Smallmouth Bass Growth Dynamics in South Dakota Glacial Lakes

Smallmouth bass Micropterus dolomieu have become an important component of fish assemblages in northeastern South Dakota glacial lakes.  Despite being introduced into state waters beginning only in the mid-1980s, abundant and self-sustaining populations of smallmouth bass have become established in most glacial lakes.  While popularity of smallmouth bass continues to grow among South Dakota anglers, limited information is known regarding bass dynamics and the impacts of bass introductions on food webs in glacial lakes.  Juvenile and adult smallmouth bass are opportunistic predators that consume a variety of prey fishes.  The prey-fish base in many northeastern South Dakota glacial lakes consists of yellow perch Perca flavescens which is used by other predators in these systems such as walleye Sander vitreus and northern pike Esox lucius.  Knowledge of smallmouth bass growth dynamics and food habits will aid in their management and in the understanding of their interactions with fishes native to the region.  To evaluate smallmouth bass food habits and growth in South Dakota glacial lakes, we used previously-quantified food habits data and compared bioenergetics model predictions of smallmouth bass growth and consumption in lakes with and without established populations of yellow perch.  Model predictions of growth were also compared for populations of smallmouth bass subject to differing food habits simulations (e.g., a population consuming only fish compared to a population consuming only macroinvertebrates).  Predicted growth of smallmouth bass exhibited varying levels of response to different food habits, but the strongest responses were in relation to simulated diets consisting solely of fish or solely of macroinvertebrates.  Results ultimately provide information essential for effective smallmouth bass management and suggest that prey limitations could significantly affect growth rates, maximum attainable size of fish, interspecific interactions, and overall quality of the smallmouth bass fishery in northeastern South Dakota glacial lakes.