DNA in water can be used to assess aquatic biodiversity and detect the presence of rare species. Environmental DNA (eDNA) sampling targets species of interest with less disturbance of wild populations and no sampling-related mortality of fish. However, eDNA is not always detectable due to dilution or decay in natural environments. The purpose of this project is to develop and evaluate the potential application of eDNA sampling for monitoring a critically endangered fish (delta smelt, Hypomesus transpacificus) in the San Francisco Estuary. Water samples were filtered and tested for presence of delta smelt eDNA using a species-specific mtDNA qPCR assay.
Results/Conclusions
Here we present the preliminary results of eDNA field sampling and experiments. Delta smelt eDNA was detected at 3 of 4 sites where delta smelt were captured by kodiak trawl. Delta smelt eDNA was not detected at any sites where delta smelt were not captured by trawl (n=7). eDNA extracts contained PCR inhibitors (probably from suspended particulates) which impaired eDNA detection, but could be removed. We demonstrate that wild delta smelt eDNA is detectable in natural environments, and highlight the challenges of detecting a rare fish in estuarine environments. The results of this study will determine the feasibility of implementing eDNA monitoring as part of the delta smelt management strategy.