The lake sturgeon is Minnesota's biggest fish. It can weigh more than an adult human.

Identification

General description: The torpedo-shaped lake sturgeon lacks scales. It is covered instead with plates, called scutes. Its nose is flattened and slightly upturned, with four barbels underneath. Its mouth, which it can extend like a tube, is set back from the end of the snout. The top of its tail is longer than the bottom.

Size: Lake sturgeon generally range from 5 to 40 pounds and 20 to 55 inches long. But sturgeon may grow to more than 300 pounds and 8 feet long. The Minnesota record lake sturgeon, caught in the Kettle River, weighed 94 pounds, 4 ounces.

Color: Sturgeon are green-yellow to blue-gray to black. The young are reddish-brown. Like most fish, their color changes as they get older and larger.

Reproduction

Female lake sturgeon don't spawn until they're about 20 to 25 years old, and then only once every several years. Males and females come together to breed in April through June in moving water or lake shallows. The males gather around females, vibrating, leaping, and thrashing about as she releases her eggs--50,000 to a million or more. The eggs stick to bottom of the lake or stream and hatch in about a week.

Food

Sturgeon vacuum food off the bottom of the lake or river with their hoselike mouths. Their meals consist mainly of crayfish and other small animals like snails, clams, and small aquatic insects.

Predators

Predatory fish eat young sturgeon, but adults are too large for most predators. Humans eat sturgeon and also use their eggs for caviar.

Habitat and range

In Minnesota, sturgeon are found in large rivers and lakes, including the Red River of the North, Mississippi, and St. Croix.

Population and management

The sturgeon is listed as a species of special concern in Minnesota. Its population was very low through most of the 20th century due to overfishing, habitat loss, and pollution. However, in the 1970s, with pollution control and harvesting regulations, sturgeon populations began to rebound. Fishing for sturgeon is not allowed except on a few rivers bordering Canada and Wisconsin.

Fun facts

Sturgeon grow slowly, but they also live a long time. One was reported to have lived to be more than 150 years old.