SAVANNAH, Ga. – While most people may never see a shortnose or Atlantic sturgeon swimming through the Savannah River, a team of researchers is getting up-close-and-personal with these elusive, endangered species.
Thanks to a partnership between the U.S. Army Corps of Engineers and the South Carolina Department of Natural Resources (SC DNR), researchers are safely catching sturgeon, inserting sonic transmitters inside them, and releasing them back into the river.
The fish-safe technology allows scientists to monitor and record the sturgeon’s movements using an array of fixed receivers installed along the river.
“Our cooperative agreement with the SC DNR allows us to capitalize on their previous and ongoing research, giving us a better understanding of sturgeon distribution and migration patterns in strategic locations throughout the river,” said William Bailey, planning division chief at the Corps’ Savannah District.
Under the partnership, SC DNR biologists are tagging sturgeon for two separate studies: one in the estuary, and the other upstream at the New Savannah Bluff Lock and Dam near Augusta, Georgia. The four-man research team began work on the studies in August of 2013.
“South Carolina DNR has been conducting sturgeon research in the Savannah River since the mid-80s,” said Bill Post, diadromous fishes coordinator with the SC DNR. “We have the skills and expertise to perform these studies in a way that is safe for the fish while producing reliable data.”
The sturgeon studies are required as part of the Corps’ pre-construction monitoring plan for the Savannah Harbor Expansion Project (SHEP). The SHEP will deepen the Savannah federal shipping channel by 5 feet to increase transportation efficiencies and strengthen the national economy.
Harbor deepening would allow additional saltwater to enter the harbor and travel further upstream into areas currently used by endangered sturgeon species. The increased salinity may reduce the suitability of some of these areas for young sturgeon. To compensate for those impacts, the SHEP includes construction of a large fish bypass around the first dam up the Savannah River, the New Savannah Bluff Lock and Dam.
“The fish bypass will enable sturgeon and other species to access historical spawning grounds at the Augusta Shoals—an area that has been unavailable to them since the lock and dam was built in the 1930s,” said Corps biologist Mary Richards.
“The data collected from the SC DNR studies will establish a baseline for measuring potential impacts of the harbor deepening on sturgeon,” Richards said. “The data will also help us measure the effectiveness of the fish bypass once it is built, and will be useful if we need to take any corrective actions as part of adaptive management.” Corrective actions would come in the form of adjustments to the fish bypass.
While it’s not quite time to start digging, the Corps has already begun several environmental monitoring activities that must be in place at least one year before harbor deepening begins.
“We have been very proactive in our environmental monitoring schedule,” Bailey said. “Our goal is that once final funding negotiations are made and we get the ‘green light’ to start construction, we will have fulfilled the environmental monitoring requirements and can move directly to deepening the channel.”
Last year the Corps awarded $375,000 in federal funding to SC DNR to cover the first year of the sturgeon distribution studies. The estuary sturgeon study is scheduled to continue before, during and after harbor deepening construction. The upstream study is scheduled only during the pre- and post-construction phases of the project.
As of July, researchers have tagged 16 shortnose sturgeon and 29 Atlantic sturgeon in the Savannah River estuary (where the river meets the ocean). The sampling includes a mixture of adults, sub-adults and juveniles.
As for the upstream study, researchers have not yet caught any Atlantic or shortnose sturgeon, but they have tagged seven striped bass and 12 American shad.
“The upstream study is not only focused on sturgeon, but will monitor a variety of species representative of the lock and dam fish community, such as striped bass, robust redhorse, and American shad,” Post said. “These fish share similar spawning habitats of sturgeon.”
Post said that since Atlantic sturgeon appear to spawn in the fall, his team hopes to tag a few later this year. Shortnose sturgeon spawn in the spring, but higher river flows this spring reduced the sampling window.
The shortnose and Atlantic sturgeon are anadromous fish—meaning they live their adult lives in the ocean but migrate to freshwater rivers and streams to reproduce or spawn. Both species are distributed along the Atlantic coast and are federally-protected.
Sturgeon are considered to be among the most primitive bony fishes with origins dating back 120 million years, according to the National Oceanic and Atmospheric Administration (NOAA) Northeast Fisheries Science Center. They are easily identified by five rows of bony plates called “scutes” along their back.
“It’s important to protect and preserve the sturgeon population because they have been around for millions of years in the Savannah River ecosystem,” Post said. “Therefore, their existence is a direct indicator of other factors for a healthy ecosystem, such as dissolved oxygen and water quality.”
To catch fish for the studies, researchers place 100-yard-long gill nets in strategic locations on the river and wait for fish to swim into them.
“We know the river very well and the data we collect tells us even more as we go along. We know where sturgeon have been found in the past, and that increases our effectiveness the next time we want to catch and tag more of them,” Post said.
Once a fish is netted, researchers carefully bring it onboard the vessel and determine if it has been previously tagged. If it has, they record its measurements and location. If the fish is untagged and is considered healthy, they take measurements and prep the fish for surgery. Using industry-safe equipment and procedures, they make an incision on the underside of the fish, implant a small transmitter, and stitch it back up.
The sonic transmitter is about the size of a double-A battery. It transmits a signal that can be picked up via a network of 56 receivers deployed from the mouth of the Savannah River all the way up to the New Savannah Bluff Lock and Dam.
Researchers visit the receiver sites once a month to record the data and determine which tagged fish have been in the area. Periodically, the researchers will also manually track individual sturgeon to identify the habitat conditions they are using at that time.
SC DNR researchers are using the same sonic transmitter technology they also using in a study for the NOAA National Marine Fisheries Service. That study is called “Research and Management of Endangered and Threatened Species in the Southeast: Riverine Movements of Shortnose and Atlantic sturgeon.”
Data from the SC DNR sturgeon distribution studies are reported every month to the Corps, who sends it to the University of Georgia Center for Geospatial Research and for posting on a public website. There are also plans to share the data with the Clemson University Intelligent River Program. Both universities are involved in the SHEP Environmental Monitoring effort.
The public can view monthly progress reports from the sturgeon distribution studies (and other environmental monitoring data) by visiting the SHEP Environmental Monitoring website at http://www.shep.uga.edu and click on “Reports.”
“We have a great relationship with the Corps,” Post said. “We’ve had the pleasure of conducting several studies with the Corps’ Savannah District and the Charleston District, including earlier harbor deepening studies and joint studies with the Georgia Ports Authority.”
“We take our environmental responsibilities very seriously,” Bailey said. “By working with state and federal partners and with academia, we collaborate and share expertise to ensure the integrity of our monitoring and adaptive management program.”