Lake Taneycomo, a 700-hectare hydroelectric impoundment in Taney County, southwestern Missouri, is fed by cool hypolimnetic waters from an upstream reservoir. A popular put-grow-and-take fishery for rainbow trout Salmo gairdneri has become established in Lake Taneycomo, but fishing success and effort decline each fall when oxygen-depleted waters enter the lake. The fishery was examined in detail from June 1978 through May 1980. During this period, catch rates of rainbow trout averaged 0.55 fish/hour, and were influenced by dissolved-oxygen concentration, number of fish available to be caught, discharge rates from the upstream reservoir, angler experience, and water temperature. A decrease of 1 mg/liter dissolved oxygen, between 6.0 and 2.4 mg/liter, reduced catch rates by 0.1 fish/hour. During the fall, a change in catch rate of 0.1 fish/hour can result in a change of 20,000 hours of fishing at Lake Taneycomo. The expected annual economic loss to the Taney County economy due to low concentrations of dissolved oxygen is $358,000 (range, $267,000-$432,000).
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