Field Exposure of Seven Species or Subspecies of Salmonids toMyxobolus cerebralisin the Colorado River, Middle Park, Colorado

Publisher Website
Google Scholar
Abstract
Recent failures in recruitment of rainbow trout Oncorhynchus mykiss in the Colorado River in Middle Park, Colorado, USA, led to studies of the effect of the myxosporean parasite Myxobolus cerebralis, the causative agent of whirling disease, on the wild trout fishery in the river. During 1995–1996 and 1996–1997, we conducted field exposures of sentinel fish to examine the vulnerability of seven species or subspecies of salmonids exposed to the parasite in the Colorado River. During 1995–1996, brook trout Salvelinus fontinalis and Colorado River cutthroat trout O. clarki pleuriticus experienced 85% or higher mortality within 4 months of exposure. Groups of fish introduced at greater mean weight or later in the summer tended to survive better than others, but mortality often was severe among these groups during the second summer. By April 1996, dead fish or sacrificed fish representing seven groups were shown by histology to contain mature M. cerebralis spores. During 1996–1997, three groups of cutt...