Knowledge Bank

Invasive species can threaten fishing success and fisheries production by altering food web structure and dynamics. In this vein, Bythotrephes longimanus, a large-bodied, invasive zooplankton species that has recently colonized Lake Erie’s west basin may underlie the recent decline in angler harvest rates of Yellow Perch (Perca flavescens) despite its population size remaining stable. Given previous research conducted in Lake Erie’s central and east basins, which has established that Yellow Perch consume Bythotrephes when present in the water column, we hypothesized that increased availability and consumption of Bythotrephes is responsible for decreased angling success by reducing the effectiveness of artificial prey (i.e., fishing lures). Towards this end, I conducted a “natural” experiment, replicating angler behavior using three common gear types (e.g., spreader, crappie, and Sabiki rigs) across a range of Bythotrephes densities. Additionally, we analyzed the diets of angled Yellow Perch to determine how feeding varied with Bythotrephes availability. A significant relationship was found between Bythotrephes density in the water and CPUE for certain gears, indicating that CPUE tends to increase as Bythotrephes density increases (GAM, P < 0.05). However, we also found that an interaction between Bythotrephes density in the water and water temperature significantly influenced Yellow Perch catch-per-unit-effort for select gear types (CPUE; GAM, P < 0.05). Furthermore, CPUE varied among gear types, and CPUE’s associated with Sabiki gear were lower compared to the other gear types (one-way ANOVA, Tukey HSD, P < 0.05). As discussed herein, our results should provide fisheries management agencies (e.g., Ohio Division of Wildlife) with an enhanced ability to predict Yellow Perch harvest, set realistic angler expectations, and share insights to anglers on how to improve Yellow Perch catch rates in the western basin with continued Bythotrephes presence.