A Comparison of eDNA and Visual Survey Methods for Detection of Longnose Darter Percina nasuta in Missouri

The longnose darter Percina nasuta is a rare and cryptic fish that recently disappeared from much of its historic range. We developed used an environmental DNA (eDNA) assay for paired with visual surveys to better determine the species’ range compare detection probability between sampling approaches in occupancy modeling framework. detected eDNA further upstream mainstem St. Francis River than previously reported tributary first time. Our multi-scale approach compared models where was constant against model allowed vary by survey method. received most support indicating method not strong predictor estimated at 0.70 (0.45–0.86; 95% CI) across both methods. study produced effective primers demonstrated application small-bodied, fish. 27 km their known determined snorkel are efficient if water clarity allows. recommend target sample sizes achieve various goals methods our results inform future design distributional monitoring efforts.