Fish Disease Dynamics in the Klamath River 2018

Project Objectives & Approach


This study is a continuation of an in-depth 12-month 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 will be conducted in the upper reaches of the Klamath River near Iron Gate Dam in the area of maximum salmonid infection using an alternative method of individual examination to provide more detailed and accurate data. Another year of data collection will allow for analysis of inter-annual variation in infectivity rates and distribution of polychaete worm host organisms. Continued monitoring of polychaete worms will also allow us to examine the recently court ordered increased releases from Iron Gate Dam that are intended to disrupt the Ceratonova Shasta lifecycle.
During previous years we collected polychaete worms on a monthly basis year round. In 2018 we plan on focusing our efforts on certain important times of the year. These time periods are: 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 will once again focus our efforts in the upper portion of the river (RM 160-190). We propose to collect polychaete worms so that researchers from OSU can 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 will be collected using a suction sampling device in the upper reaches of the Klamath River between Iron Gate Dam and the Shasta River. Soon after collection, samples will be sorted and polychaetes will be 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. 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 naturally-spawning Pacific salmon and steelhead.

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 efficacy 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 Chinook salmon important to the Yurok Tribe’s subsistence and commercial fisheries.