Journal Article

The influence of prey availability on ontogenetic diet shifts of a juvenile piscivore

Galarowicz, Tracy L, Adams, Julie A, Wahl, David H

2006

Overview

Young-of-year piscivores typically undergo ontogenetic diet shifts from planktivory to benthivory to piscivory. These shifts are often the result of changes in predator foraging abilities, but little is known about the influence of relative prey availability. As a result, we examined diet shifts across a range of sizes (20-150 mm) of a young-of-year piscivore, walleye (Sander vitreus), in feeding experiments in which zooplankton, benthic invertebrates, and fish were made available at different density combinations. Consumption of each prey type changed with walleye size and prey densities. Small juveniles (20 mm) selected zooplankton and fish, whereas larger walleye (40-100 mm) selected benthic invertebrates and fish. Relative prey densities influenced consumption; increased densities of more profitable prey types resulted in reduced consumption of less profitable prey. Walleye larger than 100 mm selected only fish. Foraging efficiencies also varied with size and prey types; small walleye (20 mm) were less likely to pursue benthic invertebrates and retain captured fish. These ontogenetic changes in foraging patterns are linked to prey profitability, have growth consequences for juvenile walleye, and have implications for understanding diet shifts of other juvenile fish.

• Publisher: NRC Research Press,National Research Council of Canada,Canadian Science Publishing NRC Research Press
• Subject: Ability / Animal development / Animal, plant and microbial ecology / Applied ecology / Aquatic invertebrates / Bass / Behavior / Benthic fauna / Benthos / Biological and medical sciences / Carp / Changes / Diet / Environmental conditions / Exploitation and management of natural biological resources (hunting, fishing and exploited populations survey, etc.) / Fish / Fish hatcheries / Food and nutrition / Forecasts and trends / Freshwater / Fundamental and applied biological sciences. Psychology / Growth / Invertebrates / Marine / Ontogeny / Piscivores / Plankton / Predation (Biology) / Prey / Reptiles & amphibians / Risk / Walleye (Fish) / Zooplankton