Lake Sturgeon

Description

Also called rock sturgeon, this freshwater fish is the oldest and largest native species in the Great Lakes.

These huge fish can measure six and a half feet (two meters) long and weigh close to 200 pounds (90 kilograms). Instead of scales, the lake sturgeon has coarse skin.

Range

Despite their name, lake sturgeon are found in rivers as well as lakes. The fish's range spans North America from the Hudson Bay to Mississippi River. This fish was once an abundant species in the ecosystems of the Great Lakes, but overharvesting has decreased its numbers.

Diet

Lake sturgeon feed along lake bottoms on small invertebrates, such as crayfish, snails, claims, and leeches.

Life History

Lake sturgeon migrate to shores of freshwater lakes in early summer for spawning. Female lay anywhere from two to three million eggs per season. Sturgeon may not begin spawning until they are 15 to 25 years old, and only spawn every four years on average.

These fish can live for decades. Males may reach 55 years, while females have been recorded living for 150 years.

Conservation

Lake sturgeon were once abundant throughout the Great Lakes system until overfishing in the 1800s and early 1900s decimated their populations. In 1994, lake sturgeon were designated as a threatened species in Michigan, marking the beginning of recovery programs to attempt to revive the population. Lake sturgeon, however, have reproductive traits that make rehabilitation of the species difficult, including delayed maturation and periodic interrupted spawning cycles. To make matters worse, this species is now faced with further negative impacts by pollution, the destruction of main food sources, and invasive aquatic species—impacts that are likely to be exacerbated by climate change.

Climate change is expected to further threaten this fish as rising water temperatures greatly decrease the quality and quantity of spawning and nursery habitats. Climatic variability could also disrupt the timing of sturgeon reproduction and length of optimal fish growth periods as environmental cues shift and warming waters affect stream ecological processes and ecosystem health. Lake sturgeon are also vulnerable to changes in water levels and increased runoff associated with extreme weather and climate change.

Anglers can help lake sturgeon by releasing the fish if caught. In addition, by cleaning recreational equipment and using clean ballast technology, people can help prevent the spread of invasive species and diseases that threaten these fish.

Fun Fact

Sturgeon can be seen porpoising—or jumping in the air—after entering a spawning stream.

Sources

Michigan Department of Natural Resources

National Geographic

U.S. Fish & Wildlife Service