Salmon Essay Research Paper Chinook SalmonEnvironmental Science - Реферат

Salmon Essay, Research Paper

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.

Salmon canning is one of the major industries of the pacific coast. To decrease

the rate at which the salmon population is falling the U.S. Fish and Wildlife

service yearly deposits billions of young salmon and eggs into natural breeding

grounds. Salmon are also raised in and then deposited. The National Marine

Fisheries Service has also proposed a recovery plan for the Chinook salmon.

They plan to improve migration conditions, by increasing the area around the

dams so that the salmon can get through. Also they plan to protect the fishes’

spawning habitat, by improving the general management. They would also like to

develop alternative harvesting methods.

The effects that man has had on the Chinook salmon and many other species of

salmon is very severe, any are labeled as threatened. We can reduce the causes

of their population decrease by reducing the amount of fish we catch annually,

reducing pollution dumped into their habitats, and by developing ways for the

fish to bypass the dams.

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