Environmental DNA (eDNA) is a promising tool for assessing abundance and biomass of organisms in aquatic settings. First used in enclosed systems (e.g., rivers, lakes and bays), the method is now being applied at larger scales, including the open ocean, to help improve fisheries assessments. Recent results show that eDNA can correlate with traditional survey methods, but issues related to fish catchability, detectability, and eDNA stability currently hamper the development of more robust correlations. This work builds on the results of a large-scale fisheries acoustic survey in coastal Maine that used acoustics to identify Atlantic herring (Clupea harengus) with a high degree of confidence. These acoustic estimates of herring abundance will be compared to eDNA concentrations to provide a robust test of the eDNA method for assessing fish abundance in the open ocean.
Additionally, recent findings suggest that shorter eDNA fragments have longer half-lives than longer fragments. We will work to verify these findings for herring in our lab. This information will be used to test correlations between eDNA and acoustic abundance estimates at different scales. It's expected that large-scale, longer-term patterns in herring abundance will be better captured by more stable, short-fragment eDNA, whereas small-scale patterns (e.g., at the scale of schools) will be best captured with long-fragment eDNA. In both cases, we will examine a range of spatial and physical variables to see how they influence the correlation between eDNA and acoustic abundance estimates. This study will advance the application of eDNA for making inferences about fish abundance and biomass at a range of scales that can be used in fisheries assessments.
This research is made possible through the generous support of the NOAA omics program.
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