Evaluating freshwater habitat restoration with active acoustics.

Abstract

The effectiveness of adding a submerged physical structure in order to increase fishery production is uncertain. Measuring fishery response to these alterations with conventional techniques is difficult. Electrofishing is a typical assessment method in freshwater fishery management and is often limited in sample size and sampling frequency. This study used active acoustic technology to evaluate the distribution and behavior of fish assemblages associated with added submerged rock structures in a reservoir currently undergoing habitat improvement. An acoustic water column profiler was deployed for three 1‐week intervals at each of three replicate sites consisting of adjacent treatment areas with added rock structures and control areas without added structures. Electrofishing was conducted during each sampling interval. Fish abundance and behavior at each site were assessed from the volume backscatter time series and electrofishing data. Differences between areas with and without structures were compared. Combining acoustic technology with conventional assessment methods has enabled a more thorough evaluation of habitat restoration projects and helps guide the development of future conservation efforts.