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INTRODUCTION Both walleyes Sander vitreum and saugers Sander canadense have inhabited Lewis and Clark Lake since its formation in 1956 (Walburg 1976). Sauger have historically been more abundant than walleye (Bailey and Allum 1962; Walburg 1976) and have remained so until recently (Wickstrom, 2005). Standardized fish population surveys on Lewis and Clark Lake, utilizing gill nets, have been conducted annually by Department of Game, Fish and Parks biologists since 1983. These surveys are conducted during late summer, which limits fish collection to a specific time of year. Consequently, little is known about fish distribution in Lewis and Clark Lake during other times of the year. Creel surveys have been conducted on Lewis and Clark Lake during 1984, 1994, 1995, 2000, and 2001 (Stone 1985; Wickstrom 1995; Wickstrom 1996; Mestl et al. 2001; Wickstrom et al. 2002). Typically anglers harvest more walleyes than saugers, even though, until recently, fish population surveys show a higher abundance of saugers than walleyes (Wickstrom 2005). Thus, it seems that sauger may be under utilized by recreational anglers. Bowen (1996) suggested that there should be specific reasons for doing fish species food habit studies. Results of recent fish population surveys on Lewis and Clark Lake have shown that walleye and sauger have low relative weights (Wr, Anderson 1980). During the 2005 fish population survey, stock-length (Anderson and Weithman 1978) walleye mean Wr was 81 and stock-length mean sauger Wr was 76 (Wickstrom, in press). Abundance of prey items, or prey item quality, could be a problem for walleye and sauger in Lewis and Clark Lake. Extensive hybridization and introgression between sauger and walleye has been clearly documented in Lewis and Clark Lake. In a previous study, 24% of the fish contained alleles of the other species and 29% were misidentified by morphological examination (Billington et al. 2004). A much higher proportion of fish identified as walleye (39%) had sauger alleles in them than fish identified as sauger by morphology contained walleye alleles (9%). The ability to distinguish between saugers and walleyes may have implications for this study. The objectives of this study were to: OBJECTIVES 1. Describe movement of walleyes and saugers in the Missouri River between Ft. Randall Dam and Gavins Point Dam by December 2005. 2. Compare seasonal distribution of walleyes and saugers in Lewis and Clark Lake by December 2005. 3. Document seasonal food habits of walleyes and saugers in Lewis and Clark Lake by December 2005. 4. Provide information on sauger seasonal distribution and habitat use to anglers by December 2005, in an attempt to improve angler harvest and utilization of sauger in the fishery. STUDY AREA Lewis and Clark Lake, located in southeastern South Dakota, is the lower-most mainstem Missouri River reservoir. It was formed by the closure of Gavins Point Dam near Yankton, South Dakota and covers approximately 10,500 ha. A reach of unchannelized Missouri River, approximately 60 km long, extends 1
upstream from Lewis and Clark Lake to Ft. Randall Dam. Lewis and Clark Lake has a maximum depth of 16.7 m and a mean depth of 5.0 m. The shoreline is nearly straight, except for small, shallow bays at the mouths of intermittent tributary streams. Vegetation in the reservoir is scarce. Lewis and Clark Lake does not thermally stratify due to its relatively shallow depth. For sampling purposes, Lewis and Clark Lake was divided into two zones (Figure 1). The upper zone, which extends from river kilometer (rk) 1318 to rk 1329, consists of a large expanse of shallow (2-4 m) water that is commonly turbid from frequent winds. The lower zone, which extends from rk 1305 to rk 1318, is deeper (5-12 m), clearer and less disrupted by wind than the upper zone. SITE SELECTION METHODS Sampling sites were defined by superimposing a 600 m x 600 m grid over a Lewis and Clark Lake map. A stratified-random sampling design was used to establish sampling locations by selecting three limnetic (offshore) and three littoral (near-shore) cells per reservoir zone. Littoral cells contained shoreline and limnetic cells lacked shoreline. Once a cell was selected for sampling, no adjacent cell could be selected during the same season in order to avoid the influence of a sampled cell on an adjacent cell. No cell could be selected more than once a year so as to avoid sampling a depleted cell. FIELD COLLECTION OF FISHES Walleyes and saugers were collected for tagging with gill nets, trap nets, and by pulsed, DC electrofishing. Gill nets, 50.8 mm bar measure mesh, were fished during April and May 2002 in the Missouri River upstream of Lewis and Clark Lake, mainly in Ft. Randall Dam tailwater. Gill nets were lifted approximately each hour for fish removal and tagging. Trap nets were fished April and early June in Lewis and Clark Lake between rk 1311 and rk 1318 and along the face of Gavins Point Dam. Trap nets were pulled daily for fish removal and tagging. Electrofishing (180 v, 6-8 a, and 60 pps) was done during April and May at Ft. Randall Dam tailwater, in the Missouri River from rk 1403 to 1408 and rk 1340 to 1347, in Lewis and Clark Lake from rk 1313 to 1322. Walleyes and saugers were measured and 300 mm and longer fish had dangler tags attached as described by Riis (1983). Tagged fish were released in the vicinity of where they were caught. Walleyes and saugers were collected from Lewis and Clark Lake using 91.4 m by 1.8 m experimental gill nets with 15.2 m panels of 12.7 mm, 19.1 mm, 25.4 mm, 31.8 mm, 38.1 mm, and 50.8 mm bar measure meshes. Three gill nets were fished in each of three littoral and three limnetic cells in two reservoir zones during three seasons. Appendix 1 and 2 provide universal transverse mercator coordinates of gill nets set in Lewis and Clark Lake. A total of 36 gill nets were fished overnight (approximately 20 h) each month during May, July, and September (spring, summer, and autumn) 2002 and 2003. Surface water temperature, conductivity, and secchi disc readings were measured during each period of time gill nets were being fished. 2
Page 1 and 2: SEASONAL DISTRIBUTION, MOVEMENT, AN
Page 3 and 4: PREFACE Information summarized in t
Page 5 and 6: Walleyes and saugers collected duri
Page 7 and 8: LIST OF TABLES Table Page 1. Summar
Page 9: List of Appendix continued… Appen
Page 13 and 14: DATA COLLECTION FROM SAMPLED FISHES
Page 15 and 16: Table 1. Summary of tagging and rec
Page 17 and 18: Over 48% of the tagged walleyes wer
Page 19 and 20: no difference in distribution durin
Page 21 and 22: Table 8. Mean relative weights (sta
Page 23 and 24: Stock Structure Indices Sauger PSD
Page 25 and 26: Table 11. Proportional stock densit
Page 27 and 28: spring through autumn. Freshwater d
Page 29 and 30: Table 12 continued… Notropis spp.
Page 31 and 32: Table 12 continued… Summer Upper-
Page 33 and 34: Table 12 continued… Autumn Upper-
Page 35 and 36: Table 12 continued… Aplodinotus g
Page 37 and 38: Table 13 continued. Unidentified in
Page 39 and 40: Table 13 continued. Isopoda 2.3 0.1
Page 41 and 42: Table 13 continued. 250-379 11 81.8
Page 43 and 44: Table 13 continued. Hexagenia sp. 3
Page 45 and 46: Table 13 continued. Dorosoma cepedi
Page 47 and 48: Table 14. Percent diet overlap (Sho
Page 49 and 50: Isaak, L.C., R.M. Neumann, and D.W.
Page 51 and 52: APPENDICES Appendix 1. Universal tr
Page 53 and 54: Appendix 3. Analysis of variance re
Page 55 and 56: Appendix 8. Results of pairwise com
Page 57 and 58: Appendix 12. Analysis of variance r

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