Cooperative Fish and Wildlife Research Units Program: West Virginia
Education, Research and Technical Assistance for Managing Our Natural Resources

Data collected over the past three years has indicated 1) skin lesions of bass and sunfish the numerous fish kills observed in sporadic locations appear to be associated with a variety of opportunistic pathogens including the bacteria Flavobacteria columnare (Flexibacter columnaris) and Aeromonas salmonicida, numerous protozoan pathogens on skin and gills and possibly largemouth bass virus; 2) in 2006 sucker kills occurred and were also associated with gill lesions and opportunistic pathogens; 3) in fish collected at many sites there are high helminth and myxosporidian parasite loads; 4) there is a high incidence of intersex throughout the Potomac and Shenandoah drainages; 5) there are multiple stressors that probably eventually combine to cause kills. It has been recognized that it is difficult to demonstrate causal associations between exposure to various chemicals and ecological or population-level effects. Hence, it is important to document the extent of the biological effects, determine if population effects are occurring as a result and provide information that may be useful in managing the problem. Samples have been collected over the past two years that will allow researchers to: 1) assess seasonal changes in disease resistance, parasite loads, reproductive abnormalities and serum factors; 2) compare sites for parasite loads, testicular oocyte prevalence and severity, other gonadal factors, disease resistance and presence of specific pathogens including the bacteria Flavobacterium columnare, Aeromonas salmonicida, and largemouth bass virus; 3) compare microscopic (histopathological) observations during pre-kill periods and during fish kills in an attempt to identify causes and predisposing factors.