They are naturally distributed throughout most of the northern hemisphere from the temperate zone to beyond the Arctic circle. Now is limited in a few rivers in eastern Maine and Canada. Pollution, impassable dams near the mouths of river, over fishing, destruction of spawning grounds through deforestation, and loss of young in power plant turbines have all contributed to the loss of this fish.
In the first form salmon farming, eggs are hatched, fry are grown, smolt are produced placed in saltwater cages to grow until market size. Smolt are young salmon that undergone internal changes that allow them to live in saltwater.
The second type, referred to as salmon ranching, the smolts are released into their natural environment to feed and grow, many of the salmon will be harvested when they return to the rivers and spawn.
Salmon feed on different foods such as:
➥Fry and parr eat mainly the larvae of aquatic insects, such as blackflies, stoneflies, caddisflies, and chironmids.
➥ Smolts feed on amphipods (small shrimp- like crustaceans.
➥Later stages feed on smaller fish.