The U.S. Army Corps of Engineers, Mobile District, is working with the Auburn University School of Fisheries, Aquaculture, and Aquatic Sciences to facilitate a study on the effectiveness of conservation lockages on migratory fish species in the Alabama-Coosa-Tallapoosa River Basin.
The study is part of a continuing effort by the district and members of academia to identify how lock and dam operators can better support the passage of migratory fish through our Nation’s waterways.
“We understand the role that dams play in breaking up habitats and migratory pathways for fish that utilize fresh water for spawning,” said Brian Zettle, USACE Inland Environment Team Chief. “As good stewards of these government resources, it’s important that we look for opportunities… to minimize potential impacts on the ecosystem.”
The Auburn University portion of the study is led by Dr. Russell Wright and Dr. Dennis DeVries. Wright explained what can happen if migratory fish are unable to get upstream to spawn.
“When you put a dam across a river it’s going to block migrations of fish and that can affect reproduction and sustainability of those populations,” said Wright. “They need very specific kinds of habitats to spawn and for their eggs to survive.”
Because most lock and dam systems are already established there are limited options that can be used to facilitate the movement of fish upstream.
“If you are going to move fish past a lock or dam you really have two choices,” Wright explained. “You can build a system to get them over the dam, like a fish ladder or a diversion canal, but that can get quite expensive. [But] if we can encourage fish to go through the locks and get them to go out the other side, then you have a cost-effective way to get them upstream.”
The second option, called conservation lockages, has been implemented in the past with moderate success. In fact, a similar study that the district took part in on the Apalachicola-Chattahoochee-Flint River Basin indicated a high rate of effectiveness with the Alabama shad.
“We conducted a study that showed [conservation] lockages can be effective with the Alabama shad,” said Zettle. “During that study, nearly 98% of fish that were captured were spawned up in the Flint River, which means they had to get past our dam to get up there.”
Despite the success with the Alabama shad, other studies have suggested that you may need to introduce artificial stimuli for the lockages to be effective.
“We did a study to look at the paddlefish,” said Wright. “What we found is you can… attract them into the lock chamber with an attraction flow, but when you raise the water… and open the gates there is no obvious stimulus to get [them] to exit into the upstream reservoir. So, they often would just ride the water back down.”
In an attempt to better understand this phenomena, the team from Auburn will install listening devices and radio antennas around Miller’s Ferry Lock and Dam and Claiborne Lock and Dam to determine the various stimuli that elicit a fish response. The study is expected to last approximately five years and will track four to five different species including the smallmouth buffalo, southeastern blue sucker, and the Gulf-strain striped bass.
“We hope to determine the levels of flow that will work, where and when it needs to be released, and how we can manipulate [it] to make it easier for fish to pass,” said Wright. “We might find that there isn’t [much] we can do, or maybe we find that we just need to put a splash (or sound) device upstream so they know… to leave the chamber and continue upstream to spawn.”