Foraging behavior, morphology, and life history variation determine the ontogeny of piscivory in two closely related predators

Abstract

The ontogeny of piscivory is an important process during the early life history of many fishes, and why ontogenetic patterns of closely related species vary is unclear. We experimentally evaluated the importance of several factors that can determine the switch to piscivory in two predators with different dietary ontogenies: walleye (Sander vitreus), a specialist piscivore, and yellow perch (Perca flavescens), a dietary generalist. We conducted growth and prey selection experiments across several sizes of both predators using fish, zooplankton, and benthic invertebrates as prey. Walleye exhibited piscivorous feeding behavior throughout all size classes (20–80 mm), whereas yellow perch were generalist predators, showing negative to neutral selection for fish prey and lower growth than walleye when feeding on fish. Walleye foraged more efficiently than yellow perch on all prey types, in part because gape widths of walleye increased more quickly with size. Bioenergetic model simulations showed that walleye grew slower than yellow perch when the proportion of fish was low in diets, but walleye growth was faster than yellow perch on a diet dominated by fish. Feeding behavior, morphology, and life history patterns likely work in combination, allowing walleye to switch to piscivory earlier than yellow perch.

Use of computational fluid dynamics to study forces exerted on prey by aquatic suction feeders

“…Since the prey is located close to the mouth during a suction feeding event, these changes result in significant changes in the forces exerted on the prey (solid line, 08; dotted line, 158; dashed dotted line, 308; dashed line, 458). fish prey selection (Werner & Hall 1974), and studies repeatedly show that fish prefer prey between 25-50 per cent of mouth diameter (Wainwright & Richard 1995;Turesson et al 2002;Graeb et al 2005). Prey in this size range offer the highest energy return for the energy spent pursuing, capturing and handling them (Werner 1974(Werner , 1977Kislalioglu & Gibson 1976).…”

Feeding biomechanics of juvenile red snapper (Lutjanus campechanus) from the northwestern Gulf of Mexico

“…By developing a stronger bite, off-ridge juveniles may compensate for any gape limitations by biting pieces of prey larger than their mouth. A fish diet is high in caloric value, so an earlier switch to piscivory promotes faster growth and survival (Persson and Brönmark, 2002;Post, 2003;Graeb et al, 2005), which may explain the higher growth rates of juvenile red snapper reported in off-ridge areas (Rooker et al, 2004;Geary et al, 2007). In general, faster growing fish resulting from an early switch to piscivory represent the population majority within the cohort, and therefore contribute more individuals to the adult population (Olson, 1996;Ludsin and DeVries, 1997;Persson and Brönmark, 2002).…”

“…Ecomorphological studies are also useful in examining the functional consequences of ontogenetic changes on morphology and diet shifts in teleosts (e.g. Osenberg et al, 1988;Hyndes et al, 1997;Hunt von Herbing, 2001;Graeb et al, 2005;Monteiro et al, 2005). Ontogenetic shifts reduce competition through intraspecific (Hernandez and Motta, 1997;Hyndes et al, 1997;Soto et al, 1998) or interspecific (Mittelbach et al, 1992;Huskey and Turingan, 2001) resource partitioning.…”

Intraspecific Variation in a Predator Affects Community Structure and Cascading Trophic Interactions

“…Gape width and gill raker spacing are two morphological traits that influence the foraging behavior and efficiency of planktivorous fish (Mummert and Drenner 1986, Lazzaro 1987, Macneill and Brandt 1990, Graeb et al 2005. Anadromous alewives have larger gape and wider gill raker spacing than landlocked alewives (Palkovacs 2007, Palkovacs et al 2008; see Plate 1).…”