Silent Spring: Chapter 9 Summary & Analysis

Carson begins with a nostalgic description of the idyllic salmon breeding grounds of the Miramichi, a river in New Brunswick, Canada. She describes their journey from the Atlantic upstream to their spawning grounds in rich detail, before revealing that pesticides have had a destructive impact here, too. Spraying to prevent the spread of budworm populations in Canada’s balsam forests doused millions of acres with DDT in 1954, including the Miramichi.

Errant spray killed trout and young salmon, but also wiped out the caddis fly larvae that they depended on for survival, so that returning salmon to the stream would not be easy. In the meantime, even repeated sprayings had failed to halt the budworm, and caused fundamental changes in stream life. Although a strange series of events surrounding heavy rainfall connected to Hurricane Edna led to an unusually good year for salmon in the Northwest in 1955, overall destruction across the region was massive, threatening the fishing industry’s survival.

Continuing her chronicle of death in river systems, Carson mentions reduced salmon runs in Maine that are also associated with budworm spraying, and describes fish blinded by DDT who are so disoriented that they can be plucked from the stream by hand. She goes on to discuss contamination of the Yellowstone River from 1955-57, when dead fish lined the riverbanks and an oily film covered the water. Agencies studied the destruction caused by spraying 900,000 acres in that area and concluded by taking a pledge to cooperate to minimize losses in future control attempts.

In British Columbia, though, even after those engaging in spraying had agreed to cooperate with forestry services, having seen the negative effects spraying had had on the Miramichi, many streams were still disastrously affected. 100 percent of salmon were killed in at least four streams, and could only be repopulated by transplanting young salmon artificially, since salmon return only to the place in the stream where they were born.

The threat of pesticides to fish is threefold: direct spraying of forest streams with DDT, bleaching of chemicals into the water table, and pesticides that reach marshes and bays. Commercial and recreational fishing are seriously endangered as a result. Individual accounts from all over the country reinforce this danger. In Alabama, runoff containing the chemical toxaphene after heavy rains resulted in massive fish kills. Fish are very sensitive, and can be an indicator of the ways in which toxic chemicals persist in streams.

International examples, from Rhodesia (present-day Zimbabwe) and the Philippines, also illustrate the pervasive threat. In these countries, insecticides that inadvertently contaminate fishponds used to raise important stocks of local fish have a serious effect on the food supply. After a pond is infected, it is nearly impossible to remove all chemical traces.

In 1961, contamination of the Colorado River below Austin, Texas led to massive fish death for 200 miles downstream before contaminated water was diverted into the Gulf of Mexico. Investigators discovered that a pesticide plant in Austin had been dumping chemicals for years – heavy rains from a recent storm had displaced deposits of these chemicals coating sewers, and the resulting runoff annihilated river life for hundreds of miles.

In 1955 on the eastern coast of Florida, in the Indian River country, 2,000 acres of salt marsh were treated with Dieldrin in an attempt to kill sandfly larvae. The treatment led to massive fish and crustacean mortality (20-30 tons of dead fish, or 1,175,000 individual fish). Sharks were seen swimming through the water, eating the masses of dead fish.

This episode shows that research is needed to determine the effects of chemical runoffs at sea and in important estuary/salt marsh environments. These areas serve as the breeding ground for many interconnected species. Shrimp fry and plankton have been shown to be very sensitive to pesticides, even at miniscule concentrations of parts per billion, and they serve as a vehicle for bio-magnification that could pass poisons up the chain to human consumers, according to Dr. Philip Butler.

So much is unknown, concludes Carson, and these waterways are so vitally important, that the public should demand facts and the suspension of spraying in the meantime.