Figure 1: --Lewis and Clark Lake, a mainstem Missouri River reservoir. 



methods remained essentially the same through 

 1961. Beginning in 1959 another study area, 18 

 miles above the dam, was added to investigate 

 the upper reaches of the reservoir. 



Methods used by the Bureau of Sport Fisher- 

 ies and Wildlife to sample the reservoir in 1962 

 were similar to those employed by South Dakota. 

 Six study areas were established, extending from 

 the dam to the mouth of the Niobrara River , and 

 each area was sampled eight times from May 

 through October. Sampling equipment included 

 two frame or modified fyke nets with 75 -foot leads 

 (mesh size, 2 1/2 inches stretch measure), two 

 250-foot nylon gill nets (one with mesh sizes 0.5, 

 1.5, 2.5, 4.0, and 6.0 inches stretch measure, 

 and the other with mesh sizes 1.0, 2.0, 3.0, 5.0, 

 and 7.0 inches stretch measure), a 40-foot, 1/4- 

 inch -mesh, bag seine, a 220-volt boom electro - 

 shocker boat, and a 16-foot semiballoon trawl. 

 Data collected with the two latter types of sampling 

 gear and the gill net mesh sizes not fished in 

 former years were not used for comparison with 

 previous years' studies. 



A scale sample, total length, weight, sex, 

 and maturity were obtained from as many as 25 



fish of each species collected at each station by 

 each gear. Length frequency was recorded for 

 as many as 100 fish of each species collected at 

 each station. Scale samples were selected to 

 include all size groups, and fish used for length 

 frequency were selected at random . Shore sein- 

 ing was completed in a manner similar to that 

 of previous years. Common and scientific 

 names of fishes collected are listed in appendix 

 B. Nomenclature follows that of Bailey et al. 

 (1960) . 



RELATIVE ABUNDANCE 



The fish species found in Lewis and Clark 

 Lake were those which occurred in this section 

 of the Missouri River before closure of Gavins 

 Point Dam. By mutual agreement among Nebraska, 

 South Dakota, and the Bureau of Sport Fisheries 

 and Wildlife, fish stocking in the reservoir wa« 

 limited to four species (table 1). Numbers of 

 fish captured by gill and frame nets in June, July, 

 and August, 1956 through 1962, were used to 

 determine trends in abundance of those species 

 vulnerable to these gears (table 2). Thirty -three 

 species, exclusive of minnows, were collected 

 from the reservoir during these years, but only 

 23 were taken in 1962 . Most abundant fishes were 



