Sturgeon, some of the most ancient fish on Earth, are found in the Mississippi River system. These long-lived species belong to a group whose lineage stretches back over 100 million years, giving them a distinct, armor-plated appearance. The Mississippi River and its vast network of tributaries provide habitat for three distinct species of these prehistoric dwellers.
Sturgeon Species Found in the River System
Three species of sturgeon are native to the Mississippi River basin, each possessing unique physical characteristics. The Lake Sturgeon (Acipenser fulvescens) is the largest, capable of reaching lengths over six feet and weights approaching 300 pounds. It is identified by its conical, rounded snout and smooth, unfringed barbels located near the mouth.
The Shovelnose Sturgeon (Scaphirhynchus platorynchus) is the most common and smallest species, rarely exceeding 30 inches in length or five pounds. This fish has a flattened, spade-like snout and a long, slender filament extending from the upper lobe of its tail fin. All four of its sensory barbels are roughly equal in length, forming a straight line across the underside of the snout.
The Pallid Sturgeon (Scaphirhynchus albus) closely resembles the shovelnose but is significantly larger, often growing to between 30 and 72 inches. It is distinguished by a longer, more pointed snout and a paler, grayish-white color. Unlike the shovelnose, the inner two barbels on a pallid sturgeon are noticeably shorter than the outer pair, forming a distinct crescent shape.
Distribution Across the Mississippi Watershed
The distribution of sturgeon species varies across the Mississippi River watershed. Lake Sturgeon populations are primarily associated with the Upper Mississippi River, particularly in the river pools and tailwaters immediately below navigation dams. Although their numbers are lower than historical levels, restoration efforts have helped re-establish them in this northern reach.
The Shovelnose Sturgeon is widely distributed throughout the entire Mississippi River and its major tributaries, including the Missouri and Ohio Rivers. This species tolerates a broader range of habitat conditions compared to its relatives. Its presence extends from the upper reaches down to the river’s delta.
The Pallid Sturgeon has the most restricted distribution, principally confined to the Missouri River and the Lower Mississippi River downstream of the Illinois River. Historically, this species was rare in the Upper Mississippi, preferring the turbid, main channel habitats of the lower, free-flowing sections. The Missouri River serves as a significant, though fragmented, portion of the pallid sturgeon’s remaining range.
Conservation Status and Protection
The conservation status of the three sturgeon species in the Mississippi system reflects the profound impact of human activity on the rivers. The Pallid Sturgeon was federally listed as an Endangered species under the Endangered Species Act (ESA) in 1990 due to sharp population declines. Its decline was driven by habitat loss, particularly the construction of dams and channelization for navigation, which eliminated the shallow, braided channels necessary for spawning.
Recovery efforts for the pallid sturgeon focus on captive breeding and stocking programs, releasing hatchery-raised fish to augment the wild population. Habitat restoration is also a priority, involving modifications like dike notching to reintroduce slow-moving side channels and promote natural flow dynamics. Researchers monitor the threat of hybridization with the more common shovelnose sturgeon, which can dilute the pallid sturgeon’s distinct genetics.
The Lake Sturgeon is not federally listed, but its populations are protected at the state level, often designated as threatened or a species of special concern. Commercial harvest was closed decades ago following population crashes caused by overfishing and barriers to spawning migration. Restoration programs, including reintroduction and efforts to ensure fish passage around dams, have led to a slow rebound in some areas of the Upper Mississippi.
The Shovelnose Sturgeon, while abundant, is listed as threatened due to its “similarity of appearance” to the endangered Pallid Sturgeon. This classification prevents the accidental or intentional harvest of the endangered pallid sturgeon by anglers or commercial fishers. Consequently, harvest of all sturgeon species is prohibited in many river sections to ensure the survival of the rarest species.