Seasonal Consumptive Demand and Prey Use by Stocked Saugeyes in Ohio Reservoirs

Abstract

Community structure and species composition may be strongly influenced by predator-prey interactions resulting from and leading to episodes of population abundance or scarcity. We quantified diets of stocked saugeyes (female walleye Sander vitreus × male sauger S. canadensis) and estimated biomass of their primary prey, gizzard shad Dorosoma cepedianum, in three Ohio reservoirs at quarterly intervals during July 2002-July 2003 to determine whether saugeye consumptive demand could exceed the supply of available gizzard shad prey, resulting in a shift to alternative prey. We incorporated water temperature and saugeye diet composition, growth, and mortality into walleye bioenergetics models, which allowed us to compare estimated prey-specific consumption rates by saugeyes with gizzard shad standing stocks estimated with acoustics. Spring and summer were critical seasons. During spring, gizzard shad biomass was low, saugeye consumptive demand was low, and saugeyes consumed primarily alternative prey. During summer, when age-0 gizzard shad became available as prey, saugeyes consumed similar proportions of gizzard shad and alternative prey. Saugeye cumulative consumptive demand in summer was high and approached the gizzard shad standing stock. However, during fall and winter, gizzard shad supply was adequate to support high (fall) or declining (winter) saugeye consumptive demand. Across reservoirs and seasons, saugeyes consumed alternative prey to varying degrees, primarily sunfishes Lepomis spp., yellow perch Perca flavescens, logperch Percina caprodes, and minnows Pimephales spp. Seasonal asynchrony between saugeye consumptive demand and gizzard shad biomass during spring and summer indicated that a saugeye population with high survival, growth, and consumptive demand will opportunistically increase use of prey other than gizzard shad. The manner in which saugeye predation quantitatively influences these prey species could not be assessed. However, overexploitation of gizzard shad prey appears to be unlikely at current saugeye population sizes, particularly considering the opportunistic use of alternative prey and the high reproductive potential of gizzard shad.

Movement, home range and habitat selection of stocked juvenile muskellunge, Esox masquinongy, in Forbes Lake, Illinois: exploring the effects of latitudinal origin

“…For example, an understanding of the selection and avoidance of various habitat types by juvenile muskellunge may help to inform the stocking of the most appropriate lakes and reservoirs (Wahl 1995). Additionally, introducing multiple top predators into lentic systems is often used in an effort to exploit abundant prey (Denlinger & Hale 2006) and potentially induce top‐down control (Eby et al. 2006; Carey & Wahl 2010).…”

“…For example, an understanding of the selection and avoidance of various habitat types by juvenile muskellunge may help to inform the stocking of the most appropriate lakes and reservoirs (Wahl 1995). Additionally, introducing multiple top predators into lentic systems is often used in an effort to exploit abundant prey (Denlinger & Hale 2006) and potentially induce top-down control (Eby et al 2006;Carey & Wahl 2010). Understanding the habitat use and selection preferences of juvenile muskellunge, coupled with an understanding of home range sizes and movement, may help biologists to understand the direct and indirect interactions between introduced muskellunge and other native and introduced top predators (Curry et al 2007).…”

Modeling Brook Trout Carrying Capacity in Owhi Lake, Washington, Using Bioenergetics

“…Bioenergetics modeling has been useful to explicate predator–prey dynamics (Denlinger et al. ; Vatland et al. ; Bunnell et al.…”

“…Quantifying fish consumption demand (hereafter, "demand") is necessary to gauge the cause of prey scarcity and can be accomplished by using bioenergetics modeling (Hanson et al 1997;Beauchamp et al 2007). Bioenergetics modeling has been useful to explicate predator-prey dynamics (Denlinger et al 2006;Vatland et al 2008;Bunnell et al 2011), assess the effects of increasing predator populations (Baldwin et al 2000;Cyterski et al 2002;Blair et al 2013), and identify potential predator-prey imbalances due to high predator demand (Rand et al 1993;Cross et al 2005;Raborn et al 2007;Negus et al 2008;Evans et al 2014). After demand is estimated through modeling, it can be compared with prey biomass and production estimates to aid in explaining a system's capacity for certain populations (e.g., Hayes et al 2007).…”

Hatch Timing Variations among Reservoir Gizzard Shad Populations: Implications for Stocked Sander spp. Fingerlings

“…When gizzard shad are abundant (during late spring through fall), age-0 gizzard shad dominate the diets of reservoir predators. However, predator diet breadth widens when gizzard shad availability is reduced (during late fall through early spring ;Michaletz 1998a;Denlinger et al 2006), potentially increasing predation-related mortality of stocked Sander spp. fingerlings (Aman 2006).…”