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

Tennessee is home to some of the most diverse freshwater fish communities in the world as well as some of the most highly-regulated rivers in the United States. The Caney Fork River below Center Hill Dam in middle Tennessee has three tributaries; thus, there was an opportunity to evaluate differences in biotic integrity among three tributaries of a regulated river. The purpose of this study was to calculate and compare indices of biotic integrity (IBI) in those three tributaries over two seasons using two sampling protocols. The protocol developed by the Tennessee Valley Authority (TVA) relies on species accumulation curves to dictate sampling effort. The second protocol developed for Wisconsin streams requires sampling a reach that is 35 times the mean stream width (35MSW). At five sites in those three tributaries over two seasons in 2010, more than 27,000 fish were collected representing 53 fish species. The IBI scores were “good to excellent” at three of the five sites, “good” at one site, and “fair” at one site. More species were collected at most sites both seasons when following the 35MSW protocol. When compared to the 35MSW protocol, the TVA protocol tended to inadequately sample the species present. Sampling small (28 m2) quadrats allowed many fish to avoid the electric field; this was particularly evident when sampling pools. Another consideration when following the TVA protocol is the need to accurately and immediately identify fish after each quadrat sample, which may result in inefficient use of time in the field. Compared to the TVA protocol, the 35MSW protocol required sampling a greater area. However, due to the time required to measure each sample area and process each catch when using the TVA protocol, IBI sampling using the 35MSW protocol may not take any more time to conduct.