Long-Term Changes in Fish Community Structure in Relation to Asian Carp Establishment

Using data from the Long Term Resource Monitoring Program (LTRMP), we assessed the similarity of the fish community within the Illinois River before and after the establishment of Asian carp (Hypothalmychthyes spp.).  Data included mean annual species catch-per-unit effort among several sampling gears and river habitats.  Non-metric multidimensional scaling and ANOSIM were used to compare the pre- (1993-1999) and post-establishment (2000-2012) fish communities among multiple gears in multiple habitats.  Significant differences between fish communities were observed for electrofishing (p = 0.016) and fyke netting (p = 0.001) in backwaters, electrofishing (p = 0.02) in side channel borders, and hoop netting (p = 0.003 and p = 0.03; large and small, respectively) in main channel borders.  Several other gears exhibited differences in the community pre- and post-establishment, yet were not statistically significant.  Further analysis of percent similarities (SIMPER) indicated that white bass, common carp, and freshwater drum were the primary reason for these differences, with all three species being less abundant after the establishment of Asian carp.  Emerald shiners also contributed to community dissimilarity with higher abundances observed post Asian carp establishment.  These patterns indicate that Asian carp may have altered the fish community structure within the Illinois River.