Impact of Introduced Rough Shiner (Notropis baileyi) on the Native Fish Community in the Chattahoochee River System

Abstract

Historical and contemporary fish collection data were used to compare the relative abundance of introduced rough shiner (Notropis baileyi) in the Chattahoochee River (Halawakee and Mountain Oak creeks) to native populations in the Tallapoosa River and to examine the effect of the introduction on the native Chattahoochee River fish community. Absent during the 1981–1985 survey of Mountain Oak Creek, the rough shiner was the fourth most abundant species (10.5% of catch) taken in 1995. In Halawakee Creek mean relative abundance of rough shiner increased from 9.8% in 1971 to 19.8% in 1995. The rough shiner was not collected above the milldam in Halawakee Creek during the historical and contemporary surveys. The rough shiner tended to be more abundant in Halawakee Creek than in its native Tallapoosa River (t = −2.11; df = 11; P = 0.06), where species richness is higher. In Mountain Oak Creek, blacktip shiner (Lythrurus atrapiculus) and golden shiner (Notemigonus crysoleucas) were abundant historically, but were not taken during the contemporary survey. Their absence, however, was not due to the introduction of the rough shiner. Faunal similarity (relative abundance of the 15 most common species) over time was high in Halawakee (Morisita's Index; Im = 0.85) and Mountain Oak creeks (Im = 0.70). These findings indicate that species-rich fish communities can adjust to enrichment with minimal impact on native species. Despite having little effect on overall community structure (Im values over 0.70), the rough shiner appears to be contributing to changes in the relative abundances of two resident species (bluehead chub, Nocomis leptocephalus; weed shiner, Notropis texanus). The relative abundance of bluehead chub, a nest-associate with rough shiner, increased significantly following the introduction of rough shiner to Mountain Oak Creek. Abundance of weed shiner decreased sharply in both Halawakee and Mountain Oak creeks. The significant negative correlation (r = −0.46; P = 0.03) between relative abundances of rough shiner and weed shiner suggests that the rough shiner is limiting weed shiner through competition for food or habitat.