Hydroacoustic Surveys Underestimate Yellow Perch Population Abundance: The Importance of Considering Habitat Use

When estimating fish population abundance, it is important to recognize that differing habitat use may cause one gear type to be more effective and less biased than another. We generated and compared population abundance estimates (PE) for adult Yellow Perch Perca flavescens in Crystal Lake, Wisconsin using a spring mini-fyke net mark–recapture survey and summer hydroacoustic surveys. Mean PE from the spring mark–recapture survey was 11,051 adult Yellow Perch (95% confidence limits of 9,878 and 12,541). This mean was 4.0–8.5 times greater than the range of mean summer hydroacoustic estimates (mean ± 95% CI = 1,291 ± 312 and 2,912 ± 703). Due to Yellow Perch spawning behavior, we assumed that the spring mark–recapture survey sampled the entire adult population, while summer hydroacoustics sampled the postspawn pelagic component. Using the mean of all hydroacoustic surveys (PE = 2,492; n = 5), we estimated that approximately 22% of adult Yellow Perch selected for pelagic habitats postspawn. Our study emphasizes the importance of evaluating gear bias and has implications for future assessments, particularly when the target species may exhibit multiple habitat preferences within a lake.