Estimating diel, depth-specific foraging opportunities with a visual encounter rate model for pelagic piscivores

Abstract

We developed a visual foraging model for piscivores that predicts search volume as a function of light and turbidity. We combined this model with diel hydroacoustic measurements of depth-specific prey fish densities during summer stratification in Lake Tahoe, Lake Washington, and Strawberry Reservoir to examine differences in diel, depth-specific visual encounter rates of prey. These study sites were selected to represent gradients of increasing limnetic prey fish density and declining transparency. The model predicted over a 30-fold difference in maximum depth-specific diel encounter rates among the three lakes. Lake Washington, which was characterized by intermediate transparency and moderate limnetic prey density, had the highest predicted prey encounter rates. The pattern of prey encounter rates among the three lakes was similar to the proportional contribution of limnetic prey fishes observed in the diet of piscivores from these waters. This approach may be used to construct temporally and spatially explicit trophic interaction models for examining mechanisms underlying predator and prey distributions or to predict the response of existing or introduced predators to changing environmental conditions, prey abundance, or distribution.

Bioenergetic evaluation of diel vertical migration by bull trout (Salvelinus confluentus) in a thermally stratified reservoir

“…Search volume was modelled as a function of reaction distance of predators to their prey (RD = m) and predator swimming speed (SS = m·hr −1 ). Beauchamp et al (1999) derived swimming speeds from laboratory data (Henderson & Northcote, 1985) of Dolly Varden.…”

“…To this end, we quantified bull trout diets, the distribution of redside shiner prey, and patterns of thermal stratification in summer (July and August). With these data, we parameterised foraging (Beauchamp, Baldwin, Vogel, & Gubala, 1999;Mazur & Beauchamp, 2006) and bioenergetics models (Mesa, Weiland, Christiansen, Sauter, & Beauchamp, 2013) to evaluate growth associated with constant depth use and DVM to various depths.…”

Growth of rainbow trout (Oncorhynchus mykiss) in warm-temperate lakes: implications for environmental change

“…However, excessive primary productivity can become detrimental to certain fish species. Foraging of visual predators may be impaired by high turbidity in eutrophic lakes (Beauchamp et al 1999;Ranåker et al 2012), and the volume of cool habitat in the hypolimnion may be reduced by low dissolved oxygen (DO) concentrations (Plumb and Blanchfield 2009). In warm, productive lakes, growth rate potential of coolwater species decreases with increasing chlorophyll a (chl a) concentrations (Budy et al 2011).…”

Quantifying Aggregation and Association in Three-Dimensional Landscapes

“…6). This likely reflects the visual foraging nature of the piscivores in this system (Beauchamp et al 1999). The negative association between predators and prey at relatively larger spatial scales (Ͼ2 m) may reflect consumption by the predators or active predator avoidance by the prey Leggett 1990, Horne and.…”