NEBRASKA POLLINATOR WEEK
June 20- 26, 2022
photo credit NEBRASKAland Magazine/NGPC
photo credit U.S. Fish and Wildlife Service, Fish and Aquatic Conservation
photo credit Robert Elliott, U.S. Fish and Wildlife Service (Midwest)
photo credit U.S. Fish and Wildlife Service, Midwest
photo credit U.S. Fish and Wildlife Service, Midwest
FEDERAL: not listed
Sturgeon, as a species, have been around for more than 150 million years and existed during the Jurassic Era, when dinosaurs roamed the earth. These fish are considered living fossils, having changed little from their ancestors.
Sturgeon have long, torpedo-shaped bodies, long, bony snouts and are armored with five rows of sharp, bony plates called scutes. They also have four barbels (whiskers) that dangle from the snout in front of the mouth.
The barbels help them locate food and find their way. Lake sturgeons have developed small eyes and larger outer barbels, apparently adaptations for feeding in turbid or muddy water. Lake sturgeon have short, rounded snouts compared to those of our other sturgeon species. Also, the four barbels on a lake sturgeon are smooth and not fringed or serrated. Adult lake sturgeon are solid dark brown or slate-colored with a white belly.
The lake sturgeon is a very long-lived fish and mature slowly. Lake sturgeon can reach eight feet in length and a weight of 300 pounds. One long-lived lake sturgeon lived to 150 years. In the Missouri River along the Nebraska border, they rarely exceed 10 pounds.
Lake sturgeon can be found in the Mississippi and St. Lawrence River drainages north into Canada but has rarely been collected from the lower Platte River and is uncommon in the Missouri River bordering Nebraska. As their name implies, lake sturgeon inhabit large lake regions, such as Hudson Bay and the Great Lakes, in addition to river systems. Lake sturgeon may be capable of extremely long migrations but are prevented by natural barriers and human alteration of river and lake systems.
Sturgeon tend to select main channel habitats in the Mississippi River stretch and main channel areas with islands or sand bars in the upper Missouri River system, including the Platte. Their preferred habitat has a diversity of depths and velocities formed by braided channels, sand bars, islands, sand flats and gravel bars.
Lake sturgeon are opportunistic feeders eating both fish and insects when available. Juveniles feed primarily on aquatic insect larvae including mayfly and midge larvae. Adults feed on both aquatic insects and fish with fish becoming more prevalent as the sturgeon grows larger.
Lake sturgeon do not reproduce until they are quite mature, males typically at 14-16 years, while females mature at 24-26 years. In addition, males spawn annually or biennially while females may spawn every 3-6 years. Lake sturgeon will move great distances to spawn, which occurs from late April to late June. Adhesive eggs are scattered and attach to gravel, rocks and snags.
Lake sturgeon are listed as either threatened or endangered by 19 of the 20 states within its original range in the United States. In Nebraska it is listed as a threatened species.
Today, much of the Missouri River, upstream of Gavins Point Dam, is “lake-like,” with no moving water. An overabundance of non-native fish, combined with changes in river flow and water quality have all played a role in the decline of pallid and lake sturgeon populations. These changes also directly affect the resource (food) base these fish depend on for all life stages. Adding to the problem of habitat decline, is their poor reproductive success and low, or no, recruitment of wild juveniles to the adult population. The fish that are reproductively mature today were all spawned before construction of the dam systems, and are thought to be nearing the end of their lifespan. It is speculated that a single sturgeon at spawning time is already having a hard time finding a mate.
MANAGEMENT & OUTLOOK
The U.S. Fish and Wildlife Service designated four “Recovery Priority Management Areas” within the length of the Missouri River. These areas include the mouth of the Platte River.
Fish and wildlife agencies are working with the U.S. Army Corps of Engineers and many other state and federal organizations to better regulate flows on the Missouri River for the benefit of several threatened and endangered species.
A Platte River study evaluating pollution levels in sturgeon stated that “Pallid sturgeon may be especially at risk to contaminants in the lower Platte River that bio-accumulate and cause reproductive impairment because they eat more fish and are a long-lived species.”
Today, evidence indicates that hatchery raised pallid sturgeon (not lake sturgeon) are surviving, growing, reaching reproductive maturity and now spawning. However, habitat restoration will be essential to realize the recovery of this species and other sturgeon species, as well.
Dryer, M.P., and Sandvol, A.J., 1993, Recovery plan for the pallid sturgeon (Scaphirhynchus albus): U.S. Fish and Wildlife Service, 55 p.
DeLonay, A.J., et al. 2009, Ecological requirements for pallid sturgeon reproduction and recruitment in the Lower Missouri River: A research synthesis 2005–08: U.S. Geological Survey Scientific Investigations Report 2009–5201, 59 p.
Schwarz, M. S., et al. 2006. A health risk evaluation for pallid sturgeon (Scaphirhynchus albus) in the lower Platte River using shovelnose sturgeon (Scaphirhynchus platorynchus) as a surrogate. U.S. Fish and Wildlife Service, Division of Environmental Quality, Region 6, Final Report, Grand Island, NE.
Peters, E. J., and J. E. Parham. 2008. Ecology and management of sturgeon in the lower Platte River, Nebraska. Nebraska Game and Parks Commission, Nebraska Technical Series No. 18, Lincoln, Nebraska.
Gordon, R. P., T. L Wirth, C. W. Threinen, S. Hickey. 1974. The lake sturgeon: its life history, ecology and management. Wisconsin Dept of Natural Resources, Madison, Wis. : Dept. of Natural Resources. no. 4-3600(74).
Copyright 2017. Published by the Nebraska Game & Parks Commission with funds from the Nebraska Environmental Trust.
NOTE: New data of the occurrence and distribution of this species are being collected constantly and some of the information in the pamphlet may be outdated. The information in this pamphlet should be used for a general understanding of the species and not as the sole source of range location for any report, project, regional or local planning, or for environmental impact assessments. For current information on this species, please contact the Nebraska Game & Parks Commission, Wildlife Division.