Identification of Putative Migratory Pheromones from Pacific Lamprey

Pacific lamprey, Entosphenus tridentatus, has declined precipitously throughout their range in the Columbia River basin.  Tribal Nations and Federal and State agencies are engaged in efforts to restore these fish.  Understanding whether Pacific lamprey emit and detect migratory pheromones is particularly important for these restoration efforts.  Using behavioural assays, we demonstrated that migratory adult Pacific lampreys are attracted to odors emanating from their larval conspecifics. We then identified putative pheromones released by larval Pacific lampreys.   Chemical analysis of the conditioned water from larval lampreys using LC/MS revealed that the Pacific lamprey can release petromyzonamine disulfate (PADS), petromyzosterol disulfate (PSDS), and petromyzonol sulfate (PZS). Electro-olfactogram studies further demonstrated that adult Pacific lampreys can smell those bile acid compounds.  Our data strongly indicate that the Pacific lamprey employ a chemical communication system mediated by a mixture of bile acids, as evidenced by pheromonal functions of the bile acid compounds in guiding migratory adult sea lampreys to the spawning streams.  Comprehensive understanding of the chemical communications involved in lamprey migratory behavior may lead to improved scientific approaches for restoration efforts.