Mark‐Recapture Surveys Impact Nest Site Fidelity but not Reproductive Timing of Male Smallmouth Bass

AbstractFish population surveys in north‐temperate lakes are often conducted in the fall or spring when individuals are easy to capture with traditional fisheries techniques. Because some fishes are preparing to spawn or are spawning during these seasons, there is a critical need to better understand the potential influences of these surveys on decisions related to fish reproduction. We tested whether spring mark‐recapture surveys using fyke nets followed by electrofishing affect reproductive behaviors of male Smallmouth Bass Micropterus dolomieu in a northern Wisconsin lake. Fyke‐netting, electrofishing, and whole‐lake nest snorkeling surveys were conducted during 2001‐2008, and Floy‐tagged males were tracked across years to test whether capture in the fyke nets only, or capture in the electrofishing survey influenced inter‐year nest site fidelity and reproductive timing. The mark‐recapture surveys were conducted preceding Smallmouth Bass spawning, and returning males caught in the electrofishing survey nested ~50 m farther from their prior year's nest than both males captured only in fyke nets and males that were captured by neither method. Average inter‐year nest distances were ~200 m and median inter‐year nest distances were ~90 m for males not captured in the electrofishing survey. Electrofishing and fyke netting did not influence timing of reproduction. Spring electrofishing surveys for Smallmouth Bass have the potential to displace breeding males from preferred nesting habitats. If displacement negatively influences fitness (i.e., age‐0 survivorship to maturation), spring electrofishing surveys would not be recommended for assessing Smallmouth Bass populations. However, spring population surveys often occur soon after ice off, and surveys conducted at these colder temperatures are typically less stressful and less likely to result in mortality. Future research should test for fitness implications of reduced nest site fidelity following electrofishing in Smallmouth Bass, while considering potential fitness trade‐offs if surveys are moved later in the year.