Shovelnose Sturgeon - Life Cycle

Shovelnose sturgeon spawning in Wisconsin occurs during May and June. In the Red Cedar-Chippewa rivers during 1972, shovelnose sturgeon spawned the last week in May through the first week in June at water temperatures of 19.5-21.1 C (67-70° F). In the St. Croix River (Wisconsin-Minnesota boundary water) large numbers migrate up from Lake St. Croix and gather under the dam at St. Croix Falls, where they spawn on the rocks in the swift water below the dam.

It is generally accepted that shovelnose sturgeon migrate upstream for spawning, and migrations into smaller streams have been reported. Spawning migrations in the Mississippi River can be variable: best when the river is low in spring and poor when it is high. It is believed that the species seeks an optimal volume of flow, departing from the largest rivers to enter tributaries for spawning in years when streams are high.

In shovelnose sturgeon from the Chippewa River, the adhesive eggs appear to fall into three major groups: (1) yellow and/or white, (2) white and black, and (3) black (the mature eggs in the enlarged ovaries). Since at least three stages of egg development occurred essentially without relation to the size of the female, it is apparent that females do not spawn every year; but the spawning chronology is not readily evident. Females generally produce 10,000 - 50,000 eggs.

Little is known about early development of the shovelnose sturgeon. Young-of-year as small as 43 mm (1.7 in) FL were taken in the upper Mississippi River during late June by trawling. All successful trawl tows were rather far from shore; they were usually located in main channel or main channel border habitat. The most successful hauls were those associated with submerged rock wing dams. Young taken on July 11th from the Mississippi River at Fairport measured 71 mm SL.

On the Mississippi River female shovelnose sturgeon mature at age VII, while most males spawn at age V. Only one age-V female was found with developing eggs. An investigation of the sexual maturity of 374 males and 503 females from fish markets at Lansing and Muscatine, Iowa, determined that, of fish under 635 mm (25 in) FL, 25% of the males and 7% of the females were mature; over 635 mm (25 in) FL, 62% and 58%, respectively.

Mississippi River shovelnose sturgeon length at age...

For more information, please contact:

Karl Scheidegger, Fisheries Biologist
(608) 267-7498