Chinook Salmon Environmental Science Wednesday, February 26, 1997 Among the many kinds of fish harvested each year by commercial fisheries is the Oncorhynchus tshawytscha or Chinook salmon. The United States catches an averages of about three hundred million pounds of salmon each year. However some Chinook salmon have been recently listed as threatened. Man has been the main cause for the decline in Chinook salmon populations. The populations of Chinook salmon have declined for several reasons. Hydropower and it's destructiveness to the environment, pollution, and overfishing are the three main causes for the decline.