Title
Relating American Eel Anguilla rostrata abundance to environmental DNA concentration in the Bronx River
Author(s)
Chin, Sam C.;Waldman, John;Bednarski, Mike;Camhi, Merry;LaBelle, Jake;Alter, S. Elizabeth
Published
2021
Publisher
North American Journal of Fisheries Management
Abstract
The American Eel (Anguilla rostrata) population has experienced a marked decline due to a multitude of threats including pollution, overfishing, and damming. Government agencies responsible for eel management have identified gaps in survey coverage and understanding of habitat needs as critical obstacles to recovery. However, efforts to expand eel monitoring are hindered by this species’ resistance to capture, the wide variety of habitats in which they occur, and their extensive natural range, which would be cost‐prohibitive to survey using established techniques. Surveys based on analysis of environmental DNA (eDNA) may offer an affordable and efficient means of closing these gaps. While eDNA methods are increasingly used as a rapid, minimally invasive means of detecting species presence, attempts to use them to produce quantitative estimates of abundance have yielded mixed results. In order to evaluate the viability of eDNA as a quantitative eel monitoring tool, we compared the concentration of eel DNA in water samples to estimates of numerical and biomass density measured by electrofishing in the Bronx River, NY. Our results revealed a strong, positive association between DNA concentration and numerical density, but no relationship with biomass density. Mass‐specific eDNA production rates were found to decline with mean eel weight. While further study will be required to determine whether the observed relationship between DNA concentration and numerical abundance is consistent across sites, and whether it can be generalized to other systems, our findings suggest that eDNA is likely to be a feasible and cost‐effective option for surveying eel abundance throughout their range.
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PUB26328