Field surveillance and sentinel exposures to detect Ceratonova shasta in Chinook Salmon from the Lake Washington watershed

Ceratomyxosis, characterized by enteritis, enteronecrosis,and abdominal distension, is caused by the myxozoan parasite Ceratonova shasta. Ceratonova shasta is capable of infecting a range of salmonids, including Chinook salmon, often resulting in increased morbidity and mortality in infected populations. Ceratonova shasta is endemic in the Pacific Northwest, however there is limited data on the prevalence, distribution, and severity of C. shasta in the Lake Washington watershed. Field surveillance of returning adult Chinook Salmon compared C. shasta infection loads in fish suffering from prespawn mortality to salmon that successfully spawned. Sentinel caging studies were conducted with juvenile Chinook Salmon in various areas of the watershed to determine regions that may serve as C. shasta infection zones. Mortality and C. shasta levels were tracked in salmon following their sentinel caging as a way to determine relative infection levels across the sites.