Slate-gray to gray-blue above, fading to somewhat lighter beneath. They can easily be distinguished from all other Iowa fish by the immensely elongated snout, extremely long gill covers and shark-like mouth. The skeleton is largely cartilaginous. Jaws and palate of young fish are covered with numerous fine teeth, but the jaws become large, feeble and toothless as the fish reaches maturity. The body is naked, or scaleless.
Mississippi and Missouri Rivers as well as lower reaches of some larger tributaries of the Mississippi
Zooplankton, insect larvae. The food organisms are filtered from the water by the gill rakers as the fish swims about with its mouth open.
107 pounds - Missouri River, Monona County , March 1981 - Robert Pranschke, Onawa, Iowa
Almost all Paddlefish are caught by snagging below a dam in the spring.
Missouri River Paddlefish Season and Regulations
Paddlefish are most often collected and seen in the Great Border Rivers; but, it is not unusual for anglers to take them in the lower portion of the Des Moines, Cedar, Iowa and, Skunk rivers. It was formerly rather common, but is now absent in East and West Okoboji Lakes and Spirit Lake.
Paddlefish are one of the most primitive of fish. It is a remnant of ancient life, differing from other fish by its elongated paddle-like snout, long gill covers and shark-like body. It was formerly abundant in the Mississippi valley, but over-exploitation, changes in environmental conditions, or both, have reduced its numbers and it is no longer common except in certain places along the river.
Its large size and bizarre shape have made Paddlefish interesting to anglers and scientists alike. Fish over 6-feet long have been taken from Iowa, placing it at or near the top of the list for "big fish" honors. Early growth of Paddlefish is fast with fish reaching 10- to 14- and 21- to 24-inches in their second and third years of life. Seventeen-year-old fish average nearly 60-inches long and weigh about 37-pounds. Paddlefish are long-lived fish with 20 years common and 30 years or more not unusual. The larger fish are females.
Different theories have been shared about the function of the paddle-like snout. It has been suggested that it is used to stir up the bottom to help with feeding, serves as a "rudder" to guide the fish and/or is a sense organ to find food organisms. The Paddlefish is not a bottom feeder and the snout has an elaborate system of sense organs, making the latter theory seem logical as the primary function of the appendage.
Paddlefish spawn in April and May when water temperature is around 55-60 degrees. The spawning run up the larger streams is closely connected with periods of high flow. Spawning activity takes place over flooded gravel bars. The female starts spawning in the deeper water and completes a spawning "rush" at the surface of the water at which time rapid agitation of the caudal fin can be seen above the surface of the water. The female is accompanied by one or more males on this rush.
Studies in Iowa show that most male Paddlefish mature at age six and seven. Females mature at a greater age and produce about 7,500 eggs per pound of body weight. The fertilized eggs are adhesive and attach to the first material they find. Hatching success is highest on clean-swept gravel where siltation is least and aeration is good. Paddlefish eggs hatch in seven days or less at temperatures of 65-70 degrees. The larvae start to swim immediately after hatching and are swept downstream into pool areas.