Using eDNA Sampling to Detect Pacific Lamprey in a Large River: 2016 Wenatchee River Pilot Study
Summary
Although Pacific Lampreys were historically abundant in the Pacific Northwest, runs have declined dramatically as a result of barriers to upstream passage, juvenile entrainment, habitat loss, and compromised water quality. Defining the current distribution of Pacific Lamprey is a major component of the Pacific Lamprey Conservation Initiative and is central to lamprey recovery efforts. Environmental DNA (eDNA) sampling may be a time-saving and cost-effective method to broadly assess habitat for Pacific Lamprey presence. However, aquatic macrofaunal eDNA methods are relatively new, with many studies occurring in small streams, and focusing on free-swimming fishes. This pilot study expanded the application of eDNA sampling methods to [...]
Summary
Although Pacific Lampreys were historically abundant in the Pacific Northwest, runs have declined dramatically as a result of barriers to upstream passage, juvenile entrainment, habitat loss, and compromised water quality. Defining the current distribution of Pacific Lamprey is a major component of the Pacific Lamprey Conservation Initiative and is central to lamprey recovery efforts. Environmental DNA (eDNA) sampling may be a time-saving and cost-effective method to broadly assess habitat for Pacific Lamprey presence. However, aquatic macrofaunal eDNA methods are relatively new, with many studies occurring in small streams, and focusing on free-swimming fishes. This pilot study expanded the application of eDNA sampling methods to a benthically-oriented species in a large river system. We evaluated the capacity of eDNA sampling to detect Pacific Lamprey presence in the Wenatchee River, Washington in June 2016. The initial results of this study are promising: Pacific Lamprey DNA was detected at all (n = 5) Lower Wenatchee River sites located within the known distribution of the species. Pacific Lamprey DNA was also detected at four sites in the Upper Wenatchee River near locations where adult Pacific Lampreys had been re-introduced three months earlier. Pacific Lamprey DNA concentrations from paired-transect samples were similar (within an order of magnitude), suggesting that single samples at one river bank may be sufficient to document lamprey presence at a given location. These results suggest that eDNA sampling can be a valuable tool for evaluating Pacific Lamprey presence. However, because questions remain about detection probabilities when the target species is extremely rare, we recommend that eDNA methods be combined with traditional sampling methods, especially in systems where little is known about Pacific Lamprey distribution.
