The Ballad of Ceratonova shasta
The Klamath River Basin, stretching across the border of Oregon and
California, has long been the spawning ground for multiple species of Pacific salmon and has a rich history of fishing. Historically, native tribes such as Yurok and Hoopa relied heavily on the river with its annual salmon runs, and continue their relationship with the river today. However, modern development of the river system has altered the ecosystem, as recreational fishing, agricultural irrigation, and hydroelectric demands have altered dynamics in river processes and greatly impacted salmon spawning and juvenile fish mortality.
Over the past two decades, researchers at Oregon State University,
led by Dr. Jerri Bartholomew, have helped shed light on factors that impact
salmon and trout populations of the Klamath. In particular, they have
revealed how the fish are affected by a deadly myxozoan parasite, Ceratonova shasta. Using molecular tools for genetically identifying unknown DNA, they established that the C. shasta life cycle involves two distinct spore morphologies that alternate between salmonid fish and polychaete worm hosts in the river. The researchers now monitor the rivers parasite spore concentrations, polychaete worm distribution, and water flow dynamics to reduce parasite effects. They know that warm, slow moving waters can stress smolts (young salmon), and if accompanied by elevated parasite concentrations, this can lead to lethal consequences for the fish hosts. Scientists and law makers now have a greater understanding of how to mitigate the mortality of juvenile salmon in the basin.
The waters of the Klamath are a limited resource, with many people who have diverse needs, and whose livelihoods rely on their well-informed, responsible management. Decisions on water distribution commonly disadvantage certain stakeholders while benefiting others, which has lead to long standing legal battles over water rights in the watershed. While water is needed for agricultural use, law makers periodically order hydroelectric dams along the river to increase water flow rates during migration seasons to flush the river of C. shasta spores and help to prevent the collapse of salmon fisheries in the Klamath. Efforts are also underway to eventually remove dams along the Klamath River to revive fisheries and improve water quality.