AbstractWhile catch per unit effort (CPUE) is the most widely used metric for expressing and comparing boat electrofishing catch data, “effort” has been inconsistently defined. Boat electrofishing guidelines refer to both time‐ and distance‐based metrics, with little consensus about the appropriateness of one over the other. Catch rate metrics that use time‐based effort may potentially be biased by gear saturation due to handling time. We evaluated the potential for bias resulting from effort metric choice by comparing catch rates based on one temporal and two spatial effort metrics—time, shoreline length, and a GPS‐based areal measurement—using 3 years of data from 288 sampling occasions when all three metrics were recorded simultaneously. We used pairwise comparisons to isolate the effect of effort metric choice and fit six candidate models to each potential pair of CPUE metrics: a simple linear model, four models with separate slopes for survey variables (lake, season, night or day, and habitat), and an asymptotic model. The best‐fit model was asymptotic when the time‐based CPUE metric was compared with both space‐based metrics, and the linear model accounting for habitat was the best‐fit model for the comparison between both spatial methods. These results indicate that using a time‐based measure of effort resulted in hyperstable CPUE when fish densities were high due to gear saturation. By comparison, spatial measures of effort were robust to changes in fish density. Observed habitat‐based variation in the relationship between the two spatial metrics suggests that a CPUE measurement based on shoreline distance is adequate for assessing trends in abundance within waters or areas with homogenous habitat but not locations with contrasting conditions. We recommend the use of an areal‐based effort metric due to its robustness to gear saturation, comparability between waters, and potential for incorporating other variables that influence the performance of CPUE.