Fish Disease Dynamics in the Klamath River 2019

In 2019 we focused our efforts on certain important times of the year. These time periods were: late winter (worms are beginning to grow), spring (during the juvenile salmonid outmigration), mid-summer (when water temperatures are high and flows are low) and fall (during the spawning season). We focused our efforts in the upper portion of the river (RM 160-190), and introduce a new sampling area near Tully Creek on the Yurok Indian Reservation (RM 20) that recent environmental DNA work has shown to also be a highly infectious reach. We were attempting to determine the myxozoan infection rates, life cycle dynamics, and relative abundance of polychaete worms at index sites in the mainstem Klamath River to help monitor the efficiency of management action to reduce the myxozoan disease infectivity of the Klamath River.

Polychaete worms were collected using a suction sampling device at the two proposed sites . Soon after collection, samples were sorted and polychaetes were enumerated by YTFP staff to determine relative abundance at sample locations. A small portion of the collected worms will be sent to Oregon State University for genetic analysis to determine rate of infection at a later date. The results of the analysis will be included in a collaborative report with OSU and will be prepared after all field and lab work has been completed. Data from previous years of collection and analysis will also be included in this report.

PCSRF Goals, Objectives and Priorities addressed:
Understanding the life history and geographic distribution of the myxozoan disease C. shasta, is a crucial first step toward devising management strategies to reduce the impacts of this devastating disease. Reduction of impacts of this disease would fulfill many of the goals and objectives of the PCSRF including improving the status of ESA-listed coho salmon and ensuring the overall sustainability of Tribal Trust held salmon and steelhead.

Objectives were identified as priority SONCC coho salmon recovery tasks in:
• CA Dept. of Fish and Game’s Recovery Strategy for California Coho Salmon (CDFW 2004)
• NOAA’s Recovery Plan for the Evolutionarily Significant Unit of SONCC Coho Salmon Public Draft Version: January 2012 (NOAA 2012).

Outcomes & Benefits
-Determine the myxozoan infection rates, life cycle dynamics, and relative abundance of polychaete worm at an index site in the mainstem Klamath River to help monitor the effectiveness of management action to reduce the myxozoan disease infectivity of the Klamath River.

-Provide data so that management actions (primarily water management related to the operation of the federally owned Klamath Irrigation Project and the Trinity Division of the Central Valley 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 Tribal Trust held Chinook salmon which are important to the Yurok Tribe’s subsistence and commercial fisheries.