Re-Establishing Long Distance Fish Migration Pathways: Feasibility of Passing Fish Through Two Alabama River Lock Structures

Fish passage facilities are a widely accepted mitigation tool at many dams in the United States.  Trapping/hauling, fish ladders, slotted fishways, and fish bypasses are all extensively used to assist migratory fish species to upstream spawning areas in rivers on the U.S. Atlantic and Pacific coasts. However, relatively few of these structures have been constructed in the southeastern U.S.  Recent studies from the Mississippi River and Chattahoochee River suggest that lock operations can reconnect navigation pools and facilitate fish spawning migrations. Here we investigated the potential to move fish through two locks on the Alabama River-- Millers Ferry Lock and Dam and Claiborne Lock and Dam-- using specialized lock operations.  We collected 6 species of migratory fish (paddlefish, striped bass, southeastern bluesucker, white bass, smallmouth buffalo, freshwater drum) in the vicinity of each dam in the spring and implanted each with a sonic tag.  We used manual tracking combined with submersible ultrasonic receivers (SUR) deployed both above and below each dam, as well as inside the navigational lock chamber to determine whether fish passage occurred.  We recorded over 65,000 detections with the SURs and 110 manual detections. Upstream fish movement through the navigational lock chambers occurred during spring, when many riverine fish make spawning migrations; several fish were also detected entering the lock chambers in the summer.  Downriver movements at the two dams also occurred during the spring and summer, but were less dependent on the use of navigational lock chambers.  Our results suggest that specialized lock operations along the Alabama River may facilitate fish passage.