Whirling Disease: Reviews and Current Topics

Evaluation of Risk of High Elevation Colorado Waters to the Establishment of Myxobolus cerebralis

George J. Schisler and Eric P. Bergersen

doi: https://doi.org/10.47886/9781888569377.ch3

ABSTRACT. During 1992 and 1996, fish were inadvertently stocked into 226 waters in Colorado from hatcheries that were later identified as Myxobolus cerebralis-positive. Seventy-two high-elevation waters, previously classified as M. cerebralis-negative, were sampled to determine if stocking of fish from those hatcheries contributed to the spread of M. cerebralis in these locations. Pepsin-trypsin digest (PTD) and polymerase chain reaction (PCR) tests were used to test for M. cerebralis in 1,743 fish. A total of 190 fish and 23 separate waters were identified as M. cerebralis-positive, with PTD. PCR identified 410 fish and 42 waters as positive for the parasite. Logistic regression and Akaiki information criterion model selection was used to identify parameters contributing to the M. cerebralis establishment in these high elevation waters. Within-drainage distance to the nearest known M. cerebralis-positive water and relative abundance of Tubifex tubifex habitat were found to be more important contributors to the establishment of M. cerebralis than the accidental stocking events.