Warm temperatures and spring blooms aren’t the only things arriving early this year, according to scientists who study the Savannah River’s rarest fish.
“Everything seems to be two or three weeks earlier than usual,” said Bill Post, a biologist and diadromous fishes coordinator for South Carolina’s Department of Natural Resources.
Post and his colleagues are in Augusta this week observing migration patterns of American shad and downloading data from some of the 54 radio receivers deployed along the river to monitor the endangered shortnose sturgeon.
“We checked all the receivers from Augusta down to Jackson,” he said. “It turns out one of the tagged fish had already been up here — just three days earlier.”
Post and scientists from the University of Georgia, North Carolina State University and other institutions are sharing a grant to expand sturgeon-tagging studies in major Southeastern river systems, including the Savannah, where about 30 sturgeon have been tagged.
In all, he said, 275 transmitters have been placed in major rivers in hopes of learning more about the sturgeon’s spawning habits and to determine how far inland they swim.
The studies have already yielded new insight into one of the planet’s oldest living fish species – which has existed since prehistoric times.
“The network that’s being created has given us information we’ve never had before,” he said. “We’ve had fish from Delaware down here in Georgia and found fish from the Edisto River (S.C.) that ended up as far away as New York and up the Delaware River.”
The shortnose sturgeon and its larger cousin, the Atlantic sturgeon, are among several ocean species that make annual spawning migrations up the river toward Augusta. Others include striped bass and American shad.
One focus of concern for those species is New Savannah Bluff Lock and Dam near Augusta Regional Airport. Since its construction in 1937, it has halted or impeded upstream fish movement.
The lock, built to serve a commercial shipping industry that vanished decades ago, remains operable for recreational boats. Under a contract between the Army Corps of Engineers and the city of Augusta, the lock is also opened 50 times per year — beginning March 12 — in hopes of allowing fish to move upriver.
One project under way this week involves the use of dual frequency sonar – which produces imagery much like ultrasound – to record video of fish moving through the lock during those openings.
Studies of shad movement through similar locks in other rivers have shown that more fish move through during afternoon hours, while the Savannah River lock is typically opened in the mornings.
That four-day study will involve recording fish movement two mornings, and two afternoons, to see if more fish move through the lock during either period. Also involved in the project are Corps of Engineers biologist Jamie Sikes and research scientist Jason Moak of the Southeastern Natural Sciences Academy.
The eventual plan to improve fish migration is to build a custom-designed rock ramp on the South Carolina side of the river, where a series of ledges would allow fish to move around and past the dam.
The ongoing effort to deepen Savannah Harbor includes a proposed mitigation plan that would provide about $7 million for the Augusta project.