Savannah River Dinosaurs
By: Jason Moak & Kelsey Laymon
There are dinosaurs living in the Savannah River. While they may not be as fearsome as a Tyrannosaurus rex, they are every bit as primitive. These river dinosaurs are fish – the shortnose sturgeon (Acipenser brevirostrum) and Atlantic sturgeon (Acipenser oxyrinchus). Scientists have thought of sturgeon species as living fossils because their anatomy has not changed in over 100 million years. Sturgeons are long-lived, slow growing species that have been captured as a source of food and caviar which has contributed to their decline and landed them on the list of federally endangered species since 1967.
Sturgeon are unique among bony fishes because their skeleton is almost all cartilaginous. Unlike most fish, they are covered with bony plates called scutes instead of scales. They have an elongated body and barbels, similar to a catfish’s whiskers, which help them find their food, commonly aquatic insects, mollusks, and crustaceans. Both of these species can live more than 60 years, and while shortnose sturgeon typically grow to about 3 feet long, some Atlantic sturgeon reach lengths of up to 14 feet!
Atlantic and shortnose sturgeons are found in rivers, estuaries and the sea all along the Eastern coast of North America. They are anadromous, a fisheries term meaning they spend most of their time in saltwater, but migrate up freshwater rivers from time to time for reproduction. In the Savannah River, the shortnose sturgeon spawns in the spring, but typically begin their upstream migration in January or February. Atlantic Sturgeon spawn from spring to fall, and can be found in the freshwater portion of the river throughout the year.
Phinizy Center scientists have worked with other researchers since 2009 to study the movements of these fish in the Savannah River. Currently, we help monitor a network of underwater sensors that detect when a tagged sturgeon swims past. The sensors record the date and time, as well as the unique ID of the tagged fish. Using this data, researchers are gaining a better understanding of which habitats are most important for these species and when they migrate to spawn.