Decline of young-of-year walleye (Sander vitreus) growth due to Bythotrephes impacts predicted from bioenergetic principles

Abstract

Abstract Invasive species are a major threat to ecosystem structure and function. For example, Bythotrephes cederströmii (Bythotrephes hereafter) invasions have significantly reduced native zooplankton density and biomass, resulting in competitive interactions with zooplanktivorous fishes. Young of year (YOY) walleye (Sander vitreus) are initially zooplanktivorous and have recently been shown to display reduced growth in Bythotrephes invaded lakes. Here, we combined a bioenergetics model for larval walleye with changes in the zooplankton community following Bythotrephes invasion and predicted reduced larval walleye growth in the presence of Bythotrephes, supporting field observations. The model predicted greater impacts in oligotrophic versus mesotrophic lakes, whereby Bythotrephes invasion could potentially lead to walleye recruitment failure in low nutrient environments. As YOY growth, survival, and recruitment are ultimately linked to adult abundance and sustainability of managed stocks, our results highlight the potential impacts of Bythotrephes on the sustainability of walleye populations in boreal lakes.