Ceratomyxa shasta: timing of myxospore release from juvenile Chinook salmon

Author

Scott Benson

Graduation Date

2014

Document Type

Thesis

Program

Other

Program

Thesis (M.S.)--Humboldt State University, Natural Resources, Fisheries, 2014

Committee Chair Name

Gary Hendrickson

Committee Chair Affiliation

HSU Faculty or Staff

Keywords

Klamath, Disease, Myxozoa, Ceratomyxa shasta, Humboldt State University -- Theses -- Fisheries, Myxospore, Parasite, Chinook salmon, Juvenile

Abstract

Ceratomyxa shasta is a myxozoan parasite of salmonid fishes endemic to river systems of the Pacific northwest of North America. In the lower Klamath River, California, C. shasta has caused significant losses of juvenile Chinook salmon (Oncorhynchus tshawytscha) during summer outmigration for more than a decade. Population dynamics of fall-run Chinook salmon in the Klamath are affected by C. shasta. My study investigates the timing of C. shasta myxospore release from juvenile Chinook salmon. It will help determine whether juvenile Chinook salmon play a role in perpetuating the infectious cycle in the river, and also provide insight into C. shasta production in spawned adult Chinook salmon carcasses. During the summers of 2010 and 2011 juvenile Chinook salmon from Iron Gate Hatchery were held in cages in the Klamath River for 3 days, then reared at the Humboldt State University Fish Pathology Laboratory. Water samples were collected from the holding tanks and tested for C. shasta DNA with QPCR. Parasite DNA was mainly detected around the time of death and one week after death. Observations suggest the parasite is released passively from fish. Out-migrating juvenile Chinook salmon are capable of producing about 500 billion myxospores, but migration timing may place the spores at an area low enough in the river that they do not contribute significantly to the infectious cycle.

https://scholarworks.calstate.edu/concern/theses/sf268747f

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