Environmental factors regulating the recruitment of walleye Sander vitreus and white bass Morone chrysops in irrigation reservoirs

Abstract

Understanding the environmental factors that regulate fish recruitment is essential for effective management of fisheries. Generally, first-year survival, and therefore recruitment, is inherently less consistent in systems with high intra-and interannual variability. Irrigation reservoirs display sporadic patterns of annual drawdown, which can pose a substantial challenge to recruitment of fishes. We developed species-specific models using an 18-year data set compiled from state and federal agencies to investigate variables that regulate the recruitment of walleye Sander vitreus and white bass Morone chrysops in irrigation reservoirs in south-west Nebraska, USA. The candidate model set for walleye included only abiotic variables (water-level elevation, minimum daily air temperature during winter prior to hatching, annual precipitation, spring warming rate and May reservoir discharge), and the candidate model set for white bass included primarily biotic variables (catch per unit effort (CPUE) of black crappie Pomoxis nigromaculatus, CPUE of age-0 walleye, CPUE of bluegill Lepomis macrochirus and CPUE of age-3 and older white bass), each of which had a greater relative importance than the single abiotic variable (minimum daily air temperature during winter after hatching). Our findings improve the understanding of the recruitment of fishes in irrigation reservoirs and the relative roles of abiotic and biotic factors.

The Influence of a Rapid Drawdown and Prolonged Dewatering on Fishing Effort, Catch, and Harvest in a Nebraska Reservoir

“…Natural recruitment of hybrid striped bass, walleye, and white bass likely would be negatively aff ected by the decrease in water level as these species have highly variable recruitment in this region (DeBoer et al 2012) and are oft en sustained through stocking, which did not occur in Red Willow Reservoir post-drawdown. Largemouth bass were likely to experience a substantial decline in natural recruitment aft er the decrease in water level, due to the loss of littoral habitat (Meals and Miranda 1991).…”

Factors influencing recruitment of walleye and white bass to three distinct early ontogenetic stages

“…) and white bass (31%–36%, DeBoer et al. ) in multiple water bodies. Environmental factors often explain much of the variation in year‐class strength observed in fish populations (Boehlert & Mundy ; Hansen et al.…”

“…Populations of walleye and white bass in south‐west Nebraska irrigation reservoirs are dynamic (DeBoer et al. ), despite considerable effort by the Nebraska Game and Parks Commission (NGPC) stocking walleye and managing reservoirs for walleye and white bass. Age‐0 walleye feed on zooplankton and macroinvertebrates (Hoxmeier et al.…”

“…), which could result from differences in spawning seasons for adult walleye and white bass (DeBoer et al. ).…”

Masked Expression of Life-History Traits in a Highly Variable Environment

“…Walleye evolved in the relatively stable and predictable environs of glacial lakes and rivers (Scott and Crossman 1973;Bailey and Smith 1981), but the abiotic conditions of irrigation reservoirs are highly variable and unpredictable, oft en based on the nuances of agricultural needs. Th e "harsh" environment of irrigation reservoirs leads to signifi cant fl uctuation in walleye recruitment, which is closely tied to abiotic conditions, including reservoir water level (DeBoer et al 2013). Water released from reservoirs for irrigation can carry age-0 walleye and zooplankton through the dam causing a direct reduction in recruits (Walburg 1971) as well as reducing food availability for larval walleye (sensu Watson et al 1996;Kalff 2003) required at this critical life stage.…”