Pallid sturgeon (Scaphirhynchus albusare) are listed as Endangered (ESA). Their numbers have not shown any signs of recovery since listing in 1990. Pallids are endemic to the waters of the lower Mississippi River basins, and the Missouri River basins. Dams and loss of spawning habitat have played a significant role in their decreasing populations and inability to recover.
Historically, all four of the ancestral river species, the pallid sturgeon, shovelnose sturgeon, Alabama sturgeon, and lake sturgeon were harvested commercially in the States along the Missouri and Mississippi Rivers. It is believed the pallids and lake sturgeons were targeted for their roe while the smaller shovelnose and Alabama sturgeons were treated as bycatch.
Young pallids look very similar to shovelnose sturgeons, so mortality does occur from both commercial and recreational fishing activities in areas where the two species co-exist. As a result, overharvest poses an additional threat to the future of pallid sturgeons, making it extremely important for anglers and commercial fishermen to learn the principal differences between the two species.
Pallids grow much larger than shovelnose sturgeons, so size could be a distinguishable difference. The largest pallid sturgeon ever recorded was listed as weighing 85 pounds, and measured 5 feet 6 inches long, which is considerably larger than the largest recorded shovelnose. However, size can't always be a determining factor because of age variations, and environmental conditions that effect growth.
As the name implies, pallids are usually a light, pale brown color on the dorsal surface, and their underside is white. Shovelnose sturgeons are usually a darker brown color, however, as with size, coloration cannot be consistently relied upon.
The best way to differentiate between the two species is to look at the barbels. The inner barbels of the pallid sturgeon are much shorter than the outer barbels, and are attached about one-third of the way between the mouth and the tip of the snout.
The inner barbels of the shovelnose sturgeon pictured below are about the same length as the outer barbels, and are positioned halfway between the mouth and the tip of the snout.
The pallid sturgeon is a rare and elusive species, and remains one of the least known of the large, freshwater fishes. It was listed as an endangered species in 1990 in accordance with the provisions of the Endangered Species Act. Pallid sturgeons are well-adapted as bottom dwellers. They are potamodromous, and prefer the swift waters of large, turbid, free-flowing rivers. Their diet consists primarily of small fishes and crustaceans, such as flathead chubs, minnows, and crayfishes.
Pallid sturgeon were not described as a species until 1905, so little information is available concerning early distribution in North America. It is believed that pallid sturgeons were once widespread in the lower reaches of the Platte, Kansas, and Yellowstone Rivers, in the Missouri River, and in the middle and lower reaches of the Mississippi River.
Available information suggests pallid sturgeons were always rare, but with channelization, and the development of dams and reservoirs, their numbers have declined even further. Today, all that remains are small, remnant populations scattered here and there in the Yellowstone, Missouri and Mississippi rivers. The largest populations appear to be in the upper Missouri River above Fort Peck Reservoir in Montana, in the Missouri and Yellowstone rivers above Garrison Reservoir in North Dakota and Montana, and in the lower Mississippi River in southern Louisiana.
Hybridization between pallids and the smaller shovelnose is yet another threat to the future of pallid sturgeons. Researchers attribrute hybridization to deteriorating environmental conditions. In some stretches of the Mississippi River below St. Louis, Missouri, hybrids were found more often than pallids. The two primary concerns over hybridization is genetic swamping, and competition over what little foraging, and spawning habitat still remains for pallid sturgeons.
The complete one-hour documentary, "Sturgeon: Ancient Survivors of the Deep", is available at our DVD Gallery.