, G. S. Hammond, and T. A. Dewey. 2008. The Animal Diversity Web (online). Accessed at http://animaldiversity.org