Smallmouth Bass response to simulated tournament displacement in a highland Idaho reservoir

Objective Smallmouth Bass Micropterus dolomieu are frequently displaced during fishing tournaments that are held at centralized weigh-in locations, which may result in temporary stockpiling (i.e., concentration near the weigh-in location) and increased vulnerability to angling. It is unclear whether displaced individuals return to established home ranges. The objective of our study was to evaluate the effects of tournament displacement on Smallmouth Bass behavior in Dworshak Reservoir, Idaho, United States. Methods We implanted acoustic transmitters into 31 adult Smallmouth Bass during spring 2023, including 15 fish that were released at the site of capture and 16 individuals that were displaced to a popular tournament weigh-in location. Displacement distances ranged from 7.7 to 63.0 km. We assessed the duration of stockpiling, quantified the proportion of displaced fish that returned to established home ranges, characterized the timing and routes of return, and compared home range patterns between displaced and nondisplaced fish. Results Most (94%) of the displaced fish dispersed from the weigh-in location, with the majority doing so within 25 d. Ten displaced individuals returned to their original capture locations, including fish that were displaced up to 63.0 km. Six of the returning fish followed indirect routes rather than direct movement paths. Home range size and spatial use of displaced fish were similar to those of nondisplaced fish, indicating no detectable long-term behavioral effects of displacement. Conclusions Tournament-related displacement of Smallmouth Bass in Dworshak Reservoir did not result in prolonged stockpiling or long-term changes in home range behavior. Our findings suggest that additional restrictions on tournament displacement procedures are unnecessary in similar large-reservoir systems.