Using environmental DNA sampling to monitor the invasion of nonnative Esox lucius (northern pike) in the Columbia River basin, USA

Michael K. Schwartz,Kevin S. McKelvey,Michael K. Young,Joseph Caleb Dysthe,Holly McLellan,Kellie J. Carim

doi:10.1002/edn3.22

Michael K. Schwartz, Kevin S. McKelvey

Open Access

https://doi.org/10.1002/edn3.22

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Abstract

AbstractAquatic invasive species are recognized as a global threat to conservation of native species and a cost to society. To develop effective suppression and monitoring programs for invasive species, fisheries managers require accurate, affordable, and efficient tools for invasive species detection. In the U.S. Pacific Northwest, the rapid expansion of invasive Esox lucius (northern pike) poses threats to native species as well as the viability of tribal, sport, and commercial fisheries. To help monitor changes in the distribution of this species, we developed and rigorously field‐tested an environmental DNA (eDNA) assay to detect E. lucius. The assay successfully amplified tissue‐derived DNA of E. lucius from 36 locations east and west of the Continental Divide and did not amplify DNA of over 40 nontarget species. This assay was then used to assist with monitoring the distribution of invasive E. lucius in the upper Columbia River basin in Washington and Idaho. Sixty‐two eDNA samples were collected at 35 locations of known and unknown E. lucius presence. Two samples per site (one on each bank) were collected in larger waterbodies. E. lucius eDNA detections were consistent with previous observations of live fish during angler and gill‐net surveys, confirming the reliability of the eDNA assay. At two of the 35 sites, only one of the paired samples was positive for E. lucius DNA. Varying results between opposite bank samples highlight the need for increased sampling effort when the target species are at low abundance and in large waterbodies. The eDNA assay described in this paper can be used by managers to identify the presence of E. lucius, monitor their expansion in western North America, and guide E. lucius suppression projects.

Highlights

Aquatic invasive species are recognized as a global threat to conservation efforts for native species and create an economic cost to society (Gallardo, Clavero, Sánchez, & Vilà, 2016; Lovell, Stone, & Fernandez, 2006)
Our goals were to assess the efficacy of environmental DNA (eDNA) methods for detection of invasive E. lucius relative to the traditional methods and to gather additional information on E. lucius in areas around the active invasion in the Columbia River basin that are difficult to sample using traditional methods
All data presented in this manuscript will be made publically available through the eDNAtlas https://www.fs.fed.us/rm/boise/AWAE/ projects/the-aquatic-eDNAtlas-project.html and the National Genomics Center for Wildlife and Fish Conservation

Summary

| INTRODUCTION

Aquatic invasive species are recognized as a global threat to conservation efforts for native species and create an economic cost to society (Gallardo, Clavero, Sánchez, & Vilà, 2016; Lovell, Stone, & Fernandez, 2006). Sampling with traditional fisheries methods in remote areas can be difficult and time consuming Under these circumstances, environmental DNA (eDNA) sampling may be a more effective tool for determining the presence and distribution of invasive species like E. lucius (e.g., Dejean et al, 2012; Herder et al, 2013; Jerde, Mahon, Chadderton, & Lodge, 2011; Wilcox et al, 2016 [appendix C & D]). We evaluated the specificity of previously published assays by Olsen et al (2015) and Spens et al (2017) in silico to better understand the appropriate geographic range for each assay and to determine whether they could be paired with our assay for increased accuracy in eDNA results (e.g., Carim, Christianson, et al, 2016c) We coupled this assay with eDNA sampling across the leading edge of the E. lucius invasion in the Columbia River basin. Our goals were to assess the efficacy of eDNA methods for detection of invasive E. lucius relative to the traditional methods and to gather additional information on E. lucius in areas around the active invasion in the Columbia River basin that are difficult to sample using traditional methods

| METHODS

| DISCUSSION

Findings

| CONCLUSIONS