P-352
The Influence of Black Spot Infestation on Condition and Survival of John Day River Spring Chinook Salmon
Dale R. Fonken
Keith B. DeHart
Ian A. Tattam
James R. Ruzycki
Black Spot disease, caused by the parasitic fluke Neascus, is a disease that commonly affects freshwater fish. The primary host of Neascus is freshwater snails, which release free-swimming parasites into the water column. These parasites burrow into the musculature of freshwater fish and encyst, causing very visible “black spots” on infected fish. The final step of the life cycle is completed by fish-eating birds, which release eggs back into the water. From 2006 to 2014 we estimated that 9% of juvenile spring Chinook Salmon emigrating from the John Day River. We will analyze the relationships among black spot , condition factor and survival of Passive Integrated Transponder tagged juvenile Chinook salmon. We will also use juvenile abundance estimates to determine if there is density dependence in the prevalence of black spot.