Midwest Fish & Wildlife Conference 2018

AUTHORS. Jim Breck, School for Sustainability and Environment, University of Michigan; Kevin Wehrly, Institute for Fisheries Research

ABSTRACT. Bluegills are one of the most popular sport fishes in Midwest glacial lakes, and they are often prominent members of the fish assemblage. Bluegill growth rate and population size structure differ widely among lakes. Slow-growing bluegill populations and a size structure with few large fish continue to be significant concerns for fisheries managers. We review the extensive literature on bluegill growth, size structure and recruitment, which identifies a variety of influential factors and processes. These include food abundance relative to fish density, important prey taxa, predator-prey balance, aquatic vegetation as a predation refuge for juveniles, fishing pressure on large males, and the social influence of larger males on the size and age at which male reproductive behavior is initiated. In this talk we examine the influence of lake habitat and landscape context on the processes determining bluegill growth, recruitment, and population size structure. We use a variety of models and data, including lake temperature regime and bioenergetics of fish growth, to look at bluegill population responses across gradients in these habitat and landscape variables. Our goal is to provide guidelines for management of fish habitat to address concerns about bluegill growth, recruitment and size structure in ways that reflect the landscape context of individual lakes.