Lake Sturgeon (Acipenser fulvescens)

Lake Sturgeon (Acipenser fulvescens)

A member of the Acipenseridae family of sturgeon, the lake sturgeon was an important part of aboriginal culture in North America. In some cultures, spring ceremonial festivities were held at lake sturgeon spawning sites. Around 1855, a market for caviar was developed, which in turn spurred a market for smoked fish around 1860.

Caviar and smoked meat from lake sturgeon were also important exports to Europe. By 1910, however, lake sturgeon fisheries had been overexploited through the Great Lakes region. Overfishing, the building of dams, habitation alteration, and pollution have since impeded the lake sturgeon’s recovery in most areas.

For waterways with declining or extirpated populations (that is, Lake Winnipeg, Lake Erie, and Lake Ontario), lake sturgeon are being successfully raised in hatcheries for stocking. Current research shows, however, that brood stock should be taken from the water body where hatchery-raised fish will be released; yet brood stock is also rare in areas where stocking may be helpful.


These populations will require a great deal of time and improved conditions before they can recover fully. Lake sturgeon have responded positively to changes in dam discharges that facilitate or imitate river conditions. Signs of this include increased spawning activity.

Identification

The somewhat torpedo-shaped lake sturgeon has a spiracle, and the upper lobe of the caudal fin is longer than the lower lobe. The anal fin origin is behind the dorsal fin origin. The fish exhibits an olive-brown coloring, and the scutes (bony scalelike plates) on the back and along the side are the same color as the skin. There are 9 to 17 scutes on the back, 29 to 42 scutes along the sides, and 25 to 30 anal rays. There are 4 barbels on the underside of the mouth.

Size/Age

Lake sturgeon may reach 9 feet in length and have been reported to weigh between 200 and 300 pounds, although fish of 100 pounds are extremely large today, and most are in the 40-pound range and about 4 feet long. The life expectancy of lake sturgeon varies, according to different reports, but at one time it was believed to be 80 to 100 years or more. A specimen caught in 1952 was reputed to have been 152 years old, but older specimens of the modern era have ranged only to 38 years old.

Life history/Behavior

Males mature around 14 to 16 years of age and females near 24 to 26 years of age. As adults, lake sturgeon migrate as far as 125 miles to spawn. They sometimes leap out of the water during spawning and fall with a loud splash.

Spawning sturgeon migrate in the fall and then overwinter at the spawning sites. Spawning peaks in April at temperatures of 48° to 58°F; a secondary spawning probably follows in May. They spawn on gravel bars or below dams or other obstructions, in swift, shallow water, sometimes in a spectacular commotion of thrashing, rolling, and leaping.

Six to eight males spawn with each female. They broadcast their eggs and sperm over large substrate such as boulders, and the eggs adhere to the substrate. Eggs hatch at 8 to 14 days of fertilization and drift downstream to more placid waters during the night. As is typical for most sturgeon, early growth is rapid. Mature females spawn only once every several years.

Food and feeding habits

Lake sturgeon feed in freshwater, typically on the bottom. In Lake Winnebago, young lake sturgeon feed primarily on midge larvae, larvae of some moths with aquatic life phases, and water fleas. Mayfly nymphs and mollusks are also important components of the lake sturgeon’s diet. The amount of fish consumed by lake sturgeon varies by location, ranging from little or none to 25 percent of the diet. In some areas, small fish are a preferred bait.

Other Names

sturgeon, red sturgeon, rock sturgeon; Cree: nameo, nemeo.

Distribution

Lake sturgeon occur in the St. Lawrence waterway and the Great Lakes. They are found in the Hudson Bay and the Mississippi River basins from Quebec to Alberta and southward to Alabama and Louisiana, including Lake Winnipeg, Manitoba, and its tributaries.

They are rare in the Ohio and the middle Mississippi River basins. Lake sturgeon numbers are a fraction of what they once were throughout this range, and the species does not occur in some parts of its former range; some stocking efforts have been undertaken.

Habitat

Lake sturgeon are primarily freshwater fish, occurring in large lakes and rivers, usually 15 to 30 feet deep. They are found over mud, sand, or gravel bottoms but may (rarely) occur in brackish water.
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