Identification of Parasites and Bacteria and Their Role in Infections and Mortalities of Smallmouth Bass Micropterus Dolomieu in the Susquehanna River Basin and Neighboring Drainages
The objectives of this study were to determine the distribution of the myxozoan parasite Myxobolus inornatus identified in young-of-year (YOY) smallmouth bass, determine the role that this parasite is playing in infections/mortalities, identify the intermediate host(s) that may be mediating transmission of this parasite, and determine the distribution of intermediate host species to identify potential for threat of spread of condition. Based on sampling in 2013 and previous years, M. inornatus, a myxozoan parasite of muscle and connective tissue in YOY Smallmouth Bass appears to be widespread in the Susquehanna River basin, present at a lower incidence and severity in bass from the Allegheny River, and to date has not been observed in samples from the Delaware drainage. Clinical disease was only observed at one mainstem site in the Susquehanna Basin in 2013; hence evaluating the potential role of the parasite in the disease syndrome of YOY was not possible. Despite the lack of visible lesions, there were signs of disease microscopically at the other sites including the presence of myxozoan cysts and inflammation in the muscle and connective tissue associated with myxozoan infections. We are uncertain if fish with myxozoan infections that did not have clinical disease would have developed clinical disease had they not been captured.