Pathogens of Pacific Lamprey Detected Through Routine Fish Health Screenings

Interest in conservation, management, and captive rearing of Pacific Lamprey Entosphenus tridentatus in the Pacific Northwest has risen in recent years. General and specific information regarding the occurrence of fish pathogens and the risk of Pacific Lamprey as a vector for pathogens to other species is not well understood. Specific efforts to captively rear or artificially propagate Pacific Lamprey at facilities that are used for Pacific salmon Oncorhynchus spp. have increased. We performed fish health surveys on wild-caught larval and adult Pacific Lamprey from locations that were used as lamprey sources for captive research to determine the occurrence of bacteria, viruses, and parasites that may be pathogens. A variety of potential pathogens was detected, most notably Aeromonas hydrophila and Vibrio vulnificus from larval Pacific Lamprey and A. salmonicida from adult lampreys. There was a general lack of pathogenic activity and absence of viral detections from all lampreys. The diversity of bacteria encountered from the larvae in our study could be indicative of the wide diversity of bacteria that is known to be associated with larval lamprey in general. Further efforts to understand pathogenic risk from Pacific Lamprey to salmonid propagation programs are warranted.