Paddlefish (Polyodon spathula)

Status: State Threatened (1989).

Occurrence: Historic records occur for the Mississippi, St. Croix, Chippewa, Red Cedar and Wisconsin Rivers, and also in lower portions of the Baraboo River. Surveys indicate that populations have disappeared above the Prairie du Sac dam on the Wisconsin River. A map outlining Pre-1977 and 1997 to Present Distribution is available.

Aid to ID: Peculiar paddle-shaped snout, large size, shark-like tail. Grey to blue black dorsally and laterally, whitish ventrally. Also referred to as spoonbill catfish. Adult length may exceed 5 feet (1.5 m) including paddle.

Habitat: Prefer large rivers and their lakes. Widespread at variable depths. Paddlefish normally inhabit deep water, but during summer can be found near the surface.

Food Habits: Like a plankton net, the paddlefish's large mouth with fine strains filters small crustaceans, algae, ephemerid larvae and mayflies. They also occasionally feed from bottom. It has been suggested that the paddle-like bill senses plankton concentration levels.

Natural History: Spawning occurs in early spring. Eggs hatch in 12-14 days. Mature adults probably do not spawn every year.

Management Considerations: Damming of large rivers has eliminated much of the paddlefish's spawning habitat by controlling spring flooding and keeping water within its banks. The paddlefish is heavily parasitized by lampreys (Ichthyomyzon spp.). Artificial propagation of this species has had limited success in other states. Normal electro-shocking methods may result in mortality. A modification of the Kolz (1989) shocking method has proven effective under limited testing. Snagging by anglers also results in mortality and is sometimes done unintentionally. Posting signs to educate anglers about the legal status, life history, and protection of this rare species may help reduce unnecessary take.

Information compiled from publication ER-091.