Fish catch and biomass per unit effort from McDermott and Sandy Beach Lakes 2017-2020

Centarchidae spp., a warm-adapted group of fishes including basses and sunfishes, has increased in recent decades in Wisconsin. Concurrently, declines in cool-adapted species, including Walleye (Sander vitreus), have occurred but the cause is not understood. Multiple factors have been associated with these declines, including rising lake temperatures, habitat degradation, harvest, and species interactions. To quantify the role that competition and/or predation between increasing centrarchids and the rest of the fish community plays, we are conducting a whole-lake experiment to remove centrarchids from an experimental lake in northern Wisconsin while measuring the response of all other fish species. In 2018 and 2019, ~200,000 centrarchid individuals were removed, while species-specific catch-per-unit-effort (CPUE) and biomass-per-unit-effort (BPUE) were measured. Yellow Perch have increased in CPUE and BPUE, while centrarchid abundances have declined. We will continue removing centrarchids in 2021 and monitoring these populations. This information will be used to inform an understanding of the conditions necessary to support self-sustaining fish populations given global environmental change.