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U.S. Fish & Wildlife Service

U.S. Fish & Wildlife Service. Overview of infection and disease problems in the Klamath River basin. J.Scott Foott CA-NV Fish Health Center.

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U.S. Fish & Wildlife Service

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  1. U.S. Fish & Wildlife Service Overview of infection and disease problems in the Klamath River basin. J.Scott Foott CA-NV Fish Health Center The findings and conclusions in this presentation have not been formally disseminated by the USFWS and should not be construed to represent any agency determination or policy.

  2. concepts • Infection is not equivalent to disease • Infection = parasite can establish & replicate itself within host (all fish have parasites) • Disease = deviation / interruption in normal function • Many protozoans, helminths, commensal bacteria, (virus ?? Rare) are present in KR fish. Meeting focus on Cs & Pm

  3. I “It takes 3 to tango” Stress, immune function, and temperature Virulence of pathogen(s) Synergism of multiple infections Disease Replication & temperature

  4. Infectious load (challenge) • Severity of Ceratomyxosis in Klamath River suggests a shift in the host: parasite balance towards C.shasta • Chronic exposure to high levels of actinospores overwhelm resistance • Biological question = model probability of infection and disease with duration of rearing in KR

  5. Prognosis of infection Host response(s)

  6. Transmission • Contact- attach&invade- multiple in host • Congregation of juveniles and adults in thermal refugia enhance transmission of some bacteria and parasites • Fc and ICH (not Cs & Pm)

  7. synergism • Cs (enteritis) + Pm (glomerulonephritis) + external infections (ion loss) • Evidence of progressive disease leading to mortality in KR salmon under summer temperature conditions • 2002 3d exposure = >80% mortality 17d • 2006 studies

  8. Incidence of C.shasta & P.minibicornis infection in juvenile chinook in the Klamath R. & estuary, May – July (histology) Cs (KR) = 35 – 50% << Pm (KR) = 47 -92% Cs drop in KE, different fish (TR influence)

  9. External bacterial and parasitic infectionsFlavobacterium columnare and Ich • Fc = 3 – 57% POI • > 20C temperatures • disease problem of adult salmon (02 event) • Problem in all live box exposure studies in KR • Ich = both adult and juvenile fish

  10. IMPACT ? • 70 – 90% mortality estimates for Chinook fry & smolt stage due primarily to predation • MC Healey (Chinook Chapter – Pacific Salmon life histories eds Groot & Margolis) • Additional influence of > 35% dual parasite infection on the 10- 30% “normal” survival rate? • Need for in-river survival studies in KR

  11. Appreciation • Strong commitment and high level of cooperation for Fish Health work by Klamath fisheries community • Meeting organizers

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