Local and Lake‐Scale Habitat Effects on Abundance, Lengths, and Diets of Age‐0 Largemouth Bass and Bluegill in Indiana Temperate Lakes

Abstract

AbstractLittoral zones of lentic systems are important nursery habitats for age‐0 fish as they provide foraging habitat and refuge from predation. While local habitat characteristics in a lake's littoral zone can affect abundances, mean lengths, and trophic interactions of age‐0 fish, lake‐scale characteristics may also influence these factors. Given that local and lake‐scale characteristics are probably related, it may be difficult to interpret perceived associations between habitat characteristics and fish population metrics, as well as elucidate consequences of anthropogenic alterations of habitat. We used classification and regression tree (CART) analysis to evaluate relationships between local and lake‐scale habitat characteristics, abundances, and mean lengths of age‐0 Largemouth Bass Micropterus salmoides and Bluegills Lepomis macrochirus collected from glacial lakes in northern Indiana during 2009 and 2010. We also evaluated habitat influences on stomach contents of age‐0 Largemouth Bass. Our results suggest there are complex, multiscale interactions among habitat characteristics and population and diet metrics of age‐0 fish. Site‐specific abundances of both fishes were most strongly associated with local‐scale characteristics (e.g., high densities of Bluegills at sites with dense submerged vegetation), while mean lengths were associated with lake‐scale characteristics (e.g., greater mean length of age‐0 Bluegills and Largemouth Bass in small, shallow lakes). Diet composition of age‐0 Largemouth Bass was strongly related to individual fish length, though local (e.g., percent coverage by vegetation) and lake‐scale (e.g., lake depth) habitat characteristics also affected the type of prey consumed. We suggest that managers consider both local and lake‐scale features when undertaking habitat improvement activities, selecting stocking locations, or otherwise jointly managing habitat and age‐0 lentic fish populations.