Susquehanna River Columnaris Investigation (2007)
Survey Number: 707019
Survey Dates: September 13, 2007
In 2007, an outbreak of Columnaris bacteria was again documented in young smallmouth bass throughout the Pennsylvania portion of the Susquehanna River downstream of Waverly. This survey was conducted in order to document the presence/absence of Columnaris bacteria in juvenile bass within the Susquehanna R. bass population in the Binghamton area.
In 2005, a serious outbreak of Columnaris in Susquehanna River bass within the borders of PA was documented for the first time. This outbreak appeared to be limited to young-of-year and sub-adult bass only, but in some areas an estimated 50-90% of the juveniles were infected. Significant mortality was documented as well. Infection rates were highest in central and southern PA and lowest near the NY/PA border. In 2007 the Columnaris outbreak occurred in a similar fashion to that observed in 2005. Infection rates were again highest in the lower part of the drainage and were very low (just over 1%) directly south of the NY/PA border. Outbreaks in both years were believed to be related to persistent low summer flow conditions and high water temperatures, but it is still unclear why.
Examination of the bass captured in this survey revealed that 5 of the 32 smallmouth bass had patches of infected skin that looked identical to photos of Columnaris lesions shown on the PA Fish and Boat Commission website. One additional fish had an infected eye, but it is not known whether it was Columnaris related. Sample smallmouth bass sent to the Cornell lab for analysis indicated a mild Dactylogyrus sp. and Columnaris sp. infestation.
Note: the relatively high incidence rate in our sample was likely influenced/biased by our sampling gear. All of the bass collected were associated with rip-rap located at the toe of the bridge abutment within the site. Sick, lethargic fish may have been utilizing this cover to hide/rest. Large schools (100's to 1,000's) of young smallmouth bass were observed cruising the shoreline but we were unable to collect them with our shocker. I strongly suspect that most of these fish were not infected with the Columnaris bacteria.