Recent Decline of Nongame Fishes Inhabiting Small Streams in the Greater Rock River Basin Southcentral Region Water Program

In 1998 and 2000, we sampled small stream fish communities at 67 sites to evaluate the status of nongame fish species in the Greater Rock River Basin. Forty-five sites were located in the Lower Rock River sub-basin and twenty-two sites in the Sugar-Pecatonica River sub-basin. All of the sites were originally sampled as part of the Fish Distribution Study during the 1970’s. Most of the stream sites had not been sampled since that time. Survey results indicated a decline in species richness, intolerant species and species listed as Endangered Resources. Species that were found in 1974-75 but not in 1998 and 2000 included blackchin shiner (Notropis heterodon), ozark minnow (Notropis nubila), redfin shiner (Lythrurus umbratilis), lake chubsucker (Erimyzon sucetta) and rainbow darter (Etheostoma caeruleum). The number of locations supporting redside dace (Clinostomus elongatus), banded killifish (Fundulus diaphanus) and least darter (Etheostoma microperca) declined as well. The reasons for these declines can encompass water quality, physical habitat degradation and competition with exotic species. However, expanding livestock operations during the 1970’s and 1980’s may also be a contributing factor as several of the sites showing a decline in species are small streams with documented animal waste management problems.