Salmon Populations and Bottom Fauna in the Wenatchee River, Washington

Abstract

The standing crop of bottom fauna in the Wenatchee River, Washington, and its tributary Nason Creek declined from an average of 233 animals per square foot in the fall of 1940, to an average of 50 animals per square foot in the falls of 1955 and 1956. Average volumes declined from 2.7 cubic centimeters per square foot in 1940 to 0.3 and 0.4 cubic centimeters per square foot in 1955 and 1956. During this same interval the populations of chinook salmon and steelhead trout in the stream had increased greatly and the sockeye run had increased at least 7-fold. Since sockeye young migrate down the Wenatchee River after spending their juvenile period in Lake Wenatchee, it seems likely that the increase in salmonids in the stream has been an important factor in reducing the bottom fauna crop.