Polychaete Infection Prevalence in the Klamath River FY2014

We determined myxozoan infection rates, life cycle dynamics, and relative abundance of polychaete worms at an index site in the mainstem Klamath River over a 12 month period. This project helped monitor the efficacy of management action to reduce the myxozoan disease infectivity of the Klamath River. This study was a continuation of an in-depth multi-year study of polychaete worm (a key fish disease vector) infection rates, life cycle dynamics, and relative abundance in the Klamath River. Fish disease has been identified as a key limiting factor for both Chinook salmon (a primary target species for Tribal fisheries) and coho salmon (listed as Threatened under the ESA). This study was conducted in the upper reaches of the Klamath River near Iron Gate Dam in the areea of maximum salmonid infection using an alternative method of individual examination to provide more detailed and accurate data. This study allowed for analysis of inter-annual variation in infectivity rates and distribution of polychaete worm host organisms. Myxozoan parasites (Ceratomyxa shasta and Parvicapsula minibicornis) in the Klamath River kill an unacceptably high percentage of juvenile salmonid every year, including ESA listed coho salmon. These myxozoan parasites are dependent on the freshwater polychaete worm Manyunkia speciosa in addition to salmonid fishes to complete their life cycle. Determining and evaluating effective management actions to reduce myxozoan disease mortality in juvenile salmonids in the KLamath River requires a more complete understanding of the life cydle, dynamics, distribution, and infection dynamics of polychaetes. In particular, accurately determining the in-river life cycle, relative abundance, and infection rates of polychaetes prior to and after any management actions is of crucial importance. This study helped with the above mentioned goals.

Outcomes and benefits ar to provide data so that management actions (primarily water management related to the operation of the federally owned Klamath Irrigation Project) can be improved with respect to their effect on anadromous fish in general, and particularly with respect to ESA-listed SONCC coho salmon and Chinook salmon important to the Yurok Tribes subsistence and commercial fisheries.