I arrived at Indian Valley in January this year for a year-long fellowship developed through a partnership between the Sierra Institute for Community and Environment and the Feather River Chapter of Trout Unlimited. One major component of the project and, admittedly, the one which first captured my attention, is an aquatic survey and the formulation of a management plan for an invasive Eurasian pathogen which causes a disease in fish, known as whirling disease. Fresh from studying fish parasites for my Master’s thesis, moving into more aquatic pathogen work was a natural and exciting transition into a full-time position. Further, the extensive impacts of alien species worldwide to native ecosystems and biodiversity, made this step into invasive species research and management a decision which brought me into a world where I had an opportunity to effect change with far-reaching implications.
The invasive pathogen I am taking on with this project, known as Myxobolus cerebralis, can cause significant harm to Salmonid fish (e.g. trout and salmon), and whirling disease can occur following exposure to high numbers of the pathogen. Symptoms include a black tail, spinal and cranial deformities, a characteristic circular swimming behavior which earned the disease its name, and even death. Introduced to California in the 1960s, this pathogen is well-known in the Western U.S. for its devastating effects on susceptible salmonid species and resistance to eradication once established. In Colorado and Montana, severe declines in several “blue ribbon” trout fisheries were attributed to the disease following pathogen introduction.
M. cerebralis has been widely distributed around California due primarily to the stocking of otherwise healthy fish which harbored hidden infections. Incidences of whirling disease have been recorded in both wild and hatchery populations. Rainbow trout, a species which represents a significant ecological and recreational resource in California, is highly susceptible to the pathogen. In the Upper Feather River Basin, the rainbow trout in Yellow Creek have been particularly hard hit.
The silver lining to this pathogen story in California is that the growing concerns about whirling disease have prompted efforts to increase our understanding of the prevalence of the M. cerebralis and developing research and recreational practices which are increasingly conscious of human-assisted pathogen spread. It has also sparked an interest in finding ways to disrupt pathogen persistence where it is already found. As a part of my role in coordinating a M. cerebralis survey and management plan, I have reached out to representatives of various biological research, natural resources, and conservation agencies and institutions along the Pacific coast. What I have found most encouraging in the first couple of months that I have been here, is the interest and enthusiasm for cooperatively creating a management plan for M. cerebralis.
Such large-scale collaboration is essential to put in place changes necessary to protect trout in the Feather River and beyond from whirling disease. I am looking forward to the discussions throughout this project which will facilitate the long-term success of management strategies developed for the pathogen.
To learn more about whirling disease:
Myxobolus cerebralis (whirling disease agent)