Scaphirhynchus platorynchus Rafinesque
Other names -- sand sturgeon, hackleback, switchtail, flathead sturgeon.
Scaphirhynchus platorynchus Rafinesque
Other names -- sand sturgeon, hackleback, switchtail, flathead sturgeon.
This species is rather widely distributed in the Mississippi and Missouri Rivers and is occasionally collected in the larger tributaries of these rivers. Nowhere is it abundant, but it is considered common in many navigation pools of the Mississippi.
Color of the shovelnose is buff or olive-drab above and light beneath. The entire body is armored with heavy plates. The snout is markedly flattened or shovel-shaped. There are no spiracles. There is a very long, thread-like filament attached to the top lobe of the tail fin, from whence the fish gets one of its common names -- "switchtail." This filament is very fragile and is often missing, especially in older individuals. This species commonly attains a weight of 6 to 8 pounds, although 4 or 5 pound specimens are more common. The state record is 12 pounds and was caught in the Des Moines River in Van Buren County.
The shovelnose is primarily a river fish, very seldom being found in the absence of a current. In the Mississippi River it frequents the tailwaters below wing dams and other structures which accelerate current flow.
Spawning occurs in May and June, with the spawning run being greatest during years of low flow. Little is known about the spawning activity of this species. Fish mature at 5 to 7 years of age when around 20 to 24 inches in length. Females do not spawn every year, and the larger specimens produce about 50,000 eggs. Growth in the Mississippi River is 8.4 inches FL at age I, 12.5 at age II, 16.1 at age III, 18.8 at age IV, 20.7 at V, 22.5 at VI, 23.8 at VII, 25.0 at VIII, 25.9 at IX, 26.7 at X, 27.1 at XI, and 27.4 at XII. Fish over 12 years of age are very rare.
The food habits of the shovelnose are similar to those of lake sturgeon. Primarily a bottom feeder, shovelnose sturgeon feed principally upon insect larvae, small mollusks and other bottom organisms. Algae and bits of higher aquatic plants are also consumed, but ingestion is probably incidental to feeding on bottom organisms.
Shovelnose are the only sturgeon which can be legally taken in Iowa, and they are actively sought by commercial and sport fishermen. Approximately 50,000 pounds are harvested annually by commercial fishermen from the Mississippi River.
This information obtained from the Iowa Department of Natural Resources - Fisheries Department.