Photograph by Joel Sartore, National Geographic Photo Ark
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Once abundant in North America's Great Lakes and upper Mississippi River, lake sturgeon populations have plummeted. This juvenile lake sturgeon was photographed at the Genoa National Fish Hatchery in Wisconsin.

Photograph by Joel Sartore, National Geographic Photo Ark

Lake sturgeon


The lake sturgeon, with its sleek shape and rows of bony plates on its sides, looks a bit like an armored torpedo. These freshwater giants have greenish-grey coloring and elongated, spade-like snouts with two pairs of whisker-like organs that dangle near their mouths. These organs, called barbels, help the fish to locate bottom-dwelling prey, such as snails, mussels, clams, crayfish, insect larvae, and fish eggs.

Also known as the rock sturgeon, the lake sturgeon is one of 27 species of sturgeon, a family of bony fish that found around the world that first appears in the fossil record more than 200 million years ago. The lake sturgeon is the oldest and largest native fish species in North America’s Great Lakes.

Lake sturgeons can grow huge. It’s not unusual to find one six feet long and 200 pounds. In 2012, a female sturgeon caught on Lake Winnebago in Wisconsin measured more than seven feet three inches long and weighed 240 pounds.

These freshwater behemoths are also extremely long-lived. While males may live some 55 years, females can reach more than 150. They are slow to mature and don’t begin spawning until they are 15 to 25 years old. Even then, they only spawn every four years on average. Females can lay anywhere from two to three million eggs per season.

Drastic decline

Despite the name, lake sturgeons are also found in rivers and once roamed watersheds from the Mississippi River in the west to Hudson Bay in the east. About two centuries ago, lake sturgeons were so abundant (and large) they made up an estimated 90 percent of the biomass in the Great Lakes.

Intense fishing going back to the early 1800s, however, took a heavy toll on lake sturgeon numbers. The fish were first killed as a nuisance, because they damaged fishing gear. Later, they were targeted for their meat and eggs, which when salt-cured become caviar. The 20th century saw drastic drops in sturgeon catches and the closure of fisheries, as the fish only remained in the Great Lakes, and only in small numbers.

In addition to overfishing, the highly migratory lake sturgeons have also suffered from pollution and the construction of dams and other flood control measures. Returning each spring from lake habitats to spawn in the streams and rivers in which they were born, sturgeons have found tributaries blocked and spawning shoals destroyed by silt from agriculture and logging.

Recovery

In recent years, the species has made somewhat of a comeback. Tighter fishing regulations in the Great Lakes has helped, with annual harvest limits strictly enforced. Wisconsin’s Lake Winnebago river system, in particular, has become a brood source for lake sturgeon elsewhere: Eggs are taken from the river and sent to hatcheries, which then release the juvenile fish elsewhere to bolster populations.

With the population trend pointing up, the lake sturgeon could be considered a rare conservation success story.