Effects of Reservoir Elevation and Spatial Synchrony on Walleye Recruitment in Lake Oahe, Missouri River

Abstract

Recruitment is an important driver of fish population abundance and size structure and can be affected by a variety of density-dependent and density-independent factors. Walleye Sander vitreus populations often exhibit variable yearclass strength, which has been attributed to a suite of factors. In this study, we quantified variability in Walleye recruitment, assessed within-lake recruitment synchrony, and modeled recruitment variability for year-classes that were produced from 1988 to 2013 in Lake Oahe, a large Missouri River reservoir. The objectives of this study were to determine (1) whether Walleye recruit annually, (2) whether Walleye recruitment is spatially synchronous, and (3) whether Walleye recruitment is better described by biotic or abiotic factors. The variability of Walleye recruitment was indexed by using gill-net catch of age-2 Walleye across nine locations in Lake Oahe, and factors affecting recruitment were evaluated by using stock-recruit analysis. Over the 26 years that were assessed, all year-classes were present and four exceptionally large year-classes were produced. Recruitment synchrony was apparent among locations within Lake Oahe, but this relationship was largely influenced by the spatial synchrony of the four exceptionally large year-classes and was no longer detectable when those year-classes were removed. The relative abundance of age-4 and older Walleye, taken as an index of spawner abundance, was a poor predictor of Walleye recruitment, indicating that Walleye recruitment was regulated by density-independent factors across the range of observations. The interactive effects of reservoir elevation and elevation change improved model fit to explain 59% of the recruitment variation and indicated that increased elevation from the previous year improved recruitment. Our results indicate that Walleye recruitment may be favored by increasing the water levels in the reservoir in spring. Recruitment is often the most variable rate that influences the abundance and size structure of fish populations (Gulland 1982; Allen and Pine 2000; Hansen and Nate 2014). Year-class strength and subsequent recruitment to a fishery can be influenced by density-dependent effects on juvenile production and survival as well as many densityindependent abiotic and biotic factors. Spawner abundance may influence recruitment through compensatory density dependence, with high juvenile survival at low spawner abundance and low juvenile survival at high

Factors affecting walleye and sauger recruitment in Lewis and Clark Lake, South Dakota, 2001–2022

“…Furthermore, we found recruitment synchrony (correlation) between walleye and sauger age-0 abundances, unlike an analysis of older age-classes of walleye and sauger in Lewis and Clark Lake (Graeb, 2006). Furthermore, walleye recruitment was spatially synchronous among locations in Lake Oahe (Felts et al, 2020).…”

Informing Management of Henrys Lake, Idaho, using an IntegratedCatch‐at‐AgeModel

“…However, collecting a time series of catch‐at‐age data from such fisheries is not uncommon (e.g., Parsons and Pereira 2001; Felts et al. 2020; McDougall et al. 2020; Budy et al.…”

“…Moreover, we are unaware of any published integrated assessments for fisheries that are maintained or supplemented through juvenile fish stocking. However, collecting a time series of catch-at-age data from such fisheries is not uncommon (e.g., Parsons and Pereira 2001;Felts et al 2020;McDougall et al 2020;Budy et al 2021). Estimating recruitment using catch-atage models for populations with natural recruitment can add considerable uncertainty to estimated parameters and predictions (Fournier and Archibald 1982;Maunder and Deriso 2003;Maunder and Piner 2015).…”

Smallmouth Bass and Walleye predation on stocked age‐0 Walleye in Lake Oahe, South Dakota

“…The Walleye Sander vitreus is an economically important sport fish that is native throughout much of North America (Fenton et al 1996;Locke et al 2005;Hoagstrom et al 2007). However, unsuitable spawning habitat (Foust and Haynes 2007;Raabe and Bozek 2012;Raabe et al 2020), high angler harvest (Sullivan 2002(Sullivan , 2003Beard et al 2003), and variable natural recruitment due to environmental conditions (Hansen et al 2015a;Felts et al 2020) have led to the implementation of stocking programs in many areas throughout the species' range (Ellison and Franzin 1992;Fenton et al 1996;Lathrop et al 2002). A suite of factors can influence the poststocking survival of Walleye (Nate et al 2003;Harmon 2009;Grausgruber and Weber 2020a), but predation is one of the most commonly cited factors.…”

“…2015a; Felts et al. 2020) have led to the implementation of stocking programs in many areas throughout the species' range (Ellison and Franzin 1992; Fenton et al. 1996; Lathrop et al.…”