Are smallmouth bass more mobile in large lakes than once thought?

Abstract

Smallmouth bass Micropterus dolomieu are generally considered to be a sedentary species. Previous tagging studies in lentic systems have found low annual movements based on fishery-dependent tag returns or limited detections from electronic transmitters, though occasional long-distance movements have been observed (i.e., >30 km). In this study, we implanted 23 smallmouth bass sampled from a recreational tournament in Lake Erie with acoustic transmitters and monitored their movements for two years (September 2018–September 2020) using a large-scale array of passive acoustic receivers. We documented 42 percent (8/19) of the at-large fish making long-distance movements throughout Lake Erie; these fish moved an average distance of 109.9 ± 26.6 km (mean ± SE; ranging 3.5–355.1 km) per year. Importantly, six of eight fish crossed jurisdictional boundaries (five into Ontario waters and one into Michigan waters). One individual moved a total of 505.3 km over the two years, the furthest distance an individual smallmouth bass has been documented moving across the literature. While observed movements may have been initially biased due to tournament displacement and capture method, tagged fish continued to make long-distance movements in the second-year post-release. Previous movement studies may have underestimated smallmouth bass movement scope in large, lentic systems due to low spatial and temporal coverage of recapture effort (including receiver coverage) relative to system size. Our results suggest that some smallmouth bass can make consistent long-distance movements in large systems like the Laurentian Great Lakes, indicating this species’ spatial ecology remains understudied in large lentic systems.