Fish Production in Two Idaho Streams

We estimated fish production (tissue elaboration) in two tributaries of the Salmon River in Idaho. Fish in Big Springs Creek produced 11.8 g/m2/yr and in the Lemhi River 13.6 g/m2/yr. In Big Springs Creek juvenile rainbow-steelhead trout comprised most (84–95%) of the biomass present and contributed most of the production (88%). In the Lemhi River, however, a large population of unexploited whitefish made up most (60–80%) of the biomass but they contributed only 52% of the production. The desired yield from Big Springs Creek, an intensively managed stream, was steelhead trout smolts and the weight of the juvenile migrants was 34% of total production in the stream. In the Lemhi River, chinook salmon smolts were the primary desired yield and weight of smolts was probably less than 11% of total production. Virtually no yield was obtained from the whitefish population in the Lemhi River.