Overview
The Robust Redhorse (Moxostoma robustum) is a magnificent, heavy-bodied freshwater sucker that represents one of the most famous rediscovery stories in modern American ichthyology. Originally described in 1869 by Edward Drinker Cope, it was thought completely extinct for 122 years until a small population was dramatically rediscovered in Georgia’s Oconee River in 1991.
Biology and Physical Characteristics
The Robust Redhorse is a heavy, deep-bodied fish with a thick head, brassy-golden scales, and reddish fins with a warm bronze or slate-red caudal fin. Its subterminal mouth is equipped with fleshy plicate lips and massive, heavy molar-like pharyngeal throat teeth capable of pulverizing thick clam shells. Breeding adults develop prominent white tubercles on their snouts and anal fins.
Behavior and Ecology
A powerful big-river swimmer, the Robust Redhorse spends summer months in deep river pools around submerged fallen logs. In May, adults migrate upstream to shallow, high-velocity gravel shoals. Spawning occurs in trios (two males flanking one female) as the fish violently thrash their tails to excavate gravel depressions, burying fertilized eggs deep within oxygenated gravel beds.
Conservation and Human Impact
Listed as Vulnerable by the IUCN, the Robust Redhorse is fiercely protected through the multi-agency Robust Redhorse Conservation Committee. Historic dams have fragmented migration corridors, sedimentation from agricultural erosion chokes gravel spawning shoals, and invasive flathead catfish prey heavily on juveniles.
Interesting Factoid
The Robust Redhorse was written off as completely extinct for over a century until 1991, when biologists netting fish in Georgia pulled up an unknown 15-pound giant with molar teeth that turned out to be the lost species.