Lake Sturgeon

Characteristics

Young Lake Sturgeon are tan, or buff-colored, sometimes contrastingly blotched with dark, becoming more uniformly dark as they grow older. Adults are slate-gray to black above and light beneath. Its body is partially covered with five longitudinal rows of heavy, bony plates or scales. Its head is roundly pointed, and not flattened. Spiracles, or openings from the throat cavity to the outside above and behind the eyes, are present. Its mouth is inferior and almost sucker-like, capable of being protracted to easily suck foods off the bottom. The fish feeds entirely by taste and has four fleshy barbels on the underside of the snout, which act as sense organs to judge the distance from the mouth to the bottom.

Distribution

Confined to the Mississippi River, and possibly the lower end of its major tributaries. Fish have been collected from the Des Moines and Maquoketa Rivers, the first documented occurrences of this species in Iowa’s interior waters.

Foods

Insect larvae, snails, bits of aquatic plants and other litter from the floor of a lake or stream. Young fish less than 8-inches long eat small crustaceans.

State Record

Not allowed for threatened or endangered species.

Expert Tip

It is illegal to fish for, take or possess threatened or endangered species, including the Lake Sturgeon.

Details

Distribution of the Lake Sturgeon in Iowa is confined to the Mississippi River, where it is reported very rarely in commercial fishing operations and by anglers. The Lake Sturgeon is considered endangered (571 IAC 77.2(1) (2015)) as it has steadily decreased in abundance since 1900. The main reason for its decline seems to be overharvest, but others include pollution and dam construction, which fragments the Lake Sturgeon’s habitat and stifles migration. 

The Lake Sturgeon is a bottom dweller living in the quiet-waters of large rivers and lakes. It prefers shallow shoals in lakes and the deepest parts of large rivers. In the Mississippi and Missouri Rivers, the Lake Sturgeon seeks firm, silt-free bottoms of sand, gravel and rock. It is known to migrate more than 100 miles upstream to spawn while lake populations are non-migratory. Populations of Lake Sturgeon are declining in most states from dam construction, commercial exploitation, pollution or “deliberate elimination of a large nuisance fish by man”.

Lake Sturgeon spawn in late spring or early summer, usually in streams, but they have been seen in the shallow areas of lakes in locations where it is native to lentic waters. This fish is not native to Iowa lakes, and little is known of its spawning habits in our rivers. In Wisconsin, female Lake Sturgeon mature at 24-26 years of age, when about 55-inches long. The females spawn once every 4-6 years, the males mature at a smaller size and spawn every year or two. Each female produces as many as 700,000 eggs. The eggs hatch in 8 days at 55 degrees. The male and female grow at the same rate;  females are longer lived, 97 percent of the fish over 30 years old are female. It reaches a weight of several hundred pounds in some waters, but the largest reported from Iowa is about 100-pounds.

There is no open season for Lake Sturgeon in Iowa, precluding any commercial or sport fishing value. It is viewed as critically imperiled according to the Iowa Wildlife Action Plan, and is on Iowa's endangered, threatened, or special concern species list (571 IAC 77.2(2) (2015)).

Recent small stream sampling has not found any individual Lake Sturgeon, which is unsurprising since they live only in large Iowa rivers.

Sources:

Harlan, J.R., E.B. Speaker, and J. Mayhew. 1987. Iowa fish and fishing. Iowa Conservation Commission, Des Moines, Iowa. 323pp.

Iowa Department of Natural Resources, Iowa Wildlife Action Plan

Loan-Wilsey, A. K., C. L. Pierce, K. L. Kane, P. D. Brown and R. L. McNeely. 2005. The Iowa Aquatic Gap Analysis Project Final Report. Iowa Cooperative Fish and Wildlife Research Unit, Iowa State University, Ames.

Illustration by Maynard Reece, from Iowa Fish and Fishing.