Movement and Habitat Use of Shoal Bass Micropterus cataractae in a Regulated Section of the Chattahoochee River, Georgia

Shoal Bass Micropterus cataractae are endemic to the Apalachicola drainage and have been designated as a species of High Conservation Concern in Alabama and of Special Concern in Georgia and Florida.   Much of their original distribution in the Chattahoochee River has been reduced due to impoundments, particularly in the Fall Line region, where 9 dams occur in a 64-km reach.  However, isolated populations persist in the headwaters or tailwaters of these dams.  The study section is regulated by West Point Dam, which is a hydro-peaking facility.  To examine the habitat use and behavior of shoal bass in this section, 40 Shoal Bass were collected and implanted with 3.6-g radio tags in the headwaters of Bartletts Ferry Reservoir, below a small lowhead dam.  These fish were tracked approximately every 7-d over a 35-week period for a total of 784 locations.  During July-September, seven diel surveys were conducted, where 8 fish were tracked throughout a 12-h period.  The goal of these surveys were to determine the effects of hydropeaking operations on fish distribution, movement, and habitat use.  Home ranges were calculated using fixed kernel density estimation in Home Range Tools 9 for ArcMap 9.3.  Shoal Bass were commonly found using bedrock and boulder habitat rather than vegetated and sandy habitat, especially during times of higher flow.  Fish movement was the highest in the spring, which can be associated to spawning, and lowest in late-fall due to cooler water temperatures.  Several fish moved back and forth between the tailwater and a nearby tributary stream that flowed into the Chattahoochee River, possibly for refuge from peaking hydropower flows for spawning.  However, no fish moved through the reservoir to access other tributaries with quality habitat.  Thus, dams may not only present a physical barrier to upstream movement, but also the reservoirs formed by dams may hinder movement.   Fish displayed greater movement on a daily basis (m/d) compared to a diel basis (m/h).  As flows increased fish moved into areas with current, possibly for foraging.   This suggests the fish are not negatively affected by the hydropeaking operation.  Although the effects of hydropower peaking flows and dam fragmentation on obligate river species continue to be poorly understood, this study suggests several strategies used by these species to adapt to altered flow regimes.