Using eDNA as a Method for Prioritizing River Restoration Projects in the Greater Long Island Sound Region.

Vander Werff, Jon C., Save the Sound, New Haven, CT

Environmental DNA (eDNA) is a relatively new technology to be used as a fishery sampling technique. The methodology depends on fish releasing DNA into the water around them, and that DNA being captured in a water sample. That sample is then analyzed in laboratory settings and a catalog of all DNA present is created. Save the Sound is interested in the use of eDNA as a presence/absence survey to assist in prioritizing future river restoration projects based on diadromous fish inhabitance. This method was used during the 2022 spring diadromous fish run, in target streams along coastal Connecticut and Westchester, New York. Samples were collected at the same eight Connecticut locations and seven New York locations on two separate dates to reduce bias and ensure as many species as possible were captured for analysis. Location of collection along each river was chosen strategically downstream of the first barrier on the river to show if fish were able to migrate to that point in the watershed. Diadromous fish were present in most of the rivers but not all. The eDNA collected will be used to aid Save the Sound and Project Partners and Managers in prioritizing restoration efforts in the greater Long Island Sound region. This proof-of-concept study design acted as a positive indication eDNA can be used as a presence / absence survey to be used by managers and biologists.