Detection and Identification of Lampreys in Great Lakes Streams Using Environmental DNA

Environmental DNA (eDNA) is the DNA of an organism that persists in the environment via sources such as mucus, feces, sloughed off cells, and decomposing remains.  This DNA can be collected and the species of origin identified.  We have developed eDNA assays that detect and distinguish the invasive Sea Lamprey Petromyzon marinus from the four native lamprey species (Ichthyomyzon spp. and American Brook Lamprey Lethenteron appendix) in the Great Lakes basin.  Control of Sea Lamprey depends largely on treatment of infested tributaries with lampricides that kill the burrowing larvae.  These lampricides, however, are also lethal to native lampreys and specificity is achieved through targeted treatment of stream reaches containing Sea Lamprey and avoidance of those where the other species reside; it is thus necessary to have accurate distribution data for both the Sea Lamprey and native lampreys.  We developed species-specific PCR-based assays, tested their performance in the laboratory (determining that eDNA signal increased with larval density and water temperature, and decreased with flow rate), and demonstrated that both spawning and larval Sea Lamprey can be detected in streams using eDNA techniques.  These methods could potentially reduce cost and increase efficiency of current management strategies for both Sea and native lampreys.