Dataset Detail
Dataset: Natural exposure of sentinel rainbow trout to M. cerebralis
| Project: Distribution and Seasonal Occurrence of Myxobolus cerebralis in the Lostine River, Oregon | |
| Dataset Abstract: Juvenile rainbow trout fry were exposed in sentinel cages for 14 days at four sites on the Lostine River (Oregon) during intervals from July 1998 to November 1999. Recovered fish were assayed by the polymerase chain reaction (PCR) for the presence of M. cerebralis DNA (indicated by % positive). A subsample of exposed fish were returned to the laboratory for five months of observation. The severity of infection was determined by histological examination, enumeration of spores isolated from the cranial cartilage and observation of clinical signs. Results indicate that the Mxyobolus cerebralis parasite is prevalent throughout the river; highest infection levels were found in sections that had lowest gradient and highest organic matter input, as well as supplemental water flows from the Wallowa River (known to be infected with the parasite). | |
| Significance of Results: The goal of the study was to establish the infectivity of M. cerebralis in this river. We did not expect to find the parasite in the headwater, high-gradient, cool temperature regions of the watershed, but a low prevalence of infection was found in those areas. In addition, the utility of using eyed eggs for sentinel exposures was established, because eggs are easy to transport and the newly hatched fry are particularly susceptible to infection in comparison to older life stages. | |
| Relevance to Managers: Detection of infection and clinical lesions in fish that received only a 14 d exposure suggest that salmonids residing in the lower river, where T. tubifex is more prevalent, receive a higher, chronic exposure to the parasite and are at risk of developing whirling disease. | |
| Utility to Researchers: Sentinel cage data could be useful as baseline data for M. cerebralis prevalence in this river. | |
| Questions Generated: Chinook salmon and bull trout migrate through this whirling disease parasite hotspot. Will their populations be negatively affected by exposure during imprinting and migration. | |
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