Project Name: Disease Reduction in Klamath River Salmon
Funding Source:
Department of Commerce/NOAA National Marine Fisheries Service

Summary: Salmon losses in the Klamath Basin have had devastating effects on tribal communities along the river and the coastal communities of Oregon and California. The closure of the salmon troll industry in 2006 was a management decision in response to the low contribution of the Klamath Basin. Disease of the Klamath stocks is a primary factor in their decline. The cost of the 2006 closure to Oregon coastal communities was estimated to be $28 million dollars (and 1,100 lost jobs) with costs and job losses in California approximately twice those amounts. The Governors of both Oregon and California declared fishery disasters that resulted in allocation of $60 million dollars in federal assistance.BARTH fed funds boats

Closures as a result of low runs in the Sacramento and Klamath Rivers have not permitted fishing to resume since 2006. Salmon trollers estimate that by reducing the effects of disease on Klamath stocks by as little as 10 percent would increase the number of Klamath River adult salmon to the point that fishing on that population could resume and allow the industry to survive.

Severe infection by the myxozoan parasite Ceratomyxa shasta has, in large part, been responsible for the declining numbers of juvenile Klamath River fall Chinook and threatened coho salmon, and subsequent impacts on later adult returns. Research conducted in 2008 and 2009 by OSU and the US Fish and Wildlife Service (USFWS) indicates that disease in Klamath River salmon has been more severe in the last two years than during any time since disease monitoring began. Findings include that Chinook and threatened coho salmon suffered higher mortality than previously anticipated.

Ceratomyxa shasta has a complex life cycle, involving an invertebrate (polychaete worm) host as well as salmon. Salmon in the Kalmath River have evolved with C. shasta and are relatively resistant to infection compared to salmon from rivers where the parasite is absent. The current severity of ceratomyxosis in these fish suggests a shift in the host/parasite balance. In 2009, researchers from OSU, the USFWS and the Tribal agencies conducted a survey to identify the area of the river in which high parasite densities and large numbers of infected invertebrate hosts result in severe disease and high mortality, thus providing a target for management actions.

In 2007, a multidisciplinary panel of fish disease experts and fishery managers developed a research plan focused on management actions to reduce disease (ceratomyxosis) in natural juvenile salmon of the KR. This proposed research effort is in addition and complementary to on-going monitoring in the basin. The reach from Iron Gate Dam to the Scott River was identified as the primary management area, based on juvenile salmon infection status and data from fish exposures, invertebrate host surveys and water sampling studies.BARTH fed app lifecycle

Management actions have the goal of:
1. Reducing polychaete host populations in the selected KR reach
2. Reducing the effects of the infectious actinospore on juvenile salmon
3. Reducing the input of myxospores from specific salmonid fishes
4. Decreasing fish exposure/Increasing fish resistance

A formal research group has been formed to meet the management goals. The group includes researchers from OSU, Humboldt State University, the University of California-Davis, the USFWS and the Yurok Tribe.

In 2009 the group conducted numerous studies to meet the research goals:

1. Carcass removal pilot study - Adult salmon contribute large numbers of parasites that result in infection of the worm host. Breaking this cycle may reduce the number of parasites causing infection in the juvenile salmon. This year, over 1,000 adult Chinook salmon carcasses were removed from a tributary of the Klamath River after the fish spawned and water samples were collected to measure the effect of this action. Report

2. Hydrology study - Removal of the polychaete host is considered to be the key to controlling disease. This study investigates flow strength necessary to dislodge the worm from its preferred habitats. In 2009 preliminary surveys of habitat in the infectious zone were completed.

3. Migration study - To address critical uncertainties about actions that could reduce disease in salmon, the USFWS conducted a study that tested exposure during migration. They found that as brief a period as 1 day in the infectious zone caused over 50% mortality.

This working group, as well as collaborators receiving matching funds, convened in fall 2009 to review the current status of research and determine approaches for 2010. During this next year the research will assess the effects of entry into the saltwater environment on fish infected with C. shasta. In addition, a pilot study to examine the feasibility of transporting fish around the infectious zone is proposed.

Progress report:   2010/2011 submitted March 2011

HSU 2009 final report submitted Dec 2011

Annual report: 2009/2010 submitted Dec 2011

Project Name: Disease Reduction in Klamath River Salmon
Funding Source:
Department of Commerce/NOAA National Marine Fisheries Service