1962. Information on fishes collected from 1956 

 to 1961 was obtained from Dingell -Johnson Project 

 Reports prepared by the South Dakota Departmait 

 of Game, Fish and Parks (see appendix A). The 

 1962 data were collected by the staff of the North 

 Central Reservoir Investigations. 



LEWIS AND CLARK LAKE 



Lewis and Clark Lake has the following 

 characteristics: Maximum surface area, 33,000 

 acres; length, 37 miles; average width, 2 miles; 

 maximum depth, 45 feet; average depth, 16 feet; 

 shoreline length, 100 miles; and storage capacity, 

 540,000 acre -feet. It is a re-regulatory reser- 

 voir, controlling water releases from Fort 

 Randall Dam (78 miles upstream) to provide 

 downstream navigation, power generation, and 

 flood control . The lake level is maintained 

 between 1,204 and 1,208 feet m.s.l. under normal 

 operational conditions . Weekly fluctuations in 

 water level do not normally exceed 2 feet. 



The downstream one-third of the reservoir 

 is bounded by steeply sloped banks, and the en- 

 tire river flood plain is inundated. The down- 

 stream two -thirds of the reservoir area was 

 cleared of brush and trees prior to flooding. The 

 upstream portion has a number of clusters of 

 inundated timber. The shoreline is essentially 

 straight except for a few narrow bays at the 

 mouths of small tributary streams . The lake 

 bottom is largely mud and silt with a few isolated 

 areas of sand and gravel. Six small intermittent 

 streams enter the reservoir (fig. 1)- The Nio- 

 brara River, with a mean daily flow of 1,750 

 c.f .s. , enters the Missouri River about 3 miles 

 above the reservoir. The Niobrara River carries 

 a considerable silt load and is responsible for 

 much silt deposition in the upper reservoir. This 

 condition has a marked influence on the turbidity 

 and hence the biota of Lewis and Clark Lake . 



The reservoir is characterized by a rapid 

 exchange of water. During the navigation season 

 (March through November) its entire storage 

 capacity is passed through the dam every 8 to 10 

 days. During the winter months complete water 

 exchange is possible every 30 days. The high 

 rate of water exchange is thought to have a pro- 

 found effect on the physical, chemical, and bio- 

 logical conditions found in these waters . The 



lake has no permanent thermocline during the 

 summer months . Water temperature is strongly 

 influenced by wind and rarely exceeds 82° F. 

 Dissolved oxygen concentrations during summer 

 months range from 4.9 to 9.0 p. p.m. Alkalinity 

 ranges from 140 to 177 p. p.m. and pH from 7.8 

 to 8.2. Secchi disk visibility ranges from 3 

 inches in the extreme upper reservoir to 3 feet 

 near the dam. Turbidity is influenced both by 

 the Niobrara River and by wave action stirring 

 up the lake bottom and eroding banks. 



FISH SAMPLING 



South Dakota Departm.oit of Game, Fish and 

 Parks studies in Lewis and Clark Lake were 

 designed to furnish information concerning (1) 

 relative species composition, (2) area and depth 

 distribution, (3) age and growth of scaled fishes, 



(4) reproduction success and period of spawning, 



(5) age at maturity, and (6) length-weight distri- < 

 bution. (Shields, 1957, op. cit.) Study areas " 

 were established about 3 and 11 miles upstream 

 from the dam, and in each area nets were fished 



in a 3 -to 4-mile section of the reservoir. 

 Stations were sampled three times during the 

 summer O^ne, July and August) and the sampling 

 period occupied 4 days , or 3 overnight net sets . 

 Standard netting equipment included three frame 

 or modified fyke nets with 75 -foot leads (mesh 

 size, 2.0, inch as stretch measure), two 250- 

 foot nylon experinental gill nets (mesh sizes, 

 1.5, 2.0, 2.5, 3.0, and 4.0 inches stretch 

 measure), and a 40-foot, 1/4-inch -mesh, bag 

 seine . Effort was made to fish all depths and 

 aU habitats . Gill and frame nets were fished 

 at least 16 hours with each net set before 4 p.m. 

 and lifted after 8 a.m. the following day. All 

 sets were considered comparable "24-hour" 

 sets . 



Total length, weight, sex, and maturity were 

 recorded for as many as 100 fish of each species 

 during each netting period by South Dakota fishery 

 biologists . Scale samples were obtained from 

 not more than 25 of each scaled species during 

 each netting period and were selected to represent 

 all size groups . From 10 to 20 seine hauls were 

 made during one day of each netting period, and 

 all shoreline habitats were sampled. Number of 

 hauls was dependent on shoreline conditions and 

 number and species of fish caught. Sampling 



I 



