Potential Vulnerability of Bluegill, Black Crappie, and Yellow Perch to Smallmouth Bass Predation Based on Gape Dimensions and Prey Body Depth

Smallmouth bass Micropterus dolomieu are opportunistic predators that have the potential to influence prey fish population dynamics and restructure aquatic communities.  Recent evidence on the extent of smallmouth bass predation on juvenile yellow perch Perca flavescens and bluegill Lepomis macrochirus in summer and fall suggests the potential for predation to affect recreational fisheries of these prey fish.  To understand the potential impacts that smallmouth bass may have on yellow perch and bluegill recruitment, we estimated the maximum sizes of perch and bluegill available for consumption by various sizes of smallmouth bass, defined morphometric relationships between body depth and total length for perch and bluegill, and estimated the relative vulnerability of age-0 perch and bluegill cohorts to predation by smallmouth bass.  Relationships between yellow perch and bluegill body depth and TL were developed using linear regression.  Relative vulnerability curves for each prey species were developed using prey body depth:TL relationships, a previously-defined smallmouth bass gape:TL relationship, and smallmouth bass and prey length-frequency distributions.  Overall, results provide an indication of the proportion of the yellow perch and bluegill populations that are available for consumption and further insight to the potential impact of smallmouth bass predation on prey communities.