Chinook Salmon :: essays research papers

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. The Chinook salmon is known for traveling the greatest distance back to its spawning grounds, often traveling one to two thousand miles inland. This long journey is now often interrupted by hydroelectric plants. Hydropower is a very good alternative resource for power, however it is very damaging to our salmon populations. The dams block off rivers, which block the salmon's path back to their breeding grounds. The salmon go back to the same areas, just as their ancestors did, to lay their eggs. The hydropower plant's turbines are also very dangerous to young salmon. Many of them are killed by the giant turbines on their way back to the ocean. Killing off many of the salmons new generation. Pollution is also a killer of many Chinook salmon. Pollution caused by sewage, farming, grazing, logging and mining find it's way into our waters. These harmful substances kill many species of fish and other marine life. The Chinook salmon is no exception. The chemicals are dumped into the rivers and streams and eventually these chemicals find their way to the ocean, polluting and effecting each area they pass through. The largest contributor to the decline in the Chinook salmon population is the commercial fishing industry. From a period of 1990-1992 815,000 Chinook salmon were caught by commercial fisheries. This does not include the 354,000 recreational catches. Commercial fishing is a big industry. Commercial fishers use nets, which they pull by boats. Some nets are designed so the holes in the nets are large enough for the head of the fish to fit through, and then the mesh gets caught in the fish's gills. Others are designed to circle around a school of fish and then is drawn shut. New technologies have developed factory stern trawlers which easily haul netloads of up to 100 metric tons of fish. However, when catching the salmon, fisherman use pound nets to catch the fish on their way to their spawning grounds. The average annual salmon catch in just the United States is about 300 million pounds, of that about 60 percent is canned.