Man's Impact on the Columbia River Stocks of Salmon

Abstract

The impact of man on the salmon and steelhead of the Columbia River includes 35 years of effort to prevent declines in the stocks. Between 1866 and 1940, the commercial fishery harvested an annual average of 29 million pounds of salmon and steelhead, but in the next 35 years the annual average harvest dropped to 8 million pounds. During these 35 years the habitat for anadromous fishes dropped from 163,200 to 72,800 square miles. Various approaches to mitigation were tried, but the cumulative effects of the impacts were not compensated for and the runs declined. The productivity in terms of returning adults per spawner has become less than 1 for the upper river stocks. The management flexibility of allowing additional losses at any stage in the life history of these stocks has been lost. Thus, a policy of zero impact for all new developments has been adopted.