Comparison of eDNA and Electrofishing Survey Methods for Management Purposes

Presence/absence monitoring for fish species is traditionally conducted via electrofishing surveys. This methodology is often time, labor, and cost intensive and results in low detection rates for low-density populations. An innovative technology, environmental DNA (eDNA), has the potential to significantly improve species detection rates while simultaneously requiring less time and labor than electrofishing surveys. An eDNA assay was recently developed by Strickland and Roberts (2019) for Roanoke logperch, Percina rex, a federally endangered darter endemic to the Roanoke and Chowan River basins. Although the Roanoke Logperch has a limited range, past and future impoundment removals should expand the occupied reach of this difficult to detect species. This study proposes to assess the utility of eDNA for routing monitoring by directly comparing detection rates between eDNA and electrofishing for Roanoke logperch. Additional analysis of the specific assay will be conducted by testing against co-occurring species; analyzing detection against various environmental factors such as temperature, turbidity, and drainage area; and increasing the examined distribution range by assaying in North Carolina waterways. Finally, a cost-comparison between eDNA and electrofishing will be conducted to further assess the future utility eDNA survey adoption for routine monitoring.