How quickly do fish communities recover from boat electrofishing in large lakes?

Abstract

For specific sampling questions researchers may need to target ideal habitats concurrently and collect reliable fish community data, but unfortunately, we know little about the recovery rate of fish communities in areas recently subjected to electrofishing. In small systems, electrofishing can quickly deplete a sample area but this effect is unlikely at larger spatial scales. We conducted an experiment to identify how quickly fish communities recover from electrofishing in Green Bay, an embayment of Lake Michigan. We conducted electrofishing at 31 sites that were randomly assigned to be resampled at 0.25, 1, 3, 6, 24, or 48 h postrelease of marked fish. We marked all fish ≥ 150 mm and released them at their capture site. We found no differences in catch per unit effort, mean total length, species richness, Shannon’s diversity, or Shannon’s evenness between marking and recapture runs for any length of recovery duration between electrofishing runs. We recaptured only one of 349 marked fish in the site where it was released. Recapture of five fish in areas outside where they were released was unrelated to recovery duration between electrofishing events. In large, open systems like Green Bay, we found that disturbances caused by electrofishing are temporary (< 15 min) and suspect that any fish removed are quickly replaced by new immigrants to the study area. Due to high turbidity in this eutrophic–hypereutrophic system, we suspect that electrofishing efficiency was low; therefore resampling had the potential benefit of collecting individuals missed during marking runs. We conclude that fish communities in large lakes recover quickly following electrofishing and sites can be sampled concurrently within the same day and provide similar, or additional, fish community information.