Salmon hatcheries are commonly found near rivers along the West Coast of the United States because of decline in wild salmon populations due to what activities?

Salmon populations in the United States is declining due to the following factors:

1. Over-fishing and human activities have put a major influence on the population of salmon.

2. Due to industrialization, urban growth, unplanned farming, deforestation, and pollution would have imparted strains on the stocks of salmon. Apart from this chemical contamination from the industrial run-off and agricultural activities are also declining populations of salmon.

3. Genetically modified fish from hatcheries usually escape and interbreed with wild fish, thus, changing the genetic features of the populations.

4. Construction of hydropower dams is also a major cause of the salmon population declining.

The Salmon are endothermic animals and there internal environment changes according to the external environments. The change in the external environment can lead to the sudden decline in the population.

The main factors that are responsible for the decline in salmon populations are habitat fragmentation, habitat loss, hatcheries, increased urbanization and sudden change in the external environment. The increase in the environmental population also decreases the Salmon population.