Movement and habitat use of Shoal Bass Micropterus cataractae in two Chattahoochee River tributaries

Abstract

Shoal Bass Micropterus cataractae is a fluvial specialist endemic to the Apalachicola-Chattahoochee-Flint River basin in Alabama, Georgia, and Florida. Recent studies show there is a lot of variation in movement and habitat use across systems. Shoal Bass are imperiled throughout their entire native range with some populations facing severe declines, especially in areas highly impacted by impoundments, leading to habitat fragmentation and loss of connectivity. I studied the movement patterns and habitat associations of two isolated populations within the Fall-Line ecoregion of the Chattahoochee River, Georgia, using radio telemetry. This is a relatively understudy region with high population declines, though the studied populations are considered viable and self-supporting. Throughout the 18-month tracking survey, Shoal Bass exhibited higher mean daily movement rates in the spring compared to winter and autumn. Tagged fish used greater depths in the winter months, potentially reflective of available water levels. Fish used higher velocities in winter months than in spring on both creeks, though most fish were located in relatively swift velocities year round. Tagged fish in both creeks showed an affinity for rocky substrate, though type of substrate use varied across seasons and creeks. Fish in Flat Shoals Creek used shoal complexes during the spring and boulder substrate throughout rest of year. Fish in Mulberry Creek preferred boulder and bedrock substrates year-round, but were often located in different areas seasonally. Results of this study suggest that habitat use of Shoal Bass may be determined by the amount and type of substrate available within the range of movement. This study has strong implications for managing these small populations in a highly imperiled region. Future studies should seek to investigate population dynamics and levels of reproductive success in order to predict habitat protection or restoration success.